{-# LANGUAGE TupleSections #-}
{-# LANGUAGE FlexibleContexts #-}
-- | Module used by the jpeg decoder internally, shouldn't be used
-- in user code.
module Codec.Picture.Jpg.DefaultTable( DctComponent( .. )
									 , HuffmanTree( .. )
									 , HuffmanTable
									 , HuffmanPackedTree
									 , MacroBlock
									 , QuantificationTable
									 , HuffmanWriterCode 
									 , scaleQuantisationMatrix
									 , makeMacroBlock
									 , makeInverseTable
									 , buildHuffmanTree
									 , packHuffmanTree
									 , huffmanPackedDecode

									 , defaultChromaQuantizationTable

									 , defaultLumaQuantizationTable

									 , defaultAcChromaHuffmanTree
									 , defaultAcChromaHuffmanTable

									 , defaultAcLumaHuffmanTree 
									 , defaultAcLumaHuffmanTable 

									 , defaultDcChromaHuffmanTree 
									 , defaultDcChromaHuffmanTable

                                     , defaultDcLumaHuffmanTree
									 , defaultDcLumaHuffmanTable
									 ) where

import Data.Int( Int16 )
import Foreign.Storable ( Storable )
import Control.Monad.ST( runST )
import qualified Data.Vector.Storable as SV
import qualified Data.Vector as V
import Data.Bits( unsafeShiftL, (.|.), (.&.) )
import Data.Word( Word8, Word16 )
import Data.List( foldl' )
import qualified Data.Vector.Storable.Mutable as M

import Codec.Picture.BitWriter

-- | Tree storing the code used for huffman encoding.
data HuffmanTree = Branch HuffmanTree HuffmanTree -- ^ If bit is 0 take the first subtree, if 1, the right.
                 | Leaf Word8       -- ^ We should output the value
                 | Empty            -- ^ no value present
                 deriving (Eq, Show)

type HuffmanPackedTree = SV.Vector Word16

type HuffmanWriterCode = V.Vector (Word8, Word16)

packHuffmanTree :: HuffmanTree -> HuffmanPackedTree
packHuffmanTree tree = runST $ do
    table <- M.replicate 512 0x8000
    let aux (Empty) idx = return $ idx + 1
        aux (Leaf v) idx = do
            (table `M.unsafeWrite` idx) $ (fromIntegral v .|. 0x4000)
            return $ idx + 1

        aux (Branch i1@(Leaf _) i2@(Leaf _)) idx =
            aux i1 idx >>= aux i2

        aux (Branch i1@(Leaf _) i2) idx = do
            _ <- aux i1 idx
            ix2 <- aux i2 $ idx + 2
            (table `M.unsafeWrite` (idx + 1)) $ fromIntegral $ idx + 2
            return ix2

        aux (Branch i1 i2@(Leaf _)) idx = do
            ix1 <- aux i1 (idx + 2)
            _ <- aux i2 (idx + 1)
            (table `M.unsafeWrite` idx) . fromIntegral $ idx + 2
            return ix1

        aux (Branch i1 i2) idx = do
            ix1 <- aux i1 (idx + 2)
            ix2 <- aux i2 ix1
            (table `M.unsafeWrite` idx) (fromIntegral $ idx + 2)
            (table `M.unsafeWrite` (idx + 1)) (fromIntegral ix1)
            return ix2
    _ <- aux tree 0
    SV.unsafeFreeze table

makeInverseTable :: HuffmanTree -> HuffmanWriterCode
makeInverseTable t = V.replicate 255 (0,0) V.// inner 0 0 t
  where inner _     _     Empty   = []
        inner depth code (Leaf v) = [(fromIntegral v, (depth, code))]
        inner depth code (Branch l r) =
          inner (depth + 1) shifted l ++ inner (depth + 1) (shifted .|. 1) r
            where shifted = code `unsafeShiftL` 1

