{-# LANGUAGE OverloadedStrings #-}
-- **Hyakko** is a Haskell port of
-- [docco](http://jashkenas.github.com/docco/): the original
-- quick-and-dirty, hundred-line-line, literate-programming-style
-- documentation generator. It produces HTML that displays your comments
-- alongside your code. Comments are passed through
-- [Markdown](http://daringfireball.net/projects/markdown/syntax) and code
-- is passed through [Pygments](http://pygments.org/) syntax highlighting.
-- This page is the result of running Hyakko against its own source file.
--
-- If you install Hyakko, you can run it from the command-line:
--
--     hyakko src/*.hs
--
-- ...will generate linked HTML documentation for the named source files,
-- saving it into a `docs` folder.  The [source for
-- Hyakko](https://github.com/sourrust/hyakko) available on GitHub.
--
-- To install Hyakko
--
--     git clone git://github.com/sourrust/hyakko.git
--     cd hyakko
--     cabal install
--
--  or
--
--     cabal update
--     cabal install hyakko
module Main where

import Text.Markdown

import Data.Map (Map)
import qualified Data.Map as M
import Data.ByteString.Lazy.Char8 (ByteString)
import qualified Data.ByteString.Lazy.Char8 as L
import Data.List (sort, groupBy, genericIndex)
import Data.Maybe (fromJust)
import Control.Monad (filterM, (>=>), forM)
import Text.Pandoc.Templates
import Text.Regex
import Text.Regex.PCRE ((=~))
import System.Directory ( getDirectoryContents
                        , doesDirectoryExist
                        , doesFileExist
                        , createDirectoryIfMissing
                        )
import System.Environment (getArgs)
import System.FilePath ( takeBaseName
                       , takeExtension
                       , takeFileName
                       , (</>)
                       )
import System.Process (readProcess)
import Paths_hyakko (getDataFileName)

-- ### Main Documentation Generation Functions

(><) :: ByteString -> ByteString -> ByteString
(><) = L.append
{-# INLINE (><) #-}

-- Generate the documentation for a source file by reading it in, splitting
-- it up into comment/code sections, highlighting them for the appropriate
-- language, and merging them into an HTML template.
generateDocumentation :: [FilePath] -> IO ()
generateDocumentation [] = return ()
generateDocumentation (x:xs) = do
  code <- L.readFile x
  let sections = parse (getLanguage x) code
  if null sections then
    putStrLn $ "hyakko doesn't support the language extension " ++ takeExtension x
    else do
      (output, language) <- highlight x sections
      let y = mapSections sections output language
      generateHTML x y
      generateDocumentation xs

-- Given a string of source code, parse out each comment and the code that
-- follows it, and create an individual **section** for it. Sections take
-- the form:
--
--     [
--       ("docsText", ...),
--       ("docsHtml", ...),
--       ("codeText", ...),
--       ("codeHtml", ...)
--     ]
--
inSections :: [ByteString] -> ByteString -> [Map String ByteString]
inSections xs r = [M.fromList l | l <- clump sections]
  where
    -- Bring the lists together into groups of comment and groups of code
    -- pattern.
    sections :: [[ByteString]]
    sections = ensurePair . map concat
                          -- Group code into a list
                          . groupBy' head not
                          -- Group comments into a list
                          $ groupBy' id id xs

    -- Clump sectioned off lines into doc and code text.
    clump :: [[ByteString]] -> [[(String, ByteString)]]
    clump [x] = clump $ ensurePair [x]
    clump (x:y:ys) = [ ("docsText", replace x)
                     , ("codeText", L.unlines y)
                     ] : clump ys
    clump _ = []

    -- Generalized function used to section off code and comments
    groupBy' t t1 = groupBy $ \x y ->
      and $ map (t1 . (=~ r)) [t x, t y]

    -- Replace the beggining comment symbol with nothing
    replace :: [ByteString] -> ByteString
    replace = L.unlines . map (\x ->
      let y = L.unpack x
          mkReg = mkRegex . (=~ r)
      in L.pack $ subRegex (mkReg y) y "")

