aboutsummaryrefslogtreecommitdiff
path: root/app/Server.hs
blob: f6e1d6d89a48974a314a019e47e9319d44acea5b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
{-# LANGUAGE CPP #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TupleSections #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

module Main where

import Control.Exception
  ( SomeAsyncException
  , SomeException
  , fromException
  , handle
  , throwIO
  , throwIO
  , try
  )
import Control.Monad (unless)
import Control.Monad.Except (ExceptT(..))
import Control.Monad.Reader (MonadIO, MonadReader, ReaderT(..), asks, liftIO)
import qualified Data.Aeson as A
import qualified Data.ByteString as BS
import qualified Data.ByteString.Lazy as BSL
import Data.Default (def)
import Data.Either (lefts, rights)
import qualified Data.HashMap.Strict as HM
import Data.Hashable (Hashable)
import qualified Data.IntervalMap.Strict as IVM
import qualified Data.List as L
import qualified Data.Map.Strict as M
import Data.Maybe (fromMaybe, mapMaybe)
import qualified Data.Vector as V
#if MIN_VERSION_GLASGOW_HASKELL(8,4,3,0)
import qualified GHC.Compact as C
import Data.Functor.Identity(Identity(..))
#endif
import Data.Pagination
  ( Paginated
  , hasNextPage
  , hasPrevPage
  , mkPagination
  , paginate
  , paginatedItems
  , paginatedPagesTotal
  )
import Data.Proxy (Proxy(..))
import Data.Semigroup ((<>))
import qualified Data.Serialize as Serialize
import qualified Data.Set as S
import qualified Data.Text as T
import qualified Data.Text.Encoding as TE
import Data.Text.Lazy (toStrict)
import Data.Text.Read(decimal)
import Data.Version (Version(..))
import GHC.Exts (Down(..), groupWith)
import GHC.Generics (Generic)
import qualified HaskellCodeExplorer.Types as HCE
import Network.HTTP.Types
  ( hContentEncoding
  , hContentType
  , status200
  , status404
  )
import Network.Mime (defaultMimeLookup)
import Network.Wai
  ( Application
  , Middleware
  , Response
  , pathInfo
  , responseFile
  , responseLBS
  , requestHeaders
  )
import Network.Wai.Handler.Warp (run)
import Network.Wai.Middleware.RequestLogger
  ( Destination(..)
  , OutputFormat(..)
  , RequestLoggerSettings(..)
  , mkRequestLogger
  )
import Numeric.Natural(Natural)
import Options.Applicative
  ( Parser
  , (<**>)
  , (<|>)
  , auto
  , execParser
  , fullDesc
  , help
  , helper
  , info
  , long  
  , some  
  , metavar
  , option
  , optional
  , progDesc
  , short
  , strOption
  , switch
  )
import Servant
  ( (:<|>)(..)
  , (:>)
  , Capture
  , FromHttpApiData(..)
  , Get
  , Header
  , Headers
  , QueryParam
  , ServantErr
  , ServerT
  , ToHttpApiData(..)
  , addHeader
  , err404
  , errBody
  , serve
  )
import Servant.API.ContentTypes (AllCTRender(..), JSON)
import Servant.Server (Handler(..), hoistServer)
import Servant.Utils.Links (safeLink)
import System.Directory (doesFileExist)
import System.FilePath.Find
  ( FileType(..)
  , (&&?)
  , (/=?)
  , (==?)
  , (==?)
  , depth
  , filePath
  , fileType
  , find
  )
import System.FilePath.Posix ((</>),takeFileName)
import System.Log.FastLogger
  ( LoggerSet
  , defaultBufSize
  , newFileLoggerSet
  , newStdoutLoggerSet
  )
import Text.Blaze.Html.Renderer.Text (renderHtml)
import qualified Text.Blaze.Html5 as Html hiding (html, source)
import Data.FileEmbed (embedDir, embedFile)

--------------------------------------------------------------------------------
-- Server config
--------------------------------------------------------------------------------

data ServerConfig = ServerConfig
  { configPackagesPath :: !PackagesPath
  , configPort :: !Int
  , configServeStaticFiles :: !Bool
  , configEnableExpressionInfo :: !Bool
  , configIndexDirectoryName :: !(Maybe FilePath)
  , configLog :: !HCE.Log
  , configStaticFilesUrlPrefix :: !String
  , configJsDistDirectory :: !(Maybe String)
  , configMaxPerPage :: !Int
  } deriving (Show, Eq)

data PackagesPath
  = DirectoryWithPackages FilePath
  | Directories [FilePath]
  deriving (Show, Eq)

