diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,201 +1,201 @@
-                                 Apache License
-                           Version 2.0, January 2004
-                        http://www.apache.org/licenses/
-
-   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
-
-   1. Definitions.
-
-      "License" shall mean the terms and conditions for use, reproduction,
-      and distribution as defined by Sections 1 through 9 of this document.
-
-      "Licensor" shall mean the copyright owner or entity authorized by
-      the copyright owner that is granting the License.
-
-      "Legal Entity" shall mean the union of the acting entity and all
-      other entities that control, are controlled by, or are under common
-      control with that entity. For the purposes of this definition,
-      "control" means (i) the power, direct or indirect, to cause the
-      direction or management of such entity, whether by contract or
-      otherwise, or (ii) ownership of fifty percent (50%) or more of the
-      outstanding shares, or (iii) beneficial ownership of such entity.
-
-      "You" (or "Your") shall mean an individual or Legal Entity
-      exercising permissions granted by this License.
-
-      "Source" form shall mean the preferred form for making modifications,
-      including but not limited to software source code, documentation
-      source, and configuration files.
-
-      "Object" form shall mean any form resulting from mechanical
-      transformation or translation of a Source form, including but
-      not limited to compiled object code, generated documentation,
-      and conversions to other media types.
-
-      "Work" shall mean the work of authorship, whether in Source or
-      Object form, made available under the License, as indicated by a
-      copyright notice that is included in or attached to the work
-      (an example is provided in the Appendix below).
-
-      "Derivative Works" shall mean any work, whether in Source or Object
-      form, that is based on (or derived from) the Work and for which the
-      editorial revisions, annotations, elaborations, or other modifications
-      represent, as a whole, an original work of authorship. For the purposes
-      of this License, Derivative Works shall not include works that remain
-      separable from, or merely link (or bind by name) to the interfaces of,
-      the Work and Derivative Works thereof.
-
-      "Contribution" shall mean any work of authorship, including
-      the original version of the Work and any modifications or additions
-      to that Work or Derivative Works thereof, that is intentionally
-      submitted to Licensor for inclusion in the Work by the copyright owner
-      or by an individual or Legal Entity authorized to submit on behalf of
-      the copyright owner. For the purposes of this definition, "submitted"
-      means any form of electronic, verbal, or written communication sent
-      to the Licensor or its representatives, including but not limited to
-      communication on electronic mailing lists, source code control systems,
-      and issue tracking systems that are managed by, or on behalf of, the
-      Licensor for the purpose of discussing and improving the Work, but
-      excluding communication that is conspicuously marked or otherwise
-      designated in writing by the copyright owner as "Not a Contribution."
-
-      "Contributor" shall mean Licensor and any individual or Legal Entity
-      on behalf of whom a Contribution has been received by Licensor and
-      subsequently incorporated within the Work.
-
-   2. Grant of Copyright License. Subject to the terms and conditions of
-      this License, each Contributor hereby grants to You a perpetual,
-      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
-      copyright license to reproduce, prepare Derivative Works of,
-      publicly display, publicly perform, sublicense, and distribute the
-      Work and such Derivative Works in Source or Object form.
-
-   3. Grant of Patent License. Subject to the terms and conditions of
-      this License, each Contributor hereby grants to You a perpetual,
-      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
-      (except as stated in this section) patent license to make, have made,
-      use, offer to sell, sell, import, and otherwise transfer the Work,
-      where such license applies only to those patent claims licensable
-      by such Contributor that are necessarily infringed by their
-      Contribution(s) alone or by combination of their Contribution(s)
-      with the Work to which such Contribution(s) was submitted. If You
-      institute patent litigation against any entity (including a
-      cross-claim or counterclaim in a lawsuit) alleging that the Work
-      or a Contribution incorporated within the Work constitutes direct
-      or contributory patent infringement, then any patent licenses
-      granted to You under this License for that Work shall terminate
-      as of the date such litigation is filed.
-
-   4. Redistribution. You may reproduce and distribute copies of the
-      Work or Derivative Works thereof in any medium, with or without
-      modifications, and in Source or Object form, provided that You
-      meet the following conditions:
-
-      (a) You must give any other recipients of the Work or
-          Derivative Works a copy of this License; and
-
-      (b) You must cause any modified files to carry prominent notices
-          stating that You changed the files; and
-
-      (c) You must retain, in the Source form of any Derivative Works
-          that You distribute, all copyright, patent, trademark, and
-          attribution notices from the Source form of the Work,
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-          the Derivative Works; and
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-      (d) If the Work includes a "NOTICE" text file as part of its
-          distribution, then any Derivative Works that You distribute must
-          include a readable copy of the attribution notices contained
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-          of the following places: within a NOTICE text file distributed
-          as part of the Derivative Works; within the Source form or
-          documentation, if provided along with the Derivative Works; or,
-          within a display generated by the Derivative Works, if and
-          wherever such third-party notices normally appear. The contents
-          of the NOTICE file are for informational purposes only and
-          do not modify the License. You may add Your own attribution
-          notices within Derivative Works that You distribute, alongside
-          or as an addendum to the NOTICE text from the Work, provided
-          that such additional attribution notices cannot be construed
-          as modifying the License.
-
-      You may add Your own copyright statement to Your modifications and
-      may provide additional or different license terms and conditions
-      for use, reproduction, or distribution of Your modifications, or
-      for any such Derivative Works as a whole, provided Your use,
-      reproduction, and distribution of the Work otherwise complies with
-      the conditions stated in this License.
-
-   5. Submission of Contributions. Unless You explicitly state otherwise,
-      any Contribution intentionally submitted for inclusion in the Work
-      by You to the Licensor shall be under the terms and conditions of
-      this License, without any additional terms or conditions.
-      Notwithstanding the above, nothing herein shall supersede or modify
-      the terms of any separate license agreement you may have executed
-      with Licensor regarding such Contributions.
-
-   6. Trademarks. This License does not grant permission to use the trade
-      names, trademarks, service marks, or product names of the Licensor,
-      except as required for reasonable and customary use in describing the
-      origin of the Work and reproducing the content of the NOTICE file.
-
-   7. Disclaimer of Warranty. Unless required by applicable law or
-      agreed to in writing, Licensor provides the Work (and each
-      Contributor provides its Contributions) on an "AS IS" BASIS,
-      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
-      implied, including, without limitation, any warranties or conditions
-      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
-      PARTICULAR PURPOSE. You are solely responsible for determining the
-      appropriateness of using or redistributing the Work and assume any
-      risks associated with Your exercise of permissions under this License.
-
-   8. Limitation of Liability. In no event and under no legal theory,
-      whether in tort (including negligence), contract, or otherwise,
-      unless required by applicable law (such as deliberate and grossly
-      negligent acts) or agreed to in writing, shall any Contributor be
-      liable to You for damages, including any direct, indirect, special,
-      incidental, or consequential damages of any character arising as a
-      result of this License or out of the use or inability to use the
-      Work (including but not limited to damages for loss of goodwill,
-      work stoppage, computer failure or malfunction, or any and all
-      other commercial damages or losses), even if such Contributor
-      has been advised of the possibility of such damages.
-
-   9. Accepting Warranty or Additional Liability. While redistributing
-      the Work or Derivative Works thereof, You may choose to offer,
-      and charge a fee for, acceptance of support, warranty, indemnity,
-      or other liability obligations and/or rights consistent with this
-      License. However, in accepting such obligations, You may act only
-      on Your own behalf and on Your sole responsibility, not on behalf
-      of any other Contributor, and only if You agree to indemnify,
-      defend, and hold each Contributor harmless for any liability
-      incurred by, or claims asserted against, such Contributor by reason
-      of your accepting any such warranty or additional liability.
-
-   END OF TERMS AND CONDITIONS
-
-   APPENDIX: How to apply the Apache License to your work.
-
-      To apply the Apache License to your work, attach the following
-      boilerplate notice, with the fields enclosed by brackets "[]"
-      replaced with your own identifying information. (Don't include
-      the brackets!)  The text should be enclosed in the appropriate
-      comment syntax for the file format. We also recommend that a
-      file or class name and description of purpose be included on the
-      same "printed page" as the copyright notice for easier
-      identification within third-party archives.
-
-   Copyright [yyyy] [name of copyright owner]
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/hls-plugin-api.cabal b/hls-plugin-api.cabal
--- a/hls-plugin-api.cabal
+++ b/hls-plugin-api.cabal
@@ -1,67 +1,74 @@
-cabal-version: 2.2
-name:          hls-plugin-api
-version:       1.0.0.0
-synopsis:      Haskell Language Server API for plugin communication
-description:
-  Please see the README on GitHub at <https://github.com/haskell/haskell-language-server#readme>
-homepage:      https://github.com/haskell/haskell-language-server/hls-plugin-api
-bug-reports:   https://github.com/haskell/haskell-language-server/issues
-license:       Apache-2.0
-license-file:  LICENSE
-author:        The Haskell IDE Team
-maintainer:    alan.zimm@gmail.com
-copyright:     The Haskell IDE Team
-category:      Development
-build-type:    Simple
-
-flag pedantic
-  description: Enable -Werror
-  default:     False
-  manual:      True
-
-source-repository head
-  type:     git
-  location: https://github.com/haskell/haskell-language-server
-
-library
-  exposed-modules:
-    Ide.Logger
-    Ide.Plugin.Config
-    Ide.PluginUtils
-    Ide.Types
-
-  hs-source-dirs:   src
-  build-depends:
-    , aeson
-    , base                  >=4.12    && <5
-    , containers
-    , data-default
-    , Diff
-    , lsp                   ^>=1.1.0
-    , hashable
-    , hslogger
-    , lens
-    , process
-    , regex-tdfa            >=1.3.1.0
-    , shake                 >=0.17.5
-    , text
-    , unordered-containers
-    , dependent-map
-    , dependent-sum
-    , dlist
-    , opentelemetry
-
-  if os(windows)
-      build-depends:
-        Win32
-  else
-      build-depends:
-        unix
-
-  ghc-options:      -Wall -Wredundant-constraints -Wno-name-shadowing -Wno-unticked-promoted-constructors
-
-  if flag(pedantic)
-    ghc-options: -Werror
-
-  default-language: Haskell2010
-  default-extensions: DataKinds, KindSignatures, TypeOperators
+cabal-version: 2.4
+name:          hls-plugin-api
+version:       1.1.0.0
+synopsis:      Haskell Language Server API for plugin communication
+description:
+  Please see the README on GitHub at <https://github.com/haskell/haskell-language-server#readme>
+
+homepage:      https://github.com/haskell/haskell-language-server#readme
+bug-reports:   https://github.com/haskell/haskell-language-server/issues
+license:       Apache-2.0
+license-file:  LICENSE
+author:        The Haskell IDE Team
+maintainer:    alan.zimm@gmail.com
+copyright:     The Haskell IDE Team
+category:      Development
+build-type:    Simple
+
+flag pedantic
+  description: Enable -Werror
+  default:     False
+  manual:      True
+
+source-repository head
+  type:     git
+  location: https://github.com/haskell/haskell-language-server
+
+library
+  exposed-modules:
+    Ide.Logger
+    Ide.Plugin.Config
+    Ide.Plugin.ConfigUtils
+    Ide.Plugin.Properties
+    Ide.PluginUtils
+    Ide.Types
+
+  hs-source-dirs:     src
+  build-depends:
+    , aeson
+    , base                  >=4.12    && <5
+    , containers
+    , data-default
+    , dependent-map
+    , dependent-sum
+    , Diff                  ^>=0.4.0
+    , dlist
+    , hashable
+    , hslogger
+    , lens
+    , lsp                   ^>=1.2
+    , opentelemetry
+    , process
+    , regex-tdfa            >=1.3.1.0
+    , shake                 >=0.17.5
+    , text
+    , unordered-containers
+
+  if os(windows)
+    build-depends: Win32
+
+  else
+    build-depends: unix
+
+  ghc-options:
+    -Wall -Wredundant-constraints -Wno-name-shadowing
+    -Wno-unticked-promoted-constructors
+
+  if flag(pedantic)
+    ghc-options: -Werror
+
+  default-language:   Haskell2010
+  default-extensions:
+    DataKinds
+    KindSignatures
+    TypeOperators
diff --git a/src/Ide/Logger.hs b/src/Ide/Logger.hs
--- a/src/Ide/Logger.hs
+++ b/src/Ide/Logger.hs
@@ -1,29 +1,29 @@
-{- | Provides an implementation of the ghcide @Logger@ which uses
-   @System.Log.Logger@ under the hood.
--}
-module Ide.Logger
-  (
-    logm
-  , debugm
-  , warningm
-  , errorm
-  ) where
-
-import           Control.Monad.IO.Class
-import           System.Log.Logger
-
--- ---------------------------------------------------------------------
-
-logm :: MonadIO m => String -> m ()
-logm s = liftIO $ infoM "hls" s
-
-debugm :: MonadIO m => String -> m ()
-debugm s = liftIO $ debugM "hls" s
-
-warningm :: MonadIO m => String -> m ()
-warningm s = liftIO $ warningM "hls" s
-
-errorm :: MonadIO m => String -> m ()
-errorm s = liftIO $ errorM "hls" s
-
--- ---------------------------------------------------------------------
+{- | Provides an implementation of the ghcide @Logger@ which uses
+   @System.Log.Logger@ under the hood.
