import ctypes
import sys

from PIL import Image as PILImage

from gamera.core import load_image as _load_image
from gamera.core import init_gamera as _init
from gamera.core import Image, RGB
from gamera.plugins.pil_io import from_pil as _from_pil


def gamera_init():
    sys.modules['numpy'] = None
    result = _init()
    test_image = Image((0, 0), (5, 5), RGB)
    test_string = test_image._to_raw_string()
    try:
        sys.getrefcount
    except AttributeError:
        return result
    refcount = sys.getrefcount(test_string)
    if refcount >= 3:  # no coverage
        # See: https://groups.yahoo.com/neo/groups/gamera-devel/conversations/topics/2068
        raise RuntimeError('Memory leak in Gamera')
    else:
        assert refcount == 2
    try:
        PILImage.fromstring = PILImage.frombytes
        # Gamera still uses fromstring(), which was deprecated,
        # and finally removed in Pillow 3.0.0.
        # https://pillow.readthedocs.io/en/3.0.x/releasenotes/3.0.0.html#deprecated-methods
    except AttributeError:
        pass
    return result


def load_image(filename):
    pil_image = PILImage.open(filename)
    [xdpi, ydpi] = pil_image.info.get('dpi', (0, 0))
    if xdpi <= 1 or ydpi <= 1:
        # not reliable
        dpi = None
    else:
        dpi = int(round(
            math.hypot(xdpi, ydpi) /
            math.hypot(1, 1)
        ))
    try:
        if pil_image.format == 'TIFF':
            # Gamera handles only a few TIFF color modes correctly.
            # https://bugs.debian.org/784374
            gamera_modes = ['1', 'I;16', 'L', 'RGB']
        elif pil_image.format == 'PNG':
            # Gamera doesn't handle 16-bit greyscale PNG images correctly.
            # https://groups.yahoo.com/neo/groups/gamera-devel/conversations/messages/2425
            gamera_modes = ['1', 'L', 'RGB']
        else:
            gamera_modes = []
        if pil_image.mode not in gamera_modes:
            raise IOError
        # Gamera supports more TIFF compression formats that PIL.
        # https://mail.python.org/pipermail/image-sig/2003-July/002354.html
        image = _load_image(filename)
    except IOError:
        # Gamera supports importing only 8-bit and RGB from PIL:
        if pil_image.mode[:2] in {'1', '1;', 'I', 'I;', 'L;'}:
            pil_image = pil_image.convert('L')
        elif pil_image.mode not in {'RGB', 'L'}:
            pil_image = pil_image.convert('RGB')
        assert pil_image.mode in {'RGB', 'L'}
        try:
            # Gamera still uses tostring(), which was deprecated,
            # and finally removed in Pillow 3.0.0.
            # https://pillow.readthedocs.io/en/3.0.x/releasenotes/3.0.0.html#deprecated-methods
            pil_image.tostring = pil_image.tobytes
        except AttributeError:  # no coverage
            pass
        image = _from_pil(pil_image)
    image.dpi = dpi
    return image


def to_pil_rgb(image):
    # About 20% faster than the standard .to_pil() method of Gamera 3.2.6.
    buffer = ctypes.create_string_buffer(3 * image.ncols * image.nrows)
    image.to_buffer(buffer)
    return PILImage.frombuffer('RGB', (image.ncols, image.nrows), buffer, 'raw', 'RGB', 0, 1)


path = 'didjvu/tests/data/ycbcr-jpeg.tiff'
in_image = PILImage.open(path)
if in_image.mode != 'RGB':
    in_image = in_image.convert('RGB')
assert in_image.mode == 'RGB'
gamera_init()
gamera_image = load_image(path)
out_image = to_pil_rgb(gamera_image)

in_image.save('in.jpg')
out_image.save('out.jpg')