{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts #-}

{- |
   Module      : Text.Pandoc.Readers.AsciiDoc
   Copyright   : Copyright (C) 2024 John MacFarlane
   License     : GNU GPL, version 2 or above

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

Reads and evaluates a AsciiDoc document as a Pandoc AST.
-}
module Text.Pandoc.Readers.AsciiDoc
  ( readAsciiDoc
  )
where

import Text.Pandoc.Class
import Text.Pandoc.Options
import Text.Pandoc.Definition
import Text.Pandoc.Walk
import Text.Pandoc.Shared (addPandocAttributes, blocksToInlines, safeRead,
                           tshow)
import qualified Text.Pandoc.UTF8 as UTF8
import qualified AsciiDoc as A
import Text.Pandoc.Error
import qualified Text.Pandoc.Builder as B
import Text.Pandoc.Readers.HTML (readHtml)
import Control.Monad.Except (throwError)
import Control.Monad (mplus)
import Text.Pandoc.Parsing (newPos, sourceName)
import Text.Pandoc.Logging
import Text.Pandoc.Sources
import Control.Monad.State
import Data.List (intersperse, foldl')
import Data.Char (chr, ord)
import qualified Data.Text as T
import qualified Data.Map as M
import Data.Maybe (fromMaybe)

-- import Debug.Trace

-- | Read AsciiDoc from an input string and return a Pandoc document.
readAsciiDoc :: (PandocMonad m, ToSources a) => ReaderOptions -> a -> m Pandoc
readAsciiDoc _opts inp = do
  let Sources sources = toSources inp
  (mconcat <$> mapM
   (\(sourcepos, t) ->
     A.parseDocument getIncludeFile raiseError (sourceName sourcepos) t)
    sources)
   >>= resolveFootnotes
   >>= resolveStem
   >>= resolveIcons
   >>= toPandoc
 where
  getIncludeFile fp = UTF8.toText <$> readFileStrict fp
  raiseError fp pos msg = throwError $ PandocParseError $ T.pack
                            $ msg <> " at " <> show fp <>
                              " char " <> show pos

toPandoc :: PandocMonad m => A.Document -> m Pandoc
toPandoc doc =
  Pandoc <$> doMeta (A.docMeta doc)
         <*> (B.toList <$> doBlocks (A.docBlocks doc))

resolveFootnotes :: Monad m => A.Document -> m A.Document
resolveFootnotes doc = do
  evalStateT (A.mapInlines go doc) (mempty :: M.Map T.Text [A.Inline])
 where
   go (A.Inline attr (A.Footnote (Just (A.FootnoteId fnid)) ils)) = do
     fnmap <- get
     case M.lookup fnid fnmap of
       Just ils' ->
         pure $ A.Inline attr (A.Footnote (Just (A.FootnoteId fnid)) ils')
       Nothing -> do
         put $ M.insert fnid ils fnmap
         pure $ A.Inline attr (A.Footnote (Just (A.FootnoteId fnid)) ils)
   go x = pure x

resolveStem :: Monad m => A.Document -> m A.Document
resolveStem doc = do
  let defaultType = case M.lookup "stem" (A.docAttributes (A.docMeta doc)) of
                      Just "asciimath" -> A.AsciiMath
                      _ -> A.LaTeXMath
  let doInlineStem (A.Inline attr (A.Math Nothing t)) =
        pure $ A.Inline attr (A.Math (Just defaultType) t)
      doInlineStem x = pure x
  let doBlockStem (A.Block attr mbtit (A.MathBlock Nothing t)) =
        pure $ A.Block attr mbtit (A.MathBlock (Just defaultType) t)
      doBlockStem x = A.mapInlines doInlineStem x
  A.mapBlocks doBlockStem doc