+-}
+module Ide.Logger
+  (
+    logm
+  , debugm
+  , warningm
+  , errorm
+  ) where
+
+import           Control.Monad.IO.Class
+import           System.Log.Logger
+
+-- ---------------------------------------------------------------------
+
+logm :: MonadIO m => String -> m ()
+logm s = liftIO $ infoM "hls" s
+
+debugm :: MonadIO m => String -> m ()
+debugm s = liftIO $ debugM "hls" s
+
+warningm :: MonadIO m => String -> m ()
+warningm s = liftIO $ warningM "hls" s
+
+errorm :: MonadIO m => String -> m ()
+errorm s = liftIO $ errorM "hls" s
+
+-- ---------------------------------------------------------------------
diff --git a/src/Ide/Plugin/Config.hs b/src/Ide/Plugin/Config.hs
--- a/src/Ide/Plugin/Config.hs
+++ b/src/Ide/Plugin/Config.hs
@@ -1,182 +1,174 @@
-{-# LANGUAGE RecordWildCards #-}
-{-# LANGUAGE DeriveAnyClass #-}
-{-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE DerivingStrategies #-}
-{-# LANGUAGE FlexibleInstances #-}
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE TypeFamilies #-}
-module Ide.Plugin.Config
-    ( getConfigFromNotification
-    , Config(..)
-    , parseConfig
-    , PluginConfig(..)
-    , CheckParents(..)
-    ) where
-
-import           Control.Applicative
-import qualified Data.Aeson                    as A
-import qualified Data.Aeson.Types              as A
-import           Data.Aeson              hiding ( Error )
-import           Data.Default
-import qualified Data.Text                     as T
-import qualified Data.Map as Map
-import GHC.Generics (Generic)
-
--- ---------------------------------------------------------------------
-
--- | Given a DidChangeConfigurationNotification message, this function returns the parsed
--- Config object if possible.
-getConfigFromNotification :: Config -> A.Value -> Either T.Text Config
-getConfigFromNotification defaultValue p =
-  case A.parse (parseConfig defaultValue) p of
-    A.Success c -> Right c
-    A.Error err -> Left $ T.pack err
-
--- ---------------------------------------------------------------------
-data CheckParents
-    -- Note that ordering of constructors is meaningful and must be monotonically
-    -- increasing in the scenarios where parents are checked
-    = NeverCheck
-    | CheckOnClose
-    | CheckOnSaveAndClose
-    | AlwaysCheck
-  deriving stock (Eq, Ord, Show, Generic)
-  deriving anyclass (FromJSON, ToJSON)
-
--- | We (initially anyway) mirror the hie configuration, so that existing
--- clients can simply switch executable and not have any nasty surprises.  There
--- will be surprises relating to config options being ignored, initially though.
-data Config =
-  Config
-    { checkParents                :: CheckParents
-    , checkProject                :: !Bool
-    , hlintOn                     :: !Bool
-    , diagnosticsOnChange         :: !Bool
-    , maxNumberOfProblems         :: !Int
-    , diagnosticsDebounceDuration :: !Int
-    , liquidOn                    :: !Bool
-    , completionSnippetsOn        :: !Bool
-    , formatOnImportOn            :: !Bool
-    , formattingProvider          :: !T.Text
-    , maxCompletions              :: !Int
-    , plugins                     :: !(Map.Map T.Text PluginConfig)
-    } deriving (Show,Eq)
-
-instance Default Config where
-  def = Config
-    { checkParents                = CheckOnSaveAndClose
-    , checkProject                = True
-    , hlintOn                     = True
-    , diagnosticsOnChange         = True
-    , maxNumberOfProblems         = 100
-    , diagnosticsDebounceDuration = 350000
-    , liquidOn                    = False
-    , completionSnippetsOn        = True
-    , formatOnImportOn            = True
-    -- , formattingProvider          = "brittany"
-    , formattingProvider          = "ormolu"
-    -- , formattingProvider          = "floskell"
-    -- , formattingProvider          = "stylish-haskell"
-    , maxCompletions              = 40
-    , plugins                     = Map.empty
-    }
-
--- TODO: Add API for plugins to expose their own LSP config options
-parseConfig :: Config -> Value -> A.Parser Config
-parseConfig defValue = A.withObject "Config" $ \v -> do
-    -- Officially, we use "haskell" as the section name but for
-    -- backwards compatibility we also accept "languageServerHaskell"
-    c <- v .: "haskell" <|> v .:? "languageServerHaskell"
-    case c of
-      Nothing -> return defValue
-      Just s -> flip (A.withObject "Config.settings") s $ \o -> Config
-        <$> (o .:? "checkParents" <|> v .:? "checkParents") .!= checkParents defValue
-        <*> (o .:? "checkProject" <|> v .:? "checkProject") .!= checkProject defValue
-        <*> o .:? "hlintOn"                                 .!= hlintOn defValue
-        <*> o .:? "diagnosticsOnChange"                     .!= diagnosticsOnChange defValue
-        <*> o .:? "maxNumberOfProblems"                     .!= maxNumberOfProblems defValue
-        <*> o .:? "diagnosticsDebounceDuration"             .!= diagnosticsDebounceDuration defValue
-        <*> o .:? "liquidOn"                                .!= liquidOn defValue
-        <*> o .:? "completionSnippetsOn"                    .!= completionSnippetsOn defValue
-        <*> o .:? "formatOnImportOn"                        .!= formatOnImportOn defValue
-        <*> o .:? "formattingProvider"                      .!= formattingProvider defValue
-        <*> o .:? "maxCompletions"                          .!= maxCompletions defValue
-        <*> o .:? "plugin"                                  .!= plugins defValue
-
-instance A.ToJSON Config where
-  toJSON Config{..} =
-      object [ "haskell" .= r ]
-    where
-      r = object [ "checkParents"                .= checkParents
-                 , "checkProject"                .= checkProject
-                 , "hlintOn"                     .= hlintOn
-                 , "diagnosticsOnChange"         .= diagnosticsOnChange
-                 , "maxNumberOfProblems"         .= maxNumberOfProblems
-                 , "diagnosticsDebounceDuration" .= diagnosticsDebounceDuration
-                 , "liquidOn"                    .= liquidOn
-                 , "completionSnippetsOn"        .= completionSnippetsOn
-                 , "formatOnImportOn"            .= formatOnImportOn
-                 , "formattingProvider"          .= formattingProvider
-                 , "maxCompletions"              .= maxCompletions
-                 , "plugin"                      .= plugins
-                 ]
-
--- ---------------------------------------------------------------------
-
--- | A PluginConfig is a generic configuration for a given HLS plugin.  It
--- provides a "big switch" to turn it on or off as a whole, as well as small
--- switches per feature, and a slot for custom config.
--- This provides a regular naming scheme for all plugin config.
-data PluginConfig =
-    PluginConfig
-      { plcGlobalOn      :: !Bool
-      , plcCodeActionsOn :: !Bool
-      , plcCodeLensOn    :: !Bool
-      , plcDiagnosticsOn :: !Bool
-      , plcHoverOn       :: !Bool
-      , plcSymbolsOn     :: !Bool
-      , plcCompletionOn  :: !Bool
-      , plcRenameOn      :: !Bool
-      , plcConfig        :: !A.Object
-      } deriving (Show,Eq)
-
-instance Default PluginConfig where
-  def = PluginConfig
-      { plcGlobalOn      = True
-      , plcCodeActionsOn = True
-      , plcCodeLensOn    = True
-      , plcDiagnosticsOn = True
-      , plcHoverOn       = True
-      , plcSymbolsOn     = True
-      , plcCompletionOn  = True
-      , plcRenameOn      = True
-      , plcConfig        = mempty
-      }
-
-instance A.ToJSON PluginConfig where
-    toJSON (PluginConfig g ca cl d h s c rn cfg) = r
-      where
-        r = object [ "globalOn"      .= g
-                   , "codeActionsOn" .= ca
-                   , "codeLensOn"    .= cl
-                   , "diagnosticsOn" .= d
-                   , "hoverOn"       .= h
-                   , "symbolsOn"     .= s
-                   , "completionOn"  .= c
-                   , "renameOn"      .= rn
-                   , "config"        .= cfg
-                   ]
-
-instance A.FromJSON PluginConfig where
-  parseJSON = A.withObject "PluginConfig" $ \o  -> PluginConfig
-      <$> o .:? "globalOn"      .!= plcGlobalOn def
-      <*> o .:? "codeActionsOn" .!= plcCodeActionsOn def
-      <*> o .:? "codeLensOn"    .!= plcCodeLensOn    def
-      <*> o .:? "diagnosticsOn" .!= plcDiagnosticsOn def -- AZ
-      <*> o .:? "hoverOn"       .!= plcHoverOn       def
-      <*> o .:? "symbolsOn"     .!= plcSymbolsOn     def
-      <*> o .:? "completionOn"  .!= plcCompletionOn  def
-      <*> o .:? "renameOn"      .!= plcRenameOn      def
-      <*> o .:? "config"        .!= plcConfig        def
-
--- ---------------------------------------------------------------------
+{-# LANGUAGE DeriveAnyClass     #-}
+{-# LANGUAGE DeriveGeneric      #-}
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE FlexibleInstances  #-}
+{-# LANGUAGE OverloadedStrings  #-}
+{-# LANGUAGE RecordWildCards    #-}
+{-# LANGUAGE TypeFamilies       #-}
+module Ide.Plugin.Config
+    ( getConfigFromNotification
+    , Config(..)
+    , parseConfig
+    , PluginConfig(..)
+    , CheckParents(..)
+    ) where
+
+import           Control.Applicative
+import           Data.Aeson          hiding (Error)
+import qualified Data.Aeson          as A
+import qualified Data.Aeson.Types    as A
+import           Data.Default
+import qualified Data.Map            as Map
+import qualified Data.Text           as T
+import           GHC.Generics        (Generic)
+
+-- ---------------------------------------------------------------------
+
+-- | Given a DidChangeConfigurationNotification message, this function returns the parsed
+-- Config object if possible.
+getConfigFromNotification :: Config -> A.Value -> Either T.Text Config
+getConfigFromNotification defaultValue p =
+  case A.parse (parseConfig defaultValue) p of
+    A.Success c -> Right c
+    A.Error err -> Left $ T.pack err
+
+-- ---------------------------------------------------------------------
+data CheckParents
+    -- Note that ordering of constructors is meaningful and must be monotonically
+    -- increasing in the scenarios where parents are checked
+    = NeverCheck
+    | CheckOnClose
+    | CheckOnSaveAndClose
+    | AlwaysCheck
+  deriving stock (Eq, Ord, Show, Generic)
+  deriving anyclass (FromJSON, ToJSON)
+
+-- | We (initially anyway) mirror the hie configuration, so that existing
+-- clients can simply switch executable and not have any nasty surprises.  There
+-- will be surprises relating to config options being ignored, initially though.
+data Config =
+  Config
+    { checkParents                :: CheckParents
+    , checkProject                :: !Bool
+    , hlintOn                     :: !Bool
+    , diagnosticsOnChange         :: !Bool
+    , diagnosticsDebounceDuration :: !Int
+    , liquidOn                    :: !Bool
+    , formatOnImportOn            :: !Bool
+    , formattingProvider          :: !T.Text
+    , maxCompletions              :: !Int
+    , plugins                     :: !(Map.Map T.Text PluginConfig)
+    } deriving (Show,Eq)
+
+instance Default Config where
+  def = Config
+    { checkParents                = CheckOnSaveAndClose
+    , checkProject                = True
+    , hlintOn                     = True
+    , diagnosticsOnChange         = True
+    , diagnosticsDebounceDuration = 350000
+    , liquidOn                    = False
+    , formatOnImportOn            = True
+    -- , formattingProvider          = "brittany"
+    , formattingProvider          = "ormolu"
+    -- , formattingProvider          = "floskell"
+    -- , formattingProvider          = "stylish-haskell"
+    , maxCompletions              = 40
+    , plugins                     = Map.empty
+    }
+
+-- TODO: Add API for plugins to expose their own LSP config options
+parseConfig :: Config -> Value -> A.Parser Config
+parseConfig defValue = A.withObject "Config" $ \v -> do
+    -- Officially, we use "haskell" as the section name but for
+    -- backwards compatibility we also accept "languageServerHaskell"
+    c <- v .: "haskell" <|> v .:? "languageServerHaskell"
+    case c of
+      Nothing -> return defValue
+      Just s -> flip (A.withObject "Config.settings") s $ \o -> Config
+        <$> (o .:? "checkParents" <|> v .:? "checkParents") .!= checkParents defValue
+        <*> (o .:? "checkProject" <|> v .:? "checkProject") .!= checkProject defValue
+        <*> o .:? "hlintOn"                                 .!= hlintOn defValue
+        <*> o .:? "diagnosticsOnChange"                     .!= diagnosticsOnChange defValue
+        <*> o .:? "diagnosticsDebounceDuration"             .!= diagnosticsDebounceDuration defValue
+        <*> o .:? "liquidOn"                                .!= liquidOn defValue
+        <*> o .:? "formatOnImportOn"                        .!= formatOnImportOn defValue
+        <*> o .:? "formattingProvider"                      .!= formattingProvider defValue
+        <*> o .:? "maxCompletions"                          .!= maxCompletions defValue
+        <*> o .:? "plugin"                                  .!= plugins defValue
+
+instance A.ToJSON Config where
+  toJSON Config{..} =
+      object [ "haskell" .= r ]
+    where
+      r = object [ "checkParents"                .= checkParents
+                 , "checkProject"                .= checkProject
+                 , "hlintOn"                     .= hlintOn
+                 , "diagnosticsOnChange"         .= diagnosticsOnChange
+                 , "diagnosticsDebounceDuration" .= diagnosticsDebounceDuration
+                 , "liquidOn"                    .= liquidOn
+                 , "formatOnImportOn"            .= formatOnImportOn
+                 , "formattingProvider"          .= formattingProvider
+                 , "maxCompletions"              .= maxCompletions
+                 , "plugin"                      .= plugins
+                 ]
+
+-- ---------------------------------------------------------------------
+
+-- | A PluginConfig is a generic configuration for a given HLS plugin.  It
+-- provides a "big switch" to turn it on or off as a whole, as well as small
+-- switches per feature, and a slot for custom config.