configParser :: Parser ServerConfig
configParser =
  ServerConfig <$>
  ((DirectoryWithPackages <$>
    strOption
      (long "packages" <> metavar "PATH" <>
       help "Path to a directory with Cabal packages")) <|>
   Directories <$>
   some
     (strOption
        (long "package" <> short 'p' <> metavar "PATH" <>
         help "Path to a Cabal package"))) <*>
  (pure 8080 <|>
   option
     auto
     (long "port" <> help "Port to use (default is 8080)" <> metavar "PORT")) <*>
  (not <$> switch (long "no-static" <> help "Do not serve static files")) <*>
  (not <$>
   switch
     (long "no-expressions" <>
      help "Disable queries that return expressions inside selected span")) <*>
  optional
    (strOption
       (long "index-directory" <>
        help
          "Name of a directory with index (default is '.haskell-code-explorer')" <>
        metavar "DIRECTORY_NAME")) <*>
  (pure HCE.StdOut <|>
   (HCE.ToFile <$>
    strOption
      (long "logfile" <>
       help "Path to a log file (by default log is written to stdout)" <>
       metavar "PATH"))) <*>
  (pure "files" <|>
   strOption
     (long "static-url-prefix" <> metavar "STRING" <>
      help "URL prefix for static files (default is 'files')")) <*>
  optional
    (strOption
       (long "js-path" <> help "Path to a directory with javascript files" <>
        metavar "PATH")) <*>
  (pure 50 <|>
   option
     auto
     (long "max-per-page" <> metavar "INTEGER" <>
      help "Maximum number of items per page (default is 50)"))

--------------------------------------------------------------------------------
-- Loading packages
--------------------------------------------------------------------------------

data PackageVersions = PackageVersions
  { name :: T.Text
  , versions :: [Version]
  } deriving (Show, Ord, Eq, Generic)

type PackageMap
   = HM.HashMap PackageName (M.Map Version (HCE.PackageInfo HCE.CompactModuleInfo))
     
type PackagePathMap = HM.HashMap PackageId FilePath

newtype AllPackages =
  AllPackages BSL.ByteString

newtype PackageId = PackageId
  { getPackageId :: T.Text
  } deriving (Show, Eq, Hashable)

newtype PackageName = PackageName
  { getPackageName :: T.Text
  } deriving (Show, Eq, Hashable)
  
instance A.ToJSON PackageVersions

type GlobalReferenceMap = HM.HashMap HCE.ExternalId (S.Set GlobalReferences)

data GlobalReferences = GlobalReferences
  { count :: Int
  , packageId :: T.Text
  } deriving (Show, Eq, Ord, Generic)

instance A.ToJSON GlobalReferences

loadPackages ::
     ServerConfig
  -> IO (Maybe (PackageMap, PackagePathMap, [PackageVersions], GlobalReferenceMap))
loadPackages config = do
  packageDirectories <-
    case configPackagesPath config of
      DirectoryWithPackages dir ->
        find (depth ==? 0) (fileType ==? Directory &&? filePath /=? dir) dir
      Directories dirs -> return dirs
  result <- mapM (loadPackageInfo config) packageDirectories
  let loadedPackages = rights result
      packageLoadErrors = lefts result
      packageInfos = map fst loadedPackages
      packageIds =
        map (HCE.id :: HCE.PackageInfo modInfo -> HCE.PackageId) packageInfos
  unless (null packageInfos) $ do
    putStrLn "Loaded packages : "
    mapM_ (print . HCE.packageIdToText) packageIds
  unless (null packageLoadErrors) $ do
    putStrLn "Package loading errors : "
    mapM_ (\(err, path) -> putStrLn $ path ++ " : " ++ err) packageLoadErrors
  if not . null $ loadedPackages
    then do
      let packageVersions =
            L.sortOn (T.toLower . (name :: PackageVersions -> T.Text)) .
            map
              (\(name, versions) ->
                 PackageVersions name (L.sortOn Down versions)) .
            HM.toList .
            HM.fromListWith (++) .
            map (\HCE.PackageId {..} -> (name, [version])) $
            packageIds
          packageMap =
            L.foldl'
              (\hMap packageInfo ->
                 let val = M.singleton (packageVersion packageInfo) packageInfo
                  in HM.insertWith M.union (packageName packageInfo) val hMap)
              HM.empty
              packageInfos
          packagePathMap =
            L.foldl'
              (\hMap (packageInfo, path) ->
                 let key =
                       PackageId $
                       HCE.packageIdToText
                         (HCE.id
                            (packageInfo :: HCE.PackageInfo HCE.CompactModuleInfo))
                  in HM.insert key path hMap)
              HM.empty
              loadedPackages
          globalReferenceMap =
            L.foldl'
              (\hMap (packageInfo, _path) ->
                 let references =
                       HM.map
                         (\spans ->
                            S.singleton
                              (GlobalReferences
                                 (S.size spans)
                                 (HCE.packageIdToText packageId))) .
                       HCE.externalIdOccMap $
                       packageInfo
                     packageId =
                       HCE.id
                         (packageInfo :: HCE.PackageInfo HCE.CompactModuleInfo)
                  in HM.unionWith S.union references hMap)
              HM.empty
              loadedPackages
      packageMapCompacted <- ghcCompact packageMap
      packagePathMapCompacted <- ghcCompact packagePathMap
      packageVersionsCompacted <- ghcCompact packageVersions
      globalReferenceMapCompacted <- ghcCompact globalReferenceMap
      return . Just $
        ( packageMapCompacted
        , packagePathMapCompacted
        , packageVersionsCompacted
        , globalReferenceMapCompacted)
    else return Nothing
  where
    packageName :: HCE.PackageInfo HCE.CompactModuleInfo -> PackageName
    packageName =
      PackageName .
      (HCE.name :: HCE.PackageId -> T.Text) .
      (HCE.id :: HCE.PackageInfo modInfo -> HCE.PackageId)
    packageVersion :: HCE.PackageInfo HCE.CompactModuleInfo -> Version
    packageVersion =
      HCE.version . (HCE.id :: HCE.PackageInfo modInfo -> HCE.PackageId)

