import copy

import pytest
import torch

from mmcv.cnn.bricks.drop import DropPath
from mmcv.cnn.bricks.transformer import (FFN, AdaptivePadding,
                                         BaseTransformerLayer,
                                         MultiheadAttention, PatchEmbed,
                                         PatchMerging,
                                         TransformerLayerSequence)
from mmcv.runner import ModuleList


def test_adaptive_padding():

    for padding in ('same', 'corner'):
        kernel_size = 16
        stride = 16
        dilation = 1
        input = torch.rand(1, 1, 15, 17)
        adap_pad = AdaptivePadding(
            kernel_size=kernel_size,
            stride=stride,
            dilation=dilation,
            padding=padding)
        out = adap_pad(input)
        # padding to divisible by 16
        assert (out.shape[2], out.shape[3]) == (16, 32)
        input = torch.rand(1, 1, 16, 17)
        out = adap_pad(input)
        # padding to divisible by 16
        assert (out.shape[2], out.shape[3]) == (16, 32)

        kernel_size = (2, 2)
        stride = (2, 2)
        dilation = (1, 1)

        adap_pad = AdaptivePadding(
            kernel_size=kernel_size,
            stride=stride,
            dilation=dilation,
            padding=padding)
        input = torch.rand(1, 1, 11, 13)
        out = adap_pad(input)
        # padding to divisible by 2
        assert (out.shape[2], out.shape[3]) == (12, 14)

        kernel_size = (2, 2)
        stride = (10, 10)
        dilation = (1, 1)

        adap_pad = AdaptivePadding(
            kernel_size=kernel_size,
            stride=stride,
            dilation=dilation,
            padding=padding)
        input = torch.rand(1, 1, 10, 13)
        out = adap_pad(input)
        #  no padding
        assert (out.shape[2], out.shape[3]) == (10, 13)

        kernel_size = (11, 11)
        adap_pad = AdaptivePadding(
            kernel_size=kernel_size,
            stride=stride,
            dilation=dilation,
            padding=padding)
        input = torch.rand(1, 1, 11, 13)
        out = adap_pad(input)
        #  all padding
        assert (out.shape[2], out.shape[3]) == (21, 21)

        # test padding as kernel is (7,9)
        input = torch.rand(1, 1, 11, 13)
        stride = (3, 4)
        kernel_size = (4, 5)
        dilation = (2, 2)
        # actually (7, 9)
        adap_pad = AdaptivePadding(
            kernel_size=kernel_size,
            stride=stride,
            dilation=dilation,
            padding=padding)
        dilation_out = adap_pad(input)
        assert (dilation_out.shape[2], dilation_out.shape[3]) == (16, 21)
        kernel_size = (7, 9)
        dilation = (1, 1)
        adap_pad = AdaptivePadding(
            kernel_size=kernel_size,
            stride=stride,
            dilation=dilation,
            padding=padding)
        kernel79_out = adap_pad(input)
        assert (kernel79_out.shape[2], kernel79_out.shape[3]) == (16, 21)
        assert kernel79_out.shape == dilation_out.shape

    # assert only support "same" "corner"
    with pytest.raises(AssertionError):
        AdaptivePadding(
            kernel_size=kernel_size,
            stride=stride,
            dilation=dilation,
            padding=1)


def test_patch_embed():
    B = 2
    H = 3
    W = 4
    C = 3
    embed_dims = 10
    kernel_size = 3
    stride = 1
    dummy_input = torch.rand(B, C, H, W)
    patch_merge_1 = PatchEmbed(
        in_channels=C,
        embed_dims=embed_dims,
        kernel_size=kernel_size,
        stride=stride,
        padding=0,
        dilation=1,
        norm_cfg=None)

    x1, shape = patch_merge_1(dummy_input)
    # test out shape
    assert x1.shape == (2, 2, 10)
    # test outsize is correct
    assert shape == (1, 2)
    # test L = out_h * out_w
    assert shape[0] * shape[1] == x1.shape[1]

