Type.hs

{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE TypeFamilies #-}

-- | Rendering of types.
module Ormolu.Printer.Meat.Type
  ( p_hsType,
    p_hsTypePostDoc,
    hasDocStrings,
    p_hsContext,
    p_hsTyVarBndr,
    ForAllVisibility (..),
    p_forallBndrs,
    p_conDeclFields,
    p_lhsTypeArg,
    p_hsSigType,
    tyVarsToTyPats,
    hsOuterTyVarBndrsToHsType,
    lhsTypeToSigType,
  )
where

import Control.Monad
import Data.Bool (bool)
import Data.Foldable (for_)
import GHC.Hs
import GHC.Types.Basic hiding (isPromoted)
import GHC.Types.SourceText
import GHC.Types.SrcLoc
import GHC.Types.Var
import Ormolu.Config
import Ormolu.Config.Types (FunctionArrowsStyle (..))
import Ormolu.Printer.Combinators
import Ormolu.Printer.Internal (PrevTypeCtx (..), enterLayout, getPrevTypeCtx, setPrevTypeCtx)
import Ormolu.Printer.Meat.Common
import {-# SOURCE #-} Ormolu.Printer.Meat.Declaration.OpTree (p_tyOpTree, tyOpTree)
import {-# SOURCE #-} Ormolu.Printer.Meat.Declaration.Value (p_hsSplice, p_stringLit)
import Ormolu.Printer.Operators
import Ormolu.Utils

-- | Render an "PrevTypeCtx" infix
p_after :: Bool -> R ()
p_after multilineArgs =
  getPrevTypeCtx >>= \case
    TypeCtxStart -> pure ()
    TypeCtxForall | multilineArgs -> txt " ." >> space
    TypeCtxForall -> txt "." >> space
    TypeCtxContext -> txt "=>" >> space
    TypeCtxArgument -> txt "->" >> space

-- | Like 'p_hsType' but indent properly following a forall
p_hsType :: HsType GhcPs -> R ()
p_hsType t = do
  s <-
    getPrinterOpt poFunctionArrows >>= \case
      TrailingArrows -> pure PipeStyle
      LeadingArrows -> pure CaretStyle
  layout <- getLayout
  p_hsType' (hasDocStrings t || layout == MultiLine) s t

p_hsTypePostDoc :: HsType GhcPs -> R ()
p_hsTypePostDoc t = p_hsType' (hasDocStrings t) CaretStyle t

-- | How to render Haddocks associated with a type.
data TypeDocStyle
  = PipeStyle
  | CaretStyle