ghcCompact :: forall a. a -> IO a
ghcCompact =
#if MIN_VERSION_GLASGOW_HASKELL(8,4,3,0)
  (fmap C.getCompact . C.compact)
#else
  return
#endif

loadPackageInfo ::
     ServerConfig
  -> String
  -> IO (Either (String, FilePath) ( HCE.PackageInfo HCE.CompactModuleInfo
                                   , FilePath))
loadPackageInfo config path =
  handleSync (\e -> return $ Left (show e, path)) $ do
    let indexDirectory =
          fromMaybe
            HCE.defaultOutputDirectoryName
            (configIndexDirectoryName config)
    binaryContent <-
      BS.readFile (path </> indexDirectory </> HCE.packageInfoBinaryFileName)
    let eitherPackageInfo = Serialize.decode binaryContent
        enableExpressionInfo = configEnableExpressionInfo config
    case eitherPackageInfo of
      Right packageInfo ->
        return . Right $
        ( updateEachModuleInfo
            packageInfo
            (\modInfo ->
               let source =
                     HCE.source :: HCE.CompactModuleInfo -> V.Vector T.Text
                in if not enableExpressionInfo
                     then modInfo
                            { HCE.exprInfoMap = IVM.empty
                            , HCE.source = V.force $ source modInfo
                            -- 'force' fixes this error: Data.Vector.Mutable: uninitialised element CallStack (from HasCallStack): error, called at ./Data/Vector/Mutable.hs:188:17 in vector-0.12.0.1-GGZqQZyzchy8YFPCF67wxL:Data.Vector.Mutable
                            }
                     else modInfo {HCE.source = V.force $ source modInfo})
        , path)
      Left e -> return . Left $ (e, path)

updateEachModuleInfo ::
     HCE.PackageInfo HCE.CompactModuleInfo
  -> (HCE.CompactModuleInfo -> HCE.CompactModuleInfo)
  -> HCE.PackageInfo HCE.CompactModuleInfo
updateEachModuleInfo packageInfo update =
  packageInfo {HCE.moduleMap = HM.map update $ HCE.moduleMap packageInfo}

handleSync :: (SomeException -> IO a) -> IO a -> IO a
handleSync onError =
  handle
    (\ex ->
       case fromException ex of
         Just (asyncEx :: SomeAsyncException) -> throwIO asyncEx
         _ -> onError ex)

--------------------------------------------------------------------------------
-- Servant API
--------------------------------------------------------------------------------

type API = GetAllPackages
  :<|> GetDefinitionSite  
  :<|> GetExpressions
  :<|> GetReferences
  :<|> GetIdentifiers
  :<|> GetGlobalReferences

type GetAllPackages = "api" :> "packages" :> Get '[JSON] AllPackages

type GetDefinitionSite = "api" :> "definitionSite"
  :> Capture "packageId" PackageId
  :> Capture "componentId" HCE.ComponentId
  :> Capture "moduleName" HCE.HaskellModuleName
  :> Capture "entity" HCE.LocatableEntity
  :> Capture "name" T.Text
  :> Get '[JSON] HCE.DefinitionSite

type GetExpressions = "api" :> "expressions"
  :> Capture "packageId" PackageId
  :> Capture "modulePath" HCE.HaskellModulePath
  :> Capture "lineStart" Int
  :> Capture "columnStart" Int
  :> Capture "lineEnd" Int
  :> Capture "columnEnd" Int
  :> Get '[JSON] [Expression]

type GetReferences = "api" :> "references"
  :> Capture "packageId" PackageId
  :> Capture "externalId" HCE.ExternalId
  :> QueryParam "page" Int
  :> QueryParam "per_page" Int
  :> Get '[JSON] (Headers '[Header "Link" T.Text,Header "X-Total-Count" Int]
                 [SourceFile])

