{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings   #-}
{-# LANGUAGE ScopedTypeVariables #-}
{- |
   Module      : Text.Pandoc.Writers.Haddock
   Copyright   : Copyright (C) 2014-2015,2017 John MacFarlane
   License     : GNU GPL, version 2 or above

   Maintainer  : John MacFarlane <jgm@berkeley.edu>
   Stability   : alpha
   Portability : portable

Conversion of 'Pandoc' documents to haddock markup.

Haddock:  <http://www.haskell.org/haddock/doc/html/>
-}
module Text.Pandoc.Writers.Haddock (writeHaddock) where
import Prelude
import Control.Monad.State.Strict
import Data.Default
import Data.Text (Text)
import Text.Pandoc.Class (PandocMonad, report)
import Text.Pandoc.Definition
import Text.Pandoc.Logging
import Text.Pandoc.Options
import Text.DocLayout
import Text.Pandoc.Shared
import Text.Pandoc.Templates (renderTemplate)
import Text.Pandoc.Writers.Shared

type Notes = [[Block]]
data WriterState = WriterState { stNotes :: Notes }
instance Default WriterState
  where def = WriterState{ stNotes = [] }

-- | Convert Pandoc to Haddock.
writeHaddock :: PandocMonad m => WriterOptions -> Pandoc -> m Text
writeHaddock opts document =
  evalStateT (pandocToHaddock opts{
                  writerWrapText = writerWrapText opts } document) def

-- | Return haddock representation of document.
pandocToHaddock :: PandocMonad m
                => WriterOptions -> Pandoc -> StateT WriterState m Text
pandocToHaddock opts (Pandoc meta blocks) = do
  let colwidth = if writerWrapText opts == WrapAuto
                    then Just $ writerColumns opts
                    else Nothing
  body <- blockListToHaddock opts blocks
  st <- get
  notes' <- notesToHaddock opts (reverse $ stNotes st)
  let main = body <> (if isEmpty notes' then empty else blankline <> notes')
  metadata <- metaToContext opts
               (blockListToHaddock opts)
               (fmap chomp . inlineListToHaddock opts)
               meta
  let context  = defField "body" main metadata
  return $ render colwidth $
    case writerTemplate opts of
          Nothing  -> main
          Just tpl -> renderTemplate tpl context

-- | Return haddock representation of notes.
notesToHaddock :: PandocMonad m
               => WriterOptions -> [[Block]] -> StateT WriterState m (Doc Text)
notesToHaddock opts notes =
  if null notes
     then return empty
     else do
       contents <- blockToHaddock opts $ OrderedList (1,DefaultStyle,DefaultDelim) notes
       return $ text "#notes#" <> blankline <> contents

-- | Escape special characters for Haddock.
escapeString :: String -> String
escapeString = escapeStringUsing haddockEscapes
  where haddockEscapes = backslashEscapes "\\/'`\"@<"

