From 115270a70b50c9047c6ba8dbd808cc4594faa4ab Mon Sep 17 00:00:00 2001
From: Pagwin <dev@pagwin.xyz>
Date: Mon, 8 Dec 2025 21:18:22 -0500
Subject: [PATCH] redoing markdown parsing and adding underlining

---
 src/IR.hs       |   1 +
 src/Markdown.hs | 457 ++++++++----------------------------------------
 2 files changed, 78 insertions(+), 380 deletions(-)

diff --git a/src/IR.hs b/src/IR.hs
index 29f3cd7..3aa30b0 100644
--- a/src/IR.hs
+++ b/src/IR.hs
@@ -58,6 +58,7 @@ data InlineText
   | Bold [InlineText]
   | Italic [InlineText]
   | Crossed [InlineText]
+  | Underlined [InlineText]
   | InlineCode Text
   | Link
       { linkText :: [InlineText],
diff --git a/src/Markdown.hs b/src/Markdown.hs
index 0ec8b8b..5710973 100644
--- a/src/Markdown.hs
+++ b/src/Markdown.hs
@@ -18,413 +18,110 @@ import IR
 import Logger (Logger (logDebug))
 import Text.Megaparsec (ParsecT, Stream, Token, Tokens, anySingle, anySingleBut, between, choice, count, eof, manyTill, notFollowedBy, satisfy, skipSome, try, (<?>))
 import qualified Text.Megaparsec as MP
-import Text.Megaparsec.Char (alphaNumChar, char, digitChar, string)
+import Text.Megaparsec.Char (alphaNumChar, char, digitChar, newline, string)
 
-type ParserTG = ParsecT Void
+type Parser = ParsecT Void
 
-type ParserT m = ParserTG T.Text m
+class (Token s ~ Char, Stream s, IsString (Tokens s), Show s) => Characters s
 
-type Parser = ParserT Identity
+instance Characters Text
 
-anyChar :: (Token s ~ Char, Stream s) => ParserTG s m Char
-anyChar = anySingle
+instance Characters String
 
-alphaNum :: (Token s ~ Char, Stream s) => ParserTG s m Char
-alphaNum = alphaNumChar
-
-digit :: (Token s ~ Char, Stream s) => ParserTG s m Char
-digit = digitChar
-
-noneOf :: (Token s ~ Char, Stream s) => [Char] -> ParserTG s m Char
-noneOf = MP.noneOf
-
-oneOf :: (Token s ~ Char, Stream s) => [Char] -> ParserTG s m Char
-oneOf = MP.oneOf
-
-optionMaybe :: (Token s ~ Char, Stream s) => ParserTG s m a -> ParserTG s m (Maybe a)
-optionMaybe = optional
-
-skipMany1 :: (Token s ~ Char, Stream s) => ParserTG s m a -> ParserTG s m ()
-skipMany1 = skipSome
-
-metadata :: (Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Text
+metadata :: (Logger m, Characters s) => Parser s m Text
 metadata = bound *> fmap T.pack (many $ try (char '-' <* notFollowedBy (string "--")) <|> anySingleBut '-') <* bound
   where
     bound = string "---"
 
-document :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Document
-document = do
-  logDebug "document"
-  Doc <$> many element <* eof
+document :: (Logger m, Characters s) => Parser s m Document
+document = Doc <$> many element
 
-element :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
+element :: (Logger m, Characters s) => Parser s m Element
 element =
   choice
     [ try headingBlock <?> "Element Heading",
       try fencedCodeBlock <?> "Fenced Code Block",
-      try indentedCodeBlock <?> "Indented Code Block",
       try blockquoteBlock <?> "BlockQuote",
-      try unorderedListBlock <?> "Unordered List",
-      try orderedListBlock <?> "Ordered List",
-      try horizontalRuleBlock <?> "Horizontal Rule",
+      (try $ unorderedListBlock 0) <?> "Unordered List",
+      (try $ orderedListBlock 0) <?> "Ordered List",
       try htmlBlock <?> "HTML Block",
-      try blankLines <?> "Blank Lines", -- Consume blank lines but don't add to AST
       paragraphBlock <?> "Paragarph"
     ]
+    <* blockEnding
 
