{- 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 https://mozilla.org/MPL/2.0/. -}

-- | This module contains implementations to check the latest version of a
-- package hosted by a specific service.
module SlackBuilder.LatestVersionCheck
    ( PackageOwner(..)
    , TextArguments(..)
    , latestGitHub
    , latestPackagist
    , latestText
    , stableTagTransform
    ) where

import SlackBuilder.Config
import qualified Data.Aeson as Aeson
import Data.Aeson ((.:))
import Data.Aeson.TH (defaultOptions, deriveJSON)
import Data.HashMap.Strict (HashMap)
import qualified Data.HashMap.Strict as HashMap
import Data.Text (Text)
import qualified Data.Text as Text
import qualified Data.Text.Encoding as Text.Encoding
import Data.Vector (Vector, (!?))
import qualified Data.Vector as Vector
import Network.HTTP.Req
    ( header
    , runReq
    , defaultHttpConfig
    , req
    , GET(..)
    , https
    , jsonResponse
    , NoReqBody(..)
    , (/:)
    , responseBody
    , useHttpsURI
    , bsResponse
    , POST(..)
    , ReqBodyJson(..)
    )
import Text.URI (mkURI)
import SlackBuilder.Trans
import qualified Data.Aeson.KeyMap as KeyMap
import GHC.Records (HasField(..))
import Control.Monad.Trans.Reader (asks)
import Control.Monad.IO.Class (MonadIO(..))
import Control.Monad ((>=>))

data PackageOwner = PackageOwner
    { owner :: Text
    , name :: Text
    } deriving (Eq, Show)

-- | Removes the leading "v" from the version string and returns the result if
-- it looks like a version.
stableTagTransform :: Text -> Maybe Text
stableTagTransform = Text.stripPrefix "v" >=> checkForStable
  where
    checkForStable tag
        | Text.any (`elem` ['-', '+']) tag = Nothing
        | otherwise = Just tag

-- * Packagist

newtype PackagistPackage = PackagistPackage
    { version :: Text
    } deriving (Eq, Show)

$(deriveJSON defaultOptions ''PackagistPackage)

newtype PackagistResponse = PackagistResponse
    { packages :: HashMap Text (Vector PackagistPackage)
    } deriving (Eq, Show)

$(deriveJSON defaultOptions ''PackagistResponse)

latestPackagist :: PackageOwner -> SlackBuilderT (Maybe Text)
latestPackagist PackageOwner{..} = do
    packagistResponse <- runReq defaultHttpConfig $
        let uri = https "repo.packagist.org" /: "p2"
                /: owner
                /: name <> ".json"
         in req GET uri NoReqBody jsonResponse mempty
    let packagistPackages = packages $ responseBody packagistResponse
        fullName = Text.intercalate "/" [owner, name]

    pure $ HashMap.lookup fullName packagistPackages
        >>= fmap (version . fst) . Vector.uncons

-- * Remote text file

data TextArguments = TextArguments
    { versionPicker :: Text -> Text
    , textURL :: Text
    }

latestText :: TextArguments -> SlackBuilderT (Maybe Text)
latestText TextArguments{..} = do
    uri <- liftIO $ useHttpsURI <$> mkURI textURL
    packagistResponse <- traverse (runReq defaultHttpConfig . go . fst) uri

    pure $ versionPicker . Text.Encoding.decodeUtf8 . responseBody
        <$> packagistResponse
  where
    go uri = req GET uri NoReqBody bsResponse mempty

-- * GitHub

newtype GhRefNode = GhRefNode
    { name :: Text
    } deriving (Eq, Show)

$(deriveJSON defaultOptions ''GhRefNode)

newtype GhRef = GhRef
    { nodes :: Vector GhRefNode
    } deriving (Eq, Show)

$(deriveJSON defaultOptions ''GhRef)

newtype GhRepository = GhRepository
    { refs :: GhRef
    } deriving (Eq, Show)

$(deriveJSON defaultOptions ''GhRepository)

newtype GhData = GhData
    { repository :: GhRepository
    } deriving (Eq, Show)

instance Aeson.FromJSON GhData where
    parseJSON (Aeson.Object keyMap)
        | Just data' <- KeyMap.lookup "data" keyMap =
            GhData <$> Aeson.withObject "GhData" (.: "repository") data'
    parseJSON _ = fail "data key not found in the response"

data GhVariables = GhVariables
    { name :: Text
    , owner :: Text
    } deriving (Eq, Show)

$(deriveJSON defaultOptions ''GhVariables)

data GhQuery = GhQuery
    { query :: Text
    , variables :: GhVariables
    } deriving (Eq, Show)

$(deriveJSON defaultOptions ''GhQuery)

latestGitHub
    :: PackageOwner
    -> (Text -> Maybe Text)
    -> SlackBuilderT (Maybe Text)
latestGitHub PackageOwner{..} versionTransform = do
    ghToken' <- SlackBuilderT $ asks ghToken
    ghResponse <- runReq defaultHttpConfig $
        let uri = https "api.github.com" /: "graphql"
            query = GhQuery
                {  query = githubQuery
                , variables = GhVariables
                    { owner = owner
                    , name = name
                    }
                }
            authorizationHeader = header "authorization"
                $ Text.Encoding.encodeUtf8
                $ "Bearer " <> ghToken'
         in req POST uri (ReqBodyJson query) jsonResponse
            $ authorizationHeader <> header "User-Agent" "SlackBuilder"
    let ghNodes = nodes
            $ refs
            $ (getField @"repository" :: GhData -> GhRepository)
            $ responseBody ghResponse
        refs' = Vector.reverse
            $ Vector.catMaybes
            $ versionTransform . getField @"name" <$> ghNodes
    pure $ refs' !? 0
  where
    githubQuery =
        "query ($name: String!, $owner: String!) {\n\
        \  repository(name: $name, owner: $owner) {\n\
        \    refs(last: 10, refPrefix: \"refs/tags/\", orderBy: { field: TAG_COMMIT_DATE, direction: ASC }) {\n\
        \      nodes {\n\
        \        id,\n\
        \        name\n\
        \      }\n\
        \    }\n\
        \  }\n\
        \}"