"""
Use this file to export ALLaMo weights to HuggingFace formats 
"""
import argparse
import gc
import json
import os
import shutil
import torch
from transformers import LlamaConfig, LlamaForCausalLM, MistralConfig, MistralForCausalLM
from allamo.logging import configure_logger, logger
from allamo.model.model import AllamoTransformerConfig
from allamo.train_utils import (
    get_model_checkpoint_path,
    get_config_checkpoint_path,
)

def compute_intermediate_size(config):
    return config.multiple_of * ((int(config.n_embd * 8 / 3) + config.multiple_of - 1) // config.multiple_of)

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(checkpoint_dir_path, checkpoint_name_base, hf_model_path, hf_model_type, hf_model_dtype=None, hf_model_max_position_embeddings=None):
    assert hf_model_type == "llama" or hf_model_type == "mistral", "Only llama and mistral architectures are supported"
    os.makedirs(hf_model_path, exist_ok=True)
    tmp_model_path = os.path.join(hf_model_path, "tmp")
    os.makedirs(tmp_model_path, exist_ok=True)
    
    logger.info(f"loading checkpoint from {checkpoint_dir_path}...")
    with open(get_config_checkpoint_path(checkpoint_name_base, checkpoint_dir_path), "r", encoding="utf-8") as f:
        config_checkpoint = json.load(f)
    model_checkpoint = torch.load(get_model_checkpoint_path(checkpoint_name_base, checkpoint_dir_path), map_location='cpu', weights_only=True)

    allamo_transformer_config = AllamoTransformerConfig(**config_checkpoint['model_args'])
    n_layers = allamo_transformer_config.n_layer
    intermediate_size = allamo_transformer_config.intermediate_size if hasattr(allamo_transformer_config, 'intermediate_size') else compute_intermediate_size(allamo_transformer_config)
    max_position_embeddings = allamo_transformer_config.block_size if hf_model_max_position_embeddings is None else hf_model_max_position_embeddings

    logger.info(f"converting all parameters from the checkpoint model")
    unwanted_prefix = '_orig_mod.'
    for k,v in list(model_checkpoint.items()):
        if k.startswith(unwanted_prefix):
            model_checkpoint[k[len(unwanted_prefix):]] = model_checkpoint.pop(k)
            
    param_count = 0
    index_dict = {"weight_map": {}}
    for layer_i in range(n_layers):
        logger.info(f"converting weights in layer {layer_i}")
        filename = f"pytorch_model-{layer_i + 1}-of-{n_layers + 1}.bin"
        state_dict = {
            f"model.layers.{layer_i}.self_attn.q_proj.weight": model_checkpoint[f"layers.{layer_i}.attention.q_proj.weight"],
            f"model.layers.{layer_i}.self_attn.k_proj.weight": model_checkpoint[f"layers.{layer_i}.attention.k_proj.weight"],
            f"model.layers.{layer_i}.self_attn.v_proj.weight": model_checkpoint[f"layers.{layer_i}.attention.v_proj.weight"],
            f"model.layers.{layer_i}.self_attn.o_proj.weight": model_checkpoint[f"layers.{layer_i}.attention.c_proj.weight"],
            f"model.layers.{layer_i}.mlp.gate_proj.weight": model_checkpoint[f"layers.{layer_i}.feed_forward.gate_proj.weight"],
            f"model.layers.{layer_i}.mlp.down_proj.weight": model_checkpoint[f"layers.{layer_i}.feed_forward.down_proj.weight"],
            f"model.layers.{layer_i}.mlp.up_proj.weight": model_checkpoint[f"layers.{layer_i}.feed_forward.up_proj.weight"],
            f"model.layers.{layer_i}.input_layernorm.weight": model_checkpoint[f"layers.{layer_i}.attention_norm.weight"],
            f"model.layers.{layer_i}.post_attention_layernorm.weight": model_checkpoint[f"layers.{layer_i}.ffn_norm.weight"]
        }
        if  allamo_transformer_config.bias:
                state_dict[f"model.layers.{layer_i}.self_attn.q_proj.bias"] = model_checkpoint[f"layers.{layer_i}.attention.q_proj.bias"]
                state_dict[f"model.layers.{layer_i}.self_attn.k_proj.bias"] = model_checkpoint[f"layers.{layer_i}.attention.k_proj.bias"]
                state_dict[f"model.layers.{layer_i}.self_attn.v_proj.bias"] = model_checkpoint[f"layers.{layer_i}.attention.v_proj.bias"]
                state_dict[f"model.layers.{layer_i}.self_attn.o_proj.bias"] = model_checkpoint[f"layers.{layer_i}.attention.c_proj.bias"]
                state_dict[f"model.layers.{layer_i}.mlp.gate_proj.bias"] = model_checkpoint[f"layers.{layer_i}.feed_forward.gate_proj.bias"]
                state_dict[f"model.layers.{layer_i}.mlp.down_proj.bias"] = model_checkpoint[f"layers.{layer_i}.feed_forward.down_proj.bias"]
                state_dict[f"model.layers.{layer_i}.mlp.up_proj.bias"] = model_checkpoint[f"layers.{layer_i}.feed_forward.up_proj.bias"]
        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"
    state_dict = {
        "model.embed_tokens.weight": model_checkpoint["tok_embeddings.weight"],
        "model.norm.weight": model_checkpoint["norm.weight"],
        "lm_head.weight": model_checkpoint["lm_head.weight"],
    }
    if hf_model_dtype:
        torch_dtype = {'float32': torch.float32, 'bfloat16': torch.bfloat16, 'float16': torch.float16}[hf_model_dtype]
        param_size_bytes = {'float32': 4, 'bfloat16': 2, 'float16': 2}[hf_model_dtype]
    else:
        # resolve model params dtype, e.g. torch.float16
        torch_dtype = model_checkpoint["lm_head.weight"].dtype
        param_size_bytes = 4 if torch_dtype == torch.float32 else 2