p_hsType' :: Bool -> TypeDocStyle -> HsType GhcPs -> R ()
p_hsType' multilineArgs docStyle = \case
  HsForAllTy _ tele t -> do
    case tele of
      HsForAllInvis _ bndrs -> p_forallBndrs' ForAllInvis p_hsTyVarBndr bndrs
      HsForAllVis _ bndrs -> p_forallBndrs' ForAllVis p_hsTyVarBndr bndrs
    getPrinterOpt poFunctionArrows >>= \case
      LeadingArrows | multilineArgs -> pure ()
      _ -> p_after False >> setPrevTypeCtx TypeCtxStart
    interArgBreak
    p_hsTypeR (unLoc t)
  HsQualTy _ qs' t -> do
    getPrinterOpt poFunctionArrows >>= \case
      LeadingArrows -> do
        after <- getPrevTypeCtx
        bool id (inciByExact 3) (after == TypeCtxForall) $ for_ qs' $ \qs -> do
          located qs p_hsContext
          interArgBreak
      TrailingArrows -> do
        for_ qs' $ \qs -> do
          located qs p_hsContext
          space
          txt "=>"
          interArgBreak
    setPrevTypeCtx TypeCtxContext
    case unLoc t of
      HsQualTy {} -> p_hsTypeR (unLoc t)
      HsFunTy {} -> p_hsTypeR (unLoc t)
      _ -> located t p_hsTypeR
  HsTyVar _ p n -> do
    case p of
      IsPromoted -> do
        space
        txt "'"
        case showOutputable (unLoc n) of
          _ : '\'' : _ -> space
          _ -> return ()
      NotPromoted -> return ()
    p_rdrName n
  HsAppTy _ f x -> do
    let -- In order to format type applications with multiple parameters
        -- nicer, traverse the AST to gather the function and all the
        -- parameters together.
        gatherArgs f' knownArgs =
          case f' of
            L _ (HsAppTy _ l r) -> gatherArgs l (r : knownArgs)
            _ -> (f', knownArgs)
        (func, args) = gatherArgs f [x]
    switchLayout (getLocA f : fmap getLocA args) . sitcc $ do
      located func p_hsType
      breakpoint
      inci $
        sep breakpoint (located' p_hsType) args
  HsAppKindTy _ ty kd -> sitcc $ do
    -- The first argument is the location of the "@..." part. Not 100% sure,
    -- but I think we can ignore it as long as we use 'located' on both the
    -- type and the kind.
    located ty p_hsType
    breakpoint
    inci $ do
      txt "@"
      located kd p_hsType
  HsFunTy _ arrow x y@(L _ y') -> do
    getPrinterOpt poFunctionArrows >>= \case
      LeadingArrows -> do
        after <- getPrevTypeCtx
        bool id (inciByExact 3) (after == TypeCtxForall) (located x p_hsType)
        interArgBreak
      TrailingArrows -> do
        located x p_hsType
        space
        case arrow of
          HsUnrestrictedArrow _ -> txt "->"
          HsLinearArrow _ _ -> txt "%1 ->"
          HsExplicitMult _ _ mult -> do
            txt "%"
            setPrevTypeCtx TypeCtxContext
            p_hsTypeR (unLoc mult)
            space
            txt "->"
        interArgBreak
    setPrevTypeCtx TypeCtxArgument
    case y' of
      HsFunTy {} -> do
        layout <- getLayout
        -- Render the comments properly, but keep the existing layout
        located y (enterLayout layout . p_hsTypeR)
      _ -> located y p_hsTypeR
  HsListTy _ t ->
    located t (brackets N . p_hsType)
  HsTupleTy _ tsort xs ->
    let parens' =
          case tsort of
            HsUnboxedTuple -> parensHash N
            HsBoxedOrConstraintTuple -> parens N
     in parens' $ sep commaDel (sitcc . located' p_hsType) xs
  HsSumTy _ xs ->
    parensHash N $
      sep (space >> txt "|" >> breakpoint) (sitcc . located' p_hsType) xs
  HsOpTy _ x op y -> do
    fixityOverrides <- askFixityOverrides
    fixityMap <- askFixityMap
    let opTree = OpBranches [tyOpTree x, tyOpTree y] [op]
    p_tyOpTree
      (reassociateOpTree (Just . unLoc) fixityOverrides fixityMap opTree)
  HsParTy _ t ->
    parens N $ sitcc $ located t p_hsType
  HsIParamTy _ n t -> sitcc $ do
    located n atom
    trailingArrowType
    breakpoint
    leadingArrowType
    inci (located t p_hsType)
  HsStarTy _ _ -> txt "*"
  HsKindSig _ t k -> sitcc $ do
    located t p_hsType
    trailingArrowType
    breakpoint
    leadingArrowType
    inci (located k p_hsType)
  HsSpliceTy _ splice -> p_hsSplice splice
  HsDocTy _ t str ->
    case docStyle of
      PipeStyle -> do
        p_hsDocString Pipe True str
        located t p_hsType
      CaretStyle -> do
        located t p_hsType
        newline
        p_hsDocString Caret False str
  HsBangTy _ (HsSrcBang _ u s) t -> do
    case u of
      SrcUnpack -> txt "{-# UNPACK #-}" >> space
      SrcNoUnpack -> txt "{-# NOUNPACK #-}" >> space
      NoSrcUnpack -> return ()
    case s of
      SrcLazy -> txt "~"
      SrcStrict -> txt "!"
      NoSrcStrict -> return ()
    located t p_hsType
  HsRecTy _ fields ->
    p_conDeclFields fields
  HsExplicitListTy _ p xs -> do
    case p of
      IsPromoted -> txt "'"
      NotPromoted -> return ()
    brackets N $ do
      -- If both this list itself and the first element is promoted,
      -- we need to put a space in between or it fails to parse.
      case (p, xs) of
        (IsPromoted, L _ t : _) | isPromoted t -> space
        _ -> return ()
      sep commaDel (sitcc . located' p_hsType) xs
  HsExplicitTupleTy _ xs -> do
    txt "'"
    parens N $ do
      case xs of
        L _ t : _ | isPromoted t -> space
        _ -> return ()
      sep commaDel (located' p_hsType) xs
  HsTyLit _ t ->
    case t of
      HsStrTy (SourceText s) _ -> p_stringLit s
      a -> atom a
  HsWildCardTy _ -> txt "_"
  XHsType t -> atom t
  where
    isPromoted = \case
      HsAppTy _ (L _ f) _ -> isPromoted f
      HsTyVar _ IsPromoted _ -> True
      HsExplicitTupleTy {} -> True
      HsExplicitListTy {} -> True
      _ -> False
    interArgBreak =
      if multilineArgs
        then newline
        else breakpoint
    p_hsTypeR m = do
      getPrinterOpt poFunctionArrows >>= \case
        TrailingArrows -> pure ()
        LeadingArrows -> p_after multilineArgs
      p_hsType' multilineArgs docStyle m

