-- | Byte level SDIF frame data structure.
module Sound.SDIF.Byte.Matrix where

import qualified Data.ByteString.Lazy as B
import Sound.OpenSoundControl.Coding.Byte
import Sound.SDIF.Type

-- | Data integrity check for SDIF matix byte stream.
is_matrix_b :: B.ByteString -> Bool
is_matrix_b mtx =
    let n = fromIntegral (B.length mtx)
    in matrix_b_storage_size mtx == n

-- | Matrix header size (constant).
matrix_b_header_size :: Int
matrix_b_header_size = 16

-- | Extract matrix header byte stream.
matrix_b_header :: B.ByteString -> B.ByteString
matrix_b_header mtx = section mtx 0 (fromIntegral matrix_b_header_size)

-- | Extract matrix type string.
matrix_b_type :: B.ByteString -> String
matrix_b_type mtx = map (toEnum . fromIntegral) (B.unpack (section mtx 0 4))

-- | Extract matrix element data 'Type'.
matrix_b_data_type :: B.ByteString -> Type
matrix_b_data_type mtx = decode_i32 (section mtx 4 8)

-- | Extract matrix row count.
matrix_b_rows :: B.ByteString -> Int
matrix_b_rows mtx = decode_i32 (section mtx 8 12)

-- | Extract matrix column count.
matrix_b_columns :: B.ByteString -> Int
matrix_b_columns mtx = decode_i32 (section mtx 12 16)

-- | Extract matrix element count (ie. rows by columns).
matrix_b_elements :: B.ByteString -> Int
matrix_b_elements mtx = matrix_b_rows mtx * matrix_b_columns mtx

-- | Calculate size of matrix data store (ie. elements by 'Type' size).
matrix_b_data_size :: B.ByteString -> Int
matrix_b_data_size mtx =
    let r = matrix_b_rows mtx
        c = matrix_b_columns mtx
    in r * c * data_type_size (matrix_b_data_type mtx)

-- | Variant of 'matrix_b_data_size' taking into account required padding.
matrix_b_storage_size :: B.ByteString -> Int
matrix_b_storage_size mtx =
    let pad_bytes sz = let m = sz `mod` 8
                       in if m > 0 then 8 - m else 0
        n = matrix_b_data_size mtx
    in n + pad_bytes n + 16

-- | Extract matrix data from byte stream.
matrix_b_to_matrix_v :: B.ByteString -> [Datum]
matrix_b_to_matrix_v mtx =
    let ty = matrix_b_data_type mtx
        sz = data_type_size ty
        dc = data_type_decoder ty
        go i j xs =
            if j == 0
            then reverse xs
            else let i' = i + sz
                     xs' = dc (section' mtx i i') : xs
                 in go i' (j - 1) xs'
    in go 16 (matrix_b_elements mtx) []