    B = 2
    H = 10
    W = 10
    C = 3
    embed_dims = 10
    kernel_size = 5
    stride = 2
    dummy_input = torch.rand(B, C, H, W)
    # test dilation
    patch_merge_2 = PatchEmbed(
        in_channels=C,
        embed_dims=embed_dims,
        kernel_size=kernel_size,
        stride=stride,
        padding=0,
        dilation=2,
        norm_cfg=None,
    )

    x2, shape = patch_merge_2(dummy_input)
    # test out shape
    assert x2.shape == (2, 1, 10)
    # test outsize is correct
    assert shape == (1, 1)
    # test L = out_h * out_w
    assert shape[0] * shape[1] == x2.shape[1]

    stride = 2
    input_size = (10, 10)

    dummy_input = torch.rand(B, C, H, W)
    # test stride and norm
    patch_merge_3 = PatchEmbed(
        in_channels=C,
        embed_dims=embed_dims,
        kernel_size=kernel_size,
        stride=stride,
        padding=0,
        dilation=2,
        norm_cfg=dict(type='LN'),
        input_size=input_size)

    x3, shape = patch_merge_3(dummy_input)
    # test out shape
    assert x3.shape == (2, 1, 10)
    # test outsize is correct
    assert shape == (1, 1)
    # test L = out_h * out_w
    assert shape[0] * shape[1] == x3.shape[1]

    # test the init_out_size with nn.Unfold
    assert patch_merge_3.init_out_size[1] == (input_size[0] - 2 * 4 -
                                              1) // 2 + 1
    assert patch_merge_3.init_out_size[0] == (input_size[0] - 2 * 4 -
                                              1) // 2 + 1
    H = 11
    W = 12
    input_size = (H, W)
    dummy_input = torch.rand(B, C, H, W)
    # test stride and norm
    patch_merge_3 = PatchEmbed(
        in_channels=C,
        embed_dims=embed_dims,
        kernel_size=kernel_size,
        stride=stride,
        padding=0,
        dilation=2,
        norm_cfg=dict(type='LN'),
        input_size=input_size)

    _, shape = patch_merge_3(dummy_input)
    # when input_size equal to real input
    # the out_size should be equal to `init_out_size`
    assert shape == patch_merge_3.init_out_size

    input_size = (H, W)
    dummy_input = torch.rand(B, C, H, W)
    # test stride and norm
    patch_merge_3 = PatchEmbed(
        in_channels=C,
        embed_dims=embed_dims,
        kernel_size=kernel_size,
        stride=stride,
        padding=0,
        dilation=2,
        norm_cfg=dict(type='LN'),
        input_size=input_size)

    _, shape = patch_merge_3(dummy_input)
    # when input_size equal to real input
    # the out_size should be equal to `init_out_size`
    assert shape == patch_merge_3.init_out_size

    # test adap padding
    for padding in ('same', 'corner'):
        in_c = 2
        embed_dims = 3
        B = 2

        # test stride is 1
        input_size = (5, 5)
        kernel_size = (5, 5)
        stride = (1, 1)
        dilation = 1
        bias = False

        x = torch.rand(B, in_c, *input_size)
        patch_embed = PatchEmbed(
            in_channels=in_c,
            embed_dims=embed_dims,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias)

        x_out, out_size = patch_embed(x)
        assert x_out.size() == (B, 25, 3)
        assert out_size == (5, 5)
        assert x_out.size(1) == out_size[0] * out_size[1]

        # test kernel_size == stride
        input_size = (5, 5)
        kernel_size = (5, 5)
        stride = (5, 5)
        dilation = 1
        bias = False

        x = torch.rand(B, in_c, *input_size)
        patch_embed = PatchEmbed(
            in_channels=in_c,
            embed_dims=embed_dims,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias)

        x_out, out_size = patch_embed(x)
        assert x_out.size() == (B, 1, 3)
        assert out_size == (1, 1)
        assert x_out.size(1) == out_size[0] * out_size[1]

