diff --git a/ChangeLog.md b/ChangeLog.md new file mode 100644 --- /dev/null +++ b/ChangeLog.md @@ -0,0 +1,14 @@ +# Changelog for webgear-server + +## Unreleased changes + +## [0.1.0] - 2020-08-16 + +### Added + +- Support basic traits and middlewares +- Automated tests +- Documentation + +[0.1.0]: https://github.com/rkaippully/webgear/compare/0.0.0...0.1.0 +[Unreleased]: https://github.com/rkaippully/webgear/compare/0.1.0...HEAD diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,373 @@ +Mozilla Public License Version 2.0 +================================== + +1. Definitions +-------------- + +1.1. "Contributor" + means each individual or legal entity that creates, contributes to + the creation of, or owns Covered Software. + +1.2. "Contributor Version" + means the combination of the Contributions of others (if any) used + by a Contributor and that particular Contributor's Contribution. + +1.3. "Contribution" + means Covered Software of a particular Contributor. + +1.4. "Covered Software" + means Source Code Form to which the initial Contributor has attached + the notice in Exhibit A, the Executable Form of such Source Code + Form, and Modifications of such Source Code Form, in each case + including portions thereof. + +1.5. "Incompatible With Secondary Licenses" + means + + (a) that the initial Contributor has attached the notice described + in Exhibit B to the Covered Software; or + + (b) that the Covered Software was made available under the terms of + version 1.1 or earlier of the License, but not also under the + terms of a Secondary License. + +1.6. "Executable Form" + means any form of the work other than Source Code Form. + +1.7. "Larger Work" + means a work that combines Covered Software with other material, in + a separate file or files, that is not Covered Software. + +1.8. "License" + means this document. + +1.9. "Licensable" + means having the right to grant, to the maximum extent possible, + whether at the time of the initial grant or subsequently, any and + all of the rights conveyed by this License. + +1.10. "Modifications" + means any of the following: + + (a) any file in Source Code Form that results from an addition to, + deletion from, or modification of the contents of Covered + Software; or + + (b) any new file in Source Code Form that contains any Covered + Software. + +1.11. "Patent Claims" of a Contributor + means any patent claim(s), including without limitation, method, + process, and apparatus claims, in any patent Licensable by such + Contributor that would be infringed, but for the grant of the + License, by the making, using, selling, offering for sale, having + made, import, or transfer of either its Contributions or its + Contributor Version. + +1.12. "Secondary License" + means either the GNU General Public License, Version 2.0, the GNU + Lesser General Public License, Version 2.1, the GNU Affero General + Public License, Version 3.0, or any later versions of those + licenses. + +1.13. "Source Code Form" + means the form of the work preferred for making modifications. + +1.14. "You" (or "Your") + means an individual or a legal entity exercising rights under this + License. For legal entities, "You" includes any entity that + controls, is controlled by, or is under common control with You. For + purposes of this definition, "control" means (a) the power, direct + or indirect, to cause the direction or management of such entity, + whether by contract or otherwise, or (b) ownership of more than + fifty percent (50%) of the outstanding shares or beneficial + ownership of such entity. + +2. License Grants and Conditions +-------------------------------- + +2.1. Grants + +Each Contributor hereby grants You a world-wide, royalty-free, +non-exclusive license: + +(a) under intellectual property rights (other than patent or trademark) + Licensable by such Contributor to use, reproduce, make available, + modify, display, perform, distribute, and otherwise exploit its + Contributions, either on an unmodified basis, with Modifications, or + as part of a Larger Work; and + +(b) under Patent Claims of such Contributor to make, use, sell, offer + for sale, have made, import, and otherwise transfer either its + Contributions or its Contributor Version. + +2.2. Effective Date + +The licenses granted in Section 2.1 with respect to any Contribution +become effective for each Contribution on the date the Contributor first +distributes such Contribution. + +2.3. Limitations on Grant Scope + +The licenses granted in this Section 2 are the only rights granted under +this License. No additional rights or licenses will be implied from the +distribution or licensing of Covered Software under this License. +Notwithstanding Section 2.1(b) above, no patent license is granted by a +Contributor: + +(a) for any code that a Contributor has removed from Covered Software; + or + +(b) for infringements caused by: (i) Your and any other third party's + modifications of Covered Software, or (ii) the combination of its + Contributions with other software (except as part of its Contributor + Version); or + +(c) under Patent Claims infringed by Covered Software in the absence of + its Contributions. + +This License does not grant any rights in the trademarks, service marks, +or logos of any Contributor (except as may be necessary to comply with +the notice requirements in Section 3.4). + +2.4. Subsequent Licenses + +No Contributor makes additional grants as a result of Your choice to +distribute the Covered Software under a subsequent version of this +License (see Section 10.2) or under the terms of a Secondary License (if +permitted under the terms of Section 3.3). + +2.5. Representation + +Each Contributor represents that the Contributor believes its +Contributions are its original creation(s) or it has sufficient rights +to grant the rights to its Contributions conveyed by this License. + +2.6. Fair Use + +This License is not intended to limit any rights You have under +applicable copyright doctrines of fair use, fair dealing, or other +equivalents. + +2.7. Conditions + +Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted +in Section 2.1. + +3. Responsibilities +------------------- + +3.1. Distribution of Source Form + +All distribution of Covered Software in Source Code Form, including any +Modifications that You create or to which You contribute, must be under +the terms of this License. You must inform recipients that the Source +Code Form of the Covered Software is governed by the terms of this +License, and how they can obtain a copy of this License. You may not +attempt to alter or restrict the recipients' rights in the Source Code +Form. + +3.2. Distribution of Executable Form + +If You distribute Covered Software in Executable Form then: + +(a) such Covered Software must also be made available in Source Code + Form, as described in Section 3.1, and You must inform recipients of + the Executable Form how they can obtain a copy of such Source Code + Form by reasonable means in a timely manner, at a charge no more + than the cost of distribution to the recipient; and + +(b) You may distribute such Executable Form under the terms of this + License, or sublicense it under different terms, provided that the + license for the Executable Form does not attempt to limit or alter + the recipients' rights in the Source Code Form under this License. + +3.3. Distribution of a Larger Work + +You may create and distribute a Larger Work under terms of Your choice, +provided that You also comply with the requirements of this License for +the Covered Software. If the Larger Work is a combination of Covered +Software with a work governed by one or more Secondary Licenses, and the +Covered Software is not Incompatible With Secondary Licenses, this +License permits You to additionally distribute such Covered Software +under the terms of such Secondary License(s), so that the recipient of +the Larger Work may, at their option, further distribute the Covered +Software under the terms of either this License or such Secondary +License(s). + +3.4. Notices + +You may not remove or alter the substance of any license notices +(including copyright notices, patent notices, disclaimers of warranty, +or limitations of liability) contained within the Source Code Form of +the Covered Software, except that You may alter any license notices to +the extent required to remedy known factual inaccuracies. + +3.5. Application of Additional Terms + +You may choose to offer, and to charge a fee for, warranty, support, +indemnity or liability obligations to one or more recipients of Covered +Software. However, You may do so only on Your own behalf, and not on +behalf of any Contributor. You must make it absolutely