{-# LANGUAGE CPP             #-}
{-# LANGUAGE LambdaCase      #-}
{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE RecordWildCards #-}

module Ide.Plugin.Eval.Rules (GetEvalComments(..), rules,queueForEvaluation) where

import           Control.Monad.IO.Class               (MonadIO (liftIO))
import           Data.HashSet                         (HashSet)
import qualified Data.HashSet                         as Set
import           Data.IORef
import qualified Data.Map.Strict                      as Map
import           Data.String                          (fromString)
import           Development.IDE                      (GetModSummaryWithoutTimestamps (GetModSummaryWithoutTimestamps),
                                                       GetParsedModuleWithComments (GetParsedModuleWithComments),
                                                       IdeState,
                                                       NeedsCompilation (NeedsCompilation),
                                                       NormalizedFilePath,
                                                       RuleBody (RuleNoDiagnostics),
                                                       Rules, defineEarlyCutoff,
                                                       encodeLinkableType,
                                                       fromNormalizedFilePath,
                                                       msrModSummary,
                                                       realSrcSpanToRange,
                                                       useWithStale_)
import           Development.IDE.Core.PositionMapping (toCurrentRange)
import           Development.IDE.Core.Rules           (computeLinkableTypeForDynFlags,
                                                       needsCompilationRule)
import           Development.IDE.Core.Shake           (IsIdeGlobal,
                                                       RuleBody (RuleWithCustomNewnessCheck),
                                                       addIdeGlobal,
                                                       getIdeGlobalAction,
                                                       getIdeGlobalState)
import           Development.IDE.GHC.Compat
import qualified Development.IDE.GHC.Compat           as SrcLoc
import qualified Development.IDE.GHC.Compat.Util      as FastString
import           Development.IDE.Graph                (alwaysRerun)
import           Ide.Plugin.Eval.Types


rules :: Rules ()
rules = do
    evalParsedModuleRule
    redefinedNeedsCompilation
    addIdeGlobal . EvaluatingVar =<< liftIO(newIORef mempty)

newtype EvaluatingVar = EvaluatingVar (IORef (HashSet NormalizedFilePath))
instance IsIdeGlobal EvaluatingVar

queueForEvaluation :: IdeState -> NormalizedFilePath -> IO ()
queueForEvaluation ide nfp = do
    EvaluatingVar var <- getIdeGlobalState ide
    modifyIORef var (Set.insert nfp)

#if MIN_VERSION_ghc(9,0,0)
pattern RealSrcSpanAlready :: SrcLoc.RealSrcSpan -> SrcLoc.RealSrcSpan
pattern RealSrcSpanAlready x = x
apiAnnComments' :: SrcLoc.ApiAnns -> [SrcLoc.RealLocated AnnotationComment]
apiAnnComments' = apiAnnRogueComments
#else
apiAnnComments' :: SrcLoc.ApiAnns -> [SrcLoc.Located AnnotationComment]
apiAnnComments' = concat . Map.elems . snd

pattern RealSrcSpanAlready :: SrcLoc.RealSrcSpan -> SrcSpan
pattern RealSrcSpanAlready x = SrcLoc.RealSrcSpan x Nothing
#endif

evalParsedModuleRule :: Rules ()
evalParsedModuleRule = defineEarlyCutoff $ RuleNoDiagnostics $ \GetEvalComments nfp -> do
    (ParsedModule{..}, posMap) <- useWithStale_ GetParsedModuleWithComments nfp
    let comments = foldMap (\case
                L (RealSrcSpanAlready real) bdy
                    | FastString.unpackFS (srcSpanFile real) ==
                        fromNormalizedFilePath nfp
                    , let ran0 = realSrcSpanToRange real
                    , Just curRan <- toCurrentRange posMap ran0
                    ->

                        -- since Haddock parsing is unset explicitly in 'getParsedModuleWithComments',
                        -- we can concentrate on these two
                        case bdy of
                            AnnLineComment cmt ->
                                mempty { lineComments = Map.singleton curRan (RawLineComment cmt) }
                            AnnBlockComment cmt ->
                                mempty { blockComments = Map.singleton curRan $ RawBlockComment cmt }
                            _ -> mempty
                _ -> mempty
            )
            $ apiAnnComments' pm_annotations
        -- we only care about whether the comments are null
        -- this is valid because the only dependent is NeedsCompilation
        fingerPrint = fromString $ if nullComments comments then "" else "1"
    return (Just fingerPrint, Just comments)

-- Redefine the NeedsCompilation rule to set the linkable type to Just _
-- whenever the module is being evaluated
-- This will ensure that the modules are loaded with linkables
-- and the interactive session won't try to compile them on the fly,
-- leading to much better performance of the evaluate code lens
redefinedNeedsCompilation :: Rules ()
redefinedNeedsCompilation = defineEarlyCutoff $ RuleWithCustomNewnessCheck (<=) $ \NeedsCompilation f -> do
    alwaysRerun

    EvaluatingVar var <- getIdeGlobalAction
    isEvaluating <- liftIO $ (f `elem`) <$> readIORef var


    if not isEvaluating then needsCompilationRule f else do
        ms <- msrModSummary . fst <$> useWithStale_ GetModSummaryWithoutTimestamps f
        let df' = ms_hspp_opts ms
            linkableType = computeLinkableTypeForDynFlags df'
            fp = encodeLinkableType $ Just linkableType

        -- remove the module from the Evaluating state
        liftIO $ modifyIORef var (Set.delete f)

        pure (Just fp, Just (Just linkableType))