+-- This provides a regular naming scheme for all plugin config.
+data PluginConfig =
+    PluginConfig
+      { plcGlobalOn      :: !Bool
+      , plcCodeActionsOn :: !Bool
+      , plcCodeLensOn    :: !Bool
+      , plcDiagnosticsOn :: !Bool
+      , plcHoverOn       :: !Bool
+      , plcSymbolsOn     :: !Bool
+      , plcCompletionOn  :: !Bool
+      , plcRenameOn      :: !Bool
+      , plcConfig        :: !A.Object
+      } deriving (Show,Eq)
+
+instance Default PluginConfig where
+  def = PluginConfig
+      { plcGlobalOn      = True
+      , plcCodeActionsOn = True
+      , plcCodeLensOn    = True
+      , plcDiagnosticsOn = True
+      , plcHoverOn       = True
+      , plcSymbolsOn     = True
+      , plcCompletionOn  = True
+      , plcRenameOn      = True
+      , plcConfig        = mempty
+      }
+
+instance A.ToJSON PluginConfig where
+    toJSON (PluginConfig g ca cl d h s c rn cfg) = r
+      where
+        r = object [ "globalOn"      .= g
+                   , "codeActionsOn" .= ca
+                   , "codeLensOn"    .= cl
+                   , "diagnosticsOn" .= d
+                   , "hoverOn"       .= h
+                   , "symbolsOn"     .= s
+                   , "completionOn"  .= c
+                   , "renameOn"      .= rn
+                   , "config"        .= cfg
+                   ]
+
+instance A.FromJSON PluginConfig where
+  parseJSON = A.withObject "PluginConfig" $ \o  -> PluginConfig
+      <$> o .:? "globalOn"      .!= plcGlobalOn def
+      <*> o .:? "codeActionsOn" .!= plcCodeActionsOn def
+      <*> o .:? "codeLensOn"    .!= plcCodeLensOn    def
+      <*> o .:? "diagnosticsOn" .!= plcDiagnosticsOn def -- AZ
+      <*> o .:? "hoverOn"       .!= plcHoverOn       def
+      <*> o .:? "symbolsOn"     .!= plcSymbolsOn     def
+      <*> o .:? "completionOn"  .!= plcCompletionOn  def
+      <*> o .:? "renameOn"      .!= plcRenameOn      def
+      <*> o .:? "config"        .!= plcConfig        def
+
+-- ---------------------------------------------------------------------
diff --git a/src/Ide/Plugin/ConfigUtils.hs b/src/Ide/Plugin/ConfigUtils.hs
new file mode 100644
--- /dev/null
+++ b/src/Ide/Plugin/ConfigUtils.hs
@@ -0,0 +1,126 @@
+{-# LANGUAGE GADTs             #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards   #-}
+{-# LANGUAGE ViewPatterns      #-}
+
+module Ide.Plugin.ConfigUtils where
+
+import qualified Data.Aeson            as A
+import qualified Data.Aeson.Types      as A
+import           Data.Default          (def)
+import qualified Data.Dependent.Map    as DMap
+import qualified Data.Dependent.Sum    as DSum
+import qualified Data.HashMap.Lazy     as HMap
+import           Ide.Plugin.Config
+import           Ide.Plugin.Properties (toDefaultJSON, toVSCodeExtensionSchema)
+import           Ide.Types
+import           Language.LSP.Types
+
+-- Attention:
+-- 'diagnosticsOn' will never be added into the default config or the schema,
+-- since diagnostics emit in arbitrary shake rules -- we don't know
+-- whether a plugin is capable of producing diagnostics.
+
+-- | Generates a defalut 'Config', but remains only effective items
+pluginsToDefaultConfig :: IdePlugins a -> A.Value
+pluginsToDefaultConfig IdePlugins {..} =
+  A.Object $
+    HMap.adjust
+      ( \(unsafeValueToObject -> o) ->
+          A.Object $ HMap.insert "plugin" elems o -- inplace the "plugin" section with our 'elems', leaving others unchanged
+      )
+      "haskell"
+      (unsafeValueToObject (A.toJSON defaultConfig))
+  where
+    defaultConfig@Config {} = def
+    unsafeValueToObject (A.Object o) = o
+    unsafeValueToObject _            = error "impossible"
+    elems = A.object $ mconcat $ singlePlugin <$> map snd ipMap
+    -- Splice genericDefaultConfig and dedicatedDefaultConfig
+    -- Example:
+    --
+    -- {
+    --  "plugin-id": {
+    --    "globalOn": true,
+    --    "codeActionsOn": true,
+    --    "codeLensOn": true,
+    --    "config": {
+    --      "property1": "foo"
+    --     }
+    --   }
+    -- }
+    singlePlugin PluginDescriptor {..} =
+      let x = genericDefaultConfig <> dedicatedDefaultConfig
+       in [pId A..= A.object x | not $ null x]
+      where
+        (PluginHandlers (DMap.toList -> handlers)) = pluginHandlers
+        customConfigToDedicatedDefaultConfig (CustomConfig p) = toDefaultJSON p
+        -- Example:
+        --
+        -- {
+        --   "globalOn": true,
+        --   "codeActionsOn": true,
+        --   "codeLensOn": true
+        -- }
+        --
+        -- we don't generate the config section if the plugin doesn't register any of the following six methods,
+        -- which avoids producing trivial configuration for formatters:
+        --
+        -- "stylish-haskell": {
+        --    "globalOn": true
+        -- }
+        genericDefaultConfig =
+          let x = mconcat (handlersToGenericDefaultConfig <$> handlers)
+           in ["globalOn" A..= True | not $ null x] <> x
+        -- Example:
+        --
+        -- {
+        --  "config": {
+        --      "property1": "foo"
+        --   }
+        --}
+        dedicatedDefaultConfig =
+          let x = customConfigToDedicatedDefaultConfig pluginCustomConfig
+           in ["config" A..= A.object x | not $ null x]
+
+        (PluginId pId) = pluginId
+
+        -- This function captures ide methods registered by the plugin, and then converts it to kv pairs
+        handlersToGenericDefaultConfig :: DSum.DSum IdeMethod f -> [A.Pair]
+        handlersToGenericDefaultConfig (IdeMethod m DSum.:=> _) = case m of
+          STextDocumentCodeAction     -> ["codeActionsOn" A..= True]
+          STextDocumentCodeLens       -> ["codeLensOn" A..= True]
+          STextDocumentRename         -> ["renameOn" A..= True]
+          STextDocumentHover          -> ["hoverOn" A..= True]
+          STextDocumentDocumentSymbol -> ["symbolsOn" A..= True]
+          STextDocumentCompletion     -> ["completionOn" A..= True]
+          _                           -> []
+
+-- | Generates json schema used in haskell vscode extension
+-- Similar to 'pluginsToDefaultConfig' but simpler, since schema has a flatten structure
+pluginsToVSCodeExtensionSchema :: IdePlugins a -> A.Value
+pluginsToVSCodeExtensionSchema IdePlugins {..} = A.object $ mconcat $ singlePlugin <$> map snd ipMap
+  where
+    singlePlugin PluginDescriptor {..} = genericSchema <> dedicatedSchema
+      where
+        (PluginHandlers (DMap.toList -> handlers)) = pluginHandlers
+        customConfigToDedicatedSchema (CustomConfig p) = toVSCodeExtensionSchema (withIdPrefix "config.") p
+        (PluginId pId) = pluginId
+        genericSchema = withIdPrefix "globalOn" A..= schemaEntry "plugin" : mconcat (handlersToGenericSchema <$> handlers)
+        dedicatedSchema = customConfigToDedicatedSchema pluginCustomConfig
+        handlersToGenericSchema (IdeMethod m DSum.:=> _) = case m of
+          STextDocumentCodeAction -> [withIdPrefix "codeActionsOn" A..= schemaEntry "code actions"]
+          STextDocumentCodeLens -> [withIdPrefix "codeLensOn" A..= schemaEntry "code lenses"]
+          STextDocumentRename -> [withIdPrefix "renameOn" A..= schemaEntry "rename"]
+          STextDocumentHover -> [withIdPrefix "hoverOn" A..= schemaEntry "hover"]
+          STextDocumentDocumentSymbol -> [withIdPrefix "symbolsOn" A..= schemaEntry "symbols"]
+          STextDocumentCompletion -> [withIdPrefix "completionOn" A..= schemaEntry "completions"]
+          _ -> []
+        schemaEntry desc =
+          A.object
+            [ "scope" A..= A.String "resource",
+              "type" A..= A.String "boolean",
+              "default" A..= True,
+              "description" A..= A.String ("Enables " <> pId <> " " <> desc)
+            ]
+        withIdPrefix x = "haskell.plugin." <> pId <> "." <> x
diff --git a/src/Ide/Plugin/Properties.hs b/src/Ide/Plugin/Properties.hs
new file mode 100644
--- /dev/null
+++ b/src/Ide/Plugin/Properties.hs
@@ -0,0 +1,430 @@
+{-# LANGUAGE ConstraintKinds       #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE GADTs                 #-}
+{-# LANGUAGE KindSignatures        #-}
+{-# LANGUAGE LambdaCase            #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedLabels      #-}
+{-# LANGUAGE OverloadedStrings     #-}
+{-# LANGUAGE RecordWildCards       #-}
+{-# LANGUAGE ScopedTypeVariables   #-}
+{-# LANGUAGE TypeFamilies          #-}
+{-# LANGUAGE TypeOperators         #-}
+{-# LANGUAGE UndecidableInstances  #-}
+{-# LANGUAGE ViewPatterns          #-}
+-- See Note [Constraints]
+{-# OPTIONS_GHC -Wno-redundant-constraints #-}
+
+module Ide.Plugin.Properties
+  ( PropertyType (..),
+    ToHsType,
+    MetaData (..),
+    PropertyKey (..),
+    SPropertyKey (..),
+    KeyNameProxy (..),
+    Properties,
+    HasProperty,
+    emptyProperties,
+    defineNumberProperty,
+    defineIntegerProperty,
+    defineStringProperty,
+    defineBooleanProperty,
+    defineObjectProperty,
+    defineArrayProperty,
+    defineEnumProperty,
+    toDefaultJSON,
+    toVSCodeExtensionSchema,
+    usePropertyEither,
+    useProperty,
+    (&),
+  )
+where
+
+import qualified Data.Aeson           as A
+import qualified Data.Aeson.Types     as A
+import           Data.Either          (fromRight)
+import           Data.Function        ((&))
+import           Data.Kind            (Constraint, Type)
+import qualified Data.Map.Strict      as Map
+import           Data.Proxy (Proxy (..))
+import qualified Data.Text            as T
+import           GHC.OverloadedLabels (IsLabel (..))
+import           GHC.TypeLits
+import           Unsafe.Coerce        (unsafeCoerce)
+
+-- | Types properties may have
+data PropertyType
+  = TNumber
+  | TInteger
+  | TString
+  | TBoolean
+  | TObject Type
+  | TArray Type
+  | TEnum Type
+
+type family ToHsType (t :: PropertyType) where
+  ToHsType 'TNumber = Double -- in js, there are no distinct types for integers and floating-point values
+  ToHsType 'TInteger = Int   -- so here we use Double for Number, Int for Integer
+  ToHsType 'TString = T.Text
+  ToHsType 'TBoolean = Bool
+  ToHsType ('TObject a) = a
+  ToHsType ('TArray a) = [a]
+  ToHsType ('TEnum a) = a
+
+-- ---------------------------------------------------------------------
+
+-- | Metadata of a property
+data MetaData (t :: PropertyType) where
+  MetaData ::
+    (IsTEnum t ~ 'False) =>
+    { defaultValue :: ToHsType t,
+      description :: T.Text
+    } ->
+    MetaData t
+  EnumMetaData ::
+    (IsTEnum t ~ 'True) =>
+    { defaultValue :: ToHsType t,
+      description :: T.Text,
+      enumValues :: [ToHsType t],
+      enumDescriptions :: [T.Text]
+    } ->
+    MetaData t
+
+-- | Used at type level for name-type mapping in 'Properties'
+data PropertyKey = PropertyKey Symbol PropertyType
+
+-- | Singleton type of 'PropertyKey'
+data SPropertyKey (k :: PropertyKey) where
+  SNumber :: SPropertyKey ('PropertyKey s 'TNumber)
+  SInteger :: SPropertyKey ('PropertyKey s 'TInteger)
+  SString :: SPropertyKey ('PropertyKey s 'TString)
+  SBoolean :: SPropertyKey ('PropertyKey s 'TBoolean)
+  SObject :: (A.ToJSON a, A.FromJSON a) => Proxy a -> SPropertyKey ('PropertyKey s ('TObject a))
+  SArray :: (A.ToJSON a, A.FromJSON a) => Proxy a -> SPropertyKey ('PropertyKey s ('TArray a))
+  SEnum :: (A.ToJSON a, A.FromJSON a, Eq a, Show a) => Proxy a -> SPropertyKey ('PropertyKey s ('TEnum a))
+
+-- | Existential wrapper of 'SPropertyKey', with an extra 'MetaData'
+data SomePropertyKeyWithMetaData
+  = forall k s t.