-- | Return 'True' if at least one argument in 'HsType' has a doc string
-- attached to it.
hasDocStrings :: HsType GhcPs -> Bool
hasDocStrings = \case
  HsDocTy {} -> True
  HsFunTy _ _ (L _ x) (L _ y) -> hasDocStrings x || hasDocStrings y
  HsForAllTy _ _ (L _ x) -> hasDocStrings x
  HsQualTy _ _ (L _ x) -> hasDocStrings x
  _ -> False

p_hsContext :: HsContext GhcPs -> R ()
p_hsContext = \case
  [] -> txt "()"
  [x] -> located x p_hsType
  xs -> parens N $ sep commaDel (sitcc . located' p_hsType) xs

class IsInferredTyVarBndr flag where
  isInferred :: flag -> Bool

instance IsInferredTyVarBndr () where
  isInferred () = False

instance IsInferredTyVarBndr Specificity where
  isInferred = \case
    InferredSpec -> True
    SpecifiedSpec -> False

p_hsTyVarBndr :: IsInferredTyVarBndr flag => HsTyVarBndr flag GhcPs -> R ()
p_hsTyVarBndr = \case
  UserTyVar _ flag x ->
    (if isInferred flag then braces N else id) $ p_rdrName x
  KindedTyVar _ flag l k -> (if isInferred flag then braces else parens) N . sitcc $ do
    located l atom
    trailingArrowType
    breakpoint
    leadingArrowType
    inci (located k p_hsType)

data ForAllVisibility = ForAllInvis | ForAllVis

-- | Render several @forall@-ed variables.
p_forallBndrs :: ForAllVisibility -> (a -> R ()) -> [LocatedA a] -> R ()
p_forallBndrs vis p tyvars = do
  p_forallBndrs' vis p tyvars
  p_after False

p_forallBndrs' :: ForAllVisibility -> (a -> R ()) -> [LocatedA a] -> R ()
p_forallBndrs' ForAllInvis _ [] = txt "forall" >> setPrevTypeCtx TypeCtxForall
p_forallBndrs' ForAllVis _ [] = txt "forall" >> space >> setPrevTypeCtx TypeCtxArgument
p_forallBndrs' vis p tyvars = do
  switchLayout (getLocA <$> tyvars) $ do
    txt "forall"
    breakpoint
    inci $ do
      sitcc $ sep breakpoint (sitcc . located' p) tyvars
  case vis of
    ForAllInvis -> setPrevTypeCtx TypeCtxForall
    ForAllVis -> space >> setPrevTypeCtx TypeCtxArgument