-- resolve icons as either characters in an icon font or images
resolveIcons :: Monad m => A.Document -> m A.Document
resolveIcons doc = A.mapInlines fromIcon doc
 where
   docattrs = A.docAttributes (A.docMeta doc)
   iconFont = case M.lookup "icons" docattrs of
                Just "font" -> True
                _ -> False
   iconsdir = fromMaybe "./images/icons" $ M.lookup "iconsdir" docattrs
   icontype = fromMaybe "png" $ M.lookup "icontype" docattrs
   addClasses cls (A.Attr ps kvs) =
     A.Attr ps $
      case M.lookup "role" kvs of
       Just r -> M.insert "role" (T.unwords (r : cls)) kvs
       Nothing -> M.insert "role" (T.unwords cls) kvs
   fromIcon (A.Inline attr (A.Icon name)) =
     if iconFont
        then pure $
              A.Inline (addClasses ["fa", "fa-" <> name] attr) (A.Span [])
        else pure $ -- default is to use an image
              A.Inline (addClasses ["icon"] attr)
                 (A.InlineImage
                   (A.Target
                      (iconsdir <> "/" <> name <> "." <> icontype))
                      Nothing Nothing Nothing)
   fromIcon x = pure x

addAttribution :: Maybe A.Attribution -> B.Blocks -> B.Blocks
addAttribution Nothing bs = bs
addAttribution (Just (A.Attribution t)) bs = B.fromList $
  case B.toList bs of
    [B.Div attr bls] -> [B.Div attr (bls ++ [attrBlock])]
    [B.BlockQuote bls] -> [B.BlockQuote (bls ++ [attrBlock])]
    xs -> xs ++ [attrBlock]
 where
   attrBlock = Para (B.toList $ B.text $ "\x2014 " <> t)

doMeta :: PandocMonad m => A.Meta -> m B.Meta
doMeta meta = do
  tit' <- doInlines (A.docTitle meta)
  pure $
    (if tit' == mempty
        then id
        else B.setMeta "title" tit') .
    (case A.docAuthors meta of
       [] -> id
       as -> B.setMeta "author" (map fromAuthor as)) .
    (case A.docRevision meta of
       Nothing -> id
       Just (A.Revision vers mbdate mbremark) ->
         B.setMeta "version" vers .
         maybe id (B.setMeta "date") mbdate .
         maybe id (B.setMeta "remark") mbremark) .
    flip (foldl' (\m (k,v) ->
                    -- leave out flags that are set just for processing
                    if k == "sectids" || k == "stem"
                       then m
                       else if T.null v
                               then B.setMeta k True m
                               else B.setMeta k v m))
      (M.toList (A.docAttributes meta))
    $ mempty

fromAuthor :: A.Author -> B.Inlines
fromAuthor au = B.text (A.authorName au) <>
  maybe mempty (\email ->
    " (" <> B.link ("mailto:" <> email) "" (B.str email) <> ")")
    (A.authorEmail au)

doBlocks :: PandocMonad m => [A.Block] -> m B.Blocks
doBlocks = fmap mconcat . mapM doBlock

addBlockAttr :: A.Attr -> B.Blocks -> B.Blocks
addBlockAttr (A.Attr _ kvs') bs =
  case B.toList bs of
    x@(B.OrderedList{}) : xs -> -- "start" is handled in list attribs
      addPandocAttributes (M.toList $ M.delete "start" kvs)
             (B.singleton x) <> B.fromList xs
    x:xs -> addPandocAttributes (M.toList kvs) (B.singleton x)
                <> B.fromList xs
    [] -> mempty
 where
  kvs = M.mapKeys (\k -> if k == "role" then "class" else k) kvs'

addBlockTitle :: B.Inlines -> B.Blocks -> B.Blocks
addBlockTitle tit' bs =
  let tit = B.toList tit'
  in case B.toList bs of
    [B.Table attr _ colspecs thead tbody tfoot] ->
      B.singleton $ B.Table attr (B.Caption Nothing [B.Plain tit])
                     colspecs thead tbody tfoot
    [B.Figure attr _ bs'] ->
      B.singleton $ B.Figure attr (B.Caption Nothing [B.Plain tit]) bs'
    [B.Div attr (B.Div ("",["title"],[]) [Para _] : bs')] ->
      -- replace existing title, which might be e.g. "Note"
      B.singleton $ B.Div attr (B.Div ("",["title"],[]) [B.Para tit] : bs')
    [B.Div attr bs'] -> -- put title Div inside
      B.singleton $ B.Div attr (B.Div ("",["title"],[]) [B.Para tit] : bs')
    _ -> B.divWith B.nullAttr (B.divWith ("",["title"],[]) (B.para tit') <> bs) 