+    (k ~ 'PropertyKey s t) =>
+    SomePropertyKeyWithMetaData (SPropertyKey k) (MetaData t)
+
+-- | 'Properties' is a partial implementation of json schema, without supporting union types and validation.
+-- In hls, it defines a set of properties which used in dedicated configuration of a plugin.
+-- A property is an immediate child of the json object in each plugin's "config" section.
+-- It was designed to be compatible with vscode's settings UI.
+-- Use 'emptyProperties' and 'useProperty' to create and consume 'Properties'.
+newtype Properties (r :: [PropertyKey]) = Properties (Map.Map String SomePropertyKeyWithMetaData)
+
+-- | A proxy type in order to allow overloaded labels as properties' names at the call site
+data KeyNameProxy (s :: Symbol) = KnownSymbol s => KeyNameProxy
+
+instance (KnownSymbol s', s ~ s') => IsLabel s (KeyNameProxy s') where
+  fromLabel = KeyNameProxy
+
+-- ---------------------------------------------------------------------
+
+type family IsTEnum (t :: PropertyType) :: Bool where
+  IsTEnum ('TEnum _) = 'True
+  IsTEnum _ = 'False
+
+type family FindByKeyName (s :: Symbol) (r :: [PropertyKey]) :: PropertyType where
+  FindByKeyName s ('PropertyKey s t ': _) = t
+  FindByKeyName s (_ ': xs) = FindByKeyName s xs
+
+type family Elem (s :: Symbol) (r :: [PropertyKey]) :: Constraint where
+  Elem s ('PropertyKey s _ ': _) = ()
+  Elem s (_ ': xs) = Elem s xs
+  Elem s '[] = TypeError ('Text "The key ‘" ':<>: 'Text s ':<>: 'Text "’ is missing")
+
+type family NotElem (s :: Symbol) (r :: [PropertyKey]) :: Constraint where
+  NotElem s ('PropertyKey s _ ': _) = TypeError ('Text "The key ‘" ':<>: 'Text s ':<>: 'Text "’ is already defined")
+  NotElem s (_ ': xs) = NotElem s xs
+  NotElem s '[] = ()
+
+-- | In row @r@, there is a 'PropertyKey' @k@, which has name @s@ and carries haskell type @t@
+type HasProperty s k t r = (k ~ 'PropertyKey s t, Elem s r, FindByKeyName s r ~ t, KnownSymbol s)
+
+-- ---------------------------------------------------------------------
+
+-- | Creates a 'Properties' that defines no property
+--
+-- Useful to start a definitions chain, for example:
+-- @
+-- properties =
+--  emptyProperties
+--    & defineStringProperty
+--      #exampleString
+--      "Description of exampleString"
+--      "Foo"
+--    & defineNumberProperty
+--      #exampleNumber
+--      "Description of exampleNumber"
+--      233
+-- @
+emptyProperties :: Properties '[]
+emptyProperties = Properties Map.empty
+
+insert ::
+  (k ~ 'PropertyKey s t, NotElem s r, KnownSymbol s) =>
+  KeyNameProxy s ->
+  SPropertyKey k ->
+  MetaData t ->
+  Properties r ->
+  Properties (k ': r)
+insert kn key metadata (Properties old) =
+  Properties
+    ( Map.insert
+        (symbolVal kn)
+        (SomePropertyKeyWithMetaData key metadata)
+        old
+    )
+
+find ::
+  (HasProperty s k t r) =>
+  KeyNameProxy s ->
+  Properties r ->
+  (SPropertyKey k, MetaData t)
+find kn (Properties p) = case p Map.! symbolVal kn of
+  (SomePropertyKeyWithMetaData sing metadata) ->
+    -- Note [Constraints]
+    -- It's safe to use unsafeCoerce here:
+    --   Since each property name is unique that the redefinition will be prevented by predication on the type level list,
+    --   the value we get from the name-indexed map must be exactly the singleton and metadata corresponding to the type.
+    -- We drop this information at type level: some of the above type families return '() :: Constraint',
+    -- so GHC will consider them as redundant.
+    -- But we encode it using semantically identical 'Map' at term level,
+    -- which avoids inducting on the list by defining a new type class.
+    unsafeCoerce (sing, metadata)
+
+-- ---------------------------------------------------------------------
+
+-- | Given the name of a defined property, generates a JSON parser of 'plcConfig'
+usePropertyEither ::
+  (HasProperty s k t r) =>
+  KeyNameProxy s ->
+  Properties r ->
+  A.Object ->
+  Either String (ToHsType t)
+usePropertyEither kn p = parseProperty kn (find kn p)
+
+-- | Like 'usePropertyEither' but returns 'defaultValue' on parse error
+useProperty ::
+  (HasProperty s k t r) =>
+  KeyNameProxy s ->
+  Properties r ->
+  A.Object ->
+  ToHsType t
+useProperty kn p = fromRight (defaultValue metadata) . usePropertyEither kn p
+  where
+    (_, metadata) = find kn p
+
+parseProperty ::
+  (k ~ 'PropertyKey s t, KnownSymbol s) =>
+  KeyNameProxy s ->
+  (SPropertyKey k, MetaData t) ->
+  A.Object ->
+  Either String (ToHsType t)
+parseProperty kn k x = case k of
+  (SNumber, _) -> parseEither
+  (SInteger, _) -> parseEither
+  (SString, _) -> parseEither
+  (SBoolean, _) -> parseEither
+  (SObject _, _) -> parseEither
+  (SArray _, _) -> parseEither
+  (SEnum _, EnumMetaData {..}) ->
+    A.parseEither
+      ( \o -> do
+          txt <- o A..: keyName
+          if txt `elem` enumValues
+            then pure txt
+            else
+              fail $
+                "invalid enum member: "
+                  <> show txt
+                  <> ". Expected one of "
+                  <> show enumValues
+      )
+      x
+  where
+    keyName = T.pack $ symbolVal kn
+    parseEither :: forall a. A.FromJSON a => Either String a
+    parseEither = A.parseEither (A..: keyName) x
+
+-- ---------------------------------------------------------------------
+
+-- | Defines a number property
+defineNumberProperty ::
+  (KnownSymbol s, NotElem s r) =>
+  KeyNameProxy s ->
+  -- | description
+  T.Text ->
+  -- | default value
+  Double ->
+  Properties r ->
+  Properties ('PropertyKey s 'TNumber : r)
+defineNumberProperty kn description defaultValue =
+  insert kn SNumber MetaData {..}
+
+-- | Defines an integer property
+defineIntegerProperty ::
+  (KnownSymbol s, NotElem s r) =>
+  KeyNameProxy s ->
+  -- | description
+  T.Text ->
+  -- | default value
+  Int ->
+  Properties r ->
+  Properties ('PropertyKey s 'TInteger : r)
+defineIntegerProperty kn description defaultValue =
+  insert kn SInteger MetaData {..}
+
+-- | Defines a string property
+defineStringProperty ::
+  (KnownSymbol s, NotElem s r) =>
+  KeyNameProxy s ->
+  -- | description
+  T.Text ->
+  -- | default value
+  T.Text ->
+  Properties r ->
+  Properties ('PropertyKey s 'TString : r)
+defineStringProperty kn description defaultValue =
+  insert kn SString MetaData {..}
+
+-- | Defines a boolean property
+defineBooleanProperty ::
+  (KnownSymbol s, NotElem s r) =>
+  KeyNameProxy s ->
+  -- | description
+  T.Text ->
+  -- | default value
+  Bool ->
+  Properties r ->
+  Properties ('PropertyKey s 'TBoolean : r)
+defineBooleanProperty kn description defaultValue =
+  insert kn SBoolean MetaData {..}
+
+-- | Defines an object property
+defineObjectProperty ::
+  (KnownSymbol s, NotElem s r, A.ToJSON a, A.FromJSON a) =>
+  KeyNameProxy s ->
+  -- | description
+  T.Text ->
+  -- | default value
+  a ->
+  Properties r ->
+  Properties ('PropertyKey s ('TObject a) : r)
+defineObjectProperty kn description defaultValue =
+  insert kn (SObject Proxy) MetaData {..}
+
+-- | Defines an array property
+defineArrayProperty ::
+  (KnownSymbol s, NotElem s r, A.ToJSON a, A.FromJSON a) =>
+  KeyNameProxy s ->
+  -- | description
+  T.Text ->
+  -- | default value
+  [a] ->
+  Properties r ->
+  Properties ('PropertyKey s ('TArray a) : r)
+defineArrayProperty kn description defaultValue =
+  insert kn (SArray Proxy) MetaData {..}
+
+-- | Defines an enum property
+defineEnumProperty ::
+  (KnownSymbol s, NotElem s r, A.ToJSON a, A.FromJSON a, Eq a, Show a) =>
+  KeyNameProxy s ->
+  -- | description
+  T.Text ->
+  -- | valid enum members with each of description
+  [(a, T.Text)] ->
+  a ->
+  Properties r ->
+  Properties ('PropertyKey s ('TEnum a) : r)
+defineEnumProperty kn description enums defaultValue =
+  insert kn (SEnum Proxy) $ EnumMetaData defaultValue description (fst <$> enums) (snd <$> enums)
+
+-- ---------------------------------------------------------------------
+
+-- | Converts a properties definition into kv pairs with default values from 'MetaData'
+toDefaultJSON :: Properties r -> [A.Pair]
+toDefaultJSON (Properties p) = [toEntry s v | (s, v) <- Map.toList p]
+  where
+    toEntry :: String -> SomePropertyKeyWithMetaData -> A.Pair
+    toEntry (T.pack -> s) = \case
+      (SomePropertyKeyWithMetaData SNumber MetaData {..}) ->
+        s A..= defaultValue
+      (SomePropertyKeyWithMetaData SInteger MetaData {..}) ->
+        s A..= defaultValue
+      (SomePropertyKeyWithMetaData SString MetaData {..}) ->
+        s A..= defaultValue
+      (SomePropertyKeyWithMetaData SBoolean MetaData {..}) ->
+        s A..= defaultValue
+      (SomePropertyKeyWithMetaData (SObject _) MetaData {..}) ->
+        s A..= defaultValue
+      (SomePropertyKeyWithMetaData (SArray _) MetaData {..}) ->
+        s A..= defaultValue
+      (SomePropertyKeyWithMetaData (SEnum _) EnumMetaData {..}) ->
+        s A..= defaultValue
+
+-- | Converts a properties definition into kv pairs as vscode schema
+toVSCodeExtensionSchema :: T.Text -> Properties r -> [A.Pair]
+toVSCodeExtensionSchema prefix (Properties p) =
+  [(prefix <> T.pack k) A..= toEntry v | (k, v) <- Map.toList p]
+  where
+    toEntry :: SomePropertyKeyWithMetaData -> A.Value
+    toEntry = \case
+      (SomePropertyKeyWithMetaData SNumber MetaData {..}) ->
+        A.object
+          [ "type" A..= A.String "number",
+            "markdownDescription" A..= description,
+            "default" A..= defaultValue,
+            "scope" A..= A.String "resource"
+          ]
+      (SomePropertyKeyWithMetaData SInteger MetaData {..}) ->
+        A.object
+          [ "type" A..= A.String "integer",
+            "markdownDescription" A..= description,
+            "default" A..= defaultValue,
+            "scope" A..= A.String "resource"
+          ]
+      (SomePropertyKeyWithMetaData SString MetaData {..}) ->
+        A.object
+          [ "type" A..= A.String "string",
+            "markdownDescription" A..= description,
+            "default" A..= defaultValue,
+            "scope" A..= A.String "resource"
+          ]
+      (SomePropertyKeyWithMetaData SBoolean MetaData {..}) ->
+        A.object
+          [ "type" A..= A.String "boolean",
+            "markdownDescription" A..= description,
+            "default" A..= defaultValue,
+            "scope" A..= A.String "resource"
+          ]
+      (SomePropertyKeyWithMetaData (SObject _) MetaData {..}) ->
+        A.object
+          [ "type" A..= A.String "object",
+            "markdownDescription" A..= description,
+            "default" A..= defaultValue,
+            "scope" A..= A.String "resource"
+          ]
+      (SomePropertyKeyWithMetaData (SArray _) MetaData {..}) ->
+        A.object
+          [ "type" A..= A.String "array",
+            "markdownDescription" A..= description,
+            "default" A..= defaultValue,
+            "scope" A..= A.String "resource"
+          ]
+      (SomePropertyKeyWithMetaData (SEnum _) EnumMetaData {..}) ->
+        A.object
+          [ "type" A..= A.String "string",
+            "description" A..= description,
+            "enum" A..= enumValues,
+            "enumDescriptions" A..= enumDescriptions,
+            "default" A..= defaultValue,
+            "scope" A..= A.String "resource"
+          ]
diff --git a/src/Ide/PluginUtils.hs b/src/Ide/PluginUtils.hs
--- a/src/Ide/PluginUtils.hs
+++ b/src/Ide/PluginUtils.hs
@@ -1,213 +1,232 @@
-{-# LANGUAGE FlexibleContexts  #-}
-{-# LANGUAGE OverloadedStrings #-}
-module Ide.PluginUtils
-  ( WithDeletions(..),
-    getProcessID,
-    normalize,
-    makeDiffTextEdit,
-    makeDiffTextEditAdditive,
-    diffText,
-    diffText',
-    pluginDescToIdePlugins,
-    responseError,
-    getClientConfig,
-    getPluginConfig,
-    configForPlugin,
-    pluginEnabled,
-    extractRange,
-    fullRange,
-    mkLspCommand,
-    mkLspCmdId,
-    getPid,
-  allLspCmdIds,allLspCmdIds',installSigUsr1Handler, subRange)
-where
-
-
-import           Data.Algorithm.Diff
-import           Data.Algorithm.DiffOutput
-import qualified Data.HashMap.Strict             as H
-import qualified Data.Text                       as T
-import           Ide.Types
-import           Language.LSP.Types
-import qualified Language.LSP.Types              as J
-import           Language.LSP.Types.Capabilities
-
-import qualified Data.Map.Strict                 as Map
-import           Ide.Plugin.Config
-import           Language.LSP.Server
-
--- ---------------------------------------------------------------------
-
--- | Extend to the line below and above to replace newline character.
