{-# LANGUAGE FlexibleContexts #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  Xmobar.Parsers
-- Copyright   :  (c) Andrea Rossato
-- License     :  BSD-style (see LICENSE)
--
-- Maintainer  :  Jose A. Ortega Ruiz <jao@gnu.org>
-- Stability   :  unstable
-- Portability :  unportable
--
-- Parsing for template substrings
--
-----------------------------------------------------------------------------

module Xmobar.X11.Parsers (parseString, Widget(..)) where

import Xmobar.Config.Types
import Xmobar.X11.Actions

import Control.Monad (guard, mzero)
import Text.ParserCombinators.Parsec
import Graphics.X11.Types (Button)

data Widget = Icon String | Text String

type ColorString = String
type FontIndex   = Int

-- | Runs the string parser
parseString :: Config -> String
               -> IO [(Widget, ColorString, FontIndex, Maybe [Action])]
parseString c s =
    case parse (stringParser (fgColor c) 0 Nothing) "" s of
      Left  _ -> return [(Text $ "Could not parse string: " ++ s
                          , fgColor c
                          , 0
                          , Nothing)]
      Right x -> return (concat x)

allParsers :: ColorString
           -> FontIndex
           -> Maybe [Action]
           -> Parser [(Widget, ColorString, FontIndex, Maybe [Action])]
allParsers c f a =  textParser c f a
                <|> try (iconParser c f a)
                <|> try (rawParser c f a)
                <|> try (actionParser c f a)
                <|> try (fontParser c a)
                <|> colorParser f a

-- | Gets the string and combines the needed parsers
stringParser :: String -> FontIndex -> Maybe [Action]
                -> Parser [[(Widget, ColorString, FontIndex, Maybe [Action])]]
stringParser c f a = manyTill (allParsers c f a) eof

-- | Parses a maximal string without color markup.
textParser :: String -> FontIndex -> Maybe [Action]
              -> Parser [(Widget, ColorString, FontIndex, Maybe [Action])]
textParser c f a = do s <- many1 $
                            noneOf "<" <|>
                              try (notFollowedBy' (char '<')
                                    (try (string "fc=")  <|>
                                     try (string "fn=")  <|>
                                     try (string "action=") <|>
                                     try (string "/action>") <|>
                                     try (string "icon=") <|>
                                     try (string "raw=") <|>
                                     try (string "/fn>") <|>
                                     string "/fc>"))
                      return [(Text s, c, f, a)]

-- | Parse a "raw" tag, which we use to prevent other tags from creeping in.
-- The format here is net-string-esque: a literal "<raw=" followed by a
-- string of digits (base 10) denoting the length of the raw string,
-- a literal ":" as digit-string-terminator, the raw string itself, and
-- then a literal "/>".
rawParser :: ColorString
          -> FontIndex
          -> Maybe [Action]
          -> Parser [(Widget, ColorString, FontIndex, Maybe [Action])]
rawParser c f a = do
  string "<raw="
  lenstr <- many1 digit
  char ':'
  case reads lenstr of
    [(len,[])] -> do
      guard ((len :: Integer) <= fromIntegral (maxBound :: Int))
      s <- count (fromIntegral len) anyChar
      string "/>"
      return [(Text s, c, f, a)]
    _ -> mzero

-- | Wrapper for notFollowedBy that returns the result of the first parser.
--   Also works around the issue that, at least in Parsec 3.0.0, notFollowedBy
--   accepts only parsers with return type Char.
notFollowedBy' :: Parser a -> Parser b -> Parser a
notFollowedBy' p e = do x <- p
                        notFollowedBy $ try (e >> return '*')
                        return x

iconParser :: String -> FontIndex -> Maybe [Action]
              -> Parser [(Widget, ColorString, FontIndex, Maybe [Action])]
iconParser c f a = do
  string "<icon="
  i <- manyTill (noneOf ">") (try (string "/>"))
  return [(Icon i, c, f, a)]

actionParser :: String -> FontIndex -> Maybe [Action]
                -> Parser [(Widget, ColorString, FontIndex, Maybe [Action])]
actionParser c f act = do
  string "<action="
  command <- choice [between (char '`') (char '`') (many1 (noneOf "`")),
                   many1 (noneOf ">")]
  buttons <- (char '>' >> return "1") <|> (space >> spaces >>
    between (string "button=") (string ">") (many1 (oneOf "12345")))
  let a = Spawn (toButtons buttons) command
      a' = case act of
        Nothing -> Just [a]
        Just act' -> Just $ a : act'
  s <- manyTill (allParsers c f a') (try $ string "</action>")
  return (concat s)

toButtons :: String -> [Button]
toButtons = map (\x -> read [x])

-- | Parsers a string wrapped in a color specification.
colorParser :: FontIndex -> Maybe [Action]
               -> Parser [(Widget, ColorString, FontIndex, Maybe [Action])]
colorParser f a = do
  c <- between (string "<fc=") (string ">") colors
  s <- manyTill (allParsers c f a) (try $ string "</fc>")
  return (concat s)

-- | Parsers a string wrapped in a font specification.
fontParser :: ColorString -> Maybe [Action]
              -> Parser [(Widget, ColorString, FontIndex, Maybe [Action])]
fontParser c a = do
  f <- between (string "<fn=") (string ">") colors
  s <- manyTill (allParsers c (read f) a) (try $ string "</fn>")
  return (concat s)

-- | Parses a color specification (hex or named)
colors :: Parser String
colors = many1 (alphaNum <|> char ',' <|> char '#')