clear that any +such warranty, support, indemnity, or liability obligation is offered by +You alone, and You hereby agree to indemnify every Contributor for any +liability incurred by such Contributor as a result of warranty, support, +indemnity or liability terms You offer. You may include additional +disclaimers of warranty and limitations of liability specific to any +jurisdiction. + +4. Inability to Comply Due to Statute or Regulation +--------------------------------------------------- + +If it is impossible for You to comply with any of the terms of this +License with respect to some or all of the Covered Software due to +statute, judicial order, or regulation then You must: (a) comply with +the terms of this License to the maximum extent possible; and (b) +describe the limitations and the code they affect. Such description must +be placed in a text file included with all distributions of the Covered +Software under this License. Except to the extent prohibited by statute +or regulation, such description must be sufficiently detailed for a +recipient of ordinary skill to be able to understand it. + +5. Termination +-------------- + +5.1. The rights granted under this License will terminate automatically +if You fail to comply with any of its terms. However, if You become +compliant, then the rights granted under this License from a particular +Contributor are reinstated (a) provisionally, unless and until such +Contributor explicitly and finally terminates Your grants, and (b) on an +ongoing basis, if such Contributor fails to notify You of the +non-compliance by some reasonable means prior to 60 days after You have +come back into compliance. Moreover, Your grants from a particular +Contributor are reinstated on an ongoing basis if such Contributor +notifies You of the non-compliance by some reasonable means, this is the +first time You have received notice of non-compliance with this License +from such Contributor, and You become compliant prior to 30 days after +Your receipt of the notice. + +5.2. If You initiate litigation against any entity by asserting a patent +infringement claim (excluding declaratory judgment actions, +counter-claims, and cross-claims) alleging that a Contributor Version +directly or indirectly infringes any patent, then the rights granted to +You by any and all Contributors for the Covered Software under Section +2.1 of this License shall terminate. + +5.3. In the event of termination under Sections 5.1 or 5.2 above, all +end user license agreements (excluding distributors and resellers) which +have been validly granted by You or Your distributors under this License +prior to termination shall survive termination. + +************************************************************************ +* * +* 6. Disclaimer of Warranty * +* ------------------------- * +* * +* Covered Software is provided under this License on an "as is" * +* basis, without warranty of any kind, either expressed, implied, or * +* statutory, including, without limitation, warranties that the * +* Covered Software is free of defects, merchantable, fit for a * +* particular purpose or non-infringing. The entire risk as to the * +* quality and performance of the Covered Software is with You. * +* Should any Covered Software prove defective in any respect, You * +* (not any Contributor) assume the cost of any necessary servicing, * +* repair, or correction. This disclaimer of warranty constitutes an * +* essential part of this License. No use of any Covered Software is * +* authorized under this License except under this disclaimer. * +* * +************************************************************************ + +************************************************************************ +* * +* 7. Limitation of Liability * +* -------------------------- * +* * +* Under no circumstances and under no legal theory, whether tort * +* (including negligence), contract, or otherwise, shall any * +* Contributor, or anyone who distributes Covered Software as * +* permitted above, be liable to You for any direct, indirect, * +* special, incidental, or consequential damages of any character * +* including, without limitation, damages for lost profits, loss of * +* goodwill, work stoppage, computer failure or malfunction, or any * +* and all other commercial damages or losses, even if such party * +* shall have been informed of the possibility of such damages. This * +* limitation of liability shall not apply to liability for death or * +* personal injury resulting from such party's negligence to the * +* extent applicable law prohibits such limitation. Some * +* jurisdictions do not allow the exclusion or limitation of * +* incidental or consequential damages, so this exclusion and * +* limitation may not apply to You. * +* * +************************************************************************ + +8. Litigation +------------- + +Any litigation relating to this License may be brought only in the +courts of a jurisdiction where the defendant maintains its principal +place of business and such litigation shall be governed by laws of that +jurisdiction, without reference to its conflict-of-law provisions. +Nothing in this Section shall prevent a party's ability to bring +cross-claims or counter-claims. + +9. Miscellaneous +---------------- + +This License represents the complete agreement concerning the subject +matter hereof. If any provision of this License is held to be +unenforceable, such provision shall be reformed only to the extent +necessary to make it enforceable. Any law or regulation which provides +that the language of a contract shall be construed against the drafter +shall not be used to construe this License against a Contributor. + +10. Versions of the License +--------------------------- + +10.1. New Versions + +Mozilla Foundation is the license steward. Except as provided in Section +10.3, no one other than the license steward has the right to modify or +publish new versions of this License. Each version will be given a +distinguishing version number. + +10.2. Effect of New Versions + +You may distribute the Covered Software under the terms of the version +of the License under which You originally received the Covered Software, +or under the terms of any subsequent version published by the license +steward. + +10.3. Modified Versions + +If you create software not governed by this License, and you want to +create a new license for such software, you may create and use a +modified version of this License if you rename the license and remove +any references to the name of the license steward (except to note that +such modified license differs from this License). + +10.4. Distributing Source Code Form that is Incompatible With Secondary +Licenses + +If You choose to distribute Source Code Form that is Incompatible With +Secondary Licenses under the terms of this version of the License, the +notice described in Exhibit B of this License must be attached. + +Exhibit A - Source Code Form License Notice +------------------------------------------- + + This Source Code Form is subject to the terms of the Mozilla Public + License, v. 2.0. If a copy of the MPL was not distributed with this + file, You can obtain one at http://mozilla.org/MPL/2.0/. + +If it is not possible or desirable to put the notice in a particular +file, then You may include the notice in a location (such as a LICENSE +file in a relevant directory) where a recipient would be likely to look +for such a notice. + +You may add additional accurate notices of copyright ownership. + +Exhibit B - "Incompatible With Secondary Licenses" Notice +--------------------------------------------------------- + + This Source Code Form is "Incompatible With Secondary Licenses", as + defined by the Mozilla Public License, v. 2.0. diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,9 @@ +# WebGear - HTTP API server + +[![Hackage](https://img.shields.io/hackage/v/webgear-server)](https://hackage.haskell.org/package/webgear-server) +[![Build Status](https://img.shields.io/github/workflow/status/rkaippully/webgear/Haskell%20CI/master)](https://github.com/rkaippully/webgear/actions?query=workflow%3A%22Haskell+CI%22+branch%3Amaster) + +WebGear is a Haskell library for building composable, type-safe HTTP API servers. It focuses on good documentation and +usability. + +See the documentation of WebGear module to get started. diff --git a/src/WebGear.hs b/src/WebGear.hs new file mode 100644 --- /dev/null +++ b/src/WebGear.hs @@ -0,0 +1,243 @@ +{-# OPTIONS_GHC -Wno-unused-imports #-} +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- WebGear helps to build composable, type-safe HTTP API servers. +-- +-- The documentation below gives an