-normalize :: Range -> Range
-normalize (Range (Position sl _) (Position el _)) =
-  Range (Position sl 0) (Position (el + 1) 0)
-
--- ---------------------------------------------------------------------
-
-data WithDeletions = IncludeDeletions | SkipDeletions
-  deriving Eq
-
--- | Generate a 'WorkspaceEdit' value from a pair of source Text
-diffText :: ClientCapabilities -> (Uri,T.Text) -> T.Text -> WithDeletions -> WorkspaceEdit
-diffText clientCaps old new withDeletions =
-  let
-    supports = clientSupportsDocumentChanges clientCaps
-  in diffText' supports old new withDeletions
-
-makeDiffTextEdit :: T.Text -> T.Text -> List TextEdit
-makeDiffTextEdit f1 f2 = diffTextEdit f1 f2 IncludeDeletions
-
-makeDiffTextEditAdditive :: T.Text -> T.Text -> List TextEdit
-makeDiffTextEditAdditive f1 f2 = diffTextEdit f1 f2 SkipDeletions
-
-diffTextEdit :: T.Text -> T.Text -> WithDeletions -> List TextEdit
-diffTextEdit fText f2Text withDeletions = J.List r
-  where
-    r = map diffOperationToTextEdit diffOps
-    d = getGroupedDiff (lines $ T.unpack fText) (lines $ T.unpack f2Text)
-
-    diffOps = filter (\x -> (withDeletions == IncludeDeletions) || not (isDeletion x))
-                     (diffToLineRanges d)
-
-    isDeletion (Deletion _ _) = True
-    isDeletion _              = False
-
-
-    diffOperationToTextEdit :: DiffOperation LineRange -> J.TextEdit
-    diffOperationToTextEdit (Change fm to) = J.TextEdit range nt
-      where
-        range = calcRange fm
-        nt = T.pack $ init $ unlines $ lrContents to
-
-    {-
-      In order to replace everything including newline characters,
-      the end range should extend below the last line. From the specification:
-      "If you want to specify a range that contains a line including
-      the line ending character(s) then use an end position denoting
-      the start of the next line"
-    -}
-    diffOperationToTextEdit (Deletion (LineRange (sl, el) _) _) = J.TextEdit range ""
-      where
-        range = J.Range (J.Position (sl - 1) 0)
-                        (J.Position el 0)
-
-    diffOperationToTextEdit (Addition fm l) = J.TextEdit range nt
-    -- fm has a range wrt to the changed file, which starts in the current file at l + 1
-    -- So the range has to be shifted to start at l + 1
-      where
-        range = J.Range (J.Position l 0)
-                        (J.Position l 0)
-        nt = T.pack $ unlines $ lrContents fm
-
-
-    calcRange fm = J.Range s e
-      where
-        sl = fst $ lrNumbers fm
-        sc = 0
-        s = J.Position (sl - 1) sc -- Note: zero-based lines
-        el = snd $ lrNumbers fm
-        ec = length $ last $ lrContents fm
-        e = J.Position (el - 1) ec  -- Note: zero-based lines
-
-
--- | A pure version of 'diffText' for testing
-diffText' :: Bool -> (Uri,T.Text) -> T.Text -> WithDeletions -> WorkspaceEdit
-diffText' supports (f,fText) f2Text withDeletions  =
-  if supports
-    then WorkspaceEdit Nothing (Just docChanges)
-    else WorkspaceEdit (Just h) Nothing
-  where
-    diff = diffTextEdit fText f2Text withDeletions
-    h = H.singleton f diff
-    docChanges = J.List [InL docEdit]
-    docEdit = J.TextDocumentEdit (J.VersionedTextDocumentIdentifier f (Just 0)) diff
-
--- ---------------------------------------------------------------------
-
-clientSupportsDocumentChanges :: ClientCapabilities -> Bool
-clientSupportsDocumentChanges caps =
-  let ClientCapabilities mwCaps _ _ _ = caps
-      supports = do
-        wCaps <- mwCaps
-        WorkspaceEditClientCapabilities mDc _ _ <- _workspaceEdit wCaps
-        mDc
-  in
-    Just True == supports
-
--- ---------------------------------------------------------------------
-
-pluginDescToIdePlugins :: [PluginDescriptor ideState] -> IdePlugins ideState
-pluginDescToIdePlugins plugins = IdePlugins $ Map.fromList $ map (\p -> (pluginId p, p)) plugins
-
-
--- ---------------------------------------------------------------------
--- | Returns the current client configuration. It is not wise to permanently
--- cache the returned value of this function, as clients can at runitime change
--- their configuration.
---
-getClientConfig :: MonadLsp Config m => m (Maybe Config)
-getClientConfig = getConfig
-
--- ---------------------------------------------------------------------
-
--- | Returns the current plugin configuration. It is not wise to permanently
--- cache the returned value of this function, as clients can change their
--- configuration at runtime.
-getPluginConfig :: MonadLsp Config m => PluginId -> m (Maybe PluginConfig)
-getPluginConfig plugin = do
-    config <- getClientConfig
-    return $ flip configForPlugin plugin <$> config
-
--- ---------------------------------------------------------------------
-
-extractRange :: Range -> T.Text -> T.Text
-extractRange (Range (Position sl _) (Position el _)) s = newS
-  where focusLines = take (el-sl+1) $ drop sl $ T.lines s
-        newS = T.unlines focusLines
-
--- | Gets the range that covers the entire text
-fullRange :: T.Text -> Range
-fullRange s = Range startPos endPos
-  where startPos = Position 0 0
-        endPos = Position lastLine 0
-        {-
-        In order to replace everything including newline characters,
-        the end range should extend below the last line. From the specification:
-        "If you want to specify a range that contains a line including
-        the line ending character(s) then use an end position denoting
-        the start of the next line"
-        -}
-        lastLine = length $ T.lines s
-
-subRange :: Range -> Range -> Bool
-subRange smallRange range =
-     positionInRange (_start smallRange) range
-  && positionInRange (_end smallRange) range
-
-positionInRange :: Position -> Range -> Bool
-positionInRange (Position pl po) (Range (Position sl so) (Position el eo)) =
-     pl >  sl && pl <  el
-  || pl == sl && pl == el && po >= so && po <= eo
-  || pl == sl && po >= so
-  || pl == el && po <= eo
-
--- ---------------------------------------------------------------------
-
-allLspCmdIds' :: T.Text -> IdePlugins ideState -> [T.Text]
-allLspCmdIds' pid mp = mkPlugin (allLspCmdIds pid) (Just . pluginCommands)
-    where
-        justs (p, Just x)  = [(p, x)]
-        justs (_, Nothing) = []
-
-        ls = Map.toList (ipMap mp)
-
-        mkPlugin maker selector
-            = maker $ concatMap (\(pid, p) -> justs (pid, selector p)) ls
-
-
-allLspCmdIds :: T.Text -> [(PluginId, [PluginCommand ideState])] -> [T.Text]
-allLspCmdIds pid commands = concatMap go commands
-  where
-    go (plid, cmds) = map (mkLspCmdId pid plid . commandId) cmds
-
+{-# LANGUAGE FlexibleContexts  #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeFamilies      #-}
+module Ide.PluginUtils
+  ( WithDeletions(..),
+    getProcessID,
+    normalize,
+    makeDiffTextEdit,
+    makeDiffTextEditAdditive,
+    diffText,
+    diffText',
+    pluginDescToIdePlugins,
+    responseError,
+    getClientConfig,
+    getPluginConfig,
+    configForPlugin,
+    pluginEnabled,
+    extractRange,
+    fullRange,
+    mkLspCommand,
+    mkLspCmdId,
+    getPid,
+    allLspCmdIds,
+    allLspCmdIds',
+    installSigUsr1Handler,
+    subRange,
+    usePropertyLsp)
+where
+
+
+import           Data.Algorithm.Diff
+import           Data.Algorithm.DiffOutput
+import qualified Data.HashMap.Strict             as H
+import qualified Data.Text                       as T
+import           Ide.Types
+import           Language.LSP.Types
+import qualified Language.LSP.Types              as J
+import           Language.LSP.Types.Capabilities
+
+import           Data.Containers.ListUtils       (nubOrdOn)
+import           Ide.Plugin.Config
+import           Ide.Plugin.Properties
+import           Language.LSP.Server
+
+-- ---------------------------------------------------------------------
+
+-- | Extend to the line below and above to replace newline character.
+normalize :: Range -> Range
+normalize (Range (Position sl _) (Position el _)) =
+  Range (Position sl 0) (Position (el + 1) 0)
+
+-- ---------------------------------------------------------------------
+
+data WithDeletions = IncludeDeletions | SkipDeletions
+  deriving Eq
+
+-- | Generate a 'WorkspaceEdit' value from a pair of source Text
+diffText :: ClientCapabilities -> (Uri,T.Text) -> T.Text -> WithDeletions -> WorkspaceEdit
+diffText clientCaps old new withDeletions =
+  let
+    supports = clientSupportsDocumentChanges clientCaps
+  in diffText' supports old new withDeletions
+
+makeDiffTextEdit :: T.Text -> T.Text -> List TextEdit
+makeDiffTextEdit f1 f2 = diffTextEdit f1 f2 IncludeDeletions
+
+makeDiffTextEditAdditive :: T.Text -> T.Text -> List TextEdit
+makeDiffTextEditAdditive f1 f2 = diffTextEdit f1 f2 SkipDeletions
+
+diffTextEdit :: T.Text -> T.Text -> WithDeletions -> List TextEdit
+diffTextEdit fText f2Text withDeletions = J.List r
+  where
+    r = map diffOperationToTextEdit diffOps
+    d = getGroupedDiff (lines $ T.unpack fText) (lines $ T.unpack f2Text)
+
+    diffOps = filter (\x -> (withDeletions == IncludeDeletions) || not (isDeletion x))
+                     (diffToLineRanges d)
+
+    isDeletion (Deletion _ _) = True
+    isDeletion _              = False
+
+
+    diffOperationToTextEdit :: DiffOperation LineRange -> J.TextEdit
+    diffOperationToTextEdit (Change fm to) = J.TextEdit range nt
+      where
+        range = calcRange fm
+        nt = T.pack $ init $ unlines $ lrContents to
+
+    {-
+      In order to replace everything including newline characters,
+      the end range should extend below the last line. From the specification:
+      "If you want to specify a range that contains a line including
+      the line ending character(s) then use an end position denoting
+      the start of the next line"
+    -}
+    diffOperationToTextEdit (Deletion (LineRange (sl, el) _) _) = J.TextEdit range ""
+      where
+        range = J.Range (J.Position (sl - 1) 0)
+                        (J.Position el 0)
+
+    diffOperationToTextEdit (Addition fm l) = J.TextEdit range nt
+    -- fm has a range wrt to the changed file, which starts in the current file at l + 1
+    -- So the range has to be shifted to start at l + 1
+      where
+        range = J.Range (J.Position l 0)
+                        (J.Position l 0)
+        nt = T.pack $ unlines $ lrContents fm
+
+
+    calcRange fm = J.Range s e
+      where
+        sl = fst $ lrNumbers fm
+        sc = 0
+        s = J.Position (sl - 1) sc -- Note: zero-based lines
+        el = snd $ lrNumbers fm
+        ec = length $ last $ lrContents fm
+        e = J.Position (el - 1) ec  -- Note: zero-based lines
+
+
+-- | A pure version of 'diffText' for testing
+diffText' :: Bool -> (Uri,T.Text) -> T.Text -> WithDeletions -> WorkspaceEdit
+diffText' supports (f,fText) f2Text withDeletions  =
+  if supports
+    then WorkspaceEdit Nothing (Just docChanges) Nothing
+    else WorkspaceEdit (Just h) Nothing Nothing
+  where
+    diff = diffTextEdit fText f2Text withDeletions
+    h = H.singleton f diff
+    docChanges = J.List [InL docEdit]
+    docEdit = J.TextDocumentEdit (J.VersionedTextDocumentIdentifier f (Just 0)) $ fmap InL diff
+
+-- ---------------------------------------------------------------------
+
+clientSupportsDocumentChanges :: ClientCapabilities -> Bool
+clientSupportsDocumentChanges caps =
+  let ClientCapabilities mwCaps _ _ _ = caps
+      supports = do
+        wCaps <- mwCaps
+        WorkspaceEditClientCapabilities mDc _ _ _ _ <- _workspaceEdit wCaps
+        mDc
+  in
+    Just True == supports
+
+-- ---------------------------------------------------------------------
+
+pluginDescToIdePlugins :: [PluginDescriptor ideState] -> IdePlugins ideState
+pluginDescToIdePlugins plugins =
+    IdePlugins $ map (\p -> (pluginId p, p)) $ nubOrdOn pluginId plugins
+
+
+-- ---------------------------------------------------------------------
+-- | Returns the current client configuration. It is not wise to permanently
+-- cache the returned value of this function, as clients can at runitime change
+-- their configuration.