    -- Make sure the result is in the right pairing order
    ensurePair :: [[ByteString]] -> [[ByteString]]
    ensurePair ys | even (length ys) = ys
                  | otherwise = appendList [[""]]
      where appendList | (head . head) ys =~ r = (ys ++)
                       | otherwise             = (++ ys)

parse :: Maybe (Map String ByteString)
      -> ByteString
      -> [Map String ByteString]
parse Nothing _       = []
parse (Just src) code = inSections line $ src M.! "comment"
  where line = filter ((/=) "#!" . L.take 2) $ L.lines code

-- Highlights a single chunk of Haskell code, using **Pygments** over stdio,
-- and runs the text of its corresponding comment through **Markdown**,
-- using the Markdown translator in
-- **[Pandoc](http://johnmacfarlane.net/pandoc/)**.
--
-- We process the entire file in a single call to Pygments by inserting
-- little marker comments between each section and then splitting the result
-- string wherever our markers occur.
highlight :: FilePath
          -> [Map String ByteString]
          -> IO (String, Map String ByteString)
highlight src section = do
  let language = fromJust $ getLanguage src
      options  = ["-l", L.unpack $ language M.! "name", "-f",
                  "html", "-O", "encoding=utf-8"]
      input = concatMap (\x ->
        let codeText = L.unpack $ x M.! "codeText"
            divider  = L.unpack $ language M.! "dividerText"
        in codeText ++ divider) section

  output <- readProcess "pygmentize" options input

  return (output, language)

-- After `highlight` is called, there are divider inside to show when the
-- hightlighed stop and code begins. `mapSections` is used to take out the
-- dividers and put them into `docsHtml` and `codeHtml` sections.
mapSections :: [Map String ByteString]
            -> String
            -> Map String ByteString
            -> [Map String ByteString]
mapSections section highlighted language =
  let output     = subRegex (mkRegex highlightReplace) highlighted ""
      divider    = mkRegex . L.unpack $ language M.! "dividerHtml"
      fragments  = splitRegex divider output
      packFrag   = L.pack . genericIndex fragments
      docText s  = toHTML . L.unpack $ s M.! "docsText"
      codeText i = highlightStart >< packFrag i >< highlightEnd
      sectLength = (length section) - 1
      intoMap x  = let sect = section !! x
                   in M.insert "docsHtml" (docText sect) $
                      M.insert "codeHtml" (codeText x) sect
  in map intoMap [0 .. sectLength]

-- Determine whether or not there is a `Jump to` section
multiTemplate :: Int -> [(String, String)]
multiTemplate 1 = []
multiTemplate _ = [("multi", "1")]

-- Produces a list of anchor tags to different files in docs
--
--     <a class="source" href="$href-link$">$file-name$</a>
sourceTemplate :: [FilePath] -> [(String, String)]
sourceTemplate = map source
  where source x = ("source", concat
          [ "<a class=\"source\" href=\""
          , takeFileName $ destination x
          , "\">"
          , takeFileName x
          , "</a>"
          ])

-- Produces a list of table rows that split up code and documentation
--
--     <tr id="section-$number$">
--       <td class="docs">
--         <div class="pilwrap">
--           <a class="pilcrow" href="#section-$number$">&#955;</a>
--         </div>
--         $doc-html$
--       </td>
--       <td class="code">
--         $code-html$
--       </td>
--     </tr>
sectionTemplate :: [Map String ByteString]
                -> [Int]
                -> [(String, String)]
sectionTemplate section = map sections
  where sections x =
          let x'   = x + 1
              sect = section !! x
          in ("section", concat
             [ "<tr id=\"section-"
             ,  show x'
             ,  "\"><td class=\"docs\">"
             , "<div class=\"pilwrap\">"
             , "<a class=\"pilcrow\" href=\"#section-"
             , show x'
             , "\">&#955;</a></div>"
             , L.unpack $ sect M.! "docsHtml"
             , "</td><td class=\"code\">"
             , L.unpack $ sect M.! "codeHtml"
             , "</td></tr>"
             ])

-- Once all of the code is finished highlighting, we can generate the HTML
-- file and write out the documentation. Pass the completed sections into
-- the template found in `resources/hyakko.html`
generateHTML :: FilePath -> [Map String ByteString] -> IO ()
generateHTML src section = do
  let title = takeFileName src
      dest  = destination src
  source <- sources
  html <- hyakkoTemplate $ concat
    [ [("title", title)]
    , multiTemplate $ length source
    , sourceTemplate source
    , sectionTemplate section [0 .. (length section) - 1]
    ]
  putStrLn $ "hyakko: " ++ src ++ " -> " ++ dest
  L.writeFile dest html

