# Copyright (c) Alibaba, Inc. and its affiliates.
# Copyright 2022 EleutherAI and The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import argparse
import gc
import math
import os
import shutil

import json
import torch
from transformers.models.llama import LlamaConfig

from .text_generation import LlamaForTextGeneration

# This file is mainly copied from the llama code of transformers
INTERMEDIATE_SIZE_MAP = {
    '7B': 11008,
    '13B': 13824,
    '30B': 17920,
    '65B': 22016,
}
NUM_SHARDS = {
    '7B': 1,
    '13B': 2,
    '30B': 4,
    '65B': 8,
}


def compute_intermediate_size(n):
    return int(math.ceil(n * 8 / 3) + 255) // 256 * 256


def read_json(path):
    with open(path, 'r') as f:
        return json.load(f)


def write_json(text, path):
    with open(path, 'w') as f:
        json.dump(text, f)


def write_model(model_path, input_base_path, model_size):
    os.makedirs(model_path, exist_ok=True)
    tmp_model_path = os.path.join(model_path, 'tmp')
    os.makedirs(tmp_model_path, exist_ok=True)

    params = read_json(os.path.join(input_base_path, 'params.json'))
    num_shards = NUM_SHARDS[model_size]
    n_layers = params['n_layers']
    n_heads = params['n_heads']
    n_heads_per_shard = n_heads // num_shards
    dim = params['dim']
    dims_per_head = dim // n_heads
    base = 10000.0
    inv_freq = 1.0 / (
        base**(torch.arange(0, dims_per_head, 2).float() / dims_per_head))

    # permute for sliced rotary
    def permute(w):
        return w.view(n_heads, dim // n_heads // 2, 2,
                      dim).transpose(1, 2).reshape(dim, dim)

    print(f'Fetching all parameters from the checkpoint at {input_base_path}.')
    # Load weights
    if model_size == '7B':
        # Not shared
        # (The sharded implementation would also work, but this is simpler.)
        loaded = torch.load(
            os.path.join(input_base_path, 'consolidated.00.pth'),
            map_location='cpu')
    else:
        # Sharded
        loaded = [
            torch.load(
                os.path.join(input_base_path, f'consolidated.{i:02d}.pth'),
                map_location='cpu') for i in range(num_shards)
        ]
    param_count = 0
    index_dict = {'weight_map': {}}
    for layer_i in range(n_layers):
        filename = f'pytorch_model-{layer_i + 1}-of-{n_layers + 1}.bin'
        if model_size == '7B':
            # Unsharded
            state_dict = {
                f'model.layers.{layer_i}.self_attn.q_proj.weight':
                permute(loaded[f'layers.{layer_i}.attention.wq.weight']),
                f'model.layers.{layer_i}.self_attn.k_proj.weight':
                permute(loaded[f'layers.{layer_i}.attention.wk.weight']),
                f'model.layers.{layer_i}.self_attn.v_proj.weight':
                loaded[f'layers.{layer_i}.attention.wv.weight'],
                f'model.layers.{layer_i}.self_attn.o_proj.weight':
                loaded[f'layers.{layer_i}.attention.wo.weight'],
                f'model.layers.{layer_i}.mlp.gate_proj.weight':
                loaded[f'layers.{layer_i}.feed_forward.w1.weight'],
                f'model.layers.{layer_i}.mlp.down_proj.weight':
                loaded[f'layers.{layer_i}.feed_forward.w2.weight'],
                f'model.layers.{layer_i}.mlp.up_proj.weight':
                loaded[f'layers.{layer_i}.feed_forward.w3.weight'],
                f'model.layers.{layer_i}.input_layernorm.weight':
                loaded[f'layers.{layer_i}.attention_norm.weight'],
                f'model.layers.{layer_i}.post_attention_layernorm.weight':
                loaded[f'layers.{layer_i}.ffn_norm.weight'],
            }
        else:
            # Sharded
            # Note that in the 13B checkpoint, not cloning the two following weights will result in the checkpoint
            # becoming 37GB instead of 26GB for some reason.
            state_dict = {
                f'model.layers.{layer_i}.input_layernorm.weight':
                loaded[0][f'layers.{layer_i}.attention_norm.weight'].clone(),
                f'model.layers.{layer_i}.post_attention_layernorm.weight':
                loaded[0][f'layers.{layer_i}.ffn_norm.weight'].clone(),
            }
            state_dict[
                f'model.layers.{layer_i}.self_attn.q_proj.weight'] = permute(
                    torch.cat(
                        [
                            loaded[i]
                            [f'layers.{layer_i}.attention.wq.weight'].view(
                                n_heads_per_shard, dims_per_head, dim)
                            for i in range(num_shards)
                        ],
                        dim=0,
                    ).reshape(dim, dim))
            state_dict[
                f'model.layers.{layer_i}.self_attn.k_proj.weight'] = permute(
                    torch.cat(
                        [
                            loaded[i]
                            [f'layers.{layer_i}.attention.wk.weight'].view(
                                n_heads_per_shard, dims_per_head, dim)
                            for i in range(num_shards)
                        ],
                        dim=0,
                    ).reshape(dim, dim))
            state_dict[
                f'model.layers.{layer_i}.self_attn.v_proj.weight'] = torch.cat(
                    [
                        loaded[i]
                        [f'layers.{layer_i}.attention.wv.weight'].view(
                            n_heads_per_shard, dims_per_head, dim)
                        for i in range(num_shards)
                    ],
                    dim=0,
                ).reshape(dim, dim)  # noqa