p_conDeclFields :: [LConDeclField GhcPs] -> R ()
p_conDeclFields xs =
  braces N $ sep commaDel (sitcc . located' p_conDeclField) xs

p_conDeclField :: ConDeclField GhcPs -> R ()
p_conDeclField ConDeclField {..} = do
  commaStyle <- getPrinterOpt poCommaStyle
  when (commaStyle == Trailing) $
    mapM_ (p_hsDocString Pipe True) cd_fld_doc
  sitcc $
    sep
      commaDel
      (located' (p_rdrName . rdrNameFieldOcc))
      cd_fld_names
  getPrinterOpt poFunctionArrows >>= \case
    LeadingArrows -> inci $ do
      breakpoint
      txt "::"
      space
      p_hsType (unLoc cd_fld_type)
    TrailingArrows -> do
      space
      txt "::"
      breakpoint
      sitcc . inci $ p_hsType (unLoc cd_fld_type)
  when (commaStyle == Leading) $
    mapM_ (inciByFrac (-1) . (newline >>) . p_hsDocString Caret False) cd_fld_doc

p_lhsTypeArg :: LHsTypeArg GhcPs -> R ()
p_lhsTypeArg = \case
  HsValArg ty -> located ty p_hsType
  -- first argument is the SrcSpan of the @,
  -- but the @ always has to be directly before the type argument
  HsTypeArg _ ty -> txt "@" *> located ty p_hsType
  -- NOTE(amesgen) is this unreachable or just not implemented?
  HsArgPar _ -> notImplemented "HsArgPar"

p_hsSigType :: HsSigType GhcPs -> R ()
p_hsSigType HsSig {..} =
  p_hsType $ hsOuterTyVarBndrsToHsType sig_bndrs sig_body

----------------------------------------------------------------------------
-- Conversion functions

tyVarToType :: HsTyVarBndr () GhcPs -> HsType GhcPs
tyVarToType = \case
  UserTyVar _ () tvar -> HsTyVar EpAnnNotUsed NotPromoted tvar
  KindedTyVar _ () tvar kind ->
    -- Note: we always add parentheses because for whatever reason GHC does
    -- not use HsParTy for left-hand sides of declarations. Please see
    -- <https://gitlab.haskell.org/ghc/ghc/issues/17404>. This is fine as
    -- long as 'tyVarToType' does not get applied to right-hand sides of
    -- declarations.
    HsParTy EpAnnNotUsed . noLocA $
      HsKindSig EpAnnNotUsed (noLocA (HsTyVar EpAnnNotUsed NotPromoted tvar)) kind

tyVarsToTyPats :: LHsQTyVars GhcPs -> HsTyPats GhcPs
tyVarsToTyPats HsQTvs {..} = HsValArg . fmap tyVarToType <$> hsq_explicit

-- could be generalized to also handle () instead of Specificity
hsOuterTyVarBndrsToHsType ::
  HsOuterTyVarBndrs Specificity GhcPs ->
  LHsType GhcPs ->
  HsType GhcPs
hsOuterTyVarBndrsToHsType obndrs ty = case obndrs of
  HsOuterImplicit NoExtField -> unLoc ty
  HsOuterExplicit _ bndrs ->
    HsForAllTy NoExtField (mkHsForAllInvisTele EpAnnNotUsed bndrs) ty

lhsTypeToSigType :: LHsType GhcPs -> LHsSigType GhcPs
lhsTypeToSigType ty =
  reLocA . L (getLocA ty) . HsSig NoExtField (HsOuterImplicit NoExtField) $ ty