-- | Compressed binary configuration files in the (B)INI format.
--
--
-- Parsing example:
--
-- @
-- r <- readBiniFromFile \"loadouts.ini\"
-- case r of
--  Left s -> print s
--  Right bini -> writeFile \"loadouts.ini.txt\" (show bini)
-- @
--
-- Outputfile:
--
-- @
-- [Loadout]
-- nickname = msn_playerloadout
-- archetype = ge_fighter
-- equip = ge_gf1_engine_01
-- equip = shield01_mark01_lf, HpShield01
-- equip = ge_fighter_power01
-- ...
-- @

module Data.Bini
    (-- * Reading
    readBiniFromFile,
    -- * Types
    Bini(..),
    Section(..),
    Entry(..),
    BiniVal(..)) where

import qualified Data.ByteString.Lazy as BL
import Data.Binary.Get
import Data.Word(Word32)
import Data.List(intercalate)
import qualified Data.ByteString.Lazy.Char8 as BLC
import Data.Binary.IEEE754(getFloat32le)


--helper
bstr2str :: BL.ByteString -> String
bstr2str = tail.init.show

-- |Get a String from the stringtable
getOffset :: BL.ByteString -> Int -> BL.ByteString
getOffset bstr offset = BL.takeWhile (/=0) s where
                        s = snd $ BL.splitAt (fromIntegral offset) bstr


--datatypes

-- |The abstract representation of the Bini
data Bini = Bini{ version :: Int, sections :: [Section] }

-- |The abstract representation of a section
data Section = Section{ name :: String, entries :: [Entry] }

-- |The abstract representation of an entry
data Entry = Entry{ varname :: String, values :: [BiniVal] }


-- |The abstract representation of a bini-value
data BiniVal = BiniInt Int | BiniFloat Float | BiniString String



instance Show Bini where
    show (Bini v secs) = intercalate "\n" (map show secs)

instance Show Section where
    show (Section name entries) = "["++name++"]\n"++intercalate "\n" (map show entries)++"\n"

instance Show Entry where
    show (Entry name vals) = name++" = "++intercalate ", " (map show vals)

instance Show BiniVal where
    show (BiniInt i) = show i
    show (BiniFloat f) = show f
    show (BiniString s) = s


-- |Parse a Binifile
readBiniFromFile :: String -> IO (Either String Bini)
readBiniFromFile path = do
    content <- BL.readFile path
    if "BINI"== bstr2str (BL.take 4 content) then do
        let (isBini, version, strtableoff) = runGet parseHeader content
        let (header_body, table) = BL.splitAt (fromIntegral strtableoff) content
        let body = BL.drop 12 header_body
        let secs = runGet (parseSections table) body
        return $ Right $ Bini version secs
    else return $ Left $ path++"is not a Bini-file!"

--------------------------------------------------------------------------------
---------------------- Parsing the Bini-file: ----------------------------------
--------------------------------------------------------------------------------

-- |Parse an entry
parseEntry :: BL.ByteString -> Get Entry
parseEntry ls = do
    stroffset <- getWord16le
    n_vals <- getWord8
    let entryname = bstr2str $ ls `getOffset` fromIntegral stroffset
    vals <- sequence [parseVal ls | x<-[1..(fromIntegral n_vals)]]
    return (Entry entryname vals)

-- |Parse an entry-value
parseVal :: BL.ByteString -> Get BiniVal
parseVal ls = do
    typ <- getWord8
    case fromIntegral typ of
        1 -> do
            dat <- getWord32le
            return $ BiniInt $ fromIntegral dat
        2 -> do
            dat <- getFloat32le
            return $ BiniFloat dat
        3 -> do
            dat <- getWord32le
            return $ BiniString $ bstr2str $ ls `getOffset` fromIntegral dat


parseSection :: BL.ByteString -> Get Section
parseSection table = do
    stroffset <- getWord16le
    num_e <- getWord16le
    let secname = bstr2str $ table `getOffset` fromIntegral stroffset
    let num_entries = fromIntegral num_e
    entries <- sequence [parseEntry table | x<-[1..num_entries]]
    return Section{ name = secname, entries = entries }

parseSections :: BL.ByteString -> Get [Section]
parseSections table = do
    b <- isEmpty
    if b then return []
    else do
        sec <- parseSection table
        b2 <- isEmpty
        if b2 then return [sec]
        else do
            secs <- parseSections table
            return $ sec : secs

parseHeader :: Get (Word32, Int, Int)
parseHeader = do
    isBini <- getWord32le
    version <- getWord32le
    str_table_offset <- getWord32le
    return (isBini, fromIntegral version, fromIntegral str_table_offset)