from sys import platform

import texture2ddecoder
from PIL import Image
from copy import copy
from io import BytesIO, BufferedIOBase, RawIOBase, IOBase
import struct
from ..enums import TextureFormat, BuildTarget

TF = TextureFormat
PREFER_BASISU = False

def prepare_raw_image(img, flip=True):
    _image = None
    if (isinstance(img, str) or isinstance(img, BufferedIOBase) or
        isinstance(img, RawIOBase) or isinstance(img, IOBase)):
        _image = Image.open(img)
    elif isinstance(img, Image.Image):
        _image = img
    if _image:
        if flip:
            _image = _image.transpose(Image.FLIP_TOP_BOTTOM)
        return _image.getdata()
    return None


def get_image_from_texture2d(texture_2d, flip=True) -> Image:
    """converts the given texture into PIL.Image

    :param texture_2d: texture to be converterd
    :type texture_2d: Texture2D
    :param flip: flips the image back to the original (all Unity textures are flipped by default)
    :type flip: bool
    :return: PIL.Image object
    :rtype: Image
    """
    image_data = copy(bytes(texture_2d.image_data))
    if not image_data:
        return Image.new("RGB", (0, 0))

    texture_format = texture_2d.m_TextureFormat if isinstance(texture_2d, TextureFormat) else TextureFormat(texture_2d.m_TextureFormat)
    selection = CONV_TABLE[texture_format]

    if len(selection) == 0:
        raise NotImplementedError(
            f"Not implemented texture format: {texture_format.name}"
        )

    if texture_format in XBOX_SWAP_FORMATS:
        image_data = swap_bytes_for_xbox(image_data, texture_2d.platform)

    if "Crunched" in texture_format.name:
        version = texture_2d.version
        if (version[0] > 2017 or (version[0] == 2017 and version[1] >= 3) #2017.3 and up
            or texture_format == TextureFormat.ETC_RGB4Crunched
            or texture_format == TextureFormat.ETC2_RGBA8Crunched):
            image_data = texture2ddecoder.unpack_unity_crunch(image_data)
        else:
            image_data = texture2ddecoder.unpack_crunch(image_data)

    img = selection[0](
        image_data, texture_2d.m_Width, texture_2d.m_Height, *selection[1:]
    )

    if img and flip:
        return img.transpose(Image.FLIP_TOP_BOTTOM)
    return img


def swap_bytes_for_xbox(image_data: bytes, build_target: BuildTarget) -> bytes:
    """swaps the texture bytes
    This is required for textures deployed on XBOX360.

    :param image_data: texture data
    :type image_data: bytes
    :param build_target: platform of the asset
    :type build_target: BuildTarget
    :return: swapped data if platform = XBOX360 else data
    :rtype: bytes
    """
    if (
        build_target == BuildTarget.XBOX360
    ):  # swap bytes for Xbox confirmed,PS3 not encountered
        for i in range(0, len(image_data), 2):
            image_data[i : i + 2] = image_data[i : i + 2][::-1]
    return image_data


def pillow(
    image_data: bytes, width: int, height: int, mode: str, codec: str, args, swap=False
) -> Image:
    img = (
        Image.frombytes(mode, (width, height), image_data, codec, args)
        if width
        else Image.new(mode, (width, height))
    )
    if swap:
        channels = img.split()
        img = Image.merge(mode, [channels[x] for x in swap])
    return img


def atc(image_data: bytes, width: int, height: int, alpha: bool) -> Image:
    if alpha:
        image_data = texture2ddecoder.decode_atc_rgba8(image_data, width, height)
    else:
        image_data = texture2ddecoder.decode_atc_rgb4(image_data, width, height)

    return Image.frombytes("RGBA", (width, height), image_data, "raw", "BGRA")


def astc(image_data: bytes, width: int, height: int, block_size: tuple) -> Image:
    image_data = texture2ddecoder.decode_astc(image_data, width, height, *block_size)
    return Image.frombytes("RGBA", (width, height), image_data, "raw", "BGRA")