type GetIdentifiers = "api" :> "identifiers"
  :> Capture "packageId" PackageId
  :> Capture "query" T.Text
  :> QueryParam "page" Int
  :> QueryParam "per_page" Int
  :> Get '[JSON] (Headers '[Header "Link" T.Text,Header "X-Total-Count" Int]
                 [HCE.ExternalIdentifierInfo])

type GetGlobalReferences = "api" :> "globalReferences"
  :> Capture "externalId" HCE.ExternalId  
  :> Get '[JSON] [GlobalReferences]

instance AllCTRender '[ JSON] AllPackages where
  handleAcceptH _ _ (AllPackages bytestring) =
    Just ("application/json", bytestring)

instance FromHttpApiData HCE.LocatableEntity where
  parseQueryParam "Val" = Right HCE.Val
  parseQueryParam "Typ" = Right HCE.Typ
  parseQueryParam "Inst" = Right HCE.Inst
  parseQueryParam "Mod" = Right HCE.Mod
  parseQueryParam val = Left $ T.append "Incorrect LocatableEntity : " val

instance ToHttpApiData HCE.LocatableEntity where
  toUrlPiece HCE.Val = "ValueEntity"
  toUrlPiece HCE.Typ = "TypeEntity"
  toUrlPiece HCE.Inst = "InstanceEntity"
  toUrlPiece HCE.Mod = "ModuleEntity"

instance ToHttpApiData HCE.ExternalId where
  toUrlPiece (HCE.ExternalId i) = i
  
instance ToHttpApiData PackageId where
  toUrlPiece (PackageId p) = p
  
instance FromHttpApiData HCE.HaskellModulePath where
  parseQueryParam = Right . HCE.HaskellModulePath

instance FromHttpApiData HCE.ComponentId where
  parseQueryParam = Right . HCE.ComponentId

instance FromHttpApiData HCE.HaskellModuleName where
  parseQueryParam = Right . HCE.HaskellModuleName

instance FromHttpApiData HCE.ExternalId where
  parseQueryParam = Right . HCE.ExternalId
  
instance FromHttpApiData PackageId where
  parseQueryParam = Right . PackageId
  
--------------------------------------------------------------------------------
-- Request handlers
--------------------------------------------------------------------------------

data Environment = Environment
  { envLogger :: !LoggerSet
  , envPackageMap :: !PackageMap
  , envPackageVersions :: !AllPackages
  , envGlobalReferenceMap :: !GlobalReferenceMap
  , envConfig :: !ServerConfig
  }

data Expression = Expression
  { srcSpan :: !(IVM.Interval (Int, Int))
  , info :: !HCE.ExpressionInfo
  } deriving (Show, Eq, Generic)

instance A.ToJSON Expression

data ReferenceWithSource = ReferenceWithSource
  { sourceCodeHtml :: !T.Text
  , idSrcSpan :: !HCE.IdentifierSrcSpan
  } deriving (Show, Eq, Generic)

data SourceFile = SourceFile
  { name :: !T.Text
  , references :: ![ReferenceWithSource]
  } deriving (Show, Eq, Generic)

instance A.ToJSON ReferenceWithSource
instance A.ToJSON SourceFile

getAllPackages :: ReaderT Environment IO AllPackages
getAllPackages = asks envPackageVersions

getPackageInfoAndModulePath ::
     PackageId
  -> HCE.ComponentId
  -> HCE.HaskellModuleName
  -> ReaderT Environment IO ( HCE.PackageInfo HCE.CompactModuleInfo
                            , HCE.HaskellModulePath)
getPackageInfoAndModulePath packageId componentId moduleName =
  withPackageInfo packageId $ \packageInfo ->
    case HM.lookup moduleName (HCE.moduleNameMap packageInfo) of
      Just modulePathMap ->
        case HM.lookup componentId modulePathMap of
          Just path -> return (packageInfo, path)
          Nothing ->
            error404 $
            BSL.concat
              [ "Module "
              , toLazyBS $ HCE.getHaskellModuleName moduleName
              , " not found in component "
              , toLazyBS $ HCE.getComponentId componentId
              ]
      Nothing ->
        error404 $
        BSL.concat
          [ "Module "
          , toLazyBS $ HCE.getHaskellModuleName moduleName
          , " not found in package "
          , toLazyBS $ getPackageId packageId
          ]

getExpressions ::
     PackageId  
  -> HCE.HaskellModulePath
  -> Int -- ^ Start line
  -> Int -- ^ Start column
  -> Int -- ^ End line
  -> Int -- ^ End column
  -> ReaderT Environment IO [Expression]
getExpressions packageId modulePath startLine startColumn endLine endColumn = do
  enableExpressionInfo <- asks (configEnableExpressionInfo . envConfig)
  if not enableExpressionInfo
    then error404 "Expression queries are disabled"
    else withPackageInfo packageId $ \packageInfo ->
           withModuleInfo packageInfo modulePath $ \modInfo -> do
             maxPerPage <- asks (configMaxPerPage . envConfig)
             let exprInfoMap =
                   HCE.exprInfoMap (modInfo :: HCE.CompactModuleInfo)
                 requestedInterval =
                   IVM.ClosedInterval
                     (startLine, startColumn)
                     (endLine, endColumn)
             return .
               map (uncurry Expression) .
               L.take maxPerPage . IVM.toList . IVM.within exprInfoMap $
               requestedInterval

