module Language.Haskell.Brittany.Internal.Layouters.Module (layoutModule) where

#include "prelude.inc"

import           Language.Haskell.Brittany.Internal.Types
import           Language.Haskell.Brittany.Internal.LayouterBasics
import           Language.Haskell.Brittany.Internal.Layouters.IE
import           Language.Haskell.Brittany.Internal.Layouters.Import
import           Language.Haskell.Brittany.Internal.Config.Types

import GHC (unLoc, runGhc, GenLocated(L), moduleNameString, AnnKeywordId(..))
#if MIN_VERSION_ghc(8,10,1)   /* ghc-8.10.1 */
import           GHC.Hs
import           GHC.Hs.ImpExp
#else
import           HsSyn
import           HsImpExp
#endif
import           Name
import           FieldLabel
import qualified FastString
import           BasicTypes
import           Language.Haskell.GHC.ExactPrint as ExactPrint
import           Language.Haskell.GHC.ExactPrint.Types as ExactPrint.Types

import           Language.Haskell.Brittany.Internal.Utils



layoutModule :: ToBriDoc HsModule
layoutModule lmod@(L _ mod') = case mod' of
    -- Implicit module Main
  HsModule Nothing  _   imports _ _ _ -> docLines $ map layoutImport imports
  HsModule (Just n) les imports _ _ _ -> do
    let tn = Text.pack $ moduleNameString $ unLoc n
    allowSingleLineExportList <- mAsk
      <&> _conf_layout
      .>  _lconfig_allowSingleLineExportList
      .>  confUnpack
    -- the config should not prevent single-line layout when there is no
    -- export list
    let allowSingleLine = allowSingleLineExportList || Data.Maybe.isNothing les
    docLines
      $ docSeq
          [ docNodeAnnKW lmod Nothing docEmpty
             -- A pseudo node that serves merely to force documentation
             -- before the node
          , docNodeMoveToKWDP lmod AnnModule True $ runFilteredAlternative $ do
            addAlternativeCond allowSingleLine $
              docForceSingleline
                $ docSeq
                [ appSep $ docLit $ Text.pack "module"
                , appSep $ docLit tn
                , docWrapNode lmod $ appSep $ case les of
                  Nothing -> docEmpty
                  Just x  -> layoutLLIEs True x
                , docSeparator
                , docLit $ Text.pack "where"
                ]
            addAlternative
              $ docLines
              [ docAddBaseY BrIndentRegular $ docPar
                (docSeq [appSep $ docLit $ Text.pack "module", docLit tn]
                )
                (docSeq [ docWrapNode lmod $ case les of
                            Nothing -> docEmpty
                            Just x  -> layoutLLIEs False x
                        , docSeparator
                        , docLit $ Text.pack "where"
                        ]
                )
              ]
          ]
      : map layoutImport imports