from panda3d.core import Texture, LColor
from array import array


def peeker_from_pixel(component_type, format, data):
    """ Creates a 1-pixel texture with the given settings and pixel data,
    then returns a TexturePeeker as result of calling texture.peek(). """

    tex = Texture("")
    tex.setup_1d_texture(1, component_type, format)
    tex.set_ram_image(data)
    peeker = tex.peek()
    assert peeker.has_pixel(0, 0)
    return peeker


def test_texture_peek_ubyte():
    maxval = 255
    data = array('B', (2, 1, 0, maxval))
    peeker = peeker_from_pixel(Texture.T_unsigned_byte, Texture.F_rgba, data)

    col = LColor()
    peeker.fetch_pixel(col, 0, 0)
    col *= maxval
    assert col == (0, 1, 2, maxval)


def test_texture_peek_ushort():
    maxval = 65535
    data = array('H', (2, 1, 0, maxval))
    peeker = peeker_from_pixel(Texture.T_unsigned_short, Texture.F_rgba, data)

    col = LColor()
    peeker.fetch_pixel(col, 0, 0)
    col *= maxval
    assert col == (0, 1, 2, maxval)


def test_texture_peek_uint():
    maxval = 4294967295
    data = array('I', (2, 1, 0, maxval))
    peeker = peeker_from_pixel(Texture.T_unsigned_int, Texture.F_rgba, data)

    col = LColor()
    peeker.fetch_pixel(col, 0, 0)
    col *= maxval
    assert col == (0, 1, 2, maxval)


def test_texture_peek_float():
    data = array('f', (1.0, 0.0, -2.0, 10000.0))
    peeker = peeker_from_pixel(Texture.T_float, Texture.F_rgba, data)

    col = LColor()
    peeker.fetch_pixel(col, 0, 0)
    assert col == (-2.0, 0.0, 1.0, 10000.0)


def test_texture_peek_half():
    # Python's array class doesn't support half floats, so we hardcode the
    # binary representation of these numbers:
    data = array('H', (
        0b0011110000000000, # 1.0
        0b1100000000000000, # -2.0
        0b0111101111111111, # 65504.0
        0b0011010101010101, # 0.333251953125
    ))
    peeker = peeker_from_pixel(Texture.T_half_float, Texture.F_rgba, data)

    col = LColor()
    peeker.fetch_pixel(col, 0, 0)
    assert col == (65504.0, -2.0, 1.0, 0.333251953125)


def test_texture_peek_srgb():
    # 188 = roughly middle gray
    data = array('B', [188, 188, 188])
    peeker = peeker_from_pixel(Texture.T_unsigned_byte, Texture.F_srgb, data)

    col = LColor()
    peeker.fetch_pixel(col, 0, 0)

    # We allow some imprecision.
    assert col.almost_equal((0.5, 0.5, 0.5, 1.0), 1 / 255.0)


def test_texture_peek_srgba():
    # 188 = middle gray
    data = array('B', [188, 188, 188, 188])
    peeker = peeker_from_pixel(Texture.T_unsigned_byte, Texture.F_srgb_alpha, data)

    col = LColor()
    peeker.fetch_pixel(col, 0, 0)

    # We allow some imprecision.
    assert col.almost_equal((0.5, 0.5, 0.5, 188 / 255.0), 1 / 255.0)