getDefinitionSite ::
     PackageId
  -> HCE.ComponentId
  -> HCE.HaskellModuleName
  -> HCE.LocatableEntity
  -> T.Text
  -> ReaderT Environment IO HCE.DefinitionSite
getDefinitionSite packageId componentId modName entity name =
  withPackageInfo packageId $ \packageInfo ->
    withModulePath packageInfo componentId modName $ \modPath ->
      case entity of
        HCE.Mod ->
          return $
          HCE.DefinitionSite
            (HCE.ExactLocation
               (HCE.id (packageInfo :: HCE.PackageInfo HCE.CompactModuleInfo))
               modPath
               modName
               1
               1
               1
               1)
            Nothing
        _ ->
          withModuleInfo packageInfo modPath $ \modInfo -> do
            let defSites =
                  HCE.definitionSiteMap (modInfo :: HCE.CompactModuleInfo)
                mbDefinitionSite =
                  case entity of
                    HCE.Typ ->
                      HM.lookup (HCE.OccName name) $
                      HCE.types (defSites :: HCE.DefinitionSiteMap)
                    HCE.Val ->
                      HM.lookup (HCE.OccName name) $
                      HCE.values (defSites :: HCE.DefinitionSiteMap)
                    HCE.Inst ->
                      HM.lookup name $
                      HCE.instances (defSites :: HCE.DefinitionSiteMap)
                    _ -> Nothing
            case mbDefinitionSite of
              Just definitionSite -> return definitionSite
              Nothing ->
                error404 $
                BSL.concat
                  [ toLazyBS . T.pack $ show entity
                  , " "
                  , toLazyBS name
                  , " "
                  , " not found in a module "
                  , toLazyBS $ HCE.getHaskellModulePath modPath
                  ]
              
buildLinkHeader :: T.Text -> Paginated a -> Natural -> Natural -> T.Text
buildLinkHeader url paginated currentPage perPage =
  T.intercalate
    ","
    (let addFirst
           | currentPage /= 1 =
             (:) (link (T.append url $ params 1 perPage) "first")
           | otherwise = id
         addLast
           | currentPage /= paginatedPagesTotal paginated =
             (:)
               (link
                  (T.append url $ params (paginatedPagesTotal paginated) perPage)
                  "last")
           | otherwise = id
         addNext
           | hasNextPage paginated =
             (:) (link (T.append url $ params (currentPage + 1) perPage) "next")
           | otherwise = id
         addPrev
           | hasPrevPage paginated =
             (:) (link (T.append url $ params (currentPage - 1) perPage) "prev")
           | otherwise = id
      in addFirst . addLast . addNext . addPrev $ [])
  where
    link :: T.Text -> T.Text -> T.Text
    link u rel = T.concat ["<", u, ">; rel=\"", rel, "\""]
    params :: Natural -> Natural -> T.Text
    params p pp =
      T.concat ["?page=", T.pack . show $ p, "&per_page=", T.pack . show $ pp]

initializePagination ::
     (MonadReader Environment m)
  => Maybe Int
  -> Maybe Int
  -> m (Natural, Natural)
initializePagination mbPage mbPerPage = do
  maxPerPage <- asks (configMaxPerPage . envConfig)
  let page =
        case mbPage of
          Just p ->
            if p > 0
              then p
              else 1
          Nothing -> 1
      perPage =
        case mbPerPage of
          Just pp ->
            if pp <= maxPerPage && pp > 0
              then pp
              else maxPerPage
          Nothing -> maxPerPage
  return (fromIntegral page, fromIntegral perPage)

getGlobalReferences ::
     HCE.ExternalId -> ReaderT Environment IO [GlobalReferences]
getGlobalReferences externalId = do
  refMap <- asks envGlobalReferenceMap
  return $ maybe [] S.toDescList (HM.lookup externalId refMap)  