overview of WebGear. Example +-- programs built using WebGear are available at +-- https://github.com/rkaippully/webgear/tree/master/webgear-examples. +-- +module WebGear + ( -- * Serving HTTP APIs + -- $serving + + -- * Traits and Linking + -- $traits + + -- * Handlers + -- $handlers + + -- * Middlewares + -- $middlewares + + -- * Routing + -- $routing + + -- * Running the Server + -- $running + ) where + +import Control.Applicative (Alternative (..)) +import Control.Arrow (Kleisli (..)) +import Web.HttpApiData (FromHttpApiData) + +import qualified Network.Wai as Wai + +import WebGear.Middlewares +import WebGear.Route +import WebGear.Trait +import WebGear.Trait.Body +import WebGear.Trait.Header +import WebGear.Trait.Method +import WebGear.Trait.Path +import WebGear.Types + + +-- +-- $serving +-- +-- An HTTP API server handler can be thought of as a function that +-- takes a request as input and produces a response as output in a +-- monadic context. +-- +-- @ +-- handler :: Monad m => 'Request' -> m 'Response' +-- @ +-- +-- Most APIs will require extracting some information from the +-- request, processing it and then producing a response. For example, +-- the server might require access to some HTTP header values, query +-- parameters, or the request body. WebGear allows to access such +-- information using traits. +-- +-- +-- $traits +-- +-- A trait is an attribute associated with a value. For example, a +-- @Request@ might have a header that we are interested in; the +-- 'Header' trait represents that. All traits have instances of +-- 'Trait' typeclass. This typeclass helps to 'check' the presence of +-- the trait. It also has two associated types - 'Val' and 'Fail' - to +-- represent the result of 'check'ing the presence of a trait. +-- +-- For example, the 'Header' trait has an instance of the 'Trait' +-- typeclass. The 'check' function evaluates to a 'CheckSuccess' value +-- if the header exists and can be converted to an attribute via the +-- 'FromHttpApiData' typeclass. Otherwise, it evaluates to a +-- 'CheckFail' value. +-- +-- WebGear provides type-safety by linking traits to the request or +-- response at type level. The 'Linked' data type associates a +-- 'Request' or 'Response' with a list of traits. This linking +-- guarantees that the Request or Response has the specified trait. +-- +-- These functions work with traits and linked values: +-- +-- * 'linkzero': Establish a link between a value and an empty list +-- of traits. This always succeeds. +-- * 'linkplus': Attempts to establish a link between a linked value +-- with an additional trait. +-- * 'linkminus': Removes a trait from the list of linked traits. +-- * 'unlink': Convert a linked value to a regular value without any +-- type-level traits. +-- * 'traitValue': Extract a 'Val' associated with a trait from a +-- linked value. +-- +-- For example, we make use of the @'Method' \@GET@ trait to ensure +-- that our handler is called only for GET requests. We can link a +-- request value with this trait using: +-- +-- @ +-- linkedRequest :: Monad m => 'Request' -> m (Either 'MethodMismatch' ('Linked' '['Method' GET] 'Request')) +-- linkedRequest = 'linkplus' @('Method' GET) . 'linkzero' +-- @ +-- +-- Let us modify the type signature of our handler to use linked +-- values instead of regular values: +-- +-- > handler :: Monad m => Linked req Request -> m (Linked res Response) +-- +-- Here, @req@ is a type-level list of traits associated with the +-- @Request@ that this handler requires and @res@ is a type-level list +-- of traits associated with the @Response@ that this handler will +-- produce. This implies that this handler can be called only with a +-- request possessing certain traits and it is guaranteed to produce a +-- response having certain traits. +-- +-- +-- $handlers +-- +-- Handlers in WebGear are defined with a type very similar to the +-- above. +-- +-- @ +-- type 'Handler' m req res a = 'Kleisli' m ('Linked' req 'Request') ('Linked' res ('Response' a)) +-- @ +-- +-- It is a 'Kleisli' arrow as described in the above section with +-- type-level trait lists. However, the response is parameterized by +-- the type variable @a@, which represents the type of the response +-- body. +-- +-- A handler can extract some trait attribute of a request with the +-- 'traitValue' function. It can also use 'linkplus' function to prove +-- the presence of traits in the response before returning it. +-- +-- +-- $middlewares +-- +-- A middleware is a higher-order function that takes a handler as +-- input and produces another handler with potentially different lists +-- of request and response traits. Thus middlewares can augment the +-- functionality of another handler. +-- +-- For example, here is the definition of the 'method' middleware: +-- +-- @ +-- method :: ('IsStdMethod' t, 'MonadRouter' m) => 'Handler' m ('Method' t:req) res a -> 'Handler' m req res a +-- method handler = 'Kleisli' $ 'linkplus' \@('Method' t) >=> 'either' ('const' 'rejectRoute') ('runKleisli' handler) +-- @ +-- +-- The @linkplus \@(Method t)@ function is used to prove the presence +-- of the method @t@ in the request and the @handler@ is invoked only +-- if the method matches. In case of a mismatch, this route is +-- rejected by calling 'rejectRoute'. +-- +-- Many middlewares can be composed to form complex request handling +-- logic. +-- +-- @ +-- putUser = 'method' \@PUT +-- $ 'requestContentType' \@"application/json" +-- $ 'jsonRequestBody' \@User +-- $ 'jsonResponseBody' \@User +-- $ putUserHandler +-- @ +-- +-- +-- $routing +-- +-- A typical server will have many routes and we would like to pick +-- one based on the URL path, HTTP method etc. We need a couple of +-- things to achieve this. +-- +-- First, we need a way to indicate that a handler cannot handle a +-- request, possibly because the path or method did not match with +-- what was expected. This is achieved by the 'rejectRoute' function: +-- +-- @ +-- class (Alternative m, MonadPlus m) => 'MonadRouter' m where +-- 'rejectRoute' :: m a +-- 'failHandler' :: 'Response' ByteString -> m a +-- @ +-- +-- The 'failHandler' can be used in cases where we find a matching +-- route but the request handling is aborted for some reason. For +-- example, if a route requires the request Content-type header to +-- have a particular value but the actual request had a different +-- Content-type, 'failHandler' can be used to abort and return an +-- error response. +-- +-- Second, we need a mechanism to try an alternate route when one +-- route is rejected. Since 'MonadRouter' is an 'Alternative', we can +-- use '<|>' to combine many routes. When a request arrives, a match +-- will be attempted against each route sequentially and the first +-- matching route handler will process the request. Here is an +-- example: +-- +-- @ +-- allRoutes :: 'MonadRouter' m => 'Handler' m '[] '[] ByteString +-- allRoutes = ['match'| v1\/users\/userId:Int |] -- non-TH version: 'path' \@"v1/users" . 'pathVar' \@"userId" \@Int +-- $ getUser \<|\> putUser \<|\> deleteUser +-- +-- type IntUserId = 'PathVar' "userId" Int +-- +-- getUser :: ('MonadRouter' m, 'Has' IntUserId req) => 'Handler' m req '[] ByteString +-- getUser = 'method' \@GET getUserHandler +-- +-- putUser :: ('MonadRouter' m, 'Has' IntUserId req) => 'Handler' m req '[] ByteString +-- putUser = 'method' \@PUT +-- $ 'requestContentType' \@"application/json" +-- $ 'jsonRequestBody' \@User +-- $ putUserHandler +-- +-- deleteUser :: ('MonadRouter' m, 'Has' IntUserId req) => 'Handler' m req '[] ByteString +-- deleteUser = 'method' \@DELETE deleteUserHandler +-- @ +-- +-- +-- $running +-- +-- Routable handlers can be converted to a regular function using +-- 'runRoute': +-- +-- @ +-- runRoute :: Monad m => 'Handler' (RouterT m) '[] res ByteString -> ('Wai.Request' -> m 'Wai.Response') +-- @ +-- +-- This function converts a WebGear handler to a function from +-- 'Wai.Request' to 'Wai.Response' in a monadic context @m@. Then it +-- is trivial to convert that to a WAI 'Wai.Application' and run it as a +-- warp server: +-- +-- @ +-- application :: 'Wai.Application' +-- application req respond = 'runRoute' allRoutes req >>= respond +-- +-- main :: IO () +-- main = Warp.run 3000 application +-- @ +-- diff --git a/src/WebGear/Middlewares.hs b/src/WebGear/Middlewares.