+--
+getClientConfig :: MonadLsp Config m => m Config
+getClientConfig = getConfig
+
+-- ---------------------------------------------------------------------
+
+-- | Returns the current plugin configuration. It is not wise to permanently
+-- cache the returned value of this function, as clients can change their
+-- configuration at runtime.
+getPluginConfig :: MonadLsp Config m => PluginId -> m PluginConfig
+getPluginConfig plugin = do
+    config <- getClientConfig
+    return $ flip configForPlugin plugin config
+
+-- ---------------------------------------------------------------------
+
+-- | Returns the value of a property defined by the current plugin.
+usePropertyLsp ::
+  (HasProperty s k t r, MonadLsp Config m) =>
+  KeyNameProxy s ->
+  PluginId ->
+  Properties r ->
+  m (ToHsType t)
+usePropertyLsp kn pId p = do
+  config <- getPluginConfig pId
+  return $ useProperty kn p $ plcConfig config
+
+-- ---------------------------------------------------------------------
+
+extractRange :: Range -> T.Text -> T.Text
+extractRange (Range (Position sl _) (Position el _)) s = newS
+  where focusLines = take (el-sl+1) $ drop sl $ T.lines s
+        newS = T.unlines focusLines
+
+-- | Gets the range that covers the entire text
+fullRange :: T.Text -> Range
+fullRange s = Range startPos endPos
+  where startPos = Position 0 0
+        endPos = Position lastLine 0
+        {-
+        In order to replace everything including newline characters,
+        the end range should extend below the last line. From the specification:
+        "If you want to specify a range that contains a line including
+        the line ending character(s) then use an end position denoting
+        the start of the next line"
+        -}
+        lastLine = length $ T.lines s
+
+subRange :: Range -> Range -> Bool
+subRange smallRange range =
+     positionInRange (_start smallRange) range
+  && positionInRange (_end smallRange) range
+
+positionInRange :: Position -> Range -> Bool
+positionInRange (Position pl po) (Range (Position sl so) (Position el eo)) =
+     pl >  sl && pl <  el
+  || pl == sl && pl == el && po >= so && po <= eo
+  || pl == sl && po >= so
+  || pl == el && po <= eo
+
+-- ---------------------------------------------------------------------
+
+allLspCmdIds' :: T.Text -> IdePlugins ideState -> [T.Text]
+allLspCmdIds' pid (IdePlugins ls) = mkPlugin (allLspCmdIds pid) (Just . pluginCommands)
+    where
+        justs (p, Just x)  = [(p, x)]
+        justs (_, Nothing) = []
+
+
+        mkPlugin maker selector
+            = maker $ concatMap (\(pid, p) -> justs (pid, selector p)) ls
+
+
+allLspCmdIds :: T.Text -> [(PluginId, [PluginCommand ideState])] -> [T.Text]
+allLspCmdIds pid commands = concatMap go commands
+  where
+    go (plid, cmds) = map (mkLspCmdId pid plid . commandId) cmds
+
diff --git a/src/Ide/Types.hs b/src/Ide/Types.hs
--- a/src/Ide/Types.hs
+++ b/src/Ide/Types.hs
@@ -1,378 +1,424 @@
-{-# LANGUAGE GADTs #-}
-{-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE PolyKinds #-}
-{-# LANGUAGE ViewPatterns #-}
-{-# LANGUAGE DefaultSignatures #-}
-{-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE TypeFamilies #-}
-{-# LANGUAGE DeriveAnyClass #-}
-{-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE ConstraintKinds #-}
-{-# LANGUAGE CPP #-}
-{-# LANGUAGE FlexibleInstances #-}
-{-# LANGUAGE UndecidableInstances #-}
-
-module Ide.Types
-    where
-
-#ifdef mingw32_HOST_OS
-import qualified System.Win32.Process                    as P (getCurrentProcessId)
-#else
-import           System.Posix.Signals
-import qualified System.Posix.Process                    as P (getProcessID)
-#endif
-import           Data.Aeson                    hiding (defaultOptions)
-import           GHC.Generics
-import qualified Data.Map  as Map
-import           Data.String
-import qualified Data.Text                     as T
-import           Development.Shake hiding (command)
-import           Ide.Plugin.Config
-import           Language.LSP.Types
-import           Language.LSP.VFS
-import           Language.LSP.Types.Lens as J hiding (id)
-import           Language.LSP.Types.Capabilities
-import           Language.LSP.Server (LspM, getVirtualFile)
-import           Text.Regex.TDFA.Text()
-import           Data.Dependent.Map (DMap)
-import qualified Data.Dependent.Map as DMap
-import Data.List.NonEmpty (NonEmpty(..), toList)
-import Data.GADT.Compare
-import Data.Maybe
-import Data.Semigroup
-import Control.Lens ((^.))
-import qualified Data.DList as DList
-import qualified Data.Default
-import System.IO.Unsafe
-import Control.Monad
-import OpenTelemetry.Eventlog
-import Data.Text.Encoding (encodeUtf8)
-
--- ---------------------------------------------------------------------
-
-newtype IdePlugins ideState = IdePlugins
-  { ipMap :: Map.Map PluginId (PluginDescriptor ideState)}
-
--- ---------------------------------------------------------------------
-
-data PluginDescriptor ideState =
-  PluginDescriptor { pluginId          :: !PluginId
-                   , pluginRules       :: !(Rules ())
-                   , pluginCommands    :: ![PluginCommand ideState]
-                   , pluginHandlers    :: PluginHandlers ideState
-                   }
-
--- | Methods that can be handled by plugins.
--- 'ExtraParams' captures any extra data the IDE passes to the handlers for this method
--- Only methods for which we know how to combine responses can be instances of 'PluginMethod'
-class HasTracing (MessageParams m) => PluginMethod m where
-
-  -- | Parse the configuration to check if this plugin is enabled
-  pluginEnabled :: SMethod m -> PluginId -> Config -> Bool
-
-  -- | How to combine responses from different plugins
-  combineResponses
-    :: SMethod m
-    -> Config -- ^ IDE Configuration
-    -> ClientCapabilities
-    -> MessageParams m
-    -> NonEmpty (ResponseResult m) -> ResponseResult m
-
-  default combineResponses :: Semigroup (ResponseResult m)
-    => SMethod m -> Config -> ClientCapabilities -> MessageParams m -> NonEmpty (ResponseResult m) -> ResponseResult m
-  combineResponses _method _config _caps _params = sconcat
-
-instance PluginMethod TextDocumentCodeAction where
-  pluginEnabled _ = pluginEnabledConfig plcCodeActionsOn
-  combineResponses _method _config (ClientCapabilities _ textDocCaps _ _) (CodeActionParams _ _ _ _ context) resps =
-      fmap compat $ List $ filter wasRequested $ (\(List x) -> x) $ sconcat resps
-    where
-
-      compat :: (Command |? CodeAction) -> (Command |? CodeAction)
-      compat x@(InL _) = x
-      compat x@(InR action)
-        | Just _ <- textDocCaps >>= _codeAction >>= _codeActionLiteralSupport
-        = x
-        | otherwise = InL cmd
-        where
-          cmd = mkLspCommand "hls" "fallbackCodeAction" (action ^. title) (Just cmdParams)
-          cmdParams = [toJSON (FallbackCodeActionParams (action ^. edit) (action ^. command))]
-
-      wasRequested :: (Command |? CodeAction) -> Bool
-      wasRequested (InL _) = True
-      wasRequested (InR ca)
-        | Nothing <- _only context = True
-        | Just (List allowed) <- _only context
-        , Just caKind <- ca ^. kind = caKind `elem` allowed
-        | otherwise = False
-
-instance PluginMethod TextDocumentCodeLens where
-  pluginEnabled _ = pluginEnabledConfig plcCodeLensOn
-instance PluginMethod TextDocumentRename where
-  pluginEnabled _ = pluginEnabledConfig plcRenameOn
-instance PluginMethod TextDocumentHover where
-  pluginEnabled _ = pluginEnabledConfig plcHoverOn
-  combineResponses _ _ _ _ (catMaybes . toList -> hs) = h
-    where
-      r = listToMaybe $ mapMaybe (^. range) hs
-      h = case foldMap (^. contents) hs of
-            HoverContentsMS (List []) -> Nothing
-            hh                        -> Just $ Hover hh r
-
-instance PluginMethod TextDocumentDocumentSymbol where
-  pluginEnabled _ = pluginEnabledConfig plcSymbolsOn
-  combineResponses _ _ (ClientCapabilities _ tdc _ _) params xs = res
-    where
-      uri' = params ^. textDocument . uri
-      supportsHierarchy = Just True == (tdc >>= _documentSymbol >>= _hierarchicalDocumentSymbolSupport)
-      dsOrSi = fmap toEither xs
-      res
-        | supportsHierarchy = InL $ sconcat $ fmap (either id (fmap siToDs)) dsOrSi
-        | otherwise = InR $ sconcat $ fmap (either (List . concatMap dsToSi) id) dsOrSi
-      siToDs (SymbolInformation name kind dep (Location _uri range) cont)
-        = DocumentSymbol name cont kind dep range range Nothing
-      dsToSi = go Nothing
-      go :: Maybe T.Text -> DocumentSymbol -> [SymbolInformation]
-      go parent ds =
-        let children' :: [SymbolInformation]
-            children' = concatMap (go (Just name')) (fromMaybe mempty (ds ^. children))
-            loc = Location uri' (ds ^. range)
-            name' = ds ^. name
-            si = SymbolInformation name' (ds ^. kind) (ds ^. deprecated) loc parent
-        in [si] <> children'
-
-instance PluginMethod TextDocumentCompletion where
-  pluginEnabled _ = pluginEnabledConfig plcCompletionOn
-  combineResponses _ conf _ _ (toList -> xs) = snd $ consumeCompletionResponse limit $ combine xs
-      where
-        limit = maxCompletions conf
-        combine :: [List CompletionItem |? CompletionList] -> ((List CompletionItem) |? CompletionList)
-        combine cs = go True mempty cs
-
-        go !comp acc [] =
-          InR (CompletionList comp (List $ DList.toList acc))
-        go comp acc (InL (List ls) : rest) =
-          go comp (acc <> DList.fromList ls) rest
-        go comp acc (InR (CompletionList comp' (List ls)) : rest) =
-          go (comp && comp') (acc <> DList.fromList ls) rest
-
-        -- boolean disambiguators
-        isCompleteResponse, isIncompleteResponse :: Bool
-        isIncompleteResponse = True
-        isCompleteResponse = False
-
-        consumeCompletionResponse limit it@(InR (CompletionList _ (List xx))) =
-          case splitAt limit xx of
-            -- consumed all the items, return the result as is
-            (_, []) -> (limit - length xx, it)
-            -- need to crop the response, set the 'isIncomplete' flag
-            (xx', _) -> (0, InR (CompletionList isIncompleteResponse (List xx')))
-        consumeCompletionResponse n (InL (List xx)) =
-          consumeCompletionResponse n (InR (CompletionList isCompleteResponse (List xx)))
-
-instance PluginMethod TextDocumentFormatting where
-  pluginEnabled _ pid conf = (PluginId $ formattingProvider conf) == pid
-  combineResponses _ _ _ _ (x :| _) = x
-
-instance PluginMethod TextDocumentRangeFormatting where
-  pluginEnabled _ pid conf = (PluginId $ formattingProvider conf) == pid
-  combineResponses _ _ _ _ (x :| _) = x
-
--- | Methods which have a PluginMethod instance
-data IdeMethod (m :: Method FromClient Request) = PluginMethod m => IdeMethod (SMethod m)
-instance GEq IdeMethod where
-  geq (IdeMethod a) (IdeMethod b) = geq a b
-instance GCompare IdeMethod where
-  gcompare (IdeMethod a) (IdeMethod b) = gcompare a b
-
--- | Combine handlers for the
-newtype PluginHandler a (m :: Method FromClient Request)
-  = PluginHandler (PluginId -> a -> MessageParams m -> LspM Config (NonEmpty (Either ResponseError (ResponseResult m))))
-
-newtype PluginHandlers a = PluginHandlers (DMap IdeMethod (PluginHandler a))
-
-instance Semigroup (PluginHandlers a) where
-  (PluginHandlers a) <> (PluginHandlers b) = PluginHandlers $ DMap.unionWithKey go a b
-    where
-      go _ (PluginHandler f) (PluginHandler g) = PluginHandler $ \pid ide params ->
-        (<>) <$> f pid ide params <*> g pid ide params
-
-instance Monoid (PluginHandlers a) where
-  mempty = PluginHandlers mempty
-
-type PluginMethodHandler a m = a -> PluginId -> MessageParams m -> LspM Config (Either ResponseError (ResponseResult m))
-
--- | Make a handler for plugins with no extra data
-mkPluginHandler
-  :: PluginMethod m
-  => SClientMethod m
-  -> PluginMethodHandler ideState m
-  -> PluginHandlers ideState
-mkPluginHandler m f = PluginHandlers $ DMap.singleton (IdeMethod m) (PluginHandler f')
-  where
-    f' pid ide params = pure <$> f ide pid params
-
-defaultPluginDescriptor :: PluginId -> PluginDescriptor ideState
-defaultPluginDescriptor plId =
-  PluginDescriptor
-    plId
-    mempty
-    mempty
-    mempty
-
-newtype CommandId = CommandId T.Text
-  deriving (Show, Read, Eq, Ord)
-instance IsString CommandId where
-  fromString = CommandId . T.pack
-
-data PluginCommand ideState = forall a. (FromJSON a) =>
-  PluginCommand { commandId   :: CommandId
-                , commandDesc :: T.Text
-                , commandFunc :: CommandFunction ideState a
-                }
-
--- ---------------------------------------------------------------------
-
-type CommandFunction ideState a
-  = ideState
-  -> a
-  -> LspM Config (Either ResponseError Value)
-
-newtype WithSnippets = WithSnippets Bool
-
--- ---------------------------------------------------------------------
-
-newtype PluginId = PluginId T.Text
-  deriving (Show, Read, Eq, Ord)
-instance IsString PluginId where
-  fromString = PluginId . T.pack
-
-configForPlugin :: Config -> PluginId -> PluginConfig
-configForPlugin config (PluginId plugin)
-    = Map.findWithDefault Data.Default.def plugin (plugins config)
-
--- | Checks that a given plugin is both enabled and the specific feature is
--- enabled
-pluginEnabledConfig :: (PluginConfig -> Bool) -> PluginId -> Config -> Bool
-pluginEnabledConfig f pid config = plcGlobalOn pluginConfig && f pluginConfig
-  where
-    pluginConfig = configForPlugin config pid
-
--- ---------------------------------------------------------------------
-
--- | Format the given Text as a whole or only a @Range@ of it.