getReferences ::
     PackageId
  -> HCE.ExternalId
  -> Maybe Int -- ^ Page number
  -> Maybe Int -- ^ Items per page
  -> ReaderT Environment IO (Headers '[ Header "Link" T.Text, Header "X-Total-Count" Int] [SourceFile])
getReferences packageId externalId mbPage mbPerPage =
  withPackageInfo packageId $ \packageInfo ->
    case S.toList <$> HM.lookup externalId (HCE.externalIdOccMap packageInfo) of
      Just references -> do
        (paginatedReferences, page, perPage, totalCount) <-
          paginateItems mbPage mbPerPage references
        let url =
              T.append "/" $
              toUrlPiece $
              safeLink
                (Proxy :: Proxy API)
                (Proxy :: Proxy GetReferences)
                packageId
                externalId
                Nothing
                Nothing
            linkHeader = buildLinkHeader url paginatedReferences page perPage
            addHeaders ::
                 forall a.
                 a
              -> Headers '[ Header "Link" T.Text, Header "X-Total-Count" Int] a
            addHeaders = addHeader linkHeader . addHeader totalCount
            refModulePath :: ReferenceWithSource -> HCE.HaskellModulePath
            refModulePath =
              (HCE.modulePath :: HCE.IdentifierSrcSpan -> HCE.HaskellModulePath) .
              idSrcSpan
        return $
          addHeaders $
          concatMap
            (\refs ->
               case refs of
                 ref:_ ->
                   let path =
                         HCE.getHaskellModulePath .
                         (HCE.modulePath :: HCE.IdentifierSrcSpan -> HCE.HaskellModulePath) .
                         idSrcSpan $
                         ref
                    in [SourceFile path refs]
                 _ -> []) $
          groupWith refModulePath $
          mapMaybe
            (mkReferenceWithSource packageInfo)
            (L.groupBy (\span1 span2 -> HCE.line span1 == HCE.line span2) $
             paginatedItems paginatedReferences)
      Nothing ->
        error404 $
        BSL.concat
          [ "Cannot find references to "
          , toLazyBS $ HCE.getExternalId externalId
          ]

mkReferenceWithSource ::
     HCE.PackageInfo HCE.CompactModuleInfo
  -> [HCE.IdentifierSrcSpan]
  -> Maybe ReferenceWithSource
mkReferenceWithSource packageInfo spans@(span:_) =
  let mbModule =
        HM.lookup
          (HCE.modulePath (span :: HCE.IdentifierSrcSpan))
          (HCE.moduleMap (packageInfo :: HCE.PackageInfo HCE.CompactModuleInfo))
   in case mbModule of
        Just modInfo ->
          let sourceCodeHtml =
                buildHtmlCodeSnippet
                  (HCE.source (modInfo :: HCE.CompactModuleInfo))
                  (HCE.line (span :: HCE.IdentifierSrcSpan))
                  (map
                     (\HCE.IdentifierSrcSpan {..} -> (startColumn, endColumn))
                     spans)
           in Just $ ReferenceWithSource sourceCodeHtml span
        _ -> Just $ ReferenceWithSource "" span
mkReferenceWithSource _ _ = Nothing

buildHtmlCodeSnippet :: V.Vector T.Text -> Int -> [(Int, Int)] -> T.Text
buildHtmlCodeSnippet sourceLines lineNumber positions =
  toStrict $
  renderHtml $ do
    mkLineNumber (lineNumber - 1) >>
      Html.toHtml
        (T.append (fromMaybe "" $ (V.!?) sourceLines (lineNumber - 2)) "\n")
    mkLineNumber lineNumber >>
      highlightIdentifiers
        (T.append (fromMaybe "" $ (V.!?) sourceLines (lineNumber - 1)) "\n")
    mkLineNumber (lineNumber + 1) >>
      Html.toHtml (T.append (fromMaybe "" $ (V.!?) sourceLines lineNumber) "\n")
  where
    mkLineNumber :: Int -> Html.Html
    mkLineNumber i = Html.toHtml (show i ++ "  ")
    highlightIdentifiers :: T.Text -> Html.Html
    highlightIdentifiers line =
      mapM_
        (\(text, _, mbId) ->
           case mbId of
             Just _ -> Html.b (Html.toHtml text)
             Nothing -> Html.toHtml text) $
      HCE.tokenize line (map (, ()) positions)

findIdentifiers ::
     PackageId
  -> T.Text
  -> Maybe Int
  -> Maybe Int
  -> ReaderT Environment IO (Headers '[ Header "Link" T.Text, Header "X-Total-Count" Int]
                                      [HCE.ExternalIdentifierInfo])
findIdentifiers packageId query mbPage mbPerPage =
  withPackageInfo packageId $ \packageInfo -> do
    let identifiers
          | not $ T.null query =
            S.toList $
            HCE.match (T.unpack query) (HCE.externalIdInfoMap packageInfo)
          | otherwise = []
    (paginatedIdentifiers, page, perPage, totalCount) <-
      paginateItems mbPage mbPerPage identifiers
    let url =
          T.append "/" $
          toUrlPiece $
          safeLink
            (Proxy :: Proxy API)
            (Proxy :: Proxy GetIdentifiers)
            packageId
            query
            Nothing
            Nothing
        linkHeader = buildLinkHeader url paginatedIdentifiers page perPage
        addHeaders ::
             forall a.
             a
          -> Headers '[ Header "Link" T.Text, Header "X-Total-Count" Int] a
        addHeaders = addHeader linkHeader . addHeader totalCount
    return . addHeaders . paginatedItems $ paginatedIdentifiers