        # test kernel_size == stride
        input_size = (6, 5)
        kernel_size = (5, 5)
        stride = (5, 5)
        dilation = 1
        bias = False

        x = torch.rand(B, in_c, *input_size)
        patch_embed = PatchEmbed(
            in_channels=in_c,
            embed_dims=embed_dims,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias)

        x_out, out_size = patch_embed(x)
        assert x_out.size() == (B, 2, 3)
        assert out_size == (2, 1)
        assert x_out.size(1) == out_size[0] * out_size[1]

        # test different kernel_size with different stride
        input_size = (6, 5)
        kernel_size = (6, 2)
        stride = (6, 2)
        dilation = 1
        bias = False

        x = torch.rand(B, in_c, *input_size)
        patch_embed = PatchEmbed(
            in_channels=in_c,
            embed_dims=embed_dims,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias)

        x_out, out_size = patch_embed(x)
        assert x_out.size() == (B, 3, 3)
        assert out_size == (1, 3)
        assert x_out.size(1) == out_size[0] * out_size[1]


def test_patch_merging():

    # Test the model with int padding
    in_c = 3
    out_c = 4
    kernel_size = 3
    stride = 3
    padding = 1
    dilation = 1
    bias = False
    # test the case `pad_to_stride` is False
    patch_merge = PatchMerging(
        in_channels=in_c,
        out_channels=out_c,
        kernel_size=kernel_size,
        stride=stride,
        padding=padding,
        dilation=dilation,
        bias=bias)
    B, L, C = 1, 100, 3
    input_size = (10, 10)
    x = torch.rand(B, L, C)
    x_out, out_size = patch_merge(x, input_size)
    assert x_out.size() == (1, 16, 4)
    assert out_size == (4, 4)
    # assert out size is consistent with real output
    assert x_out.size(1) == out_size[0] * out_size[1]
    in_c = 4
    out_c = 5
    kernel_size = 6
    stride = 3
    padding = 2
    dilation = 2
    bias = False
    patch_merge = PatchMerging(
        in_channels=in_c,
        out_channels=out_c,
        kernel_size=kernel_size,
        stride=stride,
        padding=padding,
        dilation=dilation,
        bias=bias)
    B, L, C = 1, 100, 4
    input_size = (10, 10)
    x = torch.rand(B, L, C)
    x_out, out_size = patch_merge(x, input_size)
    assert x_out.size() == (1, 4, 5)
    assert out_size == (2, 2)
    # assert out size is consistent with real output
    assert x_out.size(1) == out_size[0] * out_size[1]

    # Test with adaptive padding
    for padding in ('same', 'corner'):
        in_c = 2
        out_c = 3
        B = 2

        # test stride is 1
        input_size = (5, 5)
        kernel_size = (5, 5)
        stride = (1, 1)
        dilation = 1
        bias = False
        L = input_size[0] * input_size[1]

        x = torch.rand(B, L, in_c)
        patch_merge = PatchMerging(
            in_channels=in_c,
            out_channels=out_c,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias)

        x_out, out_size = patch_merge(x, input_size)
        assert x_out.size() == (B, 25, 3)
        assert out_size == (5, 5)
        assert x_out.size(1) == out_size[0] * out_size[1]

        # test kernel_size == stride
        input_size = (5, 5)
        kernel_size = (5, 5)
        stride = (5, 5)
        dilation = 1
        bias = False
        L = input_size[0] * input_size[1]

        x = torch.rand(B, L, in_c)
        patch_merge = PatchMerging(
            in_channels=in_c,
            out_channels=out_c,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias)

        x_out, out_size = patch_merge(x, input_size)
        assert x_out.size() == (B, 1, 3)
        assert out_size == (1, 1)
        assert x_out.size(1) == out_size[0] * out_size[1]