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Middlewares.hs @@ -0,0 +1,46 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Middlewares provided by WebGear. +-- +module WebGear.Middlewares + ( ok + , noContent + , badRequest + , notFound + + , module WebGear.Middlewares.Method + , module WebGear.Middlewares.Path + , module WebGear.Middlewares.Header + , module WebGear.Middlewares.Body + ) where + +import Data.String (IsString) + +import WebGear.Middlewares.Body +import WebGear.Middlewares.Header +import WebGear.Middlewares.Method +import WebGear.Middlewares.Path +import WebGear.Trait (Linked, linkzero) +import WebGear.Types (Response (..)) + +import qualified Network.HTTP.Types as HTTP + + +-- | Respond with a 200 OK +ok :: Monad m => a -> m (Linked '[] (Response a)) +ok = pure . linkzero . Response HTTP.ok200 mempty . Just + +-- | Respond with a 400 Bad Request +badRequest :: Monad m => m (Linked '[] (Response a)) +badRequest = pure $ linkzero $ Response HTTP.badRequest400 mempty Nothing + +-- | Respond with a 404 NotFound +notFound :: Monad m => m (Linked '[] (Response a)) +notFound = pure $ linkzero $ Response HTTP.notFound404 mempty Nothing + +-- | Respond with a 204 NoContent +noContent :: (Monad m, IsString s) => m (Linked '[] (Response s)) +noContent = pure $ linkzero $ Response HTTP.noContent204 mempty $ Just "" diff --git a/src/WebGear/Middlewares/Body.hs b/src/WebGear/Middlewares/Body.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Middlewares/Body.hs @@ -0,0 +1,64 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Middlewares related to HTTP body. +module WebGear.Middlewares.Body + ( jsonRequestBody + , jsonResponseBody + ) where + +import Control.Arrow (Kleisli (..)) +import Control.Monad ((>=>)) +import Control.Monad.IO.Class (MonadIO) +import Data.Aeson (FromJSON, ToJSON, encode) +import Data.ByteString.Lazy (ByteString, fromStrict) +import Data.HashMap.Strict (fromList, insert) +import Data.Text (Text) +import Data.Text.Encoding (encodeUtf8) +import Network.HTTP.Types (badRequest400, hContentType) + +import WebGear.Route (MonadRouter (..)) +import WebGear.Trait (linkplus, linkzero, unlink) +import WebGear.Trait.Body (JSONRequestBody) +import WebGear.Types (Middleware, RequestMiddleware, Response (..)) + + +-- | A middleware to parse the request body as JSON and convert it to +-- a value via a 'FromJSON' instance. +-- +-- Usage for a type @t@ which has a 'FromJSON' instance: +-- +-- > jsonRequestBody @t handler +-- +jsonRequestBody :: forall t m req res a. (FromJSON t, MonadRouter m, MonadIO m) + => RequestMiddleware m req (JSONRequestBody t:req) res a +jsonRequestBody handler = Kleisli $ + linkplus @(JSONRequestBody t) >=> either (failHandler . mkError) (runKleisli handler) + where + mkError :: Text -> Response ByteString + mkError e = Response + { respStatus = badRequest400 + , respHeaders = fromList [] + , respBody = Just $ fromStrict $ encodeUtf8 $ "Error parsing request body: " <> e + } + +-- | A middleware that converts the response that has a 'ToJSON' +-- instance to a 'ByteString' response. +-- +-- This will also set the "Content-Type" header of the response to +-- "application/json". +-- +-- Usage for a type @t@ which has a 'ToJSON' instance: +-- +-- > jsonResponseBody @t handler +-- +jsonResponseBody :: (ToJSON t, Monad m) => Middleware m req req res '[] t ByteString +jsonResponseBody handler = Kleisli $ \req -> do + x <- unlink <$> runKleisli handler req + pure $ linkzero $ Response + { respStatus = respStatus x + , respHeaders = insert hContentType "application/json" $ respHeaders x + , respBody = encode <$> respBody x + } diff --git a/src/WebGear/Middlewares/Header.hs b/src/WebGear/Middlewares/Header.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Middlewares/Header.hs @@ -0,0 +1,47 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Middlewares related to HTTP headers. +module WebGear.Middlewares.Header + ( requestContentType + ) where + +import Control.Arrow (Kleisli (..)) +import Control.Monad ((>=>)) +import Data.ByteString.Lazy (ByteString) +import Data.HashMap.Strict (fromList) +import Data.String (fromString) +import GHC.TypeLits (KnownSymbol) +import Network.HTTP.Types (badRequest400) +import Text.Printf (printf) + +import WebGear.Route (MonadRouter (..)) +import WebGear.Trait (linkplus) +import WebGear.Trait.Header (HeaderMatch, HeaderMismatch (..)) +import WebGear.Types (RequestMiddleware, Response (..)) + + +-- | A middleware to check that the Content-Type header in the request +-- has a specific value. It will fail the handler if the header did +-- not match. +-- +-- Typical usage: +-- +-- > requestContentType @"application/json" handler +-- +requestContentType :: forall c m req res a. (KnownSymbol c, MonadRouter m) + => RequestMiddleware m req (HeaderMatch "Content-Type" c:req) res a +requestContentType handler = Kleisli $ + linkplus @(HeaderMatch "Content-Type" c) >=> either (failHandler . mkError) (runKleisli handler) + where + mkError :: HeaderMismatch -> Response ByteString + mkError err = Response + { respStatus = badRequest400 + , respHeaders = fromList [] + , respBody = Just $ fromString $ + case (expectedHeader err, actualHeader err) of + (ex, Nothing) -> printf "Expected Content-Type header %s but not found" (show ex) + (ex, Just h) -> printf "Expected Content-Type header %s but found %s" (show ex) (show h) + } diff --git a/src/WebGear/Middlewares/Method.hs b/src/WebGear/Middlewares/Method.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Middlewares/Method.hs @@ -0,0 +1,32 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Middlewares related to HTTP methods. +module WebGear.Middlewares.Method + ( method + ) where + +import Control.Arrow (Kleisli (..)) +import Control.Monad ((>=>)) + +import WebGear.Route (MonadRouter (..)) +import WebGear.Trait (linkplus) +import WebGear.Trait.Method (IsStdMethod, Method) +import WebGear.Types (RequestMiddleware) + + +-- | A middleware to check whether the request has a specified HTTP +-- method. +-- +-- Typically this would be used with a type application such as: +-- +-- > method @GET handler +-- +-- It is also idiomatic to use the template haskell quasiquoter +-- 'WebGear.Middlewares.Path.match' in cases where both HTTP method +-- and path needs to be matched. +method :: forall t m req res a. (IsStdMethod t, MonadRouter m) + => RequestMiddleware m req (Method t:req) res a +method handler = Kleisli $ linkplus @(Method t) >=> either (const rejectRoute) (runKleisli handler) diff --git a/src/WebGear/Middlewares/Path.hs b/src/WebGear/Middlewares/Path.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Middlewares/Path.hs @@ -0,0 +1,115 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Middlewares related to route paths. +module WebGear.Middlewares.Path + ( path + , pathVar + , match + ) where + +import Control.Arrow (Kleisli (..)) +import Control.Monad ((>=>)) +import Data.Function ((&)) +import Data.List.NonEmpty (NonEmpty (..), toList) +import GHC.TypeLits (KnownSymbol) +import Language.Haskell.TH.Quote (QuasiQuoter (..)) +import Language.Haskell.TH.Syntax (Exp (..), Q, TyLit (..), Type (..), mkName) +import Web.HttpApiData (FromHttpApiData) + +import WebGear.Middlewares.Method (method) +import WebGear.Route (MonadRouter (..)) +import WebGear.Trait (linkplus) +import WebGear.Trait.Path (Path, PathVar) +import WebGear.Types (RequestMiddleware) +import WebGear.Util (splitOn) + +import qualified Data.List as List + + +-- | A middleware that literally matches path @s@. +-- +-- The symbol @s@ could contain one or more parts separated by a +-- forward slash character. The route will be rejected if there is no +-- match. +-- +-- For example, the following code could be used to match the URL path +-- \"a\/b\/c\" and then invoke @handler@: +-- +-- > path @"a/b/c" handler +-- +path :: forall s ts res m a. (KnownSymbol s, MonadRouter m) + => RequestMiddleware m ts (Path s:ts) res a +path handler = Kleisli $ + linkplus @(Path s) >=> either (const rejectRoute) (runKleisli handler) + +-- | A middleware that captures a path variable from a single path +-- component. +-- +-- The value captured is converted to a value of type @val@ via +-- 'FromHttpApiData'. The route will be rejected if the value is not +-- found or cannot be converted. +-- +-- For example, the following code could be used to read a path +-- component as 'Int' tagged with the symbol \"objId\", and then +-- invoke @handler@: +-- +-- > pathVar @"objId" @Int handler +-- +pathVar :: forall tag val ts res m a. (FromHttpApiData val, MonadRouter m) + => RequestMiddleware m ts (PathVar tag val:ts) res a +pathVar handler = Kleisli $ + linkplus @(PathVar tag val) >=> either (const rejectRoute) (runKleisli handler) + +-- | Produces middleware(s) to match an optional HTTP method and path. +-- +-- This quasiquoter can be used in several ways: +-- +-- * @[match|a\/b\/c]@ is equivalent to @'path' \@\"a\/b\/c\"@ +-- * @[match|a\/b\/objId:Int\/d]@ is equivalent to +-- @'path' \@\"a\/b\" . 'pathVar' \@\"objId\" \@Int . 'path' @\"d\"@ +-- * @[match|GET a\/b\/c]@ is equivalent to +-- @'method' \@GET $ 'path' \@\"a\/b\/c\"@ +-- * @[match|GET a\/b\/objId:Int\/d]@ is equivalent to +-- @'method' \@GET . 