doBlock :: PandocMonad m => A.Block -> m B.Blocks
doBlock (A.Block attr@(A.Attr ps kvs) mbtitle bt) = do
  mbtitle' <- case mbtitle of
                Nothing -> pure Nothing
                Just (A.BlockTitle ils) -> Just <$> doInlines ils
  addBlockAttr attr . maybe id addBlockTitle mbtitle' <$>
   case bt of
    A.Section (A.Level lev) ils bs -> do
      ils' <- doInlines ils
      bs' <- doBlocks bs
      pure $ (B.header lev ils') <> bs'
    A.DiscreteHeading (A.Level lev) ils ->
      B.header lev <$> doInlines ils
    A.Paragraph ils -> B.para <$> doInlines ils
    A.LiteralBlock t -> pure $ B.codeBlock t
    A.Listing mblang lns -> do
      let fromCallout (A.Callout i)
            | i <= 20 = T.pack [' ', chr (0x2460 + i - 1)]
            | otherwise = "<" <> tshow i <> ">"
      let fromSourceLine (A.SourceLine t callouts) =
            t <> mconcat (map fromCallout callouts)
      let code = T.intercalate "\n" $ map fromSourceLine lns
      let classes = case mblang of
                      Nothing -> []
                      Just (A.Language l) -> [l]
      pure $ B.codeBlockWith ("", classes, []) code
    A.IncludeListing _ _ Nothing -> pure mempty
    A.IncludeListing mblang _fp (Just lns) ->
      doBlock (A.Block mempty mbtitle (A.Listing mblang lns))
    A.ExampleBlock bs -> B.divWith ("",["example"],[]) <$> doBlocks bs
    A.Sidebar bs -> B.divWith ("",["sidebar"],[]) <$> doBlocks bs
    A.OpenBlock bs -> B.divWith ("",[],[]) <$> doBlocks bs
    A.QuoteBlock mbattrib bs ->
      addAttribution mbattrib . B.blockQuote <$> doBlocks bs
    A.Verse mbattrib bs ->
      addAttribution mbattrib . B.blockQuote <$> doBlocks bs
    -- TODO when texmath's asciimath parser works, convert:
    A.MathBlock (Just A.AsciiMath) t -> pure $ B.para $ B.displayMath t
    A.MathBlock (Just A.LaTeXMath) t -> pure $ B.para $ B.displayMath t
    A.MathBlock Nothing _ ->
      throwError $ PandocParseError "Encountered math type Nothing"
    A.List (A.BulletList _) items ->
      B.bulletList <$> mapM doItem items
    A.List A.CheckList items ->
      B.bulletList <$> mapM doItem items
    A.List (A.OrderedList _ mbstart) items -> do
      let start = fromMaybe (1 :: Int)
                    (mbstart `mplus` (M.lookup "start" kvs >>= safeRead))
      let getStyle xs = case xs of
                  "arabic":_ -> Decimal
                  "decimal":_ -> Decimal
                  "loweralpha":_ -> LowerAlpha
                  "upperalpha":_ -> UpperAlpha
                  "lowerroman":_ -> LowerRoman
                  "upperroman":_ -> UpperRoman
                  _:rest -> getStyle rest
                  [] -> DefaultStyle
      let sty = getStyle ps
      let delim = DefaultDelim
      B.orderedListWith (start, sty, delim) <$> mapM doItem items
    A.List A.CalloutList items ->
      B.divWith ("",["callout-list"],[]) . B.orderedList <$> mapM doItem items
    A.DefinitionList items
