#    Copyright 2023 Haotian Liu
#
#    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 os
import warnings
import shutil

from transformers import AutoTokenizer, AutoModelForCausalLM, AutoConfig, BitsAndBytesConfig
import torch
from llavavid.model import *
from llavavid.constants import DEFAULT_IMAGE_PATCH_TOKEN, DEFAULT_IM_START_TOKEN, DEFAULT_IM_END_TOKEN


def load_pretrained_model(model_path, model_base, model_name, load_8bit=False, load_4bit=False, device_map="auto", overwrite_config=None):
    kwargs = {"device_map": device_map}

    # import pdb;pdb.set_trace()
    if load_8bit:
        kwargs["load_in_8bit"] = True
    elif load_4bit:
        kwargs["load_in_4bit"] = True
        kwargs["quantization_config"] = BitsAndBytesConfig(load_in_4bit=True, bnb_4bit_compute_dtype=torch.float16, bnb_4bit_use_double_quant=True, bnb_4bit_quant_type="nf4")
    else:
        kwargs["torch_dtype"] = torch.float16

    if "llava" in model_name.lower():
        # Load LLaVA model
        if "lora" in model_name.lower() and model_base is None:
            warnings.warn(
                "There is `lora` in model name but no `model_base` is provided. If you are loading a LoRA model, please provide the `model_base` argument. Detailed instruction: https://github.com/haotian-liu/LLaVA#launch-a-model-worker-lora-weights-unmerged."
            )
        if "lora" in model_name.lower() and model_base is not None:
            lora_cfg_pretrained = AutoConfig.from_pretrained(model_path)
            tokenizer = AutoTokenizer.from_pretrained(model_base, use_fast=False)
            print("Loading LLaVA from base model...")
            if "mixtral" in model_name.lower():
                model = LlavaMixtralForCausalLM.from_pretrained(model_base, low_cpu_mem_usage=True, config=lora_cfg_pretrained, **kwargs)
            else:
                model = LlavaLlamaForCausalLM.from_pretrained(model_base, low_cpu_mem_usage=True, config=lora_cfg_pretrained, **kwargs)
            token_num, tokem_dim = model.lm_head.out_features, model.lm_head.in_features
            if model.lm_head.weight.shape[0] != token_num:
                model.lm_head.weight = torch.nn.Parameter(torch.empty(token_num, tokem_dim, device=model.device, dtype=model.dtype))
                model.model.embed_tokens.weight = torch.nn.Parameter(torch.empty(token_num, tokem_dim, device=model.device, dtype=model.dtype))

            print("Loading additional LLaVA weights...")
            if os.path.exists(os.path.join(model_path, "non_lora_trainables.bin")):
                non_lora_trainables = torch.load(os.path.join(model_path, "non_lora_trainables.bin"), map_location="cpu")
            else:
                # this is probably from HF Hub
                from huggingface_hub import hf_hub_download

                def load_from_hf(repo_id, filename, subfolder=None):
                    cache_file = hf_hub_download(repo_id=repo_id, filename=filename, subfolder=subfolder)
                    return torch.load(cache_file, map_location="cpu")

                non_lora_trainables = load_from_hf(model_path, "non_lora_trainables.bin")
            non_lora_trainables = {(k[11:] if k.startswith("base_model.") else k): v for k, v in non_lora_trainables.items()}
            if any(k.startswith("model.model.") for k in non_lora_trainables):
                non_lora_trainables = {(k[6:] if k.startswith("model.") else k): v for k, v in non_lora_trainables.items()}
            model.load_state_dict(non_lora_trainables, strict=False)

            from peft import PeftModel

            print("Loading LoRA weights...")
            model = PeftModel.from_pretrained(model, model_path)
            print("Merging LoRA weights...")
            model = model.merge_and_unload()
            print("Model is loaded...")
        elif model_base is not None:
            # this may be mm projector only
            print("Loading LLaVA from base model...")
            if "mpt" in model_name.lower().replace("prompt", ""):
                if not os.path.isfile(os.path.join(model_path, "configuration_mpt.py")):
                    shutil.copyfile(os.path.join(model_base, "configuration_mpt.py"), os.path.join(model_path, "configuration_mpt.py"))
                tokenizer = AutoTokenizer.from_pretrained(model_base, use_fast=True)
                cfg_pretrained = AutoConfig.from_pretrained(model_path, trust_remote_code=True)
                model = LlavaMptForCausalLM.from_pretrained(model_base, low_cpu_mem_usage=True, config=cfg_pretrained, **kwargs)
            else:
                tokenizer = AutoTokenizer.from_pretrained(model_base, use_fast=False)
                cfg_pretrained = AutoConfig.from_pretrained(model_path)
                if overwrite_config is not None:
                    print(f"Overwriting config with {overwrite_config}")
                    for k, v in overwrite_config.items():
                        setattr(cfg_pretrained, k, v)
                model = LlavaLlamaForCausalLM.from_pretrained(model_base, low_cpu_mem_usage=True, config=cfg_pretrained, **kwargs)

