{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE MultiParamTypeClasses #-}
module Get.Install (install) where

import Control.Applicative ((<$>))
import Control.Monad.Error
import Control.Monad.Reader
import Data.Function (on)
import qualified Data.List as List
import qualified Data.Maybe as Maybe
import System.Directory
import System.Exit
import System.FilePath
import System.IO
import Text.JSON

import qualified Elm.Internal.Name as N
import qualified Elm.Internal.Paths as EPath
import qualified Elm.Internal.Version as V

import Get.Library (Library)
import qualified Get.Library as Lib
import qualified Get.Registry as R
import qualified Utils.Commands as Cmd
import qualified Utils.Paths as Path
import qualified Utils.PrettyJson as Pretty

type InstallM l = ReaderT l (ErrorT String IO)

install :: Maybe Library -> ErrorT String IO ()
install maybeLib = case maybeLib of
  Just l  -> runReaderT install1 l
  Nothing -> do
    massoc <- readDepsFile
    case massoc of
      Nothing -> throwError msg
      Just asc -> do
        case List.lookup "dependencies" asc of
          Just (JSObject entries) -> do
            mapM_ (runReaderT install1 <=< mkLib) . fromJSObject $ entries
          Just _ -> throwError $ "dependencies field should be an object in" ++ EPath.dependencyFile
          _      -> throwError $ "no dependencies field found in " ++ EPath.dependencyFile
  where msg = "Could not find dependency file: " ++ EPath.dependencyFile
        mkLib (name, jsv) = do
          name' <- N.fromString' name
          case jsv of
            JSString vsn -> return $ Lib.Library' name' (Just . fromJSString $ vsn)
            _            -> throwError $ "Invalid version number " ++ show jsv

install1 :: InstallM Library ()
install1 = do
  vsn <- Cmd.inDir EPath.dependencyDirectory $ do
    (repo,version) <- Cmd.inDir Path.internals get
    liftIO $ createDirectoryIfMissing True repo
    Cmd.copyDir (Path.internals </> repo) (repo </> show version)
    return version
  withReaderT (\l -> l {Lib.version = vsn}) addToDepsFile
  Cmd.out "Success!"

get :: InstallM Library (FilePath, V.Version)
get =
  do directory <- N.toFilePath . Lib.lib <$> ask
     exists    <- liftIO $ doesDirectoryExist directory
     (if exists then update else clone) directory
     version   <- getVersion
     Cmd.inDir directory (checkout version)
     return (directory, version)
  where
    update directory = do
      name <- Lib.lib <$> ask
      Cmd.out $ "Getting updates for repo " ++ show name
      Cmd.inDir directory $ do Cmd.git ["checkout", "master"]
                               Cmd.git ["pull"]
      return ()

    clone directory = do
      name <- Lib.lib <$> ask
      Cmd.out $ "Cloning repo " ++ show name
      Cmd.git [ "clone", "--progress", "https://github.com/" ++ show name ++ ".git" ]
      liftIO $ renameDirectory (N.project name) directory

    checkout version =
        do let tag = show version
           Cmd.out $ "Checking out version " ++ tag
           Cmd.git [ "checkout", "tags/" ++ tag ]

{-| Check to see that the requested version number exists. In the case that no
version number is requested, use the latest tagless version number in the registry.
If the repo is not in the registry, warn the user and check on github.
-}
getVersion :: InstallM Lib.Library V.Version
getVersion =
    do maybeVersion <- withReaderT Lib.version validateVersion
       versions     <- withReaderT Lib.lib getVersions
       case maybeVersion of
         Nothing ->
             case filter V.tagless versions of
               [] -> errorNoTags
               vs -> return $ maximum vs
         Just version
             | version `notElem` versions -> errorNoMatch version
             | otherwise                  -> return version
    where
      validateVersion :: InstallM (Maybe String) (Maybe V.Version)
      validateVersion = do
        version <- ask
        case (version, V.fromString =<< version) of
          (Just tag, Nothing) ->
            throwError $ unlines $
            [ "tag " ++ tag ++ " is not a valid version number."
            , "It must have the following format: 0.1.2 or 0.1.2-tag"
            ]
          (_, result) -> return result