      | "ordered" `elem` ps ->
          B.orderedList <$>
             mapM (fmap (B.definitionList . (:[])) . doDefListItem) items
      | otherwise -> B.definitionList <$> mapM doDefListItem items
    A.Table specs mbHeader rows mbFooter -> do
      let toAlign A.AlignLeft = B.AlignLeft
          toAlign A.AlignCenter = B.AlignCenter
          toAlign A.AlignRight = B.AlignRight
      let fromCell (A.TableCell bs mbHorizAlign _mbVertAlign colspan rowspan) =
            B.Cell B.nullAttr (maybe B.AlignDefault toAlign mbHorizAlign)
                        (B.RowSpan rowspan) (B.ColSpan colspan) . B.toList
                   <$> doBlocks bs
      let fromRow (A.TableRow cs) = B.Row B.nullAttr <$> mapM fromCell cs
      tbody <- B.TableBody B.nullAttr (B.RowHeadColumns 0) [] <$> mapM fromRow rows
      thead <- B.TableHead B.nullAttr <$> maybe (pure []) (mapM fromRow) mbHeader
      tfoot <- B.TableFoot B.nullAttr <$> maybe (pure []) (mapM fromRow) mbFooter
      let totalWidth = sum $ map (fromMaybe 1 . A.colWidth) specs
      let toColSpec spec = (maybe B.AlignDefault toAlign (A.colHorizAlign spec),
                             maybe B.ColWidthDefault
                               (B.ColWidth . (\x ->
                                   fromIntegral x / fromIntegral totalWidth))
                               (A.colWidth spec))
      let colspecs = map toColSpec specs
      pure $ B.table (B.Caption Nothing mempty) -- added by addBlockTitle
                colspecs thead [tbody] tfoot
    A.BlockImage target mbalt mbw mbh -> do
      img' <- doInline (A.Inline mempty (A.InlineImage target mbalt mbw mbh))
      -- TODO have a global function that adds the title to caption here:
      pure $ B.figure (Caption Nothing mempty) -- added by addBlockTitle
                      (B.plain img')
    -- TODO alt text?
    A.BlockAudio (A.Target t) ->
      pure $ B.plain $ B.image t "" (B.str t)
    -- TODO alt text?
    A.BlockVideo (A.Target t) ->
      pure $ B.plain $ B.image t "" (B.str t)
    A.TOC -> pure $ B.divWith ("toc",[],[]) mempty
    A.Admonition admonitionType bs -> do
      let admon = T.pack $ show admonitionType
      bs' <- doBlocks bs
      pure $ B.divWith ("",[T.toLower admon],[])
           $ B.divWith ("",["title"],[]) (B.para (B.str admon)) <> bs'
    A.PageBreak ->
      pure $ B.divWith ("", ["page-break"], [("wrapper", "1")]) B.horizontalRule
    A.ThematicBreak -> pure $ B.horizontalRule
    A.Include fp (Just bs) ->
      B.divWith ("",["included"],[("path",T.pack fp)]) <$> doBlocks bs
    A.Include fp Nothing -> do
      report $ CouldNotLoadIncludeFile (T.pack fp) (newPos "" 0 0)
      pure mempty
    A.PassthroughBlock t ->
         case runPure (readHtml def{
                               readerExtensions = extensionsFromList [Ext_raw_html]
                               } t) of
        Left _ -> pure $ B.rawBlock "html" t
        Right (Pandoc _ bs) -> pure $ B.fromList bs

