Common.hs

{-# LANGUAGE DataKinds #-}
{-# options_ghc -Wno-unused-imports #-}
-- | Common functions for the MS Azure API
--
module MSAzureAPI.Internal.Common (
  APIPlane(..)
  , get
  , getBs
  , getLbs
  , post
  -- ** URL parameters
  , (==:)
  -- ** Helpers
  , tryReq
  -- ** JSON
  , Collection
  , aesonOptions
  ) where

import Control.Monad.IO.Class (MonadIO(..))
import Data.Proxy (Proxy)
import GHC.Generics (Generic(..))

import Data.List (sort, sortBy, stripPrefix, uncons)
import Data.Maybe (listToMaybe, fromMaybe)
-- import Data.Ord (comparing)
import Data.Char (toLower)

-- aeson
import qualified Data.Aeson as A (ToJSON(..), FromJSON(..), genericParseJSON, defaultOptions, Options(..), withObject, withText, (.:), (.:?), object, (.=), Key, Value, camelTo2)
-- bytestring
import qualified Data.ByteString as BS (ByteString)
import qualified Data.ByteString.Char8 as BS8 (pack, unpack)
import qualified Data.ByteString.Lazy as LBS (ByteString)
import qualified Data.ByteString.Lazy.Char8 as LBS8 (pack, unpack, putStrLn)
-- hoauth2
import Network.OAuth.OAuth2 (OAuth2Token(..))
import Network.OAuth.OAuth2.Internal (AccessToken(..), ExchangeToken(..), RefreshToken(..), OAuth2Error, IdToken(..))
-- modern-uri
-- import Text.URI (URI, mkURI)
-- req
import Network.HTTP.Req (Req, runReq, HttpException(..), defaultHttpConfig, req, Option, (=:), GET(..), POST(..), Url, Scheme(..), useHttpsURI, https, (/:), ReqBodyJson(..), NoReqBody(..), oAuth2Bearer, HttpResponse(..), jsonResponse, JsonResponse, lbsResponse, LbsResponse, bsResponse, BsResponse, responseBody)
-- text
import Data.Text (Text, pack, unpack)
-- unliftio
import UnliftIO (MonadUnliftIO(..))
import UnliftIO.Exception (try)

-- | URL parameters
(==:) :: Text -- ^ key
      -> Text -- ^ value
      -> Option 'Https
(==:) = (=:)

-- | @GET@ a 'LBS.ByteString' e.g. a file
getLbs :: APIPlane
       -> [Text] -- ^ URI path segments
       -> Option 'Https -> AccessToken -> Req LBS.ByteString
getLbs apiplane paths params tok = responseBody <$> req GET url NoReqBody lbsResponse opts
  where
    opts = auth <> params
    (url, auth) = msAzureReqConfig apiplane paths tok

-- | @GET@ a 'BS.ByteString' e.g. a file
getBs :: APIPlane
      -> [Text] -- ^ URI path segments
      -> Option 'Https -> AccessToken -> Req BS.ByteString
getBs apiplane paths params tok = responseBody <$> req GET url NoReqBody bsResponse opts
  where
    opts = auth <> params
    (url, auth) = msAzureReqConfig apiplane paths tok


-- | Specialized version of 'try' to 'HttpException's
--
-- This can be used to catch exceptions of composite 'Req' statements, e.g. around a @do@ block
tryReq :: Req a -> Req (Either HttpException a)
tryReq = try

-- | API control planes
--
-- https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/control-plane-and-data-plane
data APIPlane = APManagement -- ^ Management plane (@management.azure.com@ endpoints)
              | APData Text -- ^ Data plane e.g. FileREST API

-- | @POST@
post :: (A.FromJSON b, A.ToJSON a) =>
        APIPlane
     -> [Text] -- ^ URI path segments
     -> Option 'Https
     -> a -- ^ request body
     -> AccessToken -> Req b
post apiplane paths params bdy tok = responseBody <$> req POST url (ReqBodyJson bdy) jsonResponse opts
  where
    opts = auth <> params
    (url, auth) = msAzureReqConfig apiplane paths tok

-- | @GET@
get :: (A.FromJSON b) =>
       APIPlane
    -> [Text] -- ^ URI path segments
    -> Option 'Https -> AccessToken -> Req b
get apiplane paths params tok = responseBody <$> req GET url NoReqBody jsonResponse opts
  where
    opts = auth <> params
    (url, auth) = msAzureReqConfig apiplane paths tok

msAzureReqConfig :: APIPlane
                 -> [Text] -- ^ URI path segments
                 -> AccessToken
                 -> (Url 'Https, Option 'Https)
msAzureReqConfig apiplane uriRest (AccessToken ttok) = (url, os)
  where
    urlBase = case apiplane of
      APManagement -> "management.azure.com"
      APData ub -> ub
    url = (https urlBase) //: uriRest
    os = oAuth2Bearer $ BS8.pack (unpack ttok)



(//:) :: Url scheme -> [Text] -> Url scheme
(//:) = foldl (/:)


-- * aeson

-- | a collection of items with key @value@
data Collection a = Collection {
  cValue :: [a]
                               } deriving (Eq, Show, Generic)
instance A.FromJSON a => A.FromJSON (Collection a) where
  parseJSON = A.genericParseJSON (aesonOptions "c")

-- | drop the prefix and lowercase first character
--
-- e.g. @userDisplayName@ @->@ @displayName@
aesonOptions :: String -- ^ record prefix
             -> A.Options
aesonOptions pfx = A.defaultOptions { A.fieldLabelModifier = recordName pfx }

-- | drop the prefix and lowercase first character
recordName :: String -- ^ record name prefix
           -> String -- ^ JSON field name
           -> String
recordName pf str = case uncons $ dropPrefix pf str of
  Just (c, cs) -> toLower c : cs
  _ -> error "record name cannot be empty"

-- | Drops the given prefix from a list.
--   It returns the original sequence if the sequence doesn't start with the given prefix.
--
-- > dropPrefix "Mr. " "Mr. Men" == "Men"
-- > dropPrefix "Mr. " "Dr. Men" == "Dr. Men"
dropPrefix :: Eq a => [a] -> [a] -> [a]
dropPrefix a b = fromMaybe b $ stripPrefix a b