--- Range must be relative to the text to format.
--- To format the whole document, read the Text from the file and use 'FormatText'
--- as the FormattingType.
-data FormattingType = FormatText
-                    | FormatRange Range
-
-
-type FormattingMethod m =
-  ( J.HasOptions (MessageParams m) FormattingOptions
-  , J.HasTextDocument (MessageParams m) TextDocumentIdentifier
-  , ResponseResult m ~ List TextEdit
-  )
-
-type FormattingHandler a
-  =  a
-  -> FormattingType
-  -> T.Text
-  -> NormalizedFilePath
-  -> FormattingOptions
-  -> LspM Config (Either ResponseError (List TextEdit))
-
-mkFormattingHandlers :: forall a. FormattingHandler a -> PluginHandlers a
-mkFormattingHandlers f = mkPluginHandler STextDocumentFormatting (provider STextDocumentFormatting)
-                      <> mkPluginHandler STextDocumentRangeFormatting (provider STextDocumentRangeFormatting)
-  where
-    provider :: forall m. FormattingMethod m => SMethod m -> PluginMethodHandler a m
-    provider m ide _pid params
-      | Just nfp <- uriToNormalizedFilePath $ toNormalizedUri uri = do
-        mf <- getVirtualFile $ toNormalizedUri uri
-        case mf of
-          Just vf -> do
-            let typ = case m of
-                  STextDocumentFormatting -> FormatText
-                  STextDocumentRangeFormatting -> FormatRange (params ^. J.range)
-                  _ -> error "mkFormattingHandlers: impossible"
-            f ide typ (virtualFileText vf) nfp opts
-          Nothing -> pure $ Left $ responseError $ T.pack $ "Formatter plugin: could not get file contents for " ++ show uri
-
-      | otherwise = pure $ Left $ responseError $ T.pack $ "Formatter plugin: uriToFilePath failed for: " ++ show uri
-      where
-        uri = params ^. J.textDocument . J.uri
-        opts = params ^. J.options
-
--- ---------------------------------------------------------------------
-
-responseError :: T.Text -> ResponseError
-responseError txt = ResponseError InvalidParams txt Nothing
-
--- ---------------------------------------------------------------------
-
-data FallbackCodeActionParams =
-  FallbackCodeActionParams
-    { fallbackWorkspaceEdit :: Maybe WorkspaceEdit
-    , fallbackCommand       :: Maybe Command
-    }
-  deriving (Generic, ToJSON, FromJSON)
-
--- ---------------------------------------------------------------------
-
-otSetUri :: SpanInFlight -> Uri -> IO ()
-otSetUri sp (Uri t) = setTag sp "uri" (encodeUtf8 t)
-
-class HasTracing a where
-  traceWithSpan :: SpanInFlight -> a -> IO ()
-  traceWithSpan _ _ = pure ()
-
-instance {-# OVERLAPPABLE #-} (HasTextDocument a doc, HasUri doc Uri) => HasTracing a where
-  traceWithSpan sp a = otSetUri sp (a ^. J.textDocument . J.uri)
-
-instance HasTracing Value
-instance HasTracing ExecuteCommandParams
-instance HasTracing DidChangeWatchedFilesParams
-instance HasTracing DidChangeWorkspaceFoldersParams
-instance HasTracing DidChangeConfigurationParams
-instance HasTracing InitializeParams
-instance HasTracing (Maybe InitializedParams)
-instance HasTracing WorkspaceSymbolParams where
-  traceWithSpan sp (WorkspaceSymbolParams _ _ query) = setTag sp "query" (encodeUtf8 query)
-
--- ---------------------------------------------------------------------
-
-{-# NOINLINE pROCESS_ID #-}
-pROCESS_ID :: T.Text
-pROCESS_ID = unsafePerformIO getPid
-
-mkLspCommand :: PluginId -> CommandId -> T.Text -> Maybe [Value] -> Command
-mkLspCommand plid cn title args' = Command title cmdId args
-  where
-    cmdId = mkLspCmdId pROCESS_ID plid cn
-    args = List <$> args'
-
-mkLspCmdId :: T.Text -> PluginId -> CommandId -> T.Text
-mkLspCmdId pid (PluginId plid) (CommandId cid)
-  = pid <> ":" <> plid <> ":" <> cid
-
--- | Get the operating system process id for the running server
--- instance. This should be the same for the lifetime of the instance,
--- and different from that of any other currently running instance.
-getPid :: IO T.Text
-getPid = T.pack . show <$> getProcessID
-
-getProcessID :: IO Int
-installSigUsr1Handler :: IO () -> IO ()
-
-#ifdef mingw32_HOST_OS
-getProcessID = fromIntegral <$> P.getCurrentProcessId
-installSigUsr1Handler _ = return ()
-
-#else
-getProcessID = fromIntegral <$> P.getProcessID
-
-installSigUsr1Handler h = void $ installHandler sigUSR1 (Catch h) Nothing
-#endif
+{-# LANGUAGE BangPatterns         #-}
+{-# LANGUAGE CPP                  #-}
+{-# LANGUAGE ConstraintKinds      #-}
+{-# LANGUAGE DefaultSignatures    #-}
+{-# LANGUAGE DeriveAnyClass       #-}
+{-# LANGUAGE DeriveGeneric        #-}
+{-# LANGUAGE FlexibleContexts     #-}
+{-# LANGUAGE FlexibleInstances    #-}
+{-# LANGUAGE GADTs                #-}
+{-# LANGUAGE OverloadedStrings    #-}
+{-# LANGUAGE PolyKinds            #-}
+{-# LANGUAGE ScopedTypeVariables  #-}
+{-# LANGUAGE TypeFamilies         #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE ViewPatterns         #-}
+
+module Ide.Types
+    where
+
+#ifdef mingw32_HOST_OS
+import qualified System.Win32.Process            as P (getCurrentProcessId)
+#else
+import qualified System.Posix.Process            as P (getProcessID)
+import           System.Posix.Signals
+#endif
+import           Control.Lens                    ((^.))
+import           Control.Monad
+import           Data.Aeson                      hiding (defaultOptions)
+import qualified Data.DList                      as DList
+import qualified Data.Default
+import           Data.Dependent.Map              (DMap)
+import qualified Data.Dependent.Map              as DMap
+import           Data.GADT.Compare
+import           Data.List.NonEmpty              (NonEmpty (..), toList)
+import qualified Data.Map                        as Map
+import           Data.Maybe
+import           Data.Semigroup
+import           Data.String
+import qualified Data.Text                       as T
+import           Data.Text.Encoding              (encodeUtf8)
+import           Development.Shake               hiding (command)
+import           GHC.Generics
+import           Ide.Plugin.Config
+import           Ide.Plugin.Properties
+import           Language.LSP.Server             (LspM, getVirtualFile)
+import           Language.LSP.Types
+import           Language.LSP.Types.Capabilities
+import           Language.LSP.Types.Lens         as J hiding (id)
+import           Language.LSP.VFS
+import           OpenTelemetry.Eventlog
+import           System.IO.Unsafe
+import           Text.Regex.TDFA.Text            ()
+
+-- ---------------------------------------------------------------------
+
+newtype IdePlugins ideState = IdePlugins
+  { ipMap :: [(PluginId, PluginDescriptor ideState)]}
+
+-- ---------------------------------------------------------------------
+
+data PluginDescriptor ideState =
+  PluginDescriptor { pluginId           :: !PluginId
+                   , pluginRules        :: !(Rules ())
+                   , pluginCommands     :: ![PluginCommand ideState]
+                   , pluginHandlers     :: PluginHandlers ideState
+                   , pluginCustomConfig :: CustomConfig
+                   , pluginNotificationHandlers :: PluginNotificationHandlers ideState
+                   }
+
+-- | An existential wrapper of 'Properties', used only for documenting and generating config templates
+data CustomConfig = forall r. CustomConfig (Properties r)
+
+emptyCustomConfig :: CustomConfig
+emptyCustomConfig = CustomConfig emptyProperties
+
+mkCustomConfig :: Properties r -> CustomConfig
+mkCustomConfig = CustomConfig
+
+-- | Methods that can be handled by plugins.