'path' \@\"a\/b\" . 'pathVar' \@\"objId\" \@Int . 'path' \@\"d\"@ +-- +match :: QuasiQuoter +match = QuasiQuoter + { quoteExp = toExp + , quotePat = const $ fail "match cannot be used in a pattern" + , quoteType = const $ fail "match cannot be used in a type" + , quoteDec = const $ fail "match cannot be used in a declaration" + } + where + toExp :: String -> Q Exp + toExp s = case List.words s of + [m, p] -> do + let methodExp = AppTypeE (VarE 'method) (ConT $ mkName m) + pathExps <- toPathExps p + pure $ List.foldr1 compose $ methodExp :| pathExps + [p] -> do + pathExps <- toPathExps p + pure $ List.foldr1 compose pathExps + _ -> fail "match expects an HTTP method and a path or just a path" + + toPathExps :: String -> Q [Exp] + toPathExps p = splitOn '/' p + & fmap (splitOn ':') + & List.foldr joinPath [] + & fmap toPathExp + & sequence + + joinPath :: NonEmpty String -> [NonEmpty String] -> [NonEmpty String] + joinPath s [] = [s] + joinPath (s:|[]) ((s':|[]) : xs) = ((s <> "/" <> s') :| []) : xs + joinPath y (x:xs) = y:x:xs + + toPathExp :: NonEmpty String -> Q Exp + toPathExp (p :| []) = pure $ AppTypeE (VarE 'path) (LitT $ StrTyLit p) + toPathExp (v :| [t]) = pure $ AppTypeE (AppTypeE (VarE 'pathVar) (LitT $ StrTyLit v)) (ConT $ mkName t) + toPathExp xs = fail $ "Invalid path component: " <> List.intercalate ":" (toList xs) + + compose :: Exp -> Exp -> Exp + compose l = UInfixE l (VarE $ mkName ".") diff --git a/src/WebGear/Route.hs b/src/WebGear/Route.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Route.hs @@ -0,0 +1,81 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Types and functions to route HTTP requests. +module WebGear.Route + ( RouterT + , MonadRouter (..) + , runRoute + ) where + +import Control.Applicative (Alternative) +import Control.Arrow (Kleisli (..)) +import Control.Monad (MonadPlus (..)) +import Control.Monad.Except (ExceptT, MonadError (..), runExceptT) +import Data.ByteString.Lazy (ByteString) +import Data.HashMap.Strict (fromList) +import Data.Semigroup (First (..)) +import Data.String (fromString) +import Data.Version (showVersion) +import Network.HTTP.Types (Header, hServer, notFound404) + +import Paths_webgear_server (version) +import WebGear.Trait (linkzero, unlink) +import WebGear.Types (Handler, Response (..), waiResponse) + +import qualified Network.Wai as Wai + + +-- | The monad transformer stack for routing. +-- +-- * The 'ExceptT' provides short-circuiting behaviour for +-- 'rejectRoute' and 'failHandler'. +-- +-- * In case of 'rejectRoute', a 'Nothing' value is returned and in +-- case of 'failHandler', a @Response ByteString@ is returned. +-- +-- * The 'First' wrapper is provided to get instances of 'Alternative' +-- and 'MonadPlus' for 'RouterT'. +-- +type RouterT m = ExceptT (Maybe (First (Response ByteString))) m + +-- | HTTP request routing with short circuiting behavior. +class (Alternative m, MonadPlus m) => MonadRouter m where + -- | Mark the current route as rejected, alternatives can be tried + rejectRoute :: m a + + -- | Short-circuit the current handler and return a response + failHandler :: Response ByteString -> m a + +instance Monad m => MonadRouter (RouterT m) where + rejectRoute :: RouterT m a + rejectRoute = mzero + + failHandler :: Response ByteString -> RouterT m a + failHandler = throwError . Just . First + +-- | Convert a routable handler into a plain function. +-- +-- This function is typically used to convert WebGear routes to a +-- 'Wai.Application'. +runRoute :: Monad m + => Handler (RouterT m) '[] res ByteString + -> (Wai.Request -> m Wai.Response) +runRoute route req = waiResponse . addServerHeader . either (maybe notFoundResponse getFirst) id <$> runExceptT f + where + f = unlink <$> runKleisli route (linkzero req) + + notFoundResponse :: Response ByteString + notFoundResponse = Response + { respStatus = notFound404 + , respHeaders = fromList [] + , respBody = Just "Not Found" + } + + addServerHeader :: Response ByteString -> Response ByteString + addServerHeader r = r { respHeaders = respHeaders r <> fromList [serverHeader] } + + serverHeader :: Header + serverHeader = (hServer, fromString $ "WebGear/" ++ showVersion version) diff --git a/src/WebGear/Trait.hs b/src/WebGear/Trait.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Trait.hs @@ -0,0 +1,136 @@ +{-# LANGUAGE UndecidableInstances #-} +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Traits are optional attributes that a value might posess. For example, +-- a list containing totally ordered values might have a @Maximum@ trait +-- where the associated attribute is the maximum value. The trait exists +-- only if the list is non-empty. +-- +-- Traits help to access these attributes in a type-safe manner. +-- +-- Traits are somewhat similar to [refinement +-- types](https://hackage.haskell.org/package/refined), but allow +-- arbitrary attributes to be associated with a value instead of only a +-- predicate. +module WebGear.Trait + ( -- * Core Types + Trait (..) + , CheckResult (..) + , Linked + , Traits + + -- * Linking values with traits + , linkzero + , linkplus + , linkminus + , unlink + + -- * Retrive trait attributes from linked values + , Has (..) + , Have + ) where + +import Data.Kind (Constraint, Type) +import Data.Tagged (Tagged (..)) + + +-- | A 'Trait' is an optional attribute @t@ associated with a value @a@. +-- +-- The 'check' function validates the presence of the trait for a +-- given value. Checking the presence of the trait can optionally +-- modify the value as well. +class Monad m => Trait t a m where + -- | Type of the associated attribute + type Val t a + + -- | Type of check failures + type Fail t a + + -- | Checks the presence of the associated attribute. + check :: a -> m (CheckResult t a) + +-- | Result of a 'check' operation +data CheckResult t a = CheckSuccess a (Val t a) + | CheckFail (Fail t a) + +deriving instance (Eq a, Eq (Val t a), Eq (Fail t a)) => Eq (CheckResult t a) +deriving instance (Show a, Show (Val t a), Show (Fail t a)) => Show (CheckResult t a) +deriving instance (Read a, Read (Val t a), Read (Fail t a)) => Read (CheckResult t a) + + +-- | A trivial trait that is always present and whose attribute does +-- not carry any meaningful information. +instance Monad m => Trait '[] a m where + type Val '[] a = () + type Fail '[] a = () + + check :: a -> m (CheckResult '[] a) + check a = pure $ CheckSuccess a () + +-- | Combination of many traits all of which are present for a value. +instance (Trait t a m, Trait ts a m) => Trait (t:ts) a m where + type Val (t:ts) a = (Val t a, Val ts a) + type Fail (t:ts) a = Either (CheckResult t a) (CheckResult ts a) + + check :: a -> m (CheckResult (t:ts) a) + check a = check @t a >>= \case + e@(CheckFail _) -> pure $ CheckFail $ Left e + CheckSuccess a' l -> check @ts a' >>= \case + e@(CheckFail _) -> pure $ CheckFail $ Right e + CheckSuccess a'' r -> pure $ CheckSuccess a'' (l, r) + +-- | Constraint for functions that use multiple traits +type family Traits ts a m :: Constraint where + Traits '[] a m = () + Traits (t:ts) a m = (Trait t a m, Traits ts a m) + +-- | A value linked with a type-level list of traits. +data Linked (ts :: [Type]) a = Linked + { linkVal :: !(Val ts a) + , unlink :: !a -- ^ Retrive the value from a linked value + } + +-- | Link a value with the trivial trait +linkzero :: a -> Linked '[] a +linkzero = Linked () + +-- | Attempt to link an additional trait with an already linked value +linkplus :: Trait t a m => Linked ts a -> m (Either (Fail t a) (Linked (t:ts) a)) +linkplus l = do + v <- check (unlink l) + pure $ mkLinked v l + where + mkLinked :: CheckResult t a -> Linked ts a -> Either (Fail t a) (Linked (t:ts) a) + mkLinked (CheckSuccess a left) lv = Right $ Linked (left, linkVal lv) a + mkLinked (CheckFail e) _ = Left e + +-- | Remove the leading trait from the linked value +linkminus :: Linked (t:ts) a -> Linked ts a +linkminus l = Linked (snd $ linkVal l) (unlink l) + + +-- | Constraint that proves that the trait @t@ is present somewhere in +-- the list of traits @ts@. +class Has t ts where + traitValue :: Linked ts a -> Tagged t (Val t a) + +instance Has t (t:ts) where + traitValue :: Linked (t : ts) a -> Tagged t (Val t a) + traitValue (Linked (lv, _) _) = Tagged lv + +instance {-# OVERLAPPABLE #-} Has t ts => Has t (t':ts) where + traitValue :: Linked (t':ts) a -> Tagged t (Val t a) + traitValue l = traitValue (rightLinked l) + where + rightLinked :: Linked (q:qs) b -> Linked qs b + rightLinked (Linked (_, rv) a) = Linked rv a + + +-- | Constraint that proves that all the traits in the list @ts@ are +-- present in the list @qs@. +type family Have ts qs :: Constraint where + Have '[] qs = () + Have (t:ts) qs = (Has t qs, Have ts qs) diff --git a/src/WebGear/Trait/Body.hs b/src/WebGear/Trait/Body.