-- Copyright (c) 2019 The DAML Authors. All rights reserved.
-- SPDX-License-Identifier: Apache-2.0

{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE RankNTypes            #-}
{-# LANGUAGE GADTs                 #-}
{-# LANGUAGE PolyKinds             #-}

module Development.IDE.LSP.Notifications
    ( setHandlersNotifications
    ) where

import qualified Language.LSP.Server      as LSP
import           Language.LSP.Types
import qualified Language.LSP.Types       as LSP
import qualified Language.LSP.Types.Capabilities as LSP

import           Development.IDE.Core.IdeConfiguration
import           Development.IDE.Core.Service
import           Development.IDE.LSP.Server
import           Development.IDE.Core.Shake
import           Development.IDE.Types.Location
import           Development.IDE.Types.Logger
import           Development.IDE.Types.Options

import           Control.Monad.Extra
import           Data.Foldable                    as F
import           Data.Maybe
import qualified Data.HashMap.Strict              as M
import qualified Data.HashSet                     as S
import qualified Data.Text                        as Text

import           Development.IDE.Core.FileStore   (setSomethingModified, setFileModified, typecheckParents)
import           Development.IDE.Core.FileExists  (modifyFileExists, watchedGlobs)
import           Development.IDE.Core.OfInterest
import Ide.Plugin.Config (CheckParents(CheckOnClose))
import Control.Monad.IO.Class


whenUriFile :: Uri -> (NormalizedFilePath -> IO ()) -> IO ()
whenUriFile uri act = whenJust (LSP.uriToFilePath uri) $ act . toNormalizedFilePath'

setHandlersNotifications :: LSP.Handlers (ServerM c)
setHandlersNotifications = mconcat
  [ notificationHandler LSP.STextDocumentDidOpen $
      \ide (DidOpenTextDocumentParams TextDocumentItem{_uri,_version}) -> liftIO $ do
      updatePositionMapping ide (VersionedTextDocumentIdentifier _uri (Just _version)) (List [])
      whenUriFile _uri $ \file -> do
          -- We don't know if the file actually exists, or if the contents match those on disk
          -- For example, vscode restores previously unsaved contents on open
          modifyFilesOfInterest ide (M.insert file Modified{firstOpen=True})
          setFileModified ide False file
          logDebug (ideLogger ide) $ "Opened text document: " <> getUri _uri

  , notificationHandler LSP.STextDocumentDidChange $
      \ide (DidChangeTextDocumentParams identifier@VersionedTextDocumentIdentifier{_uri} changes) -> liftIO $ do
        updatePositionMapping ide identifier changes
        whenUriFile _uri $ \file -> do
          modifyFilesOfInterest ide (M.insert file Modified{firstOpen=False})
          setFileModified ide False file
        logDebug (ideLogger ide) $ "Modified text document: " <> getUri _uri

  , notificationHandler LSP.STextDocumentDidSave $
      \ide (DidSaveTextDocumentParams TextDocumentIdentifier{_uri} _) -> liftIO $ do
        whenUriFile _uri $ \file -> do
            modifyFilesOfInterest ide (M.insert file OnDisk)
            setFileModified ide True file
        logDebug (ideLogger ide) $ "Saved text document: " <> getUri _uri

  , notificationHandler LSP.STextDocumentDidClose $
        \ide (DidCloseTextDocumentParams TextDocumentIdentifier{_uri}) -> liftIO $ do
          whenUriFile _uri $ \file -> do
              modifyFilesOfInterest ide (M.delete file)
              -- Refresh all the files that depended on this
              checkParents <- optCheckParents =<< getIdeOptionsIO (shakeExtras ide)
              when (checkParents >= CheckOnClose) $ typecheckParents ide file
              logDebug (ideLogger ide) $ "Closed text document: " <> getUri _uri

  , notificationHandler LSP.SWorkspaceDidChangeWatchedFiles $
      \ide (DidChangeWatchedFilesParams fileEvents) -> liftIO $ do
        -- See Note [File existence cache and LSP file watchers] which explains why we get these notifications and
        -- what we do with them
        let events =
                mapMaybe
                    (\(FileEvent uri ev) ->
                        (, ev /= FcDeleted) . toNormalizedFilePath'
                        <$> LSP.uriToFilePath uri
                    )
                    ( F.toList fileEvents )
        let msg = Text.pack $ show events
        logDebug (ideLogger ide) $ "Files created or deleted: " <> msg
        modifyFileExists ide events
        setSomethingModified ide

  , notificationHandler LSP.SWorkspaceDidChangeWorkspaceFolders $
      \ide (DidChangeWorkspaceFoldersParams events) -> liftIO $ do
        let add       = S.union
            substract = flip S.difference
        modifyWorkspaceFolders ide
          $ add       (foldMap (S.singleton . parseWorkspaceFolder) (_added   events))
          . substract (foldMap (S.singleton . parseWorkspaceFolder) (_removed events))

  , notificationHandler LSP.SWorkspaceDidChangeConfiguration $
      \ide (DidChangeConfigurationParams cfg) -> liftIO $ do
        let msg = Text.pack $ show cfg
        logDebug (ideLogger ide) $ "Configuration changed: " <> msg
        modifyClientSettings ide (const $ Just cfg)
        setSomethingModified ide

  , notificationHandler LSP.SInitialized $ \ide _ -> do
      clientCapabilities <- LSP.getClientCapabilities
      let watchSupported = case () of
            _ | LSP.ClientCapabilities{_workspace} <- clientCapabilities
              , Just LSP.WorkspaceClientCapabilities{_didChangeWatchedFiles} <- _workspace
              , Just LSP.DidChangeWatchedFilesClientCapabilities{_dynamicRegistration} <- _didChangeWatchedFiles
              , Just True <- _dynamicRegistration
                -> True
              | otherwise -> False
      if watchSupported
      then do
        opts <- liftIO $ getIdeOptionsIO $ shakeExtras ide
        let
          regParams    = RegistrationParams (List [SomeRegistration registration])
          -- The registration ID is arbitrary and is only used in case we want to deregister (which we won't).
          -- We could also use something like a random UUID, as some other servers do, but this works for
          -- our purposes.
          registration = Registration "globalFileWatches"
                                      SWorkspaceDidChangeWatchedFiles
                                      regOptions
          regOptions =
            DidChangeWatchedFilesRegistrationOptions { _watchers = List watchers }
          -- See Note [File existence cache and LSP file watchers] for why this exists, and the choice of watch kind
          watchKind = WatchKind { _watchCreate = True, _watchChange = False, _watchDelete = True}
          -- See Note [Which files should we watch?] for an explanation of why the pattern is the way that it is
          -- The patterns will be something like "**/.hs", i.e. "any number of directory segments,
          -- followed by a file with an extension 'hs'.
          watcher glob = FileSystemWatcher { _globPattern = glob, _kind = Just watchKind }
          -- We use multiple watchers instead of one using '{}' because lsp-test doesn't
          -- support that: https://github.com/bubba/lsp-test/issues/77
          watchers = [ watcher (Text.pack glob) | glob <- watchedGlobs opts ]

        void $ LSP.sendRequest SClientRegisterCapability regParams (const $ pure ()) -- TODO handle response
      else liftIO $ logDebug (ideLogger ide) "Warning: Client does not support watched files. Falling back to OS polling"
  ]