-- | Represent a compact array of 8 * 8 values. The size
-- is not guarenteed by type system, but if makeMacroBlock is
-- used, everything should be fine size-wise
type MacroBlock a = SV.Vector a

type QuantificationTable = MacroBlock Int16

-- | Helper function to create pure macro block of the good size.
makeMacroBlock :: (Storable a) => [a] -> MacroBlock a
makeMacroBlock = SV.fromListN 64

-- | Enumeration used to search in the tables for different components.
data DctComponent = DcComponent | AcComponent
    deriving (Eq, Show)

-- | Transform parsed coefficients from the jpeg header to a
-- tree which can be used to decode data.
buildHuffmanTree :: [[Word8]] -> HuffmanTree
buildHuffmanTree table = foldl' insertHuffmanVal Empty
                       . concatMap (\(i, t) -> map (i + 1,) t)
                       $ zip ([0..] :: [Int]) table
  where isTreeFullyDefined Empty = False
        isTreeFullyDefined (Leaf _) = True
        isTreeFullyDefined (Branch l r) = isTreeFullyDefined l && isTreeFullyDefined r

        insertHuffmanVal Empty (0, val) = Leaf val
        insertHuffmanVal Empty (d, val) = Branch (insertHuffmanVal Empty (d - 1, val)) Empty
        insertHuffmanVal (Branch l r) (d, val)
            | isTreeFullyDefined l = Branch l (insertHuffmanVal r (d - 1, val))
            | otherwise            = Branch (insertHuffmanVal l (d - 1, val)) r
        insertHuffmanVal (Leaf _) _ = error "Inserting in value, shouldn't happen"

scaleQuantisationMatrix :: Int -> QuantificationTable -> QuantificationTable 
scaleQuantisationMatrix quality
    | quality < 0 = scaleQuantisationMatrix 0
        -- shouldn't show much difference than with 1,
        -- but hey, at least we're complete
    | quality == 0 = SV.map (scale (10000 :: Int))
    | quality < 50 = let qq = 5000 `div` quality
                     in SV.map (scale qq)
    | otherwise    = SV.map (scale q)
          where q = 200 - quality * 2
                scale coeff i = fromIntegral . min 255 
                                             . max 1 
                                             $ fromIntegral i * coeff `div` 100

huffmanPackedDecode :: HuffmanPackedTree -> BoolReader s Word8
huffmanPackedDecode table = getNextBitJpg >>= aux 0
  where aux idx b
            | (v .&. 0x8000) /= 0 = return  0
            | (v .&. 0x4000) /= 0 = return . fromIntegral $ v .&. 0xFF
            | otherwise = getNextBitJpg >>= aux v
          where tableIndex | b = idx + 1
                           | otherwise = idx
                v = table `SV.unsafeIndex` fromIntegral tableIndex

defaultLumaQuantizationTable :: QuantificationTable
defaultLumaQuantizationTable = makeMacroBlock
    [16, 11, 10, 16,  24,  40,  51,  61
    ,12, 12, 14, 19,  26,  58,  60,  55
    ,14, 13, 16, 24,  40,  57,  69,  56
    ,14, 17, 22, 29,  51,  87,  80,  62
    ,18, 22, 37, 56,  68, 109, 103,  77
    ,24, 35, 55, 64,  81, 104, 113,  92
    ,49, 64, 78, 87, 103, 121, 120, 101
    ,72, 92, 95, 98, 112, 100, 103,  99
    ]

defaultChromaQuantizationTable :: QuantificationTable
defaultChromaQuantizationTable = makeMacroBlock
    [17, 18, 24, 47, 99, 99, 99, 99
    ,18, 21, 26, 66, 99, 99, 99, 99
    ,24, 26, 56, 99, 99, 99, 99, 99
    ,47, 66, 99, 99, 99, 99, 99, 99
    ,99, 99, 99, 99, 99, 99, 99, 99
    ,99, 99, 99, 99, 99, 99, 99, 99
    ,99, 99, 99, 99, 99, 99, 99, 99
    ,99, 99, 99, 99, 99, 99, 99, 99
    ]

defaultDcLumaHuffmanTree :: HuffmanTree
defaultDcLumaHuffmanTree = buildHuffmanTree defaultDcLumaHuffmanTable