paginateItems ::
     Maybe Int
  -> Maybe Int
  -> [a]
  -> ReaderT Environment IO (Paginated a, Natural, Natural, Int)
paginateItems mbPage mbPerPage items = do
  (page, perPage) <- initializePagination mbPage mbPerPage
  let totalCount = L.length items
  pagination <- mkPagination perPage page
  paginated <-
    paginate
      pagination
      (fromIntegral totalCount)
      (\offset limit -> return . L.take limit . L.drop offset $ items)
  return (paginated, page, perPage, totalCount)
    
error404 :: BSL.ByteString -> ReaderT Environment IO a
error404 body = throwServantError $ err404 {errBody = body}

toLazyBS :: T.Text -> BSL.ByteString
toLazyBS = BSL.fromStrict . TE.encodeUtf8
  
withPackageInfo ::
     PackageId
  -> (HCE.PackageInfo HCE.CompactModuleInfo -> ReaderT Environment IO a)
  -> ReaderT Environment IO a
withPackageInfo packageId action
  | Just (packageName, mbVersion) <- parsePackageId packageId = do
    packageMap <- asks envPackageMap
    let mbPackageInfo =
          HM.lookup packageName packageMap >>=
          (\packages ->
             let findLastVersion :: M.Map k v -> Maybe v
                 findLastVersion = fmap (snd . fst) . L.uncons . M.toDescList
              in case mbVersion of
                   Just version ->
                     M.lookup version packages <|> findLastVersion packages
                   Nothing -> findLastVersion packages)
    case mbPackageInfo of
      Just p -> action p
      Nothing -> packageNotFound packageId
withPackageInfo packageId _ = packageNotFound packageId

packageNotFound :: PackageId -> ReaderT Environment IO a
packageNotFound packageId =
  error404 $
  BSL.concat ["Package ", toLazyBS $ getPackageId packageId, " is not found."]

withModuleInfo ::
     HCE.PackageInfo HCE.CompactModuleInfo
  -> HCE.HaskellModulePath
  -> (HCE.CompactModuleInfo -> ReaderT Environment IO a)
  -> ReaderT Environment IO a
withModuleInfo packageInfo path action =
  case HM.lookup
         path
         (HCE.moduleMap (packageInfo :: HCE.PackageInfo HCE.CompactModuleInfo)) of
    Just modInfo -> action modInfo
    Nothing ->
      error404 $
      BSL.concat
        [ "Module "
        , toLazyBS $ HCE.getHaskellModulePath path
        , " is not found in package "
        , toLazyBS $
          HCE.packageIdToText $
          HCE.id (packageInfo :: HCE.PackageInfo HCE.CompactModuleInfo)
        ]

withModulePath ::
     HCE.PackageInfo HCE.CompactModuleInfo
  -> HCE.ComponentId
  -> HCE.HaskellModuleName
  -> (HCE.HaskellModulePath -> ReaderT Environment IO a)
  -> ReaderT Environment IO a
withModulePath packageInfo componentId moduleName action =
  case HM.lookup
         (ghcPrimHack packageInfo moduleName)
         (HCE.moduleNameMap packageInfo) of
    Just modulePathMap ->
      case HM.lookup componentId modulePathMap of
        Just path -> action path
        Nothing ->
          case HM.lookup (HCE.ComponentId "lib") modulePathMap of
            Just path -> action path
            Nothing ->
              error404 $
              BSL.concat
                [ "Module "
                , toLazyBS $ HCE.getHaskellModuleName moduleName
                , " is not found in component "
                , toLazyBS $ HCE.getComponentId componentId
                ]
    Nothing ->
      error404 $
      BSL.concat
        [ "Module "
        , toLazyBS $ HCE.getHaskellModuleName moduleName
        , " is not found in package "
        , toLazyBS $
          HCE.packageIdToText $
          HCE.id (packageInfo :: HCE.PackageInfo HCE.CompactModuleInfo)
        ]

-- | Workaround for :
-- https://github.com/ghc/ghc/blob/ghc-8.2.2-release/compiler/main/Finder.hs#L310-L315
ghcPrimHack ::
     HCE.PackageInfo HCE.CompactModuleInfo
  -> HCE.HaskellModuleName
  -> HCE.HaskellModuleName
ghcPrimHack packageInfo (HCE.HaskellModuleName modName)
  | HCE.packageName packageInfo == "ghc-prim" && modName == "GHC.Prim" =
    HCE.HaskellModuleName "GHC.Prim_"
  | otherwise = HCE.HaskellModuleName modName
  
parsePackageId :: PackageId -> Maybe (PackageName, Maybe Version)
parsePackageId (PackageId text) =
  case T.splitOn "-" text of
    [name] -> Just (PackageName name, Nothing)
    chunks@(_x:_xs) ->
      case mapM decimal . T.splitOn "." . last $ chunks of
        Right numbers ->
          Just
            ( PackageName $ T.intercalate "-" . init $ chunks
            , Just $ Version (map fst numbers) [])
        Left _ -> Just (PackageName text, Nothing)
    _ -> Nothing