+-- 'ExtraParams' captures any extra data the IDE passes to the handlers for this method
+-- Only methods for which we know how to combine responses can be instances of 'PluginMethod'
+class HasTracing (MessageParams m) => PluginMethod m where
+
+  -- | Parse the configuration to check if this plugin is enabled
+  pluginEnabled :: SMethod m -> PluginId -> Config -> Bool
+
+  -- | How to combine responses from different plugins
+  combineResponses
+    :: SMethod m
+    -> Config -- ^ IDE Configuration
+    -> ClientCapabilities
+    -> MessageParams m
+    -> NonEmpty (ResponseResult m) -> ResponseResult m
+
+  default combineResponses :: Semigroup (ResponseResult m)
+    => SMethod m -> Config -> ClientCapabilities -> MessageParams m -> NonEmpty (ResponseResult m) -> ResponseResult m
+  combineResponses _method _config _caps _params = sconcat
+
+instance PluginMethod TextDocumentCodeAction where
+  pluginEnabled _ = pluginEnabledConfig plcCodeActionsOn
+  combineResponses _method _config (ClientCapabilities _ textDocCaps _ _) (CodeActionParams _ _ _ _ context) resps =
+      fmap compat $ List $ filter wasRequested $ (\(List x) -> x) $ sconcat resps
+    where
+
+      compat :: (Command |? CodeAction) -> (Command |? CodeAction)
+      compat x@(InL _) = x
+      compat x@(InR action)
+        | Just _ <- textDocCaps >>= _codeAction >>= _codeActionLiteralSupport
+        = x
+        | otherwise = InL cmd
+        where
+          cmd = mkLspCommand "hls" "fallbackCodeAction" (action ^. title) (Just cmdParams)
+          cmdParams = [toJSON (FallbackCodeActionParams (action ^. edit) (action ^. command))]
+
+      wasRequested :: (Command |? CodeAction) -> Bool
+      wasRequested (InL _) = True
+      wasRequested (InR ca)
+        | Nothing <- _only context = True
+        | Just (List allowed) <- _only context
+        , Just caKind <- ca ^. kind = caKind `elem` allowed
+        | otherwise = False
+
+instance PluginMethod TextDocumentCodeLens where
+  pluginEnabled _ = pluginEnabledConfig plcCodeLensOn
+instance PluginMethod TextDocumentRename where
+  pluginEnabled _ = pluginEnabledConfig plcRenameOn
+instance PluginMethod TextDocumentHover where
+  pluginEnabled _ = pluginEnabledConfig plcHoverOn
+  combineResponses _ _ _ _ (catMaybes . toList -> hs) = h
+    where
+      r = listToMaybe $ mapMaybe (^. range) hs
+      h = case foldMap (^. contents) hs of
+            HoverContentsMS (List []) -> Nothing
+            hh                        -> Just $ Hover hh r
+
+instance PluginMethod TextDocumentDocumentSymbol where
+  pluginEnabled _ = pluginEnabledConfig plcSymbolsOn
+  combineResponses _ _ (ClientCapabilities _ tdc _ _) params xs = res
+    where
+      uri' = params ^. textDocument . uri
+      supportsHierarchy = Just True == (tdc >>= _documentSymbol >>= _hierarchicalDocumentSymbolSupport)
+      dsOrSi = fmap toEither xs
+      res
+        | supportsHierarchy = InL $ sconcat $ fmap (either id (fmap siToDs)) dsOrSi
+        | otherwise = InR $ sconcat $ fmap (either (List . concatMap dsToSi) id) dsOrSi
+      siToDs (SymbolInformation name kind _tags dep (Location _uri range) cont)
+        = DocumentSymbol name cont kind Nothing dep range range Nothing
+      dsToSi = go Nothing
+      go :: Maybe T.Text -> DocumentSymbol -> [SymbolInformation]
+      go parent ds =
+        let children' :: [SymbolInformation]
+            children' = concatMap (go (Just name')) (fromMaybe mempty (ds ^. children))
+            loc = Location uri' (ds ^. range)
+            name' = ds ^. name
+            si = SymbolInformation name' (ds ^. kind) Nothing (ds ^. deprecated) loc parent
+        in [si] <> children'
+
+instance PluginMethod TextDocumentCompletion where
+  pluginEnabled _ = pluginEnabledConfig plcCompletionOn
+  combineResponses _ conf _ _ (toList -> xs) = snd $ consumeCompletionResponse limit $ combine xs
+      where
+        limit = maxCompletions conf
+        combine :: [List CompletionItem |? CompletionList] -> ((List CompletionItem) |? CompletionList)
+        combine cs = go True mempty cs
+
+        go !comp acc [] =
+          InR (CompletionList comp (List $ DList.toList acc))
+        go comp acc (InL (List ls) : rest) =
+          go comp (acc <> DList.fromList ls) rest
+        go comp acc (InR (CompletionList comp' (List ls)) : rest) =
+          go (comp && comp') (acc <> DList.fromList ls) rest
+
+        -- boolean disambiguators
+        isCompleteResponse, isIncompleteResponse :: Bool
+        isIncompleteResponse = True
+        isCompleteResponse = False
+
+        consumeCompletionResponse limit it@(InR (CompletionList _ (List xx))) =
+          case splitAt limit xx of
+            -- consumed all the items, return the result as is
+            (_, []) -> (limit - length xx, it)
+            -- need to crop the response, set the 'isIncomplete' flag
+            (xx', _) -> (0, InR (CompletionList isIncompleteResponse (List xx')))
+        consumeCompletionResponse n (InL (List xx)) =
+          consumeCompletionResponse n (InR (CompletionList isCompleteResponse (List xx)))
+
+instance PluginMethod TextDocumentFormatting where
+  pluginEnabled _ pid conf = (PluginId $ formattingProvider conf) == pid
+  combineResponses _ _ _ _ (x :| _) = x
+
+instance PluginMethod TextDocumentRangeFormatting where
+  pluginEnabled _ pid conf = (PluginId $ formattingProvider conf) == pid
+  combineResponses _ _ _ _ (x :| _) = x
+
+-- ---------------------------------------------------------------------
+
+-- | Methods which have a PluginMethod instance
+data IdeMethod (m :: Method FromClient Request) = PluginMethod m => IdeMethod (SMethod m)
+instance GEq IdeMethod where
+  geq (IdeMethod a) (IdeMethod b) = geq a b
+instance GCompare IdeMethod where
+  gcompare (IdeMethod a) (IdeMethod b) = gcompare a b
+
+-- | Methods which have a PluginMethod instance
+data IdeNotification (m :: Method FromClient Notification) = HasTracing (MessageParams m) => IdeNotification (SMethod m)
+instance GEq IdeNotification where
+  geq (IdeNotification a) (IdeNotification b) = geq a b
+instance GCompare IdeNotification where
+  gcompare (IdeNotification a) (IdeNotification b) = gcompare a b
+
+-- | Combine handlers for the
+newtype PluginHandler a (m :: Method FromClient Request)
+  = PluginHandler (PluginId -> a -> MessageParams m -> LspM Config (NonEmpty (Either ResponseError (ResponseResult m))))
+
+newtype PluginNotificationHandler a (m :: Method FromClient Notification)
+  = PluginNotificationHandler (PluginId -> a -> MessageParams m -> LspM Config ())
+
+newtype PluginHandlers a             = PluginHandlers             (DMap IdeMethod       (PluginHandler a))
+newtype PluginNotificationHandlers a = PluginNotificationHandlers (DMap IdeNotification (PluginNotificationHandler a))
+instance Semigroup (PluginHandlers a) where
+  (PluginHandlers a) <> (PluginHandlers b) = PluginHandlers $ DMap.unionWithKey go a b
+    where
+      go _ (PluginHandler f) (PluginHandler g) = PluginHandler $ \pid ide params ->
+        (<>) <$> f pid ide params <*> g pid ide params
+
+instance Monoid (PluginHandlers a) where
+  mempty = PluginHandlers mempty
+
+instance Semigroup (PluginNotificationHandlers a) where
+  (PluginNotificationHandlers a) <> (PluginNotificationHandlers b) = PluginNotificationHandlers $ DMap.unionWithKey go a b
+    where
+      go _ (PluginNotificationHandler f) (PluginNotificationHandler g) = PluginNotificationHandler $ \pid ide params ->
+        f pid ide params >> g pid ide params
+
+instance Monoid (PluginNotificationHandlers a) where
+  mempty = PluginNotificationHandlers mempty
+
+type PluginMethodHandler a m = a -> PluginId -> MessageParams m -> LspM Config (Either ResponseError (ResponseResult m))
+
+type PluginNotificationMethodHandler a m = a -> PluginId -> MessageParams m -> LspM Config ()
+
+-- | Make a handler for plugins with no extra data
+mkPluginHandler
+  :: PluginMethod m
+  => SClientMethod m
+  -> PluginMethodHandler ideState m
+  -> PluginHandlers ideState
+mkPluginHandler m f = PluginHandlers $ DMap.singleton (IdeMethod m) (PluginHandler f')
+  where
+    f' pid ide params = pure <$> f ide pid params
+
+-- | Make a handler for plugins with no extra data
+mkPluginNotificationHandler
+  :: HasTracing (MessageParams m)
+  => SClientMethod (m :: Method FromClient Notification)
+  -> PluginNotificationMethodHandler ideState m
+  -> PluginNotificationHandlers ideState
+mkPluginNotificationHandler m f
+    = PluginNotificationHandlers $ DMap.singleton (IdeNotification m) (PluginNotificationHandler f')
+  where
+    f' pid ide = f ide pid
+
+defaultPluginDescriptor :: PluginId -> PluginDescriptor ideState
+defaultPluginDescriptor plId =
+  PluginDescriptor
+    plId
+    mempty
+    mempty
+    mempty
+    emptyCustomConfig
+    mempty
+
+newtype CommandId = CommandId T.Text
+  deriving (Show, Read, Eq, Ord)
+instance IsString CommandId where
+  fromString = CommandId . T.pack
+
+data PluginCommand ideState = forall a. (FromJSON a) =>
+  PluginCommand { commandId   :: CommandId
+                , commandDesc :: T.Text
+                , commandFunc :: CommandFunction ideState a
+                }
+
+-- ---------------------------------------------------------------------
+
+type CommandFunction ideState a
+  = ideState
+  -> a
+  -> LspM Config (Either ResponseError Value)
+
+-- ---------------------------------------------------------------------
+
+newtype PluginId = PluginId T.Text
+  deriving (Show, Read, Eq, Ord)
+instance IsString PluginId where
+  fromString = PluginId . T.pack
+
+configForPlugin :: Config -> PluginId -> PluginConfig
+configForPlugin config (PluginId plugin)
+    = Map.findWithDefault Data.Default.def plugin (plugins config)
+
+-- | Checks that a given plugin is both enabled and the specific feature is
+-- enabled
+pluginEnabledConfig :: (PluginConfig -> Bool) -> PluginId -> Config -> Bool
+pluginEnabledConfig f pid config = plcGlobalOn pluginConfig && f pluginConfig
+  where
+    pluginConfig = configForPlugin config pid
+
+-- ---------------------------------------------------------------------
+
+-- | Format the given Text as a whole or only a @Range@ of it.
+-- Range must be relative to the text to format.
+-- To format the whole document, read the Text from the file and use 'FormatText'
+-- as the FormattingType.
+data FormattingType = FormatText
+                    | FormatRange Range
+
+
+type FormattingMethod m =
+  ( J.HasOptions (MessageParams m) FormattingOptions
+  , J.HasTextDocument (MessageParams m) TextDocumentIdentifier
+  , ResponseResult m ~ List TextEdit
+  )
+
+type FormattingHandler a
+  =  a
+  -> FormattingType
+  -> T.Text
+  -> NormalizedFilePath
+  -> FormattingOptions
+  -> LspM Config (Either ResponseError (List TextEdit))
+
+mkFormattingHandlers :: forall a. FormattingHandler a -> PluginHandlers a
+mkFormattingHandlers f = mkPluginHandler STextDocumentFormatting (provider STextDocumentFormatting)
+                      <> mkPluginHandler STextDocumentRangeFormatting (provider STextDocumentRangeFormatting)
+  where
+    provider :: forall m. FormattingMethod m => SMethod m -> PluginMethodHandler a m
+    provider m ide _pid params
+      | Just nfp <- uriToNormalizedFilePath $ toNormalizedUri uri = do
+        mf <- getVirtualFile $ toNormalizedUri uri
+        case mf of
+          Just vf -> do
+            let typ = case m of
+                  STextDocumentFormatting -> FormatText
+                  STextDocumentRangeFormatting -> FormatRange (params ^. J.range)
+                  _ -> error "mkFormattingHandlers: impossible"
+            f ide typ (virtualFileText vf) nfp opts
+          Nothing -> pure $ Left $ responseError $ T.pack $ "Formatter plugin: could not get file contents for " ++ show uri
+
+      | otherwise = pure $ Left $ responseError $ T.pack $ "Formatter plugin: uriToFilePath failed for: " ++ show uri
+      where
+        uri = params ^. J.textDocument . J.uri
+        opts = params ^. J.options
+
+-- ---------------------------------------------------------------------
+
+responseError :: T.Text -> ResponseError
+responseError txt = ResponseError InvalidParams txt Nothing
+
+-- ---------------------------------------------------------------------
+
+data FallbackCodeActionParams =
+  FallbackCodeActionParams
+    { fallbackWorkspaceEdit :: Maybe WorkspaceEdit
+    , fallbackCommand       :: Maybe Command
+    }
+  deriving (Generic, ToJSON, FromJSON)
+
+-- ---------------------------------------------------------------------
+
+otSetUri :: SpanInFlight -> Uri -> IO ()
+otSetUri sp (Uri t) = setTag sp "uri" (encodeUtf8 t)
+
+class HasTracing a where
+  traceWithSpan :: SpanInFlight -> a -> IO ()
+  traceWithSpan _ _ = pure ()
+
+instance {-# OVERLAPPABLE #-} (HasTextDocument a doc, HasUri doc Uri) => HasTracing a where
+  traceWithSpan sp a = otSetUri sp (a ^. J.textDocument . J.uri)
+
+instance HasTracing Value
+instance HasTracing ExecuteCommandParams
+instance HasTracing DidChangeWatchedFilesParams
+instance HasTracing DidChangeWorkspaceFoldersParams
+instance HasTracing DidChangeConfigurationParams
+instance HasTracing InitializeParams
+instance HasTracing (Maybe InitializedParams)
+instance HasTracing WorkspaceSymbolParams where
+  traceWithSpan sp (WorkspaceSymbolParams _ _ query) = setTag sp "query" (encodeUtf8 query)
+
+-- ---------------------------------------------------------------------
+
+{-# NOINLINE pROCESS_ID #-}
+pROCESS_ID :: T.Text
+pROCESS_ID = unsafePerformIO getPid
+
+mkLspCommand :: PluginId -> CommandId -> T.Text -> Maybe [Value] -> Command
+mkLspCommand plid cn title args' = Command title cmdId args
+  where
+    cmdId = mkLspCmdId pROCESS_ID plid cn
+    args = List <$> args'
+
+mkLspCmdId :: T.Text -> PluginId -> CommandId -> T.Text
+mkLspCmdId pid (PluginId plid) (CommandId cid)
+  = pid <> ":" <> plid <> ":" <> cid
+
+-- | Get the operating system process id for the running server
+-- instance. This should be the same for the lifetime of the instance,
+-- and different from that of any other currently running instance.
+getPid :: IO T.Text
+getPid = T.pack . show <$> getProcessID
+
+getProcessID :: IO Int
+installSigUsr1Handler :: IO () -> IO ()
+
+#ifdef mingw32_HOST_OS
+getProcessID = fromIntegral <$> P.getCurrentProcessId
+installSigUsr1Handler _ = return ()
+
+#else
+getProcessID = fromIntegral <$> P.getProcessID
+
+installSigUsr1Handler h = void $ installHandler sigUSR1 (Catch h) Nothing
+#endif