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Trait/Body.hs @@ -0,0 +1,34 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Traits related to HTTP body. +module WebGear.Trait.Body + ( JSONRequestBody + ) where + +import Control.Monad.IO.Class (MonadIO (..)) +import Data.Aeson (FromJSON, eitherDecode') +import Data.ByteString.Lazy (fromChunks) +import Data.Kind (Type) +import Data.Text (Text, pack) + +import WebGear.Trait (CheckResult (..), Trait (..)) +import WebGear.Types (Request, getRequestBodyChunk) +import WebGear.Util (takeWhileM) + + +-- | A 'Trait' for converting a JSON request body into a value. +data JSONRequestBody (t :: Type) + +instance (FromJSON t, MonadIO m) => Trait (JSONRequestBody t) Request m where + type Val (JSONRequestBody t) Request = t + type Fail (JSONRequestBody t) Request = Text + + check :: Request -> m (CheckResult (JSONRequestBody t) Request) + check r = do + chunks <- takeWhileM (/= mempty) $ repeat $ liftIO $ getRequestBodyChunk r + pure $ case eitherDecode' (fromChunks chunks) of + Left e -> CheckFail (pack e) + Right t -> CheckSuccess r t diff --git a/src/WebGear/Trait/Header.hs b/src/WebGear/Trait/Header.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Trait/Header.hs @@ -0,0 +1,71 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Traits related to HTTP headers. +module WebGear.Trait.Header + ( Header + , HeaderFail (..) + , HeaderMatch + , HeaderMismatch (..) + ) where + +import Data.ByteString (ByteString) +import Data.Kind (Type) +import Data.Proxy (Proxy (..)) +import Data.String (fromString) +import Data.Text (Text) +import GHC.TypeLits (KnownSymbol, Symbol, symbolVal) +import Web.HttpApiData (FromHttpApiData (..)) + +import WebGear.Trait (CheckResult (..), Trait (..)) +import WebGear.Types (Request, requestHeader) + + +-- | A 'Trait' for capturing a header with name @s@ in a request or +-- response and convert it to some type @t@ via 'FromHttpApiData'. +data Header (s :: Symbol) (t :: Type) + +-- | Failure in extracting a header value +data HeaderFail = HeaderNotFound | HeaderParseError Text + deriving stock (Read, Show, Eq) + +instance (KnownSymbol s, FromHttpApiData t, Monad m) => Trait (Header s t) Request m where + type Val (Header s t) Request = t + type Fail (Header s t) Request = HeaderFail + + check :: Request -> m (CheckResult (Header s t) Request) + check r = pure $ + let s = fromString $ symbolVal (Proxy @s) + in case parseHeader <$> requestHeader s r of + Nothing -> CheckFail HeaderNotFound + Just (Left e) -> CheckFail $ HeaderParseError e + Just (Right x) -> CheckSuccess r x + +-- | A 'Trait' for ensuring that a header named @s@ has value @t@. +data HeaderMatch (s :: Symbol) (t :: Symbol) + +-- | Failure in extracting a header value +data HeaderMismatch = HeaderMismatch + { expectedHeader :: ByteString + , actualHeader :: Maybe ByteString + } + deriving stock (Eq, Read, Show) + +instance (KnownSymbol s, KnownSymbol t, Monad m) => Trait (HeaderMatch s t) Request m where + type Val (HeaderMatch s t) Request = ByteString + type Fail (HeaderMatch s t) Request = HeaderMismatch + + check :: Request -> m (CheckResult (HeaderMatch s t) Request) + check r = pure $ + let + name = fromString $ symbolVal (Proxy @s) + expected = fromString $ symbolVal (Proxy @t) + in + case requestHeader name r of + Nothing -> CheckFail HeaderMismatch + {expectedHeader = expected, actualHeader = Nothing} + Just hv | hv == expected -> CheckSuccess r hv + | otherwise -> CheckFail HeaderMismatch + {expectedHeader = expected, actualHeader = Just hv} diff --git a/src/WebGear/Trait/Method.hs b/src/WebGear/Trait/Method.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Trait/Method.hs @@ -0,0 +1,68 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Trait capturing the HTTP method in a request. +module WebGear.Trait.Method + ( Method + , IsStdMethod (..) + , MethodMismatch (..) + ) where + +import Data.Proxy (Proxy (..)) + +import WebGear.Trait (CheckResult (..), Trait (..)) +import WebGear.Types (Request, requestMethod) + +import qualified Network.HTTP.Types as HTTP + + +-- | A 'Trait' for capturing the HTTP method of a request +data Method (t :: HTTP.StdMethod) + +-- | Failure to match method against an expected value +data MethodMismatch = MethodMismatch + { expectedMethod :: HTTP.Method + , actualMethod :: HTTP.Method + } + +instance (Monad m, IsStdMethod t) => Trait (Method t) Request m where + type Val (Method t) Request = HTTP.Method + type Fail (Method t) Request = MethodMismatch + + check :: Request -> m (CheckResult (Method t) Request) + check r = + let + expected = HTTP.renderStdMethod $ toStdMethod $ Proxy @t + actual = requestMethod r + in + pure $ if expected == actual + then CheckSuccess r actual + else CheckFail $ MethodMismatch expected actual + + +-- | A typeclass implemented by all 'HTTP.StdMethod's to convert them +-- from type level to term level. +class IsStdMethod t where + -- | Convert @t@ to term level. + toStdMethod :: Proxy t -> HTTP.StdMethod + +instance IsStdMethod HTTP.GET where + toStdMethod = const HTTP.GET +instance IsStdMethod HTTP.POST where + toStdMethod = const HTTP.POST +instance IsStdMethod HTTP.HEAD where + toStdMethod = const HTTP.HEAD +instance IsStdMethod HTTP.PUT where + toStdMethod = const HTTP.PUT +instance IsStdMethod HTTP.DELETE where + toStdMethod = const HTTP.DELETE +instance IsStdMethod HTTP.TRACE where + toStdMethod = const HTTP.TRACE +instance IsStdMethod HTTP.CONNECT where + toStdMethod = const HTTP.CONNECT +instance IsStdMethod HTTP.OPTIONS where + toStdMethod = const HTTP.OPTIONS +instance IsStdMethod HTTP.PATCH where + toStdMethod = const HTTP.PATCH diff --git a/src/WebGear/Trait/Path.hs b/src/WebGear/Trait/Path.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Trait/Path.hs @@ -0,0 +1,66 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Traits related to the route path of a request. +module WebGear.Trait.Path + ( Path + , PathVar + , PathVarFail (..) + ) where + +import Data.Kind (Type) +import Data.List (stripPrefix) +import Data.List.NonEmpty (toList) +import Data.Proxy (Proxy (..)) +import Data.Text (Text, pack) +import GHC.TypeLits (KnownSymbol, Symbol, symbolVal) +import Web.HttpApiData (FromHttpApiData (..)) + +import WebGear.Trait (CheckResult (..), Trait (..)) +import WebGear.Types (Request, pathInfo, setPathInfo) +import WebGear.Util (splitOn) + + +-- | A path component which is literally matched against the request +-- but discarded after that. +data Path (s :: Symbol) + +instance (KnownSymbol s, Monad m) => Trait (Path s) Request m where + type Val (Path s) Request = () + + -- | The path that could not be matched + type Fail (Path s) Request = () + + check :: Request -> m (CheckResult (Path s) Request) + check r = pure $ + let expected = map pack $ toList $ splitOn '/' $ symbolVal $ Proxy @s + actual = pathInfo r + in + case stripPrefix expected actual of + Nothing -> CheckFail () + Just rest -> CheckSuccess (setPathInfo rest r) () + + +-- | A path variable that is extracted and converted to a value of +-- type @val@. The @tag@ is usually a type-level symbol (string) to +-- uniquely identify this variable. +data PathVar tag (val :: Type) + +-- | Failure to extract a 'PathVar' +data PathVarFail = PathVarNotFound | PathVarParseError Text + deriving (Eq, Show, Read) + +instance (FromHttpApiData val, Monad m) => Trait (PathVar tag val) Request m where + type Val (PathVar tag val) Request = val + type Fail (PathVar tag val) Request = PathVarFail + + check :: Request -> m (CheckResult (PathVar tag val) Request) + check r = pure $ + case pathInfo r of + [] -> CheckFail PathVarNotFound + (x:xs) -> + case parseUrlPiece @val x of + Left e -> CheckFail $ PathVarParseError e + Right h -> CheckSuccess (setPathInfo xs r) h diff --git a/src/WebGear/Types.hs b/src/WebGear/Types.