{-# LANGUAGE OverloadedStrings #-}

module HTML (compileToHTML) where

import Data.Char (isAlphaNum, toLower)
import Data.Maybe (fromMaybe)
import qualified Data.Text as T
import IR

escapeChar :: Char -> T.Text
escapeChar '<' = "&lt;"
escapeChar '>' = "&gt;"
escapeChar '"' = "&quot;"
escapeChar '\'' = "&#39;"
escapeChar '&' = "&amp;"
escapeChar c = T.singleton c

-- not effiecient, main optimization would be to have unpack go to
-- some haskell vector or array impl rather than the list impl
escapeText :: T.Text -> T.Text
escapeText = T.concat . map escapeChar . T.unpack

genHeaderId :: Heading -> T.Text
genHeaderId header =
  T.concat
    [ " id=\"",
      T.map (toLower . textSub) $
        T.strip $
          T.filter (\c -> isAlphaNum c || c == ' ') $
            serializeInlineToHTML header.text,
      "\" "
    ]
  where
    textSub ' ' = '-'
    textSub c = c

tshow :: (Show s) => s -> T.Text
tshow = T.pack . show

compileToHTML :: Document -> T.Text
compileToHTML (Doc elements) = T.concat $ map elementToHTML elements

elementsToHTML :: [Element] -> T.Text
elementsToHTML = T.concat . map elementToHTML

spaceSep :: [T.Text] -> T.Text
spaceSep = T.intercalate " "

elementToHTML :: Element -> T.Text
elementToHTML (Heading header attrs) = T.concat ["<h", tshow header.level, headerAttrs header attrs, ">", serializeInlineToHTML header.text, "</h", tshow header.level, ">"]
--
elementToHTML (Code code_block attrs) = T.concat ["<pre class=\"sourceCode ", language, "\" ", handleAttrs attrs, "><code class=\"sourceCode ", language, "\">", escapeText code_block.code, "</code>", "</pre>"]
  where
    language = fromMaybe "" code_block.language
elementToHTML (BlockQuote (Q elems) attrs) = T.concat ["<blockquote ", handleAttrs attrs, ">", elementsToHTML elems, "</blockquote>"]
elementToHTML (List (L {list_type = Ordered {start_number, style}, items}) attrs) = spaceSep ["<ol", maybe "" handleStart start_number, maybe "" handleStyle style, ">", generateLiElems items, "</ol>"]
elementToHTML (List (L {list_type = Unordered {style}, items}) attrs) = spaceSep ["<ul", maybe "" handleStyle style, ">", generateLiElems items, "</ul>"]
elementToHTML (HTML (HTMLTag {html_content})) = html_content
elementToHTML (Paragraph (P snippets) attrs) = spaceSep ["<p", handleAttrs attrs, ">", serializeInlineToHTML snippets, "</p>"]
elementToHTML (Transparent snippets) = serializeInlineToHTML snippets
elementToHTML (HorizontalRule attrs) = "<hr " <> handleAttrs attrs <> ">"
elementToHTML (Table _ _) = error "TODO"
elementToHTML (Container _ _) = error "TODO"
elementToHTML (Footnote _ _) = error "TODO"
elementToHTML (DescriptionList _ _) = error "TODO"
elementToHTML (RawBlock _ _) = error "TODO"
elementToHTML (TaskList _ _) = error "TODO"

handleStyle :: T.Text -> T.Text
handleStyle style = T.concat ["type=\"", style, "\""]

handleStart :: Int -> T.Text
handleStart start = T.concat ["start=\"", T.show start, "\""]

handleAttrs :: Attrs -> T.Text
handleAttrs Attrs {attrId, attrClasses, attrKV} =
  spaceSep
    [ maybe "" (\id -> "id=\"" <> id <> "\"") attrId,
      "class=\"" <> T.intercalate " " attrClasses <> "\"",
      T.intercalate " " $ map (\(key, val) -> key <> "=\"" <> val <> "\"") attrKV
    ]

headerAttrs :: Heading -> Attrs -> T.Text
headerAttrs header Attrs {attrId, attrClasses, attrKV} =
  spaceSep
    -- id is overcomplicated due to header having id logic written I don't wanna bother with
    [ maybe (genHeaderId header) (\id -> "id=\"" <> id <> "\"") attrId,
      "class=\"" <> T.intercalate " " attrClasses <> "\"",
      T.intercalate " " $ map (\(key, val) -> key <> "=\"" <> val <> "\"") attrKV
    ]

generateLiElems :: [ListItem] -> T.Text
generateLiElems [] = ""
generateLiElems (element : remainder) =
  T.concat
    [ "<li>",
      elementsToHTML element.content,
      "</li>",
      generateLiElems remainder
    ]

serializeInlineToHTML :: [InlineText] -> T.Text
serializeInlineToHTML [] = ""
serializeInlineToHTML (Text t : remaining) = escapeText t <> serializeInlineToHTML remaining
serializeInlineToHTML ((Bold elems attrs) : remaining) = spaceSep ["<b", handleAttrs attrs, ">", serializeInlineToHTML elems, "</b>", serializeInlineToHTML remaining]
serializeInlineToHTML ((Italic elems attrs) : remaining) = spaceSep ["<i", handleAttrs attrs, ">", serializeInlineToHTML elems, "</i>", serializeInlineToHTML remaining]
serializeInlineToHTML ((Crossed elems attrs) : remaining) = spaceSep ["<s", handleAttrs attrs, ">", serializeInlineToHTML elems, "</s>", serializeInlineToHTML remaining]
serializeInlineToHTML ((InlineCode code attrs) : remaining) = spaceSep ["<code", handleAttrs attrs, ">", escapeText code, "</code>", serializeInlineToHTML remaining]
serializeInlineToHTML (Link {linkText, url, title, misc_attrs} : remaining) = T.concat ["<a href=\"", url, "\" ", handleAttrs misc_attrs, maybe "" (\t -> T.concat [" title=\"", escapeText t, "\""]) title, ">", serializeInlineToHTML linkText, "</a>", serializeInlineToHTML remaining]
serializeInlineToHTML (Image {altText, url, title, misc_attrs} : remaining) = T.concat ["<img src=\"", url, "\" alt=\"", escapeText altText, "\" ", maybe "" (\t -> T.concat ["title=\"", escapeText t, "\" "]) title, handleAttrs misc_attrs, ">", serializeInlineToHTML remaining]
serializeInlineToHTML (HTMLInline {inline_html_content} : remaining) = inline_html_content <> serializeInlineToHTML remaining
serializeInlineToHTML ((Superscript _ _) : remaining) = error "TODO"
serializeInlineToHTML ((Subscript _ _) : remaining) = error "TODO"
serializeInlineToHTML ((Highlighted _ _) : remaining) = error "TODO"
serializeInlineToHTML ((Insert _ _) : remaining) = error "TODO"
serializeInlineToHTML ((Math _ _) : remaining) = error "TODO"
serializeInlineToHTML ((FootnoteReference {}) : remaining) = error "TODO"
serializeInlineToHTML ((Symbol _) : remaining) = error "TODO"
serializeInlineToHTML ((RawInline _ _) : remaining) = error "TODO"
serializeInlineToHTML ((Span _ _) : remaining) = error "TODO"