--- Blank lines (consumed but not stored)
-blankLines :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-blankLines = do
-  skipMany1 (blankLine *> notFollowedBy eof)
-  element <|> fmap (const $ HTML HTMLTag {html_content = ""}) eof -- Parse the next element (or handle eof)
+lineEnding :: (Logger m, Characters s) => Parser s m ()
+lineEnding = (try eof) <|> void newline
 
-blankLine :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m ()
-blankLine = do
-  many (char ' ' <|> char '\t')
-  lineEnding
-  pure ()
+blockEnding :: (Logger m, Characters s) => Parser s m ()
+blockEnding = (try (lineEnding *> lineEnding)) <|> eof
 
--- Heading Block
-headingBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-headingBlock = do
-  hashes <- some (char '#') <?> "Heading Hashes"
-  let level = length hashes
-  guard (level <= 6) <?> "Higher than level 6"
-  many (char ' ' <|> char '\t') <?> "Pre-Text Whitespace"
-  content <- manyTill (inlineElement <?> "Header Text") (try lineEnding <?> "Header Ending")
-  pure $ Heading $ H level content
-
--- Fenced Code Block
-fencedCodeBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-fencedCodeBlock = do
-  logDebug "fenced_coding_block"
-  fence <- string "```" <|> string "~~~"
-  logDebug "fence"
-  lang <- optionMaybe languageInfo
-  logDebug "langInfo"
-  lineEnding'
-  logDebug "lineEnding"
-  codeLines <- manyTill (codeLine fence) (try $ string fence)
-  logDebug "lines"
-  pure $ Code $ C lang (T.pack $ unlines codeLines)
-
-languageInfo :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Text
-languageInfo = T.pack <$> some (alphaNum <|> char '-' <|> char '+' <|> char '.')
-
-codeLine :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => (Tokens s) -> ParserTG s m String
-codeLine fence = do
-  -- this is a hack which can only haunt me if I continue using markdown
-  line <- many $ (notFollowedBy $ string fence) *> noneOf "\n\r"
-  lineEnding'
-  pure line
-
--- Indented Code Block
-indentedCodeBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-indentedCodeBlock = do
-  lines' <- some indentedLine
-  pure $ Code $ C Nothing (T.pack $ unlines lines')
+-- TODO: check if inlineHTML needs to be handled in any markdown posts
+-- TODO: link impl
+-- TODO: image impl
+inlineText :: (Logger m, Characters s) => Parser s m InlineText
+inlineText = choice [try strikethrough, try bold, try italic, try underlined, try code, try link, try image, plain_text]
   where
-    indentedLine = do
-      count 4 (char ' ' <|> char '\t')
-      line <- many $ noneOf "\n\r"
-      lineEnding
-      pure line
+    between' start end middle_piece = between start end $ many ((notFollowedBy end) *> middle_piece)
 
