{-# 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

      ]

    ]