            mm_projector_weights = torch.load(os.path.join(model_path, "mm_projector.bin"), map_location="cpu")
            mm_projector_weights = {k: v.to(torch.float16) for k, v in mm_projector_weights.items()}
            model.load_state_dict(mm_projector_weights, strict=False)
        else:
            if "mpt" in model_name.lower().replace("prompt", ""):
                tokenizer = AutoTokenizer.from_pretrained(model_path, use_fast=True)
                model = LlavaMptForCausalLM.from_pretrained(model_path, low_cpu_mem_usage=True, **kwargs)
            elif "mixtral" in model_name.lower() and "vicuna" not in model_name.lower() and "mistral" not in model_name.lower():
                tokenizer = AutoTokenizer.from_pretrained(model_path)
                model = LlavaMixtralForCausalLM.from_pretrained(model_path, low_cpu_mem_usage=True, **kwargs)
            elif "mistral" in model_name.lower() or "zephyr" in model_name.lower():
                tokenizer = AutoTokenizer.from_pretrained(model_path)
                cfg_pretrained = AutoConfig.from_pretrained(model_path)
                # import pdb;pdb.set_trace()
                if overwrite_config is not None:
                    print(f"Overwriting config with {overwrite_config}")
                    for k, v in overwrite_config.items():
                        setattr(cfg_pretrained, k, v)
                model = LlavaMistralForCausalLM.from_pretrained(model_path, low_cpu_mem_usage=True, config=cfg_pretrained, **kwargs)
            else:
                tokenizer = AutoTokenizer.from_pretrained(model_path, use_fast=False)
                cfg_pretrained = AutoConfig.from_pretrained(model_path)
                if overwrite_config is not None:
                    print(f"Overwriting config with {overwrite_config}")
                    for k, v in overwrite_config.items():
                        setattr(cfg_pretrained, k, v)
                model = LlavaLlamaForCausalLM.from_pretrained(model_path, low_cpu_mem_usage=True, config=cfg_pretrained, **kwargs)
    else:
        # Load language model
        if model_base is not None:
            # PEFT model
            from peft import PeftModel

            tokenizer = AutoTokenizer.from_pretrained(model_base, use_fast=False)
            model = AutoModelForCausalLM.from_pretrained(model_base, torch_dtype=torch.float16, low_cpu_mem_usage=True, device_map="auto")
            print(f"Loading LoRA weights from {model_path}")
            model = PeftModel.from_pretrained(model, model_path)
            print(f"Merging weights")
            model = model.merge_and_unload()
            print("Convert to FP16...")
            model.to(torch.float16)
        else:
            use_fast = False
            if "mpt" in model_name.lower().replace("prompt", ""):
                tokenizer = AutoTokenizer.from_pretrained(model_path, use_fast=True)
                model = AutoModelForCausalLM.from_pretrained(model_path, low_cpu_mem_usage=True, trust_remote_code=True, **kwargs)
            else:
                tokenizer = AutoTokenizer.from_pretrained(model_path, use_fast=False)
                model = AutoModelForCausalLM.from_pretrained(model_path, low_cpu_mem_usage=True, **kwargs)

    image_processor = None

    assert "llava" in model_name.lower(), "Only LLaVA models are supported for video chatbot."
    mm_use_im_start_end = getattr(model.config, "mm_use_im_start_end", False)
    mm_use_im_patch_token = getattr(model.config, "mm_use_im_patch_token", True)
    if mm_use_im_patch_token:
        tokenizer.add_tokens([DEFAULT_IMAGE_PATCH_TOKEN], special_tokens=True)
    if mm_use_im_start_end:
        tokenizer.add_tokens([DEFAULT_IM_START_TOKEN, DEFAULT_IM_END_TOKEN], special_tokens=True)
    model.resize_token_embeddings(len(tokenizer))

    vision_tower = model.get_vision_tower()
    if not vision_tower.is_loaded:
        vision_tower.load_model(device_map=device_map)
    if device_map != "auto":
        vision_tower.to(device="cuda", dtype=torch.float16)
    image_processor = vision_tower.image_processor

    if hasattr(model.config, "max_sequence_length"):
        context_len = model.config.max_sequence_length
    else:
        context_len = 2048

    return tokenizer, model, image_processor, context_len