# Copyright (c) OpenMMLab. All rights reserved.
import copy

import pytest
import torch
from mmengine.model import ModuleList

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


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])


@pytest.mark.parametrize('embed_dims', [False, 256])
def test_basetransformerlayer(embed_dims):
    attn_cfgs = dict(type='MultiheadAttention', embed_dims=256, num_heads=8),
    if embed_dims:
        ffn_cfgs = dict(
            type='FFN',
            embed_dims=embed_dims,
            feedforward_channels=1024,
            num_fcs=2,
            ffn_drop=0.,
            act_cfg=dict(type='ReLU', inplace=True),
        )
    else:
        ffn_cfgs = dict(
            type='FFN',
            feedforward_channels=1024,
            num_fcs=2,
            ffn_drop=0.,
            act_cfg=dict(type='ReLU', inplace=True),
        )

    feedforward_channels = 2048
    ffn_dropout = 0.1
    operation_order = ('self_attn', 'norm', 'ffn', 'norm')

    # test deprecated_args
    baselayer = BaseTransformerLayer(
        attn_cfgs=attn_cfgs,
        ffn_cfgs=ffn_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)