            state_dict[
                f'model.layers.{layer_i}.self_attn.o_proj.weight'] = torch.cat(
                    [
                        loaded[i][f'layers.{layer_i}.attention.wo.weight']
                        for i in range(num_shards)
                    ],
                    dim=1)
            state_dict[
                f'model.layers.{layer_i}.mlp.gate_proj.weight'] = torch.cat(
                    [
                        loaded[i][f'layers.{layer_i}.feed_forward.w1.weight']
                        for i in range(num_shards)
                    ],
                    dim=0)
            state_dict[
                f'model.layers.{layer_i}.mlp.down_proj.weight'] = torch.cat(
                    [
                        loaded[i][f'layers.{layer_i}.feed_forward.w2.weight']
                        for i in range(num_shards)
                    ],
                    dim=1)
            state_dict[
                f'model.layers.{layer_i}.mlp.up_proj.weight'] = torch.cat(
                    [
                        loaded[i][f'layers.{layer_i}.feed_forward.w3.weight']
                        for i in range(num_shards)
                    ],
                    dim=0)

        state_dict[
            f'model.layers.{layer_i}.self_attn.rotary_emb.inv_freq'] = inv_freq
        for k, v in state_dict.items():
            index_dict['weight_map'][k] = filename
            param_count += v.numel()
        torch.save(state_dict, os.path.join(tmp_model_path, filename))

    filename = f'pytorch_model-{n_layers + 1}-of-{n_layers + 1}.bin'
    if model_size == '7B':
        # Unsharded
        state_dict = {
            'model.embed_tokens.weight': loaded['tok_embeddings.weight'],
            'model.norm.weight': loaded['norm.weight'],
            'lm_head.weight': loaded['output.weight'],
        }
    else:
        state_dict = {
            'model.norm.weight':
            loaded[0]['norm.weight'],
            'model.embed_tokens.weight':
            torch.cat([
                loaded[i]['tok_embeddings.weight'] for i in range(num_shards)
            ],
                      dim=1),  # noqa
            'lm_head.weight':
            torch.cat([loaded[i]['output.weight'] for i in range(num_shards)],
                      dim=0),
        }

    for k, v in state_dict.items():
        index_dict['weight_map'][k] = filename
        param_count += v.numel()
    torch.save(state_dict, os.path.join(tmp_model_path, filename))

    # Write configs
    index_dict['metadata'] = {'total_size': param_count * 2}
    write_json(index_dict,
               os.path.join(tmp_model_path, 'pytorch_model.bin.index.json'))

    config = LlamaConfig(
        hidden_size=dim,
        intermediate_size=compute_intermediate_size(dim),
        num_attention_heads=params['n_heads'],
        num_hidden_layers=params['n_layers'],
        rms_norm_eps=params['norm_eps'],
    )
    config.save_pretrained(tmp_model_path)

    # Make space so we can load the model properly now.
    del state_dict
    del loaded
    gc.collect()

    print('Loading the checkpoint in a Llama model.')
    model = LlamaForTextGeneration.from_pretrained(
        tmp_model_path, torch_dtype=torch.float16, low_cpu_mem_usage=True)
    # Avoid saving this as part of the config.
    del model.config._name_or_path

    print('Saving in the Transformers format.')
    model.save_pretrained(model_path)
    shutil.rmtree(tmp_model_path)


def write_tokenizer(tokenizer_path, input_tokenizer_path):
    print(f'Fetching the tokenizer from {input_tokenizer_path}.')
    os.makedirs(tokenizer_path, exist_ok=True)
    write_json({}, os.path.join(tokenizer_path, 'special_tokens_map.json'))
    write_json(
        {
            'bos_token': '',
            'eos_token': '',
            'model_max_length': int(1e30),
            'tokenizer_class': 'LlamaTokenizer',
            'unk_token': '',
        },
        os.path.join(tokenizer_path, 'tokenizer_config.json'),
    )
    shutil.copyfile(input_tokenizer_path,
                    os.path.join(tokenizer_path, 'tokenizer.model'))


def main():
    """
    Sample usage:

    ```
    python src/transformers/models/llama/convert_llama_weights_to_hf.py \
        --input_dir /path/to/downloaded/llama/weights --model_size 7B --output_dir /output/path
    ```
    """

    parser = argparse.ArgumentParser()
    parser.add_argument(
        '--input_dir',
        help=
        'Location of LLaMA weights, which contains tokenizer.model and model folders',
    )
    parser.add_argument(
        '--model_size',
        choices=['7B', '13B', '30B', '65B', 'tokenizer_only'],
    )
    parser.add_argument(
        '--output_dir',
        help='Location to write HF model and tokenizer',
    )
    args = parser.parse_args()
    if args.model_size != 'tokenizer_only':
        write_model(
            model_path=args.output_dir,
            input_base_path=os.path.join(args.input_dir, args.model_size),
            model_size=args.model_size,
        )
    write_tokenizer(
        tokenizer_path=args.output_dir,
        input_tokenizer_path=os.path.join(args.input_dir, 'tokenizer.model'),
    )


if __name__ == '__main__':
    main()