-- | Convert Pandoc block element to haddock.
blockToHaddock :: PandocMonad m
               => WriterOptions -- ^ Options
               -> Block         -- ^ Block element
               -> StateT WriterState m (Doc Text)
blockToHaddock _ Null = return empty
blockToHaddock opts (Div _ ils) = do
  contents <- blockListToHaddock opts ils
  return $ contents <> blankline
blockToHaddock opts (Plain inlines) = do
  contents <- inlineListToHaddock opts inlines
  return $ contents <> cr
-- title beginning with fig: indicates figure
blockToHaddock opts (Para [Image attr alt (src,'f':'i':'g':':':tit)]) =
  blockToHaddock opts (Para [Image attr alt (src,tit)])
blockToHaddock opts (Para inlines) =
  -- TODO:  if it contains linebreaks, we need to use a @...@ block
  (<> blankline) `fmap` blockToHaddock opts (Plain inlines)
blockToHaddock opts (LineBlock lns) =
  blockToHaddock opts $ linesToPara lns
blockToHaddock _ b@(RawBlock f str)
  | f == "haddock" =
      return $ text str <> text "\n"
  | otherwise = do
    report $ BlockNotRendered b
    return empty
blockToHaddock opts HorizontalRule =
  return $ blankline <> text (replicate (writerColumns opts) '_') <> blankline
blockToHaddock opts (Header level (ident,_,_) inlines) = do
  contents <- inlineListToHaddock opts inlines
  let attr' = if null ident
                 then empty
                 else cr <> text "#" <> text ident <> text "#"
  return $ nowrap (text (replicate level '=') <> space <> contents)
                 <> attr' <> blankline
blockToHaddock _ (CodeBlock (_,_,_) str) =
  return $ prefixed "> " (text str) <> blankline
-- Nothing in haddock corresponds to block quotes:
blockToHaddock opts (BlockQuote blocks) =
  blockListToHaddock opts blocks
blockToHaddock opts (Table caption aligns widths headers rows) = do
  caption' <- inlineListToHaddock opts caption
  let caption'' = if null caption
                     then empty
                     else blankline <> caption' <> blankline
  tbl <- gridTable opts blockListToHaddock
              (all null headers) (map (const AlignDefault) aligns)
                widths headers rows
  return $ prefixed "> " (tbl $$ blankline $$ caption'') $$ blankline
blockToHaddock opts (BulletList items) = do
  contents <- mapM (bulletListItemToHaddock opts) items
  return $ (if isTightList items then vcat else vsep) contents <> blankline
blockToHaddock opts (OrderedList (start,_,delim) items) = do
  let attribs = (start, Decimal, delim)
  let markers  = orderedListMarkers attribs
  let markers' = map (\m -> if length m < 3
                               then m ++ replicate (3 - length m) ' '
                               else m) markers
  contents <- zipWithM (orderedListItemToHaddock opts) markers' items
  return $ (if isTightList items then vcat else vsep) contents <> blankline
blockToHaddock opts (DefinitionList items) = do
  contents <- mapM (definitionListItemToHaddock opts) items
  return $ vcat contents <> blankline

-- | Convert bullet list item (list of blocks) to haddock
bulletListItemToHaddock :: PandocMonad m
                        => WriterOptions -> [Block] -> StateT WriterState m (Doc Text)
bulletListItemToHaddock opts items = do
  contents <- blockListToHaddock opts items
  let sps = replicate (writerTabStop opts - 2) ' '
  let start = text ('-' : ' ' : sps)
  return $ hang (writerTabStop opts) start contents $$
           if endsWithPlain items
              then cr
              else blankline

-- | Convert ordered list item (a list of blocks) to haddock
orderedListItemToHaddock :: PandocMonad m
                         => WriterOptions -- ^ options
                         -> String        -- ^ list item marker
                         -> [Block]       -- ^ list item (list of blocks)
                         -> StateT WriterState m (Doc Text)
orderedListItemToHaddock opts marker items = do
  contents <- blockListToHaddock opts items
  let sps = case length marker - writerTabStop opts of
                   n | n > 0 -> text $ replicate n ' '
                   _ -> text " "
  let start = text marker <> sps
  return $ hang (writerTabStop opts) start contents $$
           if endsWithPlain items
              then cr
              else blankline

-- | Convert definition list item (label, list of blocks) to haddock
definitionListItemToHaddock :: PandocMonad m
                            => WriterOptions
                            -> ([Inline],[[Block]])
                            -> StateT WriterState m (Doc Text)
definitionListItemToHaddock opts (label, defs) = do
  labelText <- inlineListToHaddock opts label
  defs' <- mapM (mapM (blockToHaddock opts)) defs
  let contents = (if isTightList defs then vcat else vsep) $
                 map (\d -> hang 4 empty $ vcat d <> cr) defs'
  return $ nowrap (brackets labelText) $$ contents $$
           if isTightList defs
              then cr
              else blankline