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Types.hs @@ -0,0 +1,107 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Common types and functions used throughout WebGear. +module WebGear.Types + ( -- * WebGear Request + -- | WebGear requests are WAI requests. This module reexports a number + -- of useful functions that operate on requests from "Network.Wai" + -- module. + Request + , remoteHost + , httpVersion + , isSecure + , requestMethod + , pathInfo + , setPathInfo + , queryString + , requestHeaders + , requestHeader + , requestBodyLength + , getRequestBodyChunk + + -- * WebGear Response + , Response (..) + , waiResponse + , addResponseHeader + + , Handler + , Middleware + , RequestMiddleware + , ResponseMiddleware + ) where + +import Control.Arrow (Kleisli) +import Data.ByteString (ByteString) +import Data.List (find) +import Data.Maybe (fromMaybe) +import Data.Text (Text) +import Network.HTTP.Types (Header, HeaderName, Status) +import Network.Wai (Request, getRequestBodyChunk, httpVersion, isSecure, pathInfo, queryString, + remoteHost, requestBodyLength, requestHeaders, requestMethod) + +import WebGear.Trait (Linked) + +import qualified Data.ByteString.Lazy as LBS +import qualified Data.HashMap.Strict as HM +import qualified Network.Wai as Wai + + +-- | Get the value of a request header +requestHeader :: HeaderName -> Request -> Maybe ByteString +requestHeader h r = snd <$> find ((== h) . fst) (requestHeaders r) + +-- | Get request with an updated URL path info. +setPathInfo :: [Text] -> Request -> Request +setPathInfo p r = r { pathInfo = p } + +-- | A response sent from the server to the client. +-- +-- The response contains a status, optional headers and an optional +-- body of type @a@. +data Response a = Response + { respStatus :: Status -- ^ Response status code + , respHeaders :: HM.HashMap HeaderName ByteString -- ^ Response headers + , respBody :: Maybe a -- ^ Optional response body + } + +-- | Convert a WebGear response to a WAI Response. +waiResponse :: Response LBS.ByteString -> Wai.Response +waiResponse Response{..} = Wai.responseLBS respStatus (HM.toList respHeaders) (fromMaybe "" respBody) + +-- | Create or update a response header. +addResponseHeader :: Header -> Response a -> Response a +addResponseHeader (name, val) resp = resp { respHeaders = HM.insertWith f name val (respHeaders resp) } + where + f = flip const + +-- | A handler is a function from a request to response in a monadic +-- context. Both the request and the response can have linked traits. +-- +-- The type level list @req@ contains all the traits expected to be +-- present in the request. The handler will produce a response that +-- satisfies all the traits in the type level list @res@. +type Handler m req res a = Kleisli m (Linked req Request) (Linked res (Response a)) + +-- | A middleware takes a handler as input and produces another +-- handler that usually adds some functionality. +-- +-- A middleware can do a number of things with the request +-- handling such as: +-- +-- * Change the request traits before invoking the handler. +-- * Change the response traits before passing it back to its caller. +-- * Use the linked value of any of the request or response traits. +-- * Change the response body. +-- +type Middleware m req req' res' res a' a = Handler m req' res' a' -> Handler m req res a + +-- | A middleware that manipulates only the request traits and leaves +-- the response unchanged. +type RequestMiddleware m req req' res a = Middleware m req req' res res a a + +-- | A middleware that manipulates only the response traits and leaves +-- the request unchanged. +type ResponseMiddleware m req res' res a = Middleware m req req res' res a a diff --git a/src/WebGear/Util.hs b/src/WebGear/Util.hs new file mode 100644 --- /dev/null +++ b/src/WebGear/Util.hs @@ -0,0 +1,27 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +-- Common utility functions. +module WebGear.Util + ( takeWhileM + , splitOn + ) where + +import Data.List.NonEmpty (NonEmpty (..), toList) + + +takeWhileM :: Monad m => (a -> Bool) -> [m a] -> m [a] +takeWhileM _ [] = pure [] +takeWhileM p (mx:mxs) = do + x <- mx + if p x + then (x :) <$> takeWhileM p mxs + else pure [] + +splitOn :: Eq a => a -> [a] -> NonEmpty [a] +splitOn sep = foldr f ([] :| []) + where + f x acc | x == sep = [] :| toList acc + f x (y :| ys) = (x:y) :| ys diff --git a/test/Main.hs b/test/Main.hs new file mode 100644 --- /dev/null +++ b/test/Main.hs @@ -0,0 +1,21 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +module Main where + +import Test.Tasty (TestTree, defaultMain, testGroup) + +import Properties (propertyTests) +import Unit (unitTests) + + +main :: IO () +main = defaultMain allTests + +allTests :: TestTree +allTests = testGroup "Tests" [unitTests, propertyTests, systemTests] + +systemTests :: TestTree +systemTests = testGroup "System Tests" [] diff --git a/test/Properties.hs b/test/Properties.hs new file mode 100644 --- /dev/null +++ b/test/Properties.hs @@ -0,0 +1,23 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +module Properties + ( propertyTests + ) where + +import Test.Tasty (TestTree, testGroup) + +import qualified Properties.Trait.Body as Body +import qualified Properties.Trait.Header as Header +import qualified Properties.Trait.Method as Method +import qualified Properties.Trait.Path as Path + + +propertyTests :: TestTree +propertyTests = testGroup "Property Tests" [ Body.tests + , Header.tests + , Method.tests + , Path.tests + ] diff --git a/test/Properties/Trait/Body.hs b/test/Properties/Trait/Body.hs new file mode 100644 --- /dev/null +++ b/test/Properties/Trait/Body.hs @@ -0,0 +1,53 @@ +{-# OPTIONS_GHC -Wno-deprecations #-} + +module Properties.Trait.Body + ( tests + ) where + +import Control.Monad.IO.Class (MonadIO, liftIO) +import Data.IORef (newIORef, readIORef, writeIORef) +import Data.String (fromString) +import Network.Wai (Request, defaultRequest, requestBody) +import Test.QuickCheck (Property, allProperties, counterexample, property) +import Test.QuickCheck.Instances () +import Test.QuickCheck.Monadic (assert, monadicIO, monitor) +import Test.Tasty (TestTree) +import Test.Tasty.QuickCheck (testProperties) + +import WebGear.Trait +import WebGear.Trait.Body + + +bodyToRequest :: (MonadIO m, Show a) => a -> m Request +bodyToRequest x = do + body <- liftIO $ newIORef $ Just $ fromString $ show x + let f = readIORef body >>= maybe (pure "") (\s -> writeIORef body Nothing >> pure s) + return defaultRequest { requestBody = f } + +prop_emptyRequestBodyFails :: Property +prop_emptyRequestBodyFails = monadicIO $ do + req <- bodyToRequest ("" :: String) + check @(JSONRequestBody Int) req >>= \case + CheckSuccess _ _ -> monitor (counterexample "Unexpected success") >> assert False + CheckFail _ -> assert True + +prop_validBodyParses :: Property +prop_validBodyParses = property $ \n -> monadicIO $ do + req <- bodyToRequest (n :: Integer) + check @(JSONRequestBody Integer) req >>= \case + CheckSuccess _ n' -> assert (n == n') + CheckFail _ -> assert False + +prop_invalidBodyFails :: Property +prop_invalidBodyFails = property $ \n -> monadicIO $ do + req <- bodyToRequest (n :: Integer) + check @(JSONRequestBody String) req >>= \case + CheckSuccess _ _ -> assert False + CheckFail _ -> assert True + + +-- Hack for TH splicing +return [] + +tests :: TestTree +tests = testProperties "Trait.Body" $allProperties diff --git a/test/Properties/Trait/Header.hs b/test/Properties/Trait/Header.hs new file mode 100644 --- /dev/null +++ b/test/Properties/Trait/Header.hs @@ -0,0 +1,55 @@ +module Properties.Trait.Header + ( tests + ) where + +import Data.Functor.Identity (runIdentity) +import Data.String (fromString) +import Data.Text.Encoding (encodeUtf8) +import Network.Wai (defaultRequest, requestHeaders) +import Test.QuickCheck (Property, allProperties, counterexample, property, (.&&.), (=/=), (===)) +import Test.QuickCheck.Instances () +import Test.Tasty (TestTree) +import Test.Tasty.QuickCheck (testProperties) + +import WebGear.Trait +import WebGear.Trait.Header + + +prop_headerParseError :: Property +prop_headerParseError = property $ \hval -> + let + hval' = "test-" <> hval + req = defaultRequest { requestHeaders = [("foo", encodeUtf8 hval')] } + in + case runIdentity (check @(Header "foo" Int) req) of + CheckFail e -> + e === HeaderParseError ("could not parse: `" <> hval' <> "' (input does not start with a digit)") + CheckSuccess _ v -> + counterexample ("Unexpected result: " <> show v) (property False) + +prop_headerParseSuccess :: Property +prop_headerParseSuccess = property $ \(n :: Int) -> + let + req = defaultRequest { requestHeaders = [("foo", fromString $ show n)] } + in + case runIdentity (check @(Header "foo" Int) req) of + CheckFail e -> + counterexample ("Unexpected result: " <> show e) (property False) + CheckSuccess _ n' -> n === n' + +prop_headerMatch :: Property +prop_headerMatch = property $ \v -> + let + req = defaultRequest { requestHeaders = [("foo", v)] } + in + case runIdentity (check @(HeaderMatch "foo" "bar") req) of + CheckFail e -> + expectedHeader e === "bar" .&&. actualHeader e =/= Nothing .&&. actualHeader e =/= Just "bar" + CheckSuccess _ v' -> v === "bar" .&&. v === v' + + +-- Hack for TH splicing +return [] + +tests :: TestTree +tests = testProperties "Trait.Header" $allProperties diff --git a/test/Properties/Trait/Method.hs b/test/Properties/Trait/Method.hs new file mode 100644 --- /dev/null +++ b/test/Properties/Trait/Method.hs @@ -0,0 +1,38 @@ +module Properties.Trait.Method + ( tests + ) where + +import Data.Functor.Identity (runIdentity) +import Network.HTTP.Types (StdMethod (..), methodGet, renderStdMethod) +import Network.Wai (defaultRequest, requestMethod) +import Test.QuickCheck (Arbitrary (arbitrary), Property, allProperties, elements, property, (.