{-# LANGUAGE NoMonomorphismRestriction #-}
{-# LANGUAGE OverloadedStrings         #-}
{-# LANGUAGE RecordWildCards           #-}
{-# LANGUAGE ScopedTypeVariables       #-}
{-# OPTIONS_GHC -Wall -Wwarn -fno-warn-type-defaults -fno-warn-unused-binds -fno-warn-unused-imports -Wno-unticked-promoted-constructors #-}

{- | Keep the module name in sync with its file path.

Provide CodeLenses to:
* Add a module header ("module /moduleName/ where") to empty Haskell files
* Fix the module name if incorrect
-}
module Ide.Plugin.ModuleName (
    descriptor,
) where

import           Control.Monad
import           Control.Monad.IO.Class (MonadIO (liftIO))
import           Data.Aeson             (ToJSON (toJSON), Value (Null))
import           Data.Char              (isLower)
import qualified Data.HashMap.Strict    as Map
import           Data.List              (find, intercalate, isPrefixOf)
import           Data.Maybe             (maybeToList)
import           Data.String            (IsString)
import           Data.Text              (Text, pack)
import qualified Data.Text              as T
-- import Debug.Trace (trace)
import           Development.IDE        (GetParsedModule (GetParsedModule),
                                         GhcSession (GhcSession), HscEnvEq,
                                         IdeState, List (..),
                                         NormalizedFilePath,
                                         Position (Position), Range (Range),
                                         evalGhcEnv, hscEnvWithImportPaths,
                                         realSrcSpanToRange, runAction,
                                         toNormalizedUri, uriToFilePath', use,
                                         use_)
import           GHC                    (DynFlags (importPaths), GenLocated (L),
                                         HsModule (hsmodName),
                                         ParsedModule (pm_parsed_source),
                                         SrcSpan (RealSrcSpan),
                                         getSessionDynFlags, unLoc)
import           Ide.PluginUtils        (getProcessID, mkLspCmdId)
import           Ide.Types
import           Language.LSP.Server
import           Language.LSP.Types
import           Language.LSP.VFS       (virtualFileText)
import           System.Directory       (canonicalizePath)
import           System.FilePath        (dropExtension, splitDirectories,
                                         takeFileName)

-- |Plugin descriptor
descriptor :: PluginId -> PluginDescriptor IdeState
descriptor plId =
    (defaultPluginDescriptor plId)
        { pluginHandlers = mkPluginHandler STextDocumentCodeLens codeLens
        , pluginCommands = [PluginCommand editCommandName editCommandName command]
        }

editCommandName :: IsString p => p
editCommandName = "edit"

asCodeLens :: Text -> Action -> CodeLens
asCodeLens cid Replace{..} =
    CodeLens
        aRange
        (Just $ Command aTitle cid (Just (List [toJSON aUri])))
        Nothing

-- | Generate code lenses
codeLens :: PluginMethodHandler IdeState TextDocumentCodeLens
codeLens state pluginId CodeLensParams{_textDocument=TextDocumentIdentifier uri} = do
    do
        pid <- liftIO $ pack . show <$> getProcessID
        Right . List . maybeToList . (asCodeLens (mkLspCmdId pid pluginId editCommandName) <$>) <$> action state uri

-- | (Quasi) Idempotent command execution: recalculate action to execute on command request
command :: CommandFunction IdeState Uri
command state uri = do
    actMaybe <- action state uri
    case actMaybe of
      Nothing -> pure ()
      Just act -> void $ sendRequest SWorkspaceApplyEdit (ApplyWorkspaceEditParams Nothing (asEdit act)) (\_ -> pure ())
    return (Right Null)

-- | A source code change
data Action = Replace {aUri :: Uri, aRange :: Range, aTitle :: Text, aCode :: Text} deriving (Show)

-- | Convert an Action to the corresponding edit operation
asEdit :: Action -> WorkspaceEdit
asEdit act@Replace{..} =
    WorkspaceEdit (Just $ Map.singleton aUri $ List (asTextEdits act)) Nothing Nothing

asTextEdits :: Action -> [TextEdit]
asTextEdits Replace{..} = [TextEdit aRange aCode]

-- | Required action (that can be converted to either CodeLenses or CodeActions)
action :: IdeState -> Uri -> LspM c (Maybe Action)
action state uri =
    traceAs "action" <$> do
        let Just nfp = uriToNormalizedFilePath $ toNormalizedUri uri
        let Just fp = uriToFilePath' uri

        contents <- getVirtualFile $ toNormalizedUri uri
        let emptyModule = maybe True (T.null . T.strip . virtualFileText) contents

        correctNameMaybe <- liftIO $ traceAs "correctName" <$> pathModuleName state nfp fp
        statedNameMaybe <- liftIO $ traceAs "statedName" <$> codeModuleName state nfp

        let act = Replace uri
        let todo = case (correctNameMaybe, statedNameMaybe) of
                (Just correctName, Just (nameRange, statedName))
                    | correctName /= statedName ->
                        Just $
                            act
                                nameRange
                                ("Set module name to " <> correctName)
                                correctName
                (Just correctName, _)
                    | emptyModule ->
                        let code = T.unwords ["module", correctName, "where\n"]
                         in Just $ act (Range (Position 0 0) (Position 0 0)) code code
                _ -> Nothing
        return todo

-- | The module name, as derived by the position of the module in its source directory
pathModuleName :: IdeState -> NormalizedFilePath -> String -> IO (Maybe Text)
pathModuleName state normFilePath filePath
    | isLower (head $ takeFileName filePath) = return $ Just "Main"
    | otherwise = do
        session :: HscEnvEq <- runAction "ModuleName.ghcSession" state $ use_ GhcSession normFilePath
        srcPaths <- evalGhcEnv (hscEnvWithImportPaths session) $ importPaths <$> getSessionDynFlags
        paths <- mapM canonicalizePath srcPaths
        mdlPath <- canonicalizePath filePath
        let maybePrefix = find (`isPrefixOf` mdlPath) paths

        let maybeMdlName =
                ( \prefix ->
                    intercalate "."
                        . splitDirectories
                        . drop (length prefix + 1)
                        $ dropExtension mdlPath
                )
                    <$> maybePrefix
        return $ T.pack <$> maybeMdlName

-- | The module name, as stated in the module
codeModuleName :: IdeState -> NormalizedFilePath -> IO (Maybe (Range, Text))
codeModuleName state nfp =
    ((\(L (RealSrcSpan l) m) -> (realSrcSpanToRange l, T.pack . show $ m)) <$>)
        . ((hsmodName . unLoc . pm_parsed_source) =<<)
        <$> runAction "ModuleName.GetParsedModule" state (use GetParsedModule nfp)

-- traceAs :: Show a => String -> a -> a
-- traceAs lbl a = trace (lbl ++ " = " ++ show a) a

traceAs :: b -> a -> a
traceAs _ a = a