def pvrtc(image_data: bytes, width: int, height: int, fmt: bool):
    image_data = texture2ddecoder.decode_pvrtc(image_data, width, height, fmt)
    return Image.frombytes("RGBA", (width, height), image_data, "raw", "BGRA")


def etc(image_data: bytes, width: int, height: int, fmt: list):
    if fmt[0] == 1:
        image_data = texture2ddecoder.decode_etc1(image_data, width, height)
    elif fmt[0] == 2:
        if fmt[1] == "RGB":
            image_data = texture2ddecoder.decode_etc2(image_data, width, height)
        elif fmt[1] == "A1":
            image_data = texture2ddecoder.decode_etc2a1(image_data, width, height)
        elif fmt[1] == "A8":
            image_data = texture2ddecoder.decode_etc2a8(image_data, width, height)
    else:
        raise NotImplementedError("unknown etc mode")
    return Image.frombytes("RGBA", (width, height), image_data, "raw", "BGRA")

def eac(image_data: bytes, width: int, height: int, fmt: list):
    if fmt == "EAC_R":
        image_data = texture2ddecoder.decode_eacr(image_data, width, height)
    elif fmt == "EAC_R_SIGNED":
        image_data = texture2ddecoder.decode_eacr_signed(image_data, width, height)
    elif fmt == "EAC_RG":
        image_data = texture2ddecoder.decode_eacrg(image_data, width, height)
    elif fmt == "EAC_RG_SIGNED":
        image_data = texture2ddecoder.decode_eacrg_signed(image_data, width, height)
    return Image.frombytes("RGBA", (width, height), image_data, "raw", "BGRA")

def half(
    image_data: bytes, width: int, height: int, mode: str, codec: str, args, swap=False
) -> Image:
    # convert half-float to int8
    stream = BytesIO(image_data)
    image_data = bytes(
        int(struct.unpackb("e", stream.read(2))*256)
        for i in range(width*height*len(codec))
    )
    img = (
        Image.frombytes(mode, (width, height), image_data, codec, args)
        if width
        else Image.new(mode, (width, height))
    )
    if swap:
        channels = img.split()
        img = Image.merge(mode, [channels[x] for x in swap])
    return img