&&.), + (=/=), (===)) +import Test.Tasty (TestTree) +import Test.Tasty.QuickCheck (testProperties) + +import WebGear.Trait +import WebGear.Trait.Method + + +newtype MethodWrapper = MethodWrapper StdMethod + deriving stock (Show) + +instance Arbitrary MethodWrapper where + arbitrary = elements $ MethodWrapper <$> [minBound..maxBound] + +prop_methodMatch :: Property +prop_methodMatch = property $ \(MethodWrapper v) -> + let + req = defaultRequest { requestMethod = renderStdMethod v } + in + case runIdentity (check @(Method GET) req) of + CheckSuccess _ v' -> v === GET .&&. v' === methodGet + CheckFail e -> + expectedMethod e === methodGet .&&. actualMethod e =/= methodGet + + +-- Hack for TH splicing +return [] + +tests :: TestTree +tests = testProperties "Trait.Method" $allProperties diff --git a/test/Properties/Trait/Path.hs b/test/Properties/Trait/Path.hs new file mode 100644 --- /dev/null +++ b/test/Properties/Trait/Path.hs @@ -0,0 +1,52 @@ +module Properties.Trait.Path + ( tests + ) where + +import Data.Functor.Identity (runIdentity) +import Data.String (fromString) +import Network.Wai (defaultRequest, pathInfo) +import Test.QuickCheck (Property, allProperties, property, (.&&.), (=/=), (===)) +import Test.QuickCheck.Instances () +import Test.Tasty (TestTree) +import Test.Tasty.QuickCheck (testProperties) + +import WebGear.Trait +import WebGear.Trait.Path + + +prop_pathMatch :: Property +prop_pathMatch = property $ \h -> + let + rest = ["foo", "bar"] + req = defaultRequest { pathInfo = h:rest } + in + case runIdentity (check @(Path "a") req) of + CheckSuccess req' _ -> h === "a" .&&. pathInfo req' === rest + CheckFail _ -> h =/= "a" + +prop_pathVarMatch :: Property +prop_pathVarMatch = property $ \(n :: Int) -> + let + rest = ["foo", "bar"] + req = defaultRequest { pathInfo = fromString (show n):rest } + in + case runIdentity (check @(PathVar "tag" Int) req) of + CheckSuccess req' n' -> n' === n .&&. pathInfo req' === rest + CheckFail _ -> property False + +prop_pathVarParseError :: Property +prop_pathVarParseError = property $ \(p, ps) -> + let + p' = "test-" <> p + req = defaultRequest { pathInfo = p':ps } + in + case runIdentity (check @(PathVar "tag" Int) req) of + CheckSuccess _ _ -> property False + CheckFail e -> e === PathVarParseError ("could not parse: `" <> p' <> "' (input does not start with a digit)") + + +-- Hack for TH splicing +return [] + +tests :: TestTree +tests = testProperties "Trait.Path" $allProperties diff --git a/test/Unit.hs b/test/Unit.hs new file mode 100644 --- /dev/null +++ b/test/Unit.hs @@ -0,0 +1,19 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +module Unit + ( unitTests + ) where + +import Test.Tasty (TestTree, testGroup) + +import qualified Unit.Trait.Header as Header +import qualified Unit.Trait.Path as Path + + +unitTests :: TestTree +unitTests = testGroup "Unit Tests" [ Header.tests + , Path.tests + ] diff --git a/test/Unit/Trait/Header.hs b/test/Unit/Trait/Header.hs new file mode 100644 --- /dev/null +++ b/test/Unit/Trait/Header.hs @@ -0,0 +1,45 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +module Unit.Trait.Header + ( tests + ) where + +import Network.Wai (defaultRequest, requestHeaders) +import Test.Tasty (TestTree, testGroup) +import Test.Tasty.HUnit (assertFailure, testCase, (@?=)) + +import WebGear.Trait +import WebGear.Trait.Header + + +testMissingHeaderFails :: TestTree +testMissingHeaderFails = testCase "Missing header fails Header trait" $ do + let req = defaultRequest { requestHeaders = [] } + check @(Header "foo" Int) req >>= \case + CheckSuccess _ _ -> assertFailure "unexpected success" + CheckFail e -> e @?= HeaderNotFound + +testHeaderMatchPositive :: TestTree +testHeaderMatchPositive = testCase "Header match: positive" $ do + let req = defaultRequest { requestHeaders = [("foo", "bar")] } + check @(HeaderMatch "foo" "bar") req >>= \case + CheckSuccess _ v -> v @?= "bar" + CheckFail e -> assertFailure $ "Unexpected result: " <> show e + +testHeaderMatchMissingHeader :: TestTree +testHeaderMatchMissingHeader = testCase "Header match: missing header" $ do + let req = defaultRequest { requestHeaders = [] } + check @(HeaderMatch "foo" "bar") req >>= \case + CheckSuccess _ _ -> assertFailure "unexpected success" + CheckFail e -> e @?= HeaderMismatch { expectedHeader = "bar" + , actualHeader = Nothing + } + +tests :: TestTree +tests = testGroup "Trait.Header" [ testMissingHeaderFails + , testHeaderMatchPositive + , testHeaderMatchMissingHeader + ] diff --git a/test/Unit/Trait/Path.hs b/test/Unit/Trait/Path.hs new file mode 100644 --- /dev/null +++ b/test/Unit/Trait/Path.hs @@ -0,0 +1,26 @@ +-- | +-- Copyright : (c) Raghu Kaippully, 2020 +-- License : MPL-2.0 +-- Maintainer : rkaippully@gmail.com +-- +module Unit.Trait.Path + ( tests + ) where + +import Network.Wai (defaultRequest, pathInfo) +import Test.Tasty (TestTree, testGroup) +import Test.Tasty.HUnit (assertFailure, testCase, (@?=)) + +import WebGear.Trait +import WebGear.Trait.Path + + +testMissingPathVar :: TestTree +testMissingPathVar = testCase "PathVar match: missing variable" $ do + let req = defaultRequest { pathInfo = [] } + check @(PathVar "tag" Int) req >>= \case + CheckSuccess _ _ -> assertFailure "unexpected success" + CheckFail e -> e @?= PathVarNotFound + +tests :: TestTree +tests = testGroup "Trait.Path" [ testMissingPathVar ] diff --git a/webgear-server.cabal b/webgear-server.cabal new file mode 100644 --- /dev/null +++ b/webgear-server.cabal @@ -0,0 +1,130 @@ +cabal-version: 2.4 +name: webgear-server +version: 0.1.0 +synopsis: Composable, type-safe library to build HTTP API servers +description: + WebGear is a library to for building composable, type-safe HTTP API servers. + + WebGear focuses on good documentation and usability. + + See the documentation of WebGear module to get started. +homepage: https://github.com/rkaippully/webgear#readme +bug-reports: https://github.com/rkaippully/webgear/issues +author: Raghu Kaippully +maintainer: rkaippully@gmail.com +copyright: 2020 Raghu Kaippully +license: MPL-2.0 +license-file: LICENSE +category: Web +build-type: Simple +extra-source-files: README.md + ChangeLog.md + + +source-repository head + type: git + location: https://github.com/rkaippully/webgear + + +common webgear-common + default-language: Haskell2010 + default-extensions: ApplicativeDo + BangPatterns + ConstraintKinds + DataKinds + DefaultSignatures + DeriveAnyClass + DeriveFoldable + DeriveFunctor + DeriveGeneric + DeriveLift + DeriveTraversable + DerivingStrategies + DerivingVia + EmptyCase + ExistentialQuantification + FlexibleContexts + FlexibleInstances + FunctionalDependencies + GADTs + GeneralizedNewtypeDeriving + InstanceSigs + KindSignatures + LambdaCase + MultiParamTypeClasses + MultiWayIf + NamedFieldPuns + OverloadedStrings + PatternSynonyms + PolyKinds + RankNTypes + RecordWildCards + ScopedTypeVariables + StandaloneDeriving + TemplateHaskell + TupleSections + TypeApplications + TypeFamilies + TypeFamilyDependencies + TypeOperators + build-depends: base >=4.13.0.0 && <5 + , template-haskell >=2.15.0.0 && <3 + , mtl ==2.2.* + , unordered-containers ==0.2.* + , wai ==3.2.* + , bytestring ==0.10.* + , text ==1.2.* + , http-types ==0.12.* + , http-api-data ==0.4.* + , aeson ==1.4.* + , tagged ==0.8.* + ghc-options: -fwrite-ide-info + -hiedir=.hie + -Wall + -Wno-unticked-promoted-constructors + -Wincomplete-record-updates + -Wincomplete-uni-patterns + -Wredundant-constraints + +library + import: webgear-common + exposed-modules: WebGear + , WebGear.Trait + , WebGear.Trait.Method + , WebGear.Trait.Header + , WebGear.Trait.Path + , WebGear.Trait.Body + , WebGear.Types + , WebGear.Route + , WebGear.Middlewares + , WebGear.Middlewares.Body + , WebGear.Middlewares.Header + , WebGear.Middlewares.Method + , WebGear.Middlewares.Path + other-modules: Paths_webgear_server + , WebGear.Util + autogen-modules: Paths_webgear_server + hs-source-dirs: src + +test-suite webgear-server-test + import: webgear-common + type: exitcode-stdio-1.0 + main-is: Main.hs + other-modules: Unit + , Unit.Trait.Header + , Unit.Trait.Path + , Properties + , Properties.Trait.Body + , Properties.Trait.Header + , Properties.Trait.Method + , Properties.Trait.Path + hs-source-dirs: test + ghc-options: -threaded + -rtsopts + -with-rtsopts=-N + build-depends: tasty ==1.2.* + , tasty-quickcheck ==0.10.* + , tasty-hunit ==0.10.* + , QuickCheck ==2.13.* + , quickcheck-instances ==0.3.* + , webgear-server