# Copyright (c) OpenMMLab. All rights reserved.
import argparse
import os.path as osp
from collections import OrderedDict

import mmengine
import torch
from mmengine.runner import CheckpointLoader


def convert_eva02(ckpt):

    new_ckpt = OrderedDict()
    qkv_proj = {}
    qkv_bias = {}
    w12_weight = {}
    w12_bias = {}

    banned = {
        'mask_token',
        'lm_head.weight',
        'lm_head.bias',
        'norm.weight',
        'norm.bias',
    }

    for k, v in list(ckpt.items()):

        if k in banned:
            continue

        if k.startswith('head'):
            new_k = k.replace('head.', 'head.fc.')
            new_ckpt[new_k] = v
        else:
            if k.startswith('patch_embed'):
                new_k = k.replace('proj.', 'projection.')

            elif k.startswith('fc_norm') or k.startswith('norm'):
                new_k = k.replace('norm.', 'ln2.')
                new_k = k.replace('fc_norm.', 'ln2.')

            elif k.startswith('blocks'):
                new_k = k.replace('blocks.', 'layers.')

                if 'mlp' in new_k:
                    if 'w1.' in new_k or 'w2.' in new_k:
                        # For base and large version, mlp is implemented with
                        # 2 linears, where w1 and w2 are required to integrate
                        # into w12.
                        s = new_k.split('.')  # e.g. layers.0.mlp.w1.weight
                        idx = s[1]
                        if 'weight' in new_k:
                            # w1.weight or w2.weight
                            if idx not in w12_weight:
                                w12_weight[idx] = {}
                            w12_weight[idx][s[-2]] = v
                        else:
                            # w1.bias or w2.bias
                            if idx not in w12_bias:
                                w12_bias[idx] = {}
                            w12_bias[idx][s[-2]] = v
                        continue

                    if 'ffn_ln' in new_k:
                        new_k = new_k.replace('ffn_ln.', 'norm.')

                elif 'attn' in new_k:
                    if 'q_proj.weight' in new_k or \
                            'k_proj.weight' in new_k or \
                            'v_proj.weight' in new_k:
                        # For base and large version, qkv projection is
                        # implemented with three linear layers,
                        s = new_k.split('.')
                        idx = s[1]
                        if idx not in qkv_proj:
                            qkv_proj[idx] = {}
                        qkv_proj[idx][s[-2]] = v
                        continue

                    if 'q_bias' in new_k or 'v_bias' in new_k:
                        # k_bias is 0
                        s = new_k.split('.')
                        idx = s[1]
                        if idx not in qkv_bias:
                            qkv_bias[idx] = {}
                        qkv_bias[idx][s[-1]] = v
                        continue

            else:
                new_k = k

            new_k = 'backbone.' + new_k
            new_ckpt[new_k] = v

    for idx in qkv_proj:
        q_proj = qkv_proj[idx]['q_proj']
        k_proj = qkv_proj[idx]['k_proj']
        v_proj = qkv_proj[idx]['v_proj']
        weight = torch.cat((q_proj, k_proj, v_proj))
        new_k = f'backbone.layers.{idx}.attn.qkv.weight'
        new_ckpt[new_k] = weight

    for idx in qkv_bias:
        q_bias = qkv_bias[idx]['q_bias']
        k_bias = torch.zeros_like(q_bias)
        v_bias = qkv_bias[idx]['v_bias']
        weight = torch.cat((q_bias, k_bias, v_bias))
        new_k = f'backbone.layers.{idx}.attn.qkv.bias'
        new_ckpt[new_k] = weight

    for idx in w12_weight:
        w1 = w12_weight[idx]['w1']
        w2 = w12_weight[idx]['w2']
        weight = torch.cat((w1, w2))
        new_k = f'backbone.layers.{idx}.mlp.w12.weight'
        new_ckpt[new_k] = weight

    for idx in w12_bias:
        w1 = w12_bias[idx]['w1']
        w2 = w12_bias[idx]['w2']
        weight = torch.cat((w1, w2))
        new_k = f'backbone.layers.{idx}.mlp.w12.bias'
        new_ckpt[new_k] = weight

    return new_ckpt


def main():
    parser = argparse.ArgumentParser(
        description='Convert keys in pretrained eva02 '
        'models to mmpretrain style.')
    parser.add_argument('src', help='src model path or url')
    # The dst path must be a full path of the new checkpoint.
    parser.add_argument('dst', help='save path')
    args = parser.parse_args()

    checkpoint = CheckpointLoader.load_checkpoint(args.src, map_location='cpu')

    if 'module' in checkpoint:
        state_dict = checkpoint['module']
    else:
        state_dict = checkpoint

    weight = convert_eva02(state_dict)
    mmengine.mkdir_or_exist(osp.dirname(args.dst))
    torch.save(weight, args.dst)

    print('Done!!')


if __name__ == '__main__':
    main()