--- Blockquote Block
-blockquoteBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-blockquoteBlock = do
-  lines' <- some blockquoteLine
-  pure $ BlockQuote $ Q (concat lines')
+    strikethrough = Crossed <$> (between' (string "~~") (string "~~") inlineText)
+
+    bold = Bold <$> (between' (string "**") (string "**") inlineText)
+
+    italic = Italic <$> (between' (char '*') (char '*') inlineText)
+
+    underlined = Underlined <$> (between' (string "__") (string "__") inlineText)
+
+    code = InlineCode . T.pack <$> (between' (char '`') (char '`') (notFollowedBy lineEnding *> anySingle))
+
+    link = do
+      linkText <- error "linkText parser"
+      url <- error "url parser"
+      title <- error "title parser"
+      pure Link {linkText, url, title}
+
+    image = do
+      altText <- error "altText"
+      url <- error "url"
+      title <- error "title"
+      pure Image {altText, url, title}
+
+    plain_text = Text . T.pack <$> (many ((notFollowedBy blockEnding) *> anySingle))
+
+headingBlock :: (Logger m, Characters s) => Parser s m Element
+headingBlock = do
+  heading_level <- length <$> (some $ char '#')
+  optional $ char ' '
+  text <- many $ inlineText
+  pure $ Heading $ H {level = heading_level, text}
+
+fencedCodeBlock :: (Logger m, Characters s) => Parser s m Element
+fencedCodeBlock = between (string "```") (string "```") $ do
+  language' <- T.pack <$> (many (notFollowedBy lineEnding *> anySingle))
+  lineEnding
+  code <- T.pack <$> (many ((notFollowedBy $ string "```") *> anySingle))
+  let language = if language' == "" then Just language' else Nothing
+  pure $ Code $ C {language, code}
+
+blockquoteBlock :: (Logger m, Characters s) => Parser s m Element
+blockquoteBlock = BlockQuote . Q . concat <$> (some blockquoteLine)
   where
     blockquoteLine = do
       char '>'
-      optional (char ' ')
-      content <- many $ notFollowedBy lineEnding' *> inlineElement
-      pure content
+      optional $ char ' '
+      ret <- (many ((notFollowedBy lineEnding) *> inlineText))
+      -- this dance with optional and notFollowedBy is done so we
+      -- aren't accidentally consuming part of a block ending
+      (optional ((notFollowedBy blockEnding) *> lineEnding))
+      pure ret
 
--- Horizontal Rule Block
-horizontalRuleBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-horizontalRuleBlock = do
-  choice
-    [ try (count 3 (char '*') >> many (char ' ' <|> char '*')),
-      try (count 3 (char '-') >> many (char ' ' <|> char '-')),
-      try (count 3 (char '_') >> many (char ' ' <|> char '_'))
-    ]
-  lineEnding
-  pure HorizontalRule
+unorderedListBlock :: (Logger m, Characters s) => Int -> Parser s m Element
+unorderedListBlock indent_level = error "TODO: unorderedListBlock"
 
--- Unordered List Block
-unorderedListBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-unorderedListBlock = do
-  items <- some unorderedListItem
-  lineEnding'
-  pure $ List $ L Unordered items
+orderedListBlock :: (Logger m, Characters s) => Int -> Parser s m Element
+orderedListBlock indent_level = error "TODO: orderedListBlock"
 
-unorderedListItem :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m ListItem
-unorderedListItem = do
-  oneOf "*-+"
-  optional (char ' ' <|> char '\t')
-  content <- many $ notFollowedBy lineEnding' *> inlineElement
-  lineEnding'
-  -- continuations <- many listContinuation
-  children <- maybeToList <$> (optional $ indentedList 1)
-  pure $ LI content children
+htmlBlock :: (Logger m, Characters s) => Parser s m Element
+htmlBlock = error "TODO: htmlBlock"
 