CONV_TABLE = {
#  FORMAT                  FUNC     #ARGS.....
#----------------------- -------- -------- ------------ ----------------- ------------ ----------
(  TF.Alpha8,              pillow,  "RGBA",  "raw",       "A"                                   ),
(  TF.ARGB4444,            pillow,  "RGBA",  "raw",       "RGBA;4B",          (2,1,0,3)         ),
(  TF.RGB24,               pillow,  "RGB",   "raw",       "RGB"                                 ),
(  TF.RGBA32,              pillow,  "RGBA",  "raw",       "RGBA"                                ),
(  TF.ARGB32,              pillow,  "RGBA",  "raw",       "ARGB"                                ),
(  TF.RGB565,              pillow,  "RGB",   "raw",       "BGR;16"                              ),
(  TF.R8,                  pillow,  "RGB",   "raw",       "R"                                   ),
(  TF.R16,                 pillow,  "RGB",   "raw",       "R;16"                                ),
(  TF.RG16,                                                                                     ),
(  TF.DXT1,                pillow,  "RGBA",  "bcn",       1                                     ),
(  TF.DXT5,                pillow,  "RGBA",  "bcn",       3                                     ),
(  TF.RGBA4444,            pillow,  "RGBA",  "raw",       'RGBA;4B',          (3,2,1,0)         ),
(  TF.BGRA32,              pillow,  "RGBA",  "raw",       "BGRA"                                ),
(  TF.RHalf,               half,    "R",     "raw",       "R"                                   ),
(  TF.RGHalf,                                                                                   ),
(  TF.RGBAHalf,            half,    "RGB",   "raw",       "RGB"                                 ),
(  TF.RFloat,              pillow,  "RGB",   "raw",       "RF"                                  ),
(  TF.RGFloat,                                                                                  ),
(  TF.RGBAFloat,           pillow,  "RGBA",  "raw",       "RGBAF"                               ),
(  TF.YUY2,                                                                                     ),
(  TF.RGB9e5Float,                                                                              ),
(  TF.BC4,                 pillow,  "L",     "bcn",       4                                     ),
(  TF.BC5,                 pillow,  "RGBA",  "bcn",       5                                     ),
(  TF.BC6H,                pillow,  "RGBA",  "bcn",       6                                     ),
(  TF.BC7,                 pillow,  "RGBA",  "bcn",       7                                     ),
(  TF.DXT1Crunched,        pillow,  "RGBA",  "bcn",       1                                     ),
(  TF.DXT5Crunched,        pillow,  "RGBA",  "bcn",       3                                     ),
(  TF.PVRTC_RGB2,          pvrtc,   True                                                       ),
(  TF.PVRTC_RGBA2,         pvrtc,   True                                                        ),
(  TF.PVRTC_RGB4,          pvrtc,   False                                                       ),
(  TF.PVRTC_RGBA4,         pvrtc,   False                                                        ),
(  TF.ETC_RGB4,            etc,     (1,)                                                        ),
(  TF.ATC_RGB4,            atc,     False                                                       ),
(  TF.ATC_RGBA8,           atc,     True                                                        ),
(  TF.EAC_R,               eac,     "EAC_R"                                                     ),
(  TF.EAC_R_SIGNED,        eac,     "EAC_R:SIGNED"                                              ),
(  TF.EAC_RG,              eac,     "EAC_RG"                                                    ),
(  TF.EAC_RG_SIGNED,       eac,     "EAC_RG_SIGNED"                                             ),
(  TF.ETC2_RGB,            etc,     (2,"RGB")                                                   ),
(  TF.ETC2_RGBA1,          etc,     (2, "A1")                                                   ),
(  TF.ETC2_RGBA8,          etc,     (2, "A8")                                                   ),
(  TF.ASTC_RGB_4x4,        astc,    (4,4)                                                       ),
(  TF.ASTC_RGB_5x5,        astc,    (5,5)                                                       ),
(  TF.ASTC_RGB_6x6,        astc,    (6,6)                                                       ),
(  TF.ASTC_RGB_8x8,        astc,    (8,8)                                                       ),
(  TF.ASTC_RGB_10x10,      astc,    (10,10)                                                     ),
(  TF.ASTC_RGB_12x12,      astc,    (12,12)                                                     ),
(  TF.ASTC_RGBA_4x4,       astc,    (4,4)                                                       ),
(  TF.ASTC_RGBA_5x5,       astc,    (5,5)                                                       ),
(  TF.ASTC_RGBA_6x6,       astc,    (6,6)                                                       ),
(  TF.ASTC_RGBA_8x8,       astc,    (8,8)                                                       ),
(  TF.ASTC_RGBA_10x10,     astc,    (10,10)                                                     ),
(  TF.ASTC_RGBA_12x12,     astc,    (12,12)                                                     ),
(  TF.ETC_RGB4_3DS,        etc,     (1,)                                                        ),
(  TF.ETC_RGBA8_3DS,       etc,     (1,)                                                        ),
(  TF.ETC_RGB4Crunched,    etc,     (1,)                                                        ),
(  TF.ETC2_RGBA8Crunched,  etc,     (2, "A8")                                                   ),
(  TF.ASTC_HDR_4x4,        astc,    (4,4)                                                       ),
(  TF.ASTC_HDR_5x5,        astc,    (5,5)                                                       ),
(  TF.ASTC_HDR_6x6,        astc,    (6,6)                                                       ),
(  TF.ASTC_HDR_8x8,        astc,    (8,8)                                                       ),
(  TF.ASTC_HDR_10x10,      astc,    (10,10)                                                     ),
(  TF.ASTC_HDR_12x12,      astc,    (12,12)                                                     ),
}

# format conv_table to a dict
CONV_TABLE = {line[0]: line[1:] for line in CONV_TABLE}

# XBOX Swap Formats
XBOX_SWAP_FORMATS = [TF.RGB565, TF.DXT1, TF.DXT1Crunched, TF.DXT5, TF.DXT5Crunched]