-- ### Helpers & Setup

-- A list of the languages that Hyakko supports, mapping the file extension
-- to the name of the Pygments lexer and the symbol that indicates a
-- comment. To add another language to Hyakko's repertoire, add it here.
languages :: Map String (Map String ByteString)
languages =
  let hashSymbol = ("symbol", "#")
      language   = M.fromList [
          (".hs", M.fromList [
            ("name", "haskell"), ("symbol", "--")]),
          (".coffee", M.fromList [
            ("name", "coffee-script"), hashSymbol]),
          (".js", M.fromList [
            ("name", "javascript"), ("symbol", "//")]),
          (".py", M.fromList [
            ("name", "python"), hashSymbol]),
          (".rb", M.fromList [
            ("name", "ruby"), hashSymbol])
          ]
      -- Does the line begin with a comment?
      hasComments symbol = "^\\s*" >< symbol ><  "\\s?"
      -- The dividing token we feed into Pygments, to delimit the boundaries
      -- between sections.
      tokenDivider symbol = "\n" >< symbol >< "DIVIDER\n"
      -- The mirror of `divider_text` that we expect Pygments to return. We
      -- can split on this to recover the original sections. **Note**: the
      -- class is "c" for Python and "c1" for the other languages
      htmlDivider symbol = L.concat [ "\n*<span class=\"c1?\">"
                                    , symbol
                                    , "DIVIDER</span>"
                                    ]
      intoMap lang = let symbol = lang M.! "symbol"
                  in M.insert "comment" (hasComments symbol)
                   . M.insert "dividerText" (tokenDivider symbol)
                   $ M.insert "dividerHtml" (htmlDivider symbol) lang

  -- Build out the appropriate matchers and delimiters for each language.
  in M.map intoMap language

-- Get the current language we're documenting, based on the extension.
getLanguage :: FilePath -> Maybe (Map String ByteString)
getLanguage src = M.lookup (takeExtension src) languages

-- Compute the destination HTML path for an input source file path. If the
-- source is `lib/example.hs`, the HTML will be at docs/example.html
destination :: FilePath -> FilePath
destination fp = "docs" </> (takeBaseName fp) ++ ".html"

-- Create the template that we will use to generate the Hyakko HTML page.
hyakkoTemplate :: [(String, String)] -> IO ByteString
hyakkoTemplate var = readDataFile "resources/hyakko.html" >>=
  return . renderTemplate var . L.unpack

-- The CSS styles we'd like to apply to the documentation.
hyakkoStyles :: IO ByteString
hyakkoStyles = readDataFile "resources/hyakko.css"

-- The start and end of each Pygments highlight block.
highlightStart, highlightEnd :: ByteString
highlightStart   = "<div class=\"highlight\"><pre>"
highlightEnd     = "</pre></div>"

highlightReplace :: String
highlightReplace = L.unpack highlightStart ++ "|" ++ L.unpack highlightEnd

-- Reads from resource path given in cabal package
readDataFile :: FilePath -> IO ByteString
readDataFile = getDataFileName >=> L.readFile

-- For each source file passed in as an argument, generate the
-- documentation.
sources :: IO [FilePath]
sources = do
  args <- getArgs
  files <- forM args $ \x -> do
    isDir <- doesDirectoryExist x
    if isDir then
      unpackDirectories x
      else
        return [x]
  return . sort $ concat files

-- Turns the directory give into a list of files including all of the files
-- in sub-directories.
unpackDirectories :: FilePath -> IO [FilePath]
unpackDirectories d = do
  let reg = "[^(^\\.{1,2}$)]" :: ByteString
  content <- getDirectoryContents d >>= return . filter (=~ reg)
  let content' = map (d </>) content
  files <- filterM doesFileExist content'
  subdir <- filterM doesDirectoryExist content'
  subcontent <- mapM unpackDirectories subdir >>= return . concat
  return (files ++ subcontent)

-- Run the script.
main :: IO ()
main = do
  style <- hyakkoStyles
  source <- sources
  createDirectoryIfMissing False "docs"
  L.writeFile "docs/hyakko.css" style
  generateDocumentation source