--- TODO: handle list indentation at all levels
-indentedList :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => Int -> ParserTG s m List
-indentedList n = do
-  void $ (count (4 * n) (char ' ')) <|> count n (char '\t')
-  ret <- (try indentedUnorderedList) <|> indentedOrderedList
-  pure ret <* lineEnding'
-
-indentedUnorderedList :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m List
-indentedUnorderedList = do
-  items <- some (indentedListItem (oneOf "*-+" >> void (char ' ' <|> char '\t')))
-  pure $ L Unordered items
-
-indentedOrderedList :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m List
-indentedOrderedList = do
-  items <- some (try $ indentedListItem (some digit >> char '.' >> void (char ' ' <|> char '\t')))
-  pure $ L Ordered items
-
-indentedListItem :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m () -> ParserTG s m ListItem
-indentedListItem marker = do
-  marker
-  content <- many $ notFollowedBy lineEnding' *> inlineElement
-  pure $ LI content []
-
--- Ordered List Block
-orderedListBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-orderedListBlock = do
-  items <- some orderedListItem
-  lineEnding'
-  pure $ List $ L Ordered items
-
-orderedListItem :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m ListItem
-orderedListItem = do
-  some digit
-  char '.' <|> char ')'
-  optional (char ' ' <|> char '\t')
-  content <- many $ notFollowedBy lineEnding' *> inlineElement
-  lineEnding'
-  -- continuations <- many listContinuation
-  children <- maybeToList <$> (optional $ indentedList 1)
-  pure $ LI content children
-
--- HTML Block
-htmlBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-htmlBlock = do
-  char '<'
-  -- Capture the entire HTML block as raw text
-  rest <- manyTill anyChar (try $ char '>' >> lineEnding)
-  let content = '<' : (rest <> ">")
-  return $ HTML $ HTMLTag (T.pack content)
-
--- Paragraph Block
-paragraphBlock :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m Element
-paragraphBlock = do
-  logDebug "paragraph"
-  content <- some (notFollowedBy lineEnding *> inlineElement)
-  lineEnding <|> eof
-  pure $ Paragraph $ P content
-
--- Inline Elements
-inlineElement :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-inlineElement =
-  logDebug "inlineElement"
-    *> choice
-      [ try strong <?> "Inline Strong Text",
-        try emphasis <?> "Inline Italic Text",
-        try crossedText <?> "Inline Crossed Text",
-        try codeSpan <?> "Inline Code",
-        try image <?> "Inline Image",
-        try link <?> "Inline Link",
-        try htmlInline <?> "Inline HTML",
-        try escapedChar <?> "Escaped Character",
-        plainText <?> "Inline Plain Text"
-      ]
-
--- Strong (Bold)
-strong :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-strong = strongAsterisk <|> strongUnderscore
-
-strongAsterisk :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-strongAsterisk = do
-  string "**"
-  content <- some (notFollowedBy (string "**") >> inlineElement)
-  string "**"
-  pure $ Bold content
-
-strongUnderscore :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-strongUnderscore = do
-  string "__"
-  content <- some (notFollowedBy (string "__") >> inlineElement)
-  string "__"
-  pure $ Bold content
-
-crossedText :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-crossedText = do
-  string "~~"
-  content <- some (notFollowedBy (string "~~") >> inlineElement)
-  string "~~"
-  pure $ Crossed content
-
--- Emphasis (Italic)
-emphasis :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-emphasis = emphasisAsterisk <|> emphasisUnderscore
-
-emphasisAsterisk :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-emphasisAsterisk = do
-  char '*'
-  content <- some (notFollowedBy (char '*') >> inlineElementNoAsterisk)
-  char '*'
-  pure $ Italic content
-
-emphasisUnderscore :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-emphasisUnderscore = do
-  char '_'
-  content <- some inlineElementNoUnderscore
-  char '_'
-  pure $ Italic content
-
-inlineElementNo :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => Char -> ParserTG s m InlineText
-inlineElementNo c =
-  choice
-    [ try strong,
-      try codeSpan,
-      try image,
-      try link,
-      try htmlInline,
-      try escapedChar,
-      plainTextNo [c]
-    ]
-
-plainTextNo :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => [Char] -> ParserTG s m InlineText
-plainTextNo list = do
-  plainTextNo' False list
-