      getVersions :: InstallM N.Name [V.Version]
      getVersions = do
        name <- ask
        registryVersions <- lift $ R.versions name
        case registryVersions of
          Just vs -> return vs
          Nothing -> do
            Cmd.out $ "Warning: library " ++ show name ++
                      " is not registered publicly. Checking github..."
            tags <- lines <$> Cmd.git [ "tag", "--list" ]
            return $ Maybe.mapMaybe V.fromString tags

      errorNoTags =
          throwError $ unlines
          [ "did not find any properly tagged releases of this library."
          , "Libraries have at least one tag (like 0.1.2 or 1.0) to ensure that your build"
          , "process is stable and repeatable. These tags should follow Semantic Versioning."
          ]

      errorNoMatch version =
          throwError $ unlines
          [ "could not find version " ++ show version ++ " on github."
          ]

addToDepsFile :: InstallM Lib.VsnLibrary ()
addToDepsFile =
    do exists <- liftIO $ doesFileExist file
       add (if exists then yesFile else noFile)
    where
      file = EPath.dependencyFile

      add msg = do
        yes <- liftIO $ do
          hPutStr stdout $ msg ++ " (y/n): "
          Cmd.yesOrNo
        if yes
          then liftIO . writeFile file =<< newDependencies
          else liftIO $ hPutStrLn stdout oddChoice

      oddChoice =
          "Okay, but if you decide to make this library visible to the compiler\n\
          \later, add the dependency to your " ++ file ++ " file."

      yesFile = "Should I add this library to your " ++ file ++ " file?"
      noFile =
        concat
        [ "Your project does not have a " ++ file ++ " file yet.\n"
        , "Should I create it and add the library you just installed?" ]

-- | Returns Nothing if the dependency file doesn't exist, throws an
--   error if its ill-formed
readDepsFile :: (MonadError String m, MonadIO m) => m (Maybe [(String, JSValue)])
readDepsFile = do
  exists <- liftIO $ doesFileExist EPath.dependencyFile
  if not exists
    then return Nothing
    else do
    raw <- liftIO $ withFile EPath.dependencyFile ReadMode $ \handle ->
      do stuff <- hGetContents handle
         length stuff `seq` return stuff
    case decode raw of
      Error msg -> liftIO $ do
        hPutStrLn stderr $ "Error reading " ++ EPath.dependencyFile ++ ":\n" ++ msg
        exitFailure
      Ok obj -> return . Just $ fromJSObject obj

newDependencies :: InstallM Lib.VsnLibrary String
newDependencies = do
  assocs <- maybe [] id <$> readDepsFile
  lib    <- ask
  case List.lookup "dependencies" assocs of
    Just (JSObject entries) -> do
      entries' <- liftIO $ updateEntries lib (fromJSObject entries)
      return $ addDeps assocs entries'
    _ -> return $ addDeps assocs [entry lib]

    where
      entry l = (show $ Lib.lib l, JSString . toJSString . show $ Lib.version l)

      addDeps assocs entries = show $ Pretty.object obj
          where
            assocs' = filter ((/=) "dependencies" . fst) assocs
            obj = assocs' ++ [("dependencies", JSObject $ toJSObject entries)]

      updateEntries :: Lib.VsnLibrary -> [(String, JSValue)] -> IO [(String, JSValue)]
      updateEntries l entries =
          let name = Lib.lib l
              vsn  = Lib.version l
              name' = show name
              entries' = List.insertBy (compare `on` fst) (entry l) $
                         filter ((/=) name' . fst) entries
          in
          case List.lookup name' entries of
            Just (JSString oldVersion) -> do
              hPutStr stdout $
                 name' ++ " " ++ fromJSString oldVersion ++ " is already in " ++
                 EPath.dependencyFile ++ ".\nDo you want to replace it " ++
                 "with version " ++ show vsn ++ "? (y/n): "
              yes <- Cmd.yesOrNo
              case yes of
                True -> return entries'
                False -> hPutStrLn stdout msg >> return entries
                    where msg = "Okay, but be sure to change the version number if\n\
                                \you want to use the library you just installed."

            _ -> return entries'