    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))
    logger.info(f"{param_count} params converted to HF LLaMA model")

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

    if hf_model_type == "llama":
        config = LlamaConfig(
            vocab_size=allamo_transformer_config.vocab_size,
            max_position_embeddings=max_position_embeddings,
            hidden_size=allamo_transformer_config.n_embd,
            intermediate_size=intermediate_size,
            num_attention_heads=allamo_transformer_config.n_head,
            num_key_value_heads=allamo_transformer_config.num_kv_heads,
            num_hidden_layers=n_layers,
            rms_norm_eps=allamo_transformer_config.norm_eps,
            rope_theta=allamo_transformer_config.rope_freq_base,
            attention_bias=allamo_transformer_config.bias,
            mlp_bias=allamo_transformer_config.bias,
        )
    elif hf_model_type == "mistral":
        assert not allamo_transformer_config.bias, "Mistral models don't support bias"
        config = MistralConfig(
            vocab_size=allamo_transformer_config.vocab_size,
            max_position_embeddings=max_position_embeddings,
            hidden_size=allamo_transformer_config.n_embd,
            intermediate_size=intermediate_size,
            num_attention_heads=allamo_transformer_config.n_head,
            num_key_value_heads=allamo_transformer_config.num_kv_heads,
            num_hidden_layers=n_layers,
            rms_norm_eps=allamo_transformer_config.norm_eps,
            rope_theta=allamo_transformer_config.rope_freq_base,
            sliding_window=allamo_transformer_config.sliding_window,
        )
    config.save_pretrained(tmp_model_path)
    logger.info(f"configuration for the HF LLaMA model saved")

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

    logger.info(f"loading the checkpoint in a LLaMA model with {torch_dtype} dtype")
    if hf_model_type == "llama":
        model = LlamaForCausalLM.from_pretrained(tmp_model_path, torch_dtype=torch_dtype, low_cpu_mem_usage=True)
    elif hf_model_type == "mistral":
        model = MistralForCausalLM.from_pretrained(tmp_model_path, torch_dtype=torch_dtype, low_cpu_mem_usage=True)
    # Avoid saving this as part of the config.
    del model.config._name_or_path

    logger.info(f"saving in the Transformers format")
    model.save_pretrained(hf_model_path)
    shutil.rmtree(tmp_model_path)
    logger.info(f"conversion completed!")


if __name__ == "__main__":
    configure_logger()
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--input_dir",
        help="Location of ALLaMo weights, which contains a checkpoint file",
    )
    parser.add_argument(
        "--checkpoint_name_base",
        default='ckpt',
        help="Checkpoint file name base",
    )
    parser.add_argument(
        "--output_dir",
        help="Location to write HF model",
    )
    parser.add_argument(
        "--model_type",
        choices=['llama', 'mistral'],
        default='llama',
        help="Determine model type",
    )
    parser.add_argument(
        "--output_dtype",
        choices=['float32', 'bfloat16', 'float16'],
        help="Override model dtype and save the model under a specific dtype",
    )
    parser.add_argument(
        "--max_position_embeddings",
        help="Overwrite max_position_embeddings with this value",
    )
    args = parser.parse_args()
    write_model(
        checkpoint_dir_path=args.input_dir,
        checkpoint_name_base=args.checkpoint_name_base,
        hf_model_path=args.output_dir,
        hf_model_type=args.model_type,
        hf_model_dtype=args.output_dtype,
        hf_model_max_position_embeddings=args.max_position_embeddings,
    )
