import argparse

import torch
from mmcv import Config, DictAction

from mmdet.models import build_detector

try:
    from mmcv.cnn import get_model_complexity_info
except ImportError:
    raise ImportError('Please upgrade mmcv to >0.6.2')
from mmcv.cnn.utils.flops_counter import get_model_complexity_info, flops_to_string, params_to_string

def parse_args():
    parser = argparse.ArgumentParser(description='Train a detector')
    parser.add_argument('config', help='train config file path')
    parser.add_argument(
        '--shape',
        type=int,
        nargs='+',
        default=[1280, 800],
        help='input image size')
    parser.add_argument(
        '--cfg-options',
        nargs='+',
        action=DictAction,
        help='override some settings in the used config, the key-value pair '
             'in xxx=yyy format will be merged into config file. If the value to '
             'be overwritten is a list, it should be like key="[a,b]" or key=a,b '
             'It also allows nested list/tuple values, e.g. key="[(a,b),(c,d)]" '
             'Note that the quotation marks are necessary and that no white space '
             'is allowed.')
    args = parser.parse_args()
    return args


def sra_flops(h, w, r, dim):
    return 2 * h * w * (h // r) * (w // r) * dim


def li_sra_flops(h, w, dim):
    return 2 * h * w * 7 * 7 * dim

import math

def msa_flops(H, W, dim):
    N = H * W
    return N * dim * N * 2

def hilo_flops(H, W, l_dim, h_dim, sr_ratio):
    # H = int(N ** 0.5)
    # ws = sr_ratio = 4
    ws = sr_ratio
    Hp = ws * math.ceil(H / ws)
    Wp = ws * math.ceil(W / ws)
    Np = Hp * Wp

    nW = (Hp // ws) * (Wp // ws)
    window_len = ws * ws
    window_flops = window_len * window_len * h_dim * 2

    high_flops = nW * window_flops
    kv_len = (Hp // sr_ratio) * (Wp // sr_ratio)
    low_flops = Np * l_dim * kv_len * 2

    return high_flops + low_flops

def get_flops(model, input_shape):
    flops, params = get_model_complexity_info(model, input_shape, as_strings=False)

    backbone = model.backbone
    _, H, W = input_shape
    l_dim = int(backbone.alpha * backbone.num_heads[2]) * 32
    h_dim = (backbone.num_heads[2] - int(backbone.alpha * backbone.num_heads[2])) * 32
    stage3 = hilo_flops(H // 16, W // 16, l_dim, h_dim, backbone.local_ws[2]) * len(backbone.layers[2].blocks)
    stage4 = msa_flops(H // 32, W // 32, backbone.num_heads[3] * 32) * len(backbone.layers[3].blocks)
    flops += stage3 + stage4
    return flops_to_string(flops), params_to_string(params)


def main():
    args = parse_args()

    if len(args.shape) == 1:
        input_shape = (3, args.shape[0], args.shape[0])
    elif len(args.shape) == 2:
        input_shape = (3,) + tuple(args.shape)
    else:
        raise ValueError('invalid input shape')

    cfg = Config.fromfile(args.config)
    if args.cfg_options is not None:
        cfg.merge_from_dict(args.cfg_options)
    # import modules from string list.
    if cfg.get('custom_imports', None):
        from mmcv.utils import import_modules_from_strings
        import_modules_from_strings(**cfg['custom_imports'])

    model = build_detector(
        cfg.model,
        train_cfg=cfg.get('train_cfg'),
        test_cfg=cfg.get('test_cfg'))
    if torch.cuda.is_available():
        model.cuda()
    model.eval()

    if hasattr(model, 'forward_dummy'):
        model.forward = model.forward_dummy
    else:
        raise NotImplementedError(
            'FLOPs counter is currently not currently supported with {}'.
                format(model.__class__.__name__))

    flops, params = get_flops(model, input_shape)

    split_line = '=' * 30
    print(f'{split_line}\nInput shape: {input_shape}\n'
          f'Flops: {flops}\nParams: {params}\n{split_line}')
    print('!!!Please be cautious if you use the results in papers. '
          'You may need to check if all ops are supported and verify that the '
          'flops computation is correct.')


if __name__ == '__main__':
    main()