-plainTextNo' :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => Bool -> [Char] -> ParserTG s m InlineText
-plainTextNo' block_whitespace disallow = do
-  logDebug $ "base plain Text: " <> T.show block_whitespace <> " " <> T.show disallow
-  firstChar <- noneOf (disallow <> if block_whitespace then " \t\r\n" else []) <?> "Plain Text Initial Disallow"
-  remChars <- many $ notFollowedBy lineEnding' *> plainTextCharNo disallow
-  pure $ Text $ T.map wspHandler $ T.pack $ firstChar : remChars
-  where
-    wspHandler '\n' = ' '
-    wspHandler c = c
-
-inlineElementNoAsterisk :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-inlineElementNoAsterisk = inlineElementNo '*'
-
-inlineElementNoUnderscore :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-inlineElementNoUnderscore = inlineElementNo '_'
-
--- Code Span
-codeSpan :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-codeSpan =
-  choice
-    [ try tripleBacktick,
-      try doubleBacktick,
-      singleBacktick
-    ]
-  where
-    singleBacktick = do
-      char '`'
-      content <- many $ noneOf "`\n\r"
-      char '`'
-      pure $ InlineCode (T.pack content)
-    doubleBacktick = do
-      string "``"
-      content <- manyTill anyChar (try $ string "``")
-      pure $ InlineCode (T.pack content)
-    tripleBacktick = do
-      string "```"
-      content <- manyTill anyChar (try $ string "```")
-      pure $ InlineCode (T.pack content)
-
--- Image
-image :: (Logger m, Token s ~ Char, Stream s) => ParserTG s m InlineText
-image = do
-  char '!'
-  char '['
-  alt <- T.pack <$> many (noneOf "]\n\r")
-  char ']'
-  (url, title) <- linkDestination
-  return $ Image {altText = alt, url = url, title = title}
-
--- Link
-link :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-link = do
-  char '['
-  content <- some (notFollowedBy (char ']') >> inlineElementNoBracket)
-  char ']'
-  (url, title) <- linkDestination
-  pure $ Link content url title
-
-inlineElementNoBracket :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-inlineElementNoBracket =
-  choice
-    [ try strong,
-      try emphasis,
-      try codeSpan,
-      try htmlInline,
-      try escapedChar,
-      plainTextNo "[]"
-    ]
-
-linkDestination :: (Logger m, Token s ~ Char, Stream s) => ParserTG s m (Text, Maybe Text)
-linkDestination = directLink <|> referenceLink
-  where
-    directLink = do
-      char '('
-      url <- many $ noneOf " \t\n\r)"
-      title <- optionMaybe (try $ some (char ' ' <|> char '\t') >> titleParser)
-      char ')'
-      pure (T.pack url, title)
-    referenceLink = do
-      char '['
-      ref <- some (alphaNum <|> char ' ' <|> char '\t')
-      char ']'
-      -- For simplicity, we're not resolving references here
-      -- In a real implementation, you'd look up the reference
-      pure (T.pack $ "[" ++ ref ++ "]", Nothing)
-
-titleParser :: (Logger m, Token s ~ Char, Stream s) => ParserTG s m Text
-titleParser =
-  T.pack
-    <$> choice
-      [ between (char '"') (char '"') (many $ anySingleBut '"'),
-        between (char '\'') (char '\'') (many $ anySingleBut '\''),
-        between (char '(') (char ')') (many $ anySingleBut ')')
-      ]
-
--- HTML Inline
-htmlInline :: (Logger m, Token s ~ Char, Stream s) => ParserTG s m InlineText
-htmlInline = do
-  start <- char '<'
-  content <- manyTill anyChar (try $ char '>')
-  return $ HTMLInline (T.pack (start : content ++ ">"))
-
--- Escaped Character
-escapedChar :: (Logger m, Token s ~ Char, Stream s) => ParserTG s m InlineText
-escapedChar = do
-  char '\\'
-  c <- satisfy (\x -> x >= '!' && x <= '~')
-  pure $ Text (T.singleton c)
-
--- Plain Text
-plainText :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m InlineText
-plainText = plainTextNo' False [] <?> "Baseline Plain Text"
-
-plainTextBaseDisallow :: [Char]
-plainTextBaseDisallow = "[~`_*<"
-
-plainTextCharNo :: (Logger m, Token s ~ Char, Stream s) => [Char] -> ParserTG s m Char
-plainTextCharNo additional = noneOf $ additional <> plainTextBaseDisallow
-
--- Helper Parsers
-lineEnding :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m ()
-lineEnding = void (try $ count 2 (try (string "\r\n") <|> try (string "\n") <|> string "\r")) <|> eof
-
-lineEnding' :: (Logger m, Token s ~ Char, Stream s, IsString (Tokens s)) => ParserTG s m ()
-lineEnding' = void (try (string "\r\n") <|> try (string "\n") <|> string "\r") <|> eof
+paragraphBlock :: (Logger m, Characters s) => Parser s m Element
+paragraphBlock = Paragraph . P <$> (many inlineText)