-- | Convert list of Pandoc block elements to haddock
blockListToHaddock :: PandocMonad m
                   => WriterOptions -- ^ Options
                   -> [Block]       -- ^ List of block elements
                   -> StateT WriterState m (Doc Text)
blockListToHaddock opts blocks =
  mconcat <$> mapM (blockToHaddock opts) blocks

-- | Convert list of Pandoc inline elements to haddock.
inlineListToHaddock :: PandocMonad m
                    => WriterOptions -> [Inline] -> StateT WriterState m (Doc Text)
inlineListToHaddock opts lst =
  mconcat <$> mapM (inlineToHaddock opts) lst

-- | Convert Pandoc inline element to haddock.
inlineToHaddock :: PandocMonad m
                => WriterOptions -> Inline -> StateT WriterState m (Doc Text)
inlineToHaddock opts (Span (ident,_,_) ils) = do
  contents <- inlineListToHaddock opts ils
  if not (null ident) && null ils
     then return $ "#" <> text ident <> "#"
     else return contents
inlineToHaddock opts (Emph lst) = do
  contents <- inlineListToHaddock opts lst
  return $ "/" <> contents <> "/"
inlineToHaddock opts (Strong lst) = do
  contents <- inlineListToHaddock opts lst
  return $ "__" <> contents <> "__"
inlineToHaddock opts (Strikeout lst) = do
  contents <- inlineListToHaddock opts lst
  -- not supported in haddock, but we fake it:
  return $ "~~" <> contents <> "~~"
-- not supported in haddock:
inlineToHaddock opts (Superscript lst) = inlineListToHaddock opts lst
-- not supported in haddock:
inlineToHaddock opts (Subscript lst) = inlineListToHaddock opts lst
-- not supported in haddock:
inlineToHaddock opts (SmallCaps lst) = inlineListToHaddock opts lst
inlineToHaddock opts (Quoted SingleQuote lst) = do
  contents <- inlineListToHaddock opts lst
  return $ "‘" <> contents <> "’"
inlineToHaddock opts (Quoted DoubleQuote lst) = do
  contents <- inlineListToHaddock opts lst
  return $ "“" <> contents <> "”"
inlineToHaddock _ (Code _ str) =
  return $ "@" <> text (escapeString str) <> "@"
inlineToHaddock _ (Str str) =
  return $ text $ escapeString str
inlineToHaddock _ (Math mt str) =
  return $ case mt of
    DisplayMath -> cr <> "\\[" <> text str <> "\\]" <> cr
    InlineMath  -> "\\(" <> text str <> "\\)"
inlineToHaddock _ il@(RawInline f str)
  | f == "haddock" = return $ text str
  | otherwise = do
    report $ InlineNotRendered il
    return empty
-- no line break in haddock (see above on CodeBlock)
inlineToHaddock _ LineBreak = return cr
inlineToHaddock opts SoftBreak =
  case writerWrapText opts of
       WrapAuto     -> return space
       WrapNone     -> return space
       WrapPreserve -> return cr
inlineToHaddock _ Space = return space
inlineToHaddock opts (Cite _ lst) = inlineListToHaddock opts lst
inlineToHaddock _ (Link _ txt (src, _)) = do
  let linktext = text $ escapeString $ stringify txt
  let useAuto = isURI src &&
                case txt of
                      [Str s] | escapeURI s == src -> True
                      _       -> False
  return $ nowrap $ "<" <> text src <>
           (if useAuto then empty else space <> linktext) <> ">"
inlineToHaddock opts (Image attr alternate (source, tit)) = do
  linkhaddock <- inlineToHaddock opts (Link attr alternate (source, tit))
  return $ "<" <> linkhaddock <> ">"
-- haddock doesn't have notes, but we can fake it:
inlineToHaddock opts (Note contents) = do
  modify (\st -> st{ stNotes = contents : stNotes st })
  st <- get
  let ref = text $ writerIdentifierPrefix opts ++ show (length $ stNotes st)
  return $ "<#notes [" <> ref <> "]>"