        # test kernel_size == stride
        input_size = (6, 5)
        kernel_size = (5, 5)
        stride = (5, 5)
        dilation = 1
        bias = False
        L = input_size[0] * input_size[1]

        x = torch.rand(B, L, in_c)
        patch_merge = PatchMerging(
            in_channels=in_c,
            out_channels=out_c,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias)

        x_out, out_size = patch_merge(x, input_size)
        assert x_out.size() == (B, 2, 3)
        assert out_size == (2, 1)
        assert x_out.size(1) == out_size[0] * out_size[1]

        # test different kernel_size with different stride
        input_size = (6, 5)
        kernel_size = (6, 2)
        stride = (6, 2)
        dilation = 1
        bias = False
        L = input_size[0] * input_size[1]

        x = torch.rand(B, L, in_c)
        patch_merge = PatchMerging(
            in_channels=in_c,
            out_channels=out_c,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            dilation=dilation,
            bias=bias)

        x_out, out_size = patch_merge(x, input_size)
        assert x_out.size() == (B, 3, 3)
        assert out_size == (1, 3)
        assert x_out.size(1) == out_size[0] * out_size[1]


def test_multiheadattention():
    MultiheadAttention(
        embed_dims=5,
        num_heads=5,
        attn_drop=0,
        proj_drop=0,
        dropout_layer=dict(type='Dropout', drop_prob=0.),
        batch_first=True)
    batch_dim = 2
    embed_dim = 5
    num_query = 100
    attn_batch_first = MultiheadAttention(
        embed_dims=5,
        num_heads=5,
        attn_drop=0,
        proj_drop=0,
        dropout_layer=dict(type='DropPath', drop_prob=0.),
        batch_first=True)

    attn_query_first = MultiheadAttention(
        embed_dims=5,
        num_heads=5,
        attn_drop=0,
        proj_drop=0,
        dropout_layer=dict(type='DropPath', drop_prob=0.),
        batch_first=False)

    param_dict = dict(attn_query_first.named_parameters())
    for n, v in attn_batch_first.named_parameters():
        param_dict[n].data = v.data

    input_batch_first = torch.rand(batch_dim, num_query, embed_dim)
    input_query_first = input_batch_first.transpose(0, 1)

    assert torch.allclose(
        attn_query_first(input_query_first).sum(),
        attn_batch_first(input_batch_first).sum())

    key_batch_first = torch.rand(batch_dim, num_query, embed_dim)
    key_query_first = key_batch_first.transpose(0, 1)

    assert torch.allclose(
        attn_query_first(input_query_first, key_query_first).sum(),
        attn_batch_first(input_batch_first, key_batch_first).sum())

    identity = torch.ones_like(input_query_first)

    # check deprecated arguments can be used normally

    assert torch.allclose(
        attn_query_first(
            input_query_first, key_query_first, residual=identity).sum(),
        attn_batch_first(input_batch_first, key_batch_first).sum() +
        identity.sum() - input_batch_first.sum())

    assert torch.allclose(
        attn_query_first(
            input_query_first, key_query_first, identity=identity).sum(),
        attn_batch_first(input_batch_first, key_batch_first).sum() +
        identity.sum() - input_batch_first.sum())

    attn_query_first(
        input_query_first, key_query_first, identity=identity).sum(),


def test_ffn():
    with pytest.raises(AssertionError):
        # num_fcs should be no less than 2
        FFN(num_fcs=1)
    FFN(dropout=0, add_residual=True)
    ffn = FFN(dropout=0, add_identity=True)

    input_tensor = torch.rand(2, 20, 256)
    input_tensor_nbc = input_tensor.transpose(0, 1)
    assert torch.allclose(ffn(input_tensor).sum(), ffn(input_tensor_nbc).sum())
    residual = torch.rand_like(input_tensor)
    torch.allclose(
        ffn(input_tensor, residual=residual).sum(),
        ffn(input_tensor).sum() + residual.sum() - input_tensor.sum())

    torch.allclose(
        ffn(input_tensor, identity=residual).sum(),
        ffn(input_tensor).sum() + residual.sum() - input_tensor.sum())