-- | From the Table K.3 of ITU-81 (p153)
defaultDcLumaHuffmanTable :: HuffmanTable
defaultDcLumaHuffmanTable =
    [ []
    , [0]
    , [1, 2, 3, 4, 5]
    , [6]
    , [7]
    , [8]
    , [9]
    , [10]
    , [11]
    , []
    , []
    , []
    , []
    , []
    , []
    , []
    ]

defaultDcChromaHuffmanTree :: HuffmanTree
defaultDcChromaHuffmanTree = buildHuffmanTree defaultDcChromaHuffmanTable

-- | From the Table K.4 of ITU-81 (p153)
defaultDcChromaHuffmanTable :: HuffmanTable
defaultDcChromaHuffmanTable = 
    [ []
    , [0, 1, 2]
    , [3]
    , [4]
    , [5]
    , [6]
    , [7]
    , [8]
    , [9]
    , [10]
    , [11]
    , []
    , []
    , []
    , []
    , []
    ]

defaultAcLumaHuffmanTree :: HuffmanTree
defaultAcLumaHuffmanTree = buildHuffmanTree defaultAcLumaHuffmanTable

-- | From the Table K.5 of ITU-81 (p154)
defaultAcLumaHuffmanTable :: HuffmanTable
defaultAcLumaHuffmanTable =
    [ []
    , [0x01, 0x02]
    , [0x03]
    , [0x00, 0x04, 0x11]
    , [0x05, 0x12, 0x21]
    , [0x31, 0x41]
    , [0x06, 0x13, 0x51, 0x61]
    , [0x07, 0x22, 0x71]
    , [0x14, 0x32, 0x81, 0x91, 0xA1]
    , [0x08, 0x23, 0x42, 0xB1, 0xC1]
    , [0x15, 0x52, 0xD1, 0xF0]
    , [0x24, 0x33, 0x62, 0x72]
    , []
    , []
    , [0x82]
    , [0x09, 0x0A, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x34, 0x35
      ,0x36, 0x37, 0x38, 0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x53, 0x54
      ,0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x73
      ,0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A
      ,0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7
      ,0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4
      ,0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA
      ,0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5
      ,0xF6, 0xF7, 0xF8, 0xF9, 0xFA]
    ]

type HuffmanTable = [[Word8]]

defaultAcChromaHuffmanTree :: HuffmanTree
defaultAcChromaHuffmanTree = buildHuffmanTree defaultAcChromaHuffmanTable 

defaultAcChromaHuffmanTable :: HuffmanTable
defaultAcChromaHuffmanTable = 
    [ []
    , [0x00, 0x01]
    , [0x02]
    , [0x03, 0x11]
    , [0x04, 0x05, 0x21, 0x31]
    , [0x06, 0x12, 0x41, 0x51]
    , [0x07, 0x61, 0x71]
    , [0x13, 0x22, 0x32, 0x81]
    , [0x08, 0x14, 0x42, 0x91, 0xA1, 0xB1, 0xC1]
    , [0x09, 0x23, 0x33, 0x52, 0xF0]
    , [0x15, 0x62, 0x72, 0xD1]
    , [0x0A, 0x16, 0x24, 0x34]
    , []
    , [0xE1]
    , [0x25, 0xF1]
    , [ 0x17, 0x18, 0x19, 0x1A, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x35
      , 0x36, 0x37, 0x38, 0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47
      , 0x48, 0x49, 0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59
      , 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x73
      , 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x82, 0x83, 0x84
      , 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x92, 0x93, 0x94, 0x95
      , 0x96, 0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6
      , 0xA7, 0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7
      , 0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8
      , 0xC9, 0xCA, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9
      , 0xDA, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA
      , 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA
      ]
    ]