{-# LANGUAGE DataKinds           #-}
{-# LANGUAGE DeriveGeneric       #-}
{-# LANGUAGE ExplicitNamespaces  #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeOperators       #-}

module GitHubRelease
  ( Command(..)
  , main
  , runCommand
  , upload
  , getUploadUrl
  , getTag
  , authorizationHeader
  , userAgentHeader
  , userAgent
  , versionString
  , uploadFile
  , uploadBody
  ) where

import           Options.Generic            (type (<?>))

import           Data.Aeson                 (object, (.=))
import qualified Data.Aeson                 as Aeson
import qualified Data.ByteString.Char8      as BS8
import qualified Data.ByteString.Lazy       as BSL
import qualified Data.HashMap.Strict        as HashMap
import           Data.Maybe                 (maybe)
import           Data.Monoid                ((<>))
import qualified Data.Text                  as Text
import qualified Data.Version               as Version
import qualified GHC.Generics               as Generics
import qualified Network.HTTP.Client        as Client
import qualified Network.HTTP.Client.TLS    as TLS
import qualified Network.HTTP.Types         as HTTP
import qualified Network.Mime               as MIME
import qualified Network.URI.Template       as Template
import qualified Network.URI.Template.Types as Template
import qualified Options.Generic            as Options
import qualified Paths_github_release       as This
import qualified System.IO                  as IO
import qualified Text.Printf                as Printf

data Command
  = Upload { file :: FilePath <?> "The path to the local file to upload."
          ,  name :: String <?> "The name to give the file on the release."
          ,  owner :: Maybe String <?> "The GitHub owner, either a user or organization."
          ,  repo :: String <?> "The GitHub repository name."
          ,  tag :: String <?> "The tag name."
          ,  token :: String <?> "Your OAuth2 token."}
  | Release { title :: String <?> "The name of the release"
          ,  owner :: Maybe String <?> "The GitHub owner, either a user or organization."
          ,  repo :: String <?> "The GitHub repository name."
          ,  tag :: String <?> "The tag name."
          ,  description :: Maybe String <?> "Release description."
          ,  token :: String <?> "Your OAuth2 token."
          ,  preRelease :: Maybe Bool <?> "Indicates if this is a pre-release."
          ,  draft :: Maybe Bool <?> "Indicates if this is a draft."
          }
  | Version
  deriving (Generics.Generic, Show)

instance Options.ParseRecord Command

main :: IO ()
main = do
  command <- Options.getRecord (Text.pack "Upload a file to a GitHub release.")
  runCommand command

runCommand :: Command -> IO ()
runCommand command =
  case command of
    Upload aFile aName anOwner aRepo aTag aToken ->
      upload
        (Options.unHelpful aToken)
        (Options.unHelpful anOwner)
        (Options.unHelpful aRepo)
        (Options.unHelpful aTag)
        (Options.unHelpful aFile)
        (Options.unHelpful aName)
    Release aTitle anOwner aRepo aTag aDescription aToken aPreRelease aDraft ->
      release
        (Options.unHelpful aToken)
        (Options.unHelpful anOwner)
        (Options.unHelpful aRepo)
        (Options.unHelpful aTag)
        (Options.unHelpful aTitle)
        (Options.unHelpful aDescription)
        (Options.unHelpful aPreRelease)
        (Options.unHelpful aDraft)
    Version -> putStrLn versionString

upload :: String -> Maybe String -> String -> String -> FilePath -> String -> IO ()
upload aToken anOwner aRepo aTag aFile aName = do
  manager <- Client.newManager TLS.tlsManagerSettings
  uploadUrl <- getUploadUrl manager aToken anOwner aRepo aTag
  response <- uploadFile manager uploadUrl aToken aFile aName
  case HTTP.statusCode (Client.responseStatus response) of
    201 -> pure ()
    _   -> fail "Failed to upload file to release!"

release :: String -> Maybe String -> String -> String -> String -> Maybe String -> Maybe Bool -> Maybe Bool -> IO ()
release aToken anOwner aRepo aTag aTitle aDescription aPreRelease aDraft = do
  manager <- Client.newManager TLS.tlsManagerSettings
  (owner', repo') <- getOwnerRepo anOwner aRepo
  let format = "https://api.github.com/repos/%s/%s/releases"
  let
    url :: String
    url = Printf.printf format owner' repo'
  response <- mkRelease manager url aToken aTag aTitle aDescription aPreRelease aDraft
  let body = Aeson.eitherDecode $ Client.responseBody response :: Either String Aeson.Object
  case HTTP.statusCode (Client.responseStatus response) of
    201 -> pure ()
    422 -> IO.hPutStrLn IO.stderr "Release aready exists. Ignoring."
    _   -> fail $ "Failed to create release! Reason: " <> (show body)