@pytest.mark.skipif(not torch.cuda.is_available(), reason='Cuda not available')
def test_basetransformerlayer_cuda():
    # To test if the BaseTransformerLayer's behaviour remains
    # consistent after being deepcopied
    operation_order = ('self_attn', 'ffn')
    baselayer = BaseTransformerLayer(
        operation_order=operation_order,
        batch_first=True,
        attn_cfgs=dict(
            type='MultiheadAttention',
            embed_dims=256,
            num_heads=8,
        ),
    )
    baselayers = ModuleList([copy.deepcopy(baselayer) for _ in range(2)])
    baselayers.to('cuda')
    x = torch.rand(2, 10, 256).cuda()
    for m in baselayers:
        x = m(x)
        assert x.shape == torch.Size([2, 10, 256])


def test_basetransformerlayer():
    attn_cfgs = dict(type='MultiheadAttention', embed_dims=256, num_heads=8),
    feedforward_channels = 2048
    ffn_dropout = 0.1
    operation_order = ('self_attn', 'norm', 'ffn', 'norm')

    # test deprecated_args
    baselayer = BaseTransformerLayer(
        attn_cfgs=attn_cfgs,
        feedforward_channels=feedforward_channels,
        ffn_dropout=ffn_dropout,
        operation_order=operation_order)
    assert baselayer.batch_first is False
    assert baselayer.ffns[0].feedforward_channels == feedforward_channels

    attn_cfgs = dict(type='MultiheadAttention', num_heads=8, embed_dims=256),
    feedforward_channels = 2048
    ffn_dropout = 0.1
    operation_order = ('self_attn', 'norm', 'ffn', 'norm')
    baselayer = BaseTransformerLayer(
        attn_cfgs=attn_cfgs,
        feedforward_channels=feedforward_channels,
        ffn_dropout=ffn_dropout,
        operation_order=operation_order,
        batch_first=True)
    assert baselayer.attentions[0].batch_first
    in_tensor = torch.rand(2, 10, 256)
    baselayer(in_tensor)


def test_transformerlayersequence():
    squeue = TransformerLayerSequence(
        num_layers=6,
        transformerlayers=dict(
            type='BaseTransformerLayer',
            attn_cfgs=[
                dict(
                    type='MultiheadAttention',
                    embed_dims=256,
                    num_heads=8,
                    dropout=0.1),
                dict(type='MultiheadAttention', embed_dims=256, num_heads=4)
            ],
            feedforward_channels=1024,
            ffn_dropout=0.1,
            operation_order=('self_attn', 'norm', 'cross_attn', 'norm', 'ffn',
                             'norm')))
    assert len(squeue.layers) == 6
    assert squeue.pre_norm is False
    with pytest.raises(AssertionError):
        # if transformerlayers is a list, len(transformerlayers)
        # should be equal to num_layers
        TransformerLayerSequence(
            num_layers=6,
            transformerlayers=[
                dict(
                    type='BaseTransformerLayer',
                    attn_cfgs=[
                        dict(
                            type='MultiheadAttention',
                            embed_dims=256,
                            num_heads=8,
                            dropout=0.1),
                        dict(type='MultiheadAttention', embed_dims=256)
                    ],
                    feedforward_channels=1024,
                    ffn_dropout=0.1,
                    operation_order=('self_attn', 'norm', 'cross_attn', 'norm',
                                     'ffn', 'norm'))
            ])


def test_drop_path():
    drop_path = DropPath(drop_prob=0)
    test_in = torch.rand(2, 3, 4, 5)
    assert test_in is drop_path(test_in)

    drop_path = DropPath(drop_prob=0.1)
    drop_path.training = False
    test_in = torch.rand(2, 3, 4, 5)
    assert test_in is drop_path(test_in)
    drop_path.training = True
    assert test_in is not drop_path(test_in)
