# ----------------------------------------------------------------------------
# pyglet
# Copyright (c) 2006-2008 Alex Holkner
# Copyright (c) 2008-2020 pyglet contributors
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"""Draw a NinePatch image.

NinePatch is a format for storing how to cut up a 9-part resizable
rectangular image within the image pixel data directly.

For more information on the NinePatch format, see
http://developer.android.com/guide/topics/graphics/2d-graphics.html#nine-patch.

"""

from pyglet.graphics import Group
from pyglet.gl import GL_BLEND, GL_ENABLE_BIT, GL_ONE_MINUS_SRC_ALPHA, GL_SRC_ALPHA
from pyglet.gl import glBindTexture, glBlendFunc, glEnable, glPopAttrib, glPushAttrib


class NinePatchException(Exception):
    pass


class NinePatchGroup(Group):
    def __init__(self, texture, order=0, parent=None):
        super().__init__(order, parent)
        self.texture = texture

    def set_state(self):
        glPushAttrib(GL_ENABLE_BIT)
        glEnable(GL_BLEND)
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
        glEnable(self.texture.target)
        glBindTexture(self.texture.target, self.texture.id)

    def unset_state(self):
        glPopAttrib()


class _PixelData:
    def __init__(self, image):
        image_data = image.get_image_data()
        self.has_alpha = 'A' in image_data.format
        self.data = image_data.get_data("RGBA", image.width * 4)
        self.width = image.width
        self.height = image.height

    def is_black(self, x, y):
        p = (y * self.width + x) * 4
        if self.has_alpha:
            if self.data[p + 3] == 0:
                return False  # Fully transparent

        return self.data[p:p + 3] == b'\x00\x00\x00'


class NinePatch:
    """A scalable 9-patch image.
    """

    # Content area of the image, in pixels from the edge.
    _padding_top = 0
    _padding_bottom = 0
    _padding_right = 0
    _padding_left = 0

    # Resizable area of the image, in pixels from the closest edge
    _stretch_top = 0
    _stretch_left = 0
    _stretch_right = 0
    _stretch_bottom = 0

    def __init__(self, image):
        """Create NinePatch cuts of an image

        Arguments:
            image - an ImageData (Texture, TextureRegion, etc)
            texture - force cut ImageDatas to be Textures (or Regions)
        """

        pixel_data = _PixelData(image)
        width = image.width
        height = pixel_data.height

        # Texture dimensions after removing the 9patch outline.
        self.width = width - 2
        self.height = height - 2

        # Find stretch area markers
        for x in range(1, width - 1):
            if pixel_data.is_black(x, height - 1):
                self._stretch_left = x
                break
        else:
            self._stretch_left = 1

        for x in range(width - 2, 0, -1):
            if pixel_data.is_black(x, height - 1):
                self._stretch_right = width - x
                break
        else:
            self._stretch_right = 1

        for y in range(1, height - 1):
            if pixel_data.is_black(0, y):
                self._stretch_bottom = y
                break
        else:
            self._stretch_bottom = 1

        for y in range(height - 2, 0, -1):
            if pixel_data.is_black(0, y):
                self._stretch_top = height - y
                break
        else:
            self._stretch_top = 1

        # Find content area markers, if any
        for x in range(1, width - 1):
            if pixel_data.is_black(x, 0):
                self._padding_left = x - 1
                break

        for x in range(width - 2, 0, -1):
            if pixel_data.is_black(x, 0):
                self._padding_right = self.width - x
                break

        for y in range(1, height - 1):
            if pixel_data.is_black(width - 1, y):
                self._padding_bottom = y - 1
                break

        for y in range(height - 2, 0, -1):
            if pixel_data.is_black(width - 1, y):
                self._padding_top = self.height - y
                break

        # Texture coordinates, in pixels
        u1 = 1
        v1 = 1
        u2 = self._stretch_left + 1
        v2 = self._stretch_bottom + 1
        u3 = width - self._stretch_right - 1
        v3 = height - self._stretch_top - 1
        u4 = width - 1
        v4 = height - 1

        # Texture coordinates as ratio of image size (0 to 1)
        u1, u2, u3, u4 = [s / width for s in (u1, u2, u3, u4)]
        v1, v2, v3, v4 = [s / height for s in (v1, v2, v3, v4)]

        # Scale texture coordinates to match the tex_coords pyglet gives us
        # (these aren't necessarily 0-1 as the texture may have been packed)
        (tu1, tv1, ___,
         ___, ___, ___,
         tu2, tv2, ___,
         ___, ___, ___) = image.get_texture().tex_coords
        u_scale = tu2 - tu1
        u_bias = tu1
        v_scale = tv2 - tv1
        v_bias = tv1
        u1, u2, u3, u4 = [u_bias + u_scale * s for s in (u1, u2, u3, u4)]
        v1, v2, v3, v4 = [v_bias + v_scale * s for s in (v1, v2, v3, v4)]

        # 2D texture coordinates, bottom-left to top-right
        self.tex_coords = (u1, v1,  u2, v1,  u3, v1,  u4, v1,
                           u1, v2,  u2, v2,  u3, v2,  u4, v2,
                           u1, v3,  u2, v3,  u3, v3,  u4, v3,
                           u1, v4,  u2, v4,  u3, v4,  u4, v4)

        # Quad indices
        self.indices = []
        for y in range(3):
            for x in range(3):
                self.indices.extend([x + y * 4,  (x + 1) + y * 4,  (x + 1) + (y + 1) * 4,  x + (y + 1) * 4])

    def get_vertices(self, x, y, width, height):
        """Get 16 2D vertices for the given image region"""
        x = int(x)
        y = int(y)

        if width < self.width + 2 or height < self.height + 2:
            raise NinePatchException("Requested size is smaller than the image.")

        width = int(width)
        height = int(height)

        x1 = x
        y1 = y
        x2 = x + self._stretch_left
        y2 = y + self._stretch_bottom
        x3 = x + width - self._stretch_right
        y3 = y + height - self._stretch_top
        x4 = x + width
        y4 = y + height

        # To match tex coords, vertices are bottom-left to top-right
        return (x1, y1,  x2, y1,  x3, y1,  x4, y1,
                x1, y2,  x2, y2,  x3, y2,  x4, y2,
                x1, y3,  x2, y3,  x3, y3,  x4, y3,
                x1, y4,  x2, y4,  x3, y4,  x4, y4)
