import numpy as np

from skimage._shared import testing
from skimage._shared.testing import assert_equal
from skimage.util.shape import view_as_blocks, view_as_windows


def test_view_as_blocks_block_not_a_tuple():
    A = np.arange(10)
    with testing.raises(TypeError):
        view_as_blocks(A, [5])


def test_view_as_blocks_negative_shape():
    A = np.arange(10)
    with testing.raises(ValueError):
        view_as_blocks(A, (-2,))


def test_view_as_blocks_block_too_large():
    A = np.arange(10)
    with testing.raises(ValueError):
        view_as_blocks(A, (11,))


def test_view_as_blocks_wrong_block_dimension():
    A = np.arange(10)
    with testing.raises(ValueError):
        view_as_blocks(A, (2, 2))


def test_view_as_blocks_1D_array_wrong_block_shape():
    A = np.arange(10)
    with testing.raises(ValueError):
        view_as_blocks(A, (3,))


def test_view_as_blocks_1D_array():
    A = np.arange(10)
    B = view_as_blocks(A, (5,))
    assert_equal(B, np.array([[0, 1, 2, 3, 4],
                              [5, 6, 7, 8, 9]]))


def test_view_as_blocks_2D_array():
    A = np.arange(4 * 4).reshape(4, 4)
    B = view_as_blocks(A, (2, 2))
    assert_equal(B[0, 1], np.array([[2, 3],
                                    [6, 7]]))
    assert_equal(B[1, 0, 1, 1], 13)


def test_view_as_blocks_3D_array():
    A = np.arange(4 * 4 * 6).reshape(4, 4, 6)
    B = view_as_blocks(A, (1, 2, 2))
    assert_equal(B.shape, (4, 2, 3, 1, 2, 2))
    assert_equal(B[2:, 0, 2], np.array([[[[52, 53],
                                          [58, 59]]],
                                        [[[76, 77],
                                          [82, 83]]]]))


def test_view_as_windows_input_not_array():
    A = [1, 2, 3, 4, 5]
    with testing.raises(TypeError):
        view_as_windows(A, (2,))


def test_view_as_windows_wrong_window_dimension():
    A = np.arange(10)
    with testing.raises(ValueError):
        view_as_windows(A, (2, 2))


def test_view_as_windows_negative_window_length():
    A = np.arange(10)
    with testing.raises(ValueError):
        view_as_windows(A, (-1,))


def test_view_as_windows_window_too_large():
    A = np.arange(10)
    with testing.raises(ValueError):
        view_as_windows(A, (11,))


def test_view_as_windows_step_below_one():
    A = np.arange(10)
    with testing.raises(ValueError):
        view_as_windows(A, (11,), step=0.9)


def test_view_as_windows_1D():
    A = np.arange(10)
    window_shape = (3,)
    B = view_as_windows(A, window_shape)
    assert_equal(B, np.array([[0, 1, 2],
                              [1, 2, 3],
                              [2, 3, 4],
                              [3, 4, 5],
                              [4, 5, 6],
                              [5, 6, 7],
                              [6, 7, 8],
                              [7, 8, 9]]))


def test_view_as_windows_2D():
    A = np.arange(5 * 4).reshape(5, 4)
    window_shape = (4, 3)
    B = view_as_windows(A, window_shape)
    assert_equal(B.shape, (2, 2, 4, 3))
    assert_equal(B, np.array([[[[0,  1,  2],
                                [4,  5,  6],
                                [8,  9, 10],
                                [12, 13, 14]],
                               [[1,  2,  3],
                                [5,  6,  7],
                                [9, 10, 11],
                                [13, 14, 15]]],
                              [[[4,  5,  6],
                                [8,  9, 10],
                                [12, 13, 14],
                                [16, 17, 18]],
                               [[5,  6,  7],
                                [9, 10, 11],
                                [13, 14, 15],
                                [17, 18, 19]]]]))


def test_view_as_windows_with_skip():
    A = np.arange(20).reshape((5, 4))
    B = view_as_windows(A, 2, step=2)
    assert_equal(B, [[[[0, 1],
                       [4, 5]],
                      [[2, 3],
                       [6, 7]]],
                     [[[8, 9],
                       [12, 13]],
                      [[10, 11],
                       [14, 15]]]])

    C = view_as_windows(A, 2, step=4)
    assert_equal(C.shape, (1, 1, 2, 2))


def test_views_non_contiguous():
    A = np.arange(16).reshape((4, 4))
    A = A[::2, :]

    res_b = view_as_blocks(A, (2, 2))
    res_w = view_as_windows(A, (2, 2))
    print(res_b)
    print(res_w)

    expected_b = [[[[0,  1],
                    [8,  9]],
                   [[2,  3],
                    [10, 11]]]]

    expected_w = [[[[ 0,  1],
                    [ 8,  9]],
                   [[ 1,  2],
                    [ 9, 10]],
                   [[ 2,  3],
                    [10, 11]]]]

    assert_equal(res_b, expected_b)
    assert_equal(res_w, expected_w)


def test_view_as_windows_step_tuple():
    A = np.arange(24).reshape((6, 4))
    B = view_as_windows(A, (3, 2), step=3)
    assert B.shape == (2, 1, 3, 2)
    assert B.size != A.size

    C = view_as_windows(A, (3, 2), step=(3, 2))
    assert C.shape == (2, 2, 3, 2)
    assert C.size == A.size

    assert_equal(C, [[[[0,  1],
                       [4,  5],
                       [8,  9]],
                      [[2,  3],
                       [6,  7],
                       [10, 11]]],
                     [[[12, 13],
                       [16, 17],
                       [20, 21]],
                      [[14, 15],
                       [18, 19],
                       [22, 23]]]])