getUploadUrl
  :: Client.Manager
  -> String
  -> Maybe String
  -> String
  -> String
  -> IO Template.UriTemplate
getUploadUrl manager aToken anOwner aRepo aTag = do
  json <- do
    result <- getTag manager aToken anOwner aRepo aTag
    case result of
      Left problem -> fail ("Failed to get tag JSON: " ++ show problem)
      Right json   -> pure json
  text <- case HashMap.lookup (Text.pack "upload_url") json of
    Just (Aeson.String text) -> pure text
    _ -> fail ("Failed to get upload URL: " ++ show json)
  let uploadUrl = Text.unpack text
  template <- case Template.parseTemplate uploadUrl of
    Left problem   -> fail ("Failed to parse URL template: " ++ show problem)
    Right template -> pure template
  pure template

getOwnerRepo :: Maybe String -> String -> IO ((String, String))
getOwnerRepo rawOwner rawRepo = do
  (anOwner, aRepo) <- case break (== '/') rawRepo of
    (aRepo, "") -> case rawOwner of
      Nothing      -> fail "Missing required option --owner."
      Just anOwner -> pure (anOwner, aRepo)
    (anOwner, aRepo) -> do
      case rawOwner of
        Nothing -> pure ()
        Just _  -> IO.hPutStrLn IO.stderr "Ignoring --owner option."
      pure (anOwner, drop 1 aRepo)
  return (anOwner, aRepo)

getTag
  :: Client.Manager
  -> String
  -> Maybe String
  -> String
  -> String
  -> IO (Either String Aeson.Object)
getTag manager aToken rawOwner rawRepo aTag = do
  (anOwner, aRepo) <- getOwnerRepo rawOwner rawRepo
  let format = "https://api.github.com/repos/%s/%s/releases/tags/%s"
  let
    url :: String
    url = Printf.printf format anOwner aRepo aTag
  initialRequest <- Client.parseRequest url
  let request =
        initialRequest
        {Client.requestHeaders = [authorizationHeader aToken, userAgentHeader]}
  response <- Client.httpLbs request manager
  let body = Client.responseBody response
  return (Aeson.eitherDecode body)

authorizationHeader :: String -> HTTP.Header
authorizationHeader aToken =
  (HTTP.hAuthorization, BS8.pack (Printf.printf "token %s" aToken))

userAgentHeader :: HTTP.Header
userAgentHeader = (HTTP.hUserAgent, BS8.pack userAgent)

userAgent :: String
userAgent = Printf.printf "%s/%s-%s" "tfausak" "github-release" versionString

versionString :: String
versionString = Version.showVersion This.version

uploadFile
  :: Client.Manager
  -> Template.UriTemplate
  -> String
  -> FilePath
  -> String
  -> IO (Client.Response BSL.ByteString)
uploadFile manager template aToken aFile aName = do
  contents <- BSL.readFile aFile
  let body = Client.RequestBodyLBS contents
  uploadBody manager template aToken body aName

uploadBody
  :: Client.Manager
  -> Template.UriTemplate
  -> String
  -> Client.RequestBody
  -> String
  -> IO (Client.Response BSL.ByteString)
uploadBody manager template aToken body aName = do
  let
    url :: String
    url = Template.render
      template
      [("name", Template.WrappedValue (Template.Single aName))]
  initialRequest <- Client.parseRequest url
  let request =
        initialRequest
        { Client.method = BS8.pack "POST"
        , Client.requestBody = body
        , Client.requestHeaders =
            [ authorizationHeader aToken
            , (HTTP.hContentType, MIME.defaultMimeLookup (Text.pack aName))
            , userAgentHeader
            ]
        }
  Client.httpLbs request manager

mkRelease
  :: Client.Manager
  -> String
  -> String
  -> String
  -> String
  -> Maybe String
  -> Maybe Bool
  -> Maybe Bool
  -> IO (Client.Response BSL.ByteString)
mkRelease manager url aToken aTag aTitle aDescription aPreRelease aDraft = do
  initialRequest <- Client.parseRequest url
  let requestObject = object
            [ Text.pack "tag_name" .= aTag
            , Text.pack "name"  .= aTitle
            , Text.pack "body" .= maybe "" id aDescription
            , Text.pack "prerelease" .= maybe False id aPreRelease
            , Text.pack "draft" .= maybe False id aDraft
            ]
  let request =
        initialRequest
        { Client.method = BS8.pack "POST"
        , Client.requestBody = Client.RequestBodyLBS $ Aeson.encode requestObject
        , Client.requestHeaders =
            [ authorizationHeader aToken
            , userAgentHeader
            ]
        }
  Client.httpLbs request manager