staticMiddleware :: String -> PackagePathMap -> Maybe FilePath -> Middleware
staticMiddleware staticFilesPrefix packagePathMap _ app req callback
  | ("api":_) <- pathInfo req = app req callback
  | (prefix:packageId:rest) <- pathInfo req
  , prefix == T.pack staticFilesPrefix =
    case HM.lookup (PackageId packageId) packagePathMap of
      Just basePath
        | ".." `notElem` rest -> do
          let clientAcceptsEncoding =
                fromMaybe [] $
                map T.strip . T.splitOn "," . TE.decodeUtf8 <$>
                lookup "Accept-Encoding" (requestHeaders req)
              clientAcceptsGzip = "gzip" `elem` clientAcceptsEncoding
              path = basePath </> T.unpack (T.intercalate "/" rest)
              gzPath = path ++ ".gz"
          sendGzipFile <-
            if clientAcceptsGzip
              then doesFileExist gzPath
              else return False
          if sendGzipFile
            then callback $
                 responseFile
                   status200
                   [ (hContentEncoding, "gzip")
                   , ( hContentType
                     , defaultMimeLookup . T.pack . takeFileName $ path)
                   ]
                   gzPath
                   Nothing
            else do
              exists <- doesFileExist path
              if exists
                then callback $ sendFile path
                else callback fileNotFound
      _ -> callback fileNotFound     
staticMiddleware _ _ mbJsDistPath _app req callback =
  case mbJsDistPath of
    Just jsDistPath -> do
      let path = jsDistPath </> T.unpack (T.intercalate "/" $ pathInfo req)
      exists <- doesFileExist path
      if exists
         then callback $ sendFile path
         else callback $ sendFile (jsDistPath </> "index.html")
    Nothing -> do
      let path = T.unpack $ T.intercalate "/" $ pathInfo req
      if path == ""
        then callback $ sendEmbeddedFile "index.html" indexHtml
        else case HM.lookup path staticAssets of
          Just bs -> callback $ sendEmbeddedFile path bs
          Nothing -> callback $ sendEmbeddedFile "index.html" indexHtml

staticAssets :: HM.HashMap FilePath BS.ByteString
staticAssets = HM.fromList $(embedDir "javascript/release")

indexHtml :: BS.ByteString
indexHtml = $(embedFile "javascript/release/index.html")

sendFile :: FilePath -> Response
sendFile path =
  responseFile
    status200
    [(hContentType, defaultMimeLookup $ T.pack $ takeFileName path)]
    path
    Nothing

sendEmbeddedFile :: FilePath -> BS.ByteString -> Response
sendEmbeddedFile path bs =
  responseLBS
    status200
    [(hContentType, defaultMimeLookup $ T.pack $ takeFileName path)]
    (BSL.fromStrict bs)    

fileNotFound :: Response
fileNotFound =
  responseLBS status404 [("Content-Type", "text/plain")] "Not found"

throwServantError :: (MonadIO m) => ServantErr -> m a
throwServantError = liftIO . throwIO 

server :: Environment -> ServerT API Handler
server env =
  hoistServer
    (Proxy :: Proxy API)
    toServantHandler
    (getAllPackages :<|>
     getDefinitionSite :<|>     
     getExpressions :<|>
     getReferences :<|>
     findIdentifiers :<|>
     getGlobalReferences)
  where
    toServantHandler :: ReaderT Environment IO a -> Handler a
    toServantHandler ma = Handler . ExceptT . try . runReaderT ma $ env

application :: Environment -> Application
application env = serve (Proxy :: Proxy API) (server env)

main :: IO ()
main = do
  config <-
    execParser
      (Options.Applicative.info
         (configParser <**> helper)
         (fullDesc <>
          progDesc
            "haskell-code-server provides an HTTP API for Haskell code explorer"))
  print config
  packages <- loadPackages config
  case packages of
    Just (packageMap, packagePathMap, packageVersions,globalReferenceMap) -> do
      loggerSet <-
        case configLog config of
          HCE.ToFile logfile -> newFileLoggerSet defaultBufSize logfile
          HCE.StdOut -> newStdoutLoggerSet defaultBufSize
      loggerMiddleware <-
        liftIO $
        mkRequestLogger
          def {outputFormat = Detailed True, destination = Logger loggerSet}
      let staticFilePrefix = configStaticFilesUrlPrefix config
          mbJsDistPath = configJsDistDirectory config
          environment =
            Environment
              loggerSet
              packageMap
              (AllPackages . A.encode $ packageVersions)
              globalReferenceMap
              config
          static =
            if configServeStaticFiles config
              then staticMiddleware staticFilePrefix packagePathMap mbJsDistPath
              else id
      run
        (configPort config)
        (loggerMiddleware . static $ application environment)
    Nothing -> putStrLn "No packages found."