doItem :: PandocMonad m => A.ListItem -> m B.Blocks
doItem (A.ListItem Nothing bs) = doBlocks bs
doItem (A.ListItem (Just checkstate) bs) = do
  bs' <- doBlocks bs
  let check = case checkstate of
                A.Checked -> Str "\9746"
                A.Unchecked -> Str "\9744"
  pure $ B.fromList
       $ case B.toList bs' of
           (B.Para ils : rest) -> B.Para (check : B.Space : ils) : rest
           (B.Plain ils : rest) -> B.Plain (check : B.Space : ils) : rest
           rest -> B.Para [check] : rest

doDefListItem :: PandocMonad m
              => ([A.Inline], [A.Block]) -> m (B.Inlines , [B.Blocks])
doDefListItem (lab, bs) = do
  lab' <- doInlines lab
  bs' <- doBlocks bs
  pure (lab', [bs'])

doInlines :: PandocMonad m => [A.Inline] -> m B.Inlines
doInlines = fmap mconcat . mapM doInline

doInline :: PandocMonad m => A.Inline -> m B.Inlines
doInline (A.Inline (A.Attr _ps kvs') it) = do
  let kvs = M.mapKeys (\k -> if k == "role" then "class" else k) kvs'
  addPandocAttributes (M.toList kvs) <$>
   case it of
    A.Str t -> pure $ B.text t
    A.HardBreak -> pure B.linebreak
    A.Bold ils -> B.strong <$> doInlines ils
    A.Italic ils -> B.emph <$> doInlines ils
    A.Monospace ils -> walk monospaceStr <$> doInlines ils
    A.Superscript ils -> B.superscript <$> doInlines ils
    A.Subscript ils -> B.subscript <$> doInlines ils
    A.Highlight ils -> B.spanWith ("",["mark"],[]) <$> doInlines ils
    A.Strikethrough ils -> B.strikeout <$> doInlines ils
    A.DoubleQuoted ils -> B.doubleQuoted <$> doInlines ils
    A.SingleQuoted ils -> B.singleQuoted <$> doInlines ils
    -- TODO when texmath's asciimath parser works, convert:
    A.Math (Just A.AsciiMath) t -> pure $ B.math t
    A.Math (Just A.LaTeXMath) t -> pure $ B.math t
    A.Math Nothing _ ->
      throwError $ PandocParseError "Encountered math type Nothing"
    A.Icon t -> pure $ B.spanWith ("",["icon"],[("name",t)])
                         (B.str ("[" <> t <> "]"))
    A.Button t -> pure $ B.spanWith ("",["button"],[])
                         (B.strong $ B.str ("[" <> t <> "]"))
    A.Kbd ts -> pure $ mconcat $ intersperse (B.str "+") $
         map (B.spanWith ("",["kbd"],[]) . B.strong . B.str) ts
    A.Menu ts -> pure $ B.spanWith ("",["menu"],[]) $
        B.strong $ B.text $ T.intercalate " › " ts
    -- TODO do we need linktype?
    A.Link _linkType (A.Target t) ils -> B.link t "" <$> doInlines ils
    A.InlineImage (A.Target url) mbalt mbwidth mbheight -> do
      let alt = case mbalt of
                  Just (A.AltText t) -> B.text t
                  Nothing -> mempty
          width = case mbwidth of
                  Just (A.Width n) -> [("width", T.pack $ show n <> "px")]
                  Nothing -> []
          height = case mbheight of
                  Just (A.Height n) -> [("height", T.pack $ show n <> "px")]
                  Nothing -> []
      pure $ B.imageWith ("",[], width ++ height) url "" alt
    A.Footnote _ ils -> B.note . B.para <$> doInlines ils
    A.InlineAnchor t _ -> pure $ B.spanWith (t, [], []) mempty
    A.BibliographyAnchor t _ -> pure $ B.spanWith (t, [], []) mempty
    A.CrossReference t Nothing ->
      pure $ B.linkWith ("",["cross-reference"],[]) ("#" <> t) "" (B.str t)
    A.CrossReference t (Just ils) -> do
      B.linkWith ("",["cross-reference"],[]) ("#" <> t) "" <$> doInlines ils
    A.AttributeReference (A.AttributeName t) -> -- if this is here, it's unresolved
      pure $ B.str ("{" <> t <> "}")
    A.Span ils -> B.spanWith B.nullAttr <$> doInlines ils
    A.IndexEntry (A.TermInText t) ->
      pure $ B.spanWith ("",["index"],[("term",t)]) (B.text t)
    A.IndexEntry (A.TermConcealed ts) ->
      pure $ B.spanWith ("",["index"],[("term",T.intercalate "," ts)]) mempty
    A.Counter name ctype val ->
      pure $ B.spanWith ("",["counter"],[("name",name)]) $ B.str $
        case ctype of
          A.DecimalCounter -> tshow val
          A.UpperAlphaCounter -> T.singleton $ chr (ord 'A' + val - 1)
          A.LowerAlphaCounter -> T.singleton $ chr (ord 'a' + val - 1)
    -- Passthrough is hard to get right, because pandoc's RawInline needs
    -- a format specifier. Often in asciidoc passthrough is used as a form
    -- of escaping, so the best approach seems to be treating it as HTML
    -- and parsing it:
    A.Passthrough t -> do
      case runPure (readHtml def{
                               readerExtensions = extensionsFromList [Ext_raw_html]
                               } t) of
        Left _ -> pure $ B.rawInline "html" t
        Right (Pandoc _ bs) -> pure $ B.fromList . blocksToInlines $ bs

monospaceStr :: Inline -> Inline
monospaceStr (Str t) = Code B.nullAttr t
monospaceStr x = x