# ruff: noqa: SIM117
import copy
import glob
import os
from abc import ABC, abstractmethod
from typing import (TYPE_CHECKING, Any, Dict, Generator, List, Optional, Tuple,
                    Type)

import torch
from torch import nn

from vllm.config import (VLLM_USE_MODELSCOPE, DeviceConfig, LoadConfig,
                         LoadFormat, LoRAConfig, ModelConfig, ParallelConfig,
                         SchedulerConfig, VisionLanguageConfig)
from vllm.logger import init_logger
from vllm.model_executor.model_loader.tensorizer import (
    TensorizerConfig, is_vllm_serialized_tensorizer, load_with_tensorizer,
    tensorizer_weights_iterator)
from vllm.model_executor.model_loader.utils import (get_model_architecture,
                                                    set_default_torch_dtype)
from vllm.model_executor.model_loader.weight_utils import (
    download_weights_from_hf, filter_files_not_needed_for_inference,
    get_quant_config, initialize_dummy_weights, np_cache_weights_iterator,
    pt_weights_iterator, safetensors_weights_iterator)
from vllm.model_executor.models.llava import LlavaForConditionalGeneration

if TYPE_CHECKING:
    from vllm.model_executor.layers.linear import LinearMethodBase

_VISION_MODEL_CLASSES = [
    LlavaForConditionalGeneration,
]

logger = init_logger(__name__)


def _get_linear_method(
        model_config: ModelConfig,
        load_config: LoadConfig) -> Optional["LinearMethodBase"]:
    """Get the (maybe quantized) linear method."""
    linear_method = None
    if model_config.quantization is not None:
        quant_config = get_quant_config(model_config, load_config)
        capability = torch.cuda.get_device_capability()
        capability = capability[0] * 10 + capability[1]
        if capability < quant_config.get_min_capability():
            raise ValueError(
                f"The quantization method {model_config.quantization} is not "
                "supported for the current GPU. "
                f"Minimum capability: {quant_config.get_min_capability()}. "
                f"Current capability: {capability}.")
        supported_dtypes = quant_config.get_supported_act_dtypes()
        if model_config.dtype not in supported_dtypes:
            raise ValueError(
                f"{model_config.dtype} is not supported for quantization "
                f"method {model_config.quantization}. Supported dtypes: "
                f"{supported_dtypes}")

        linear_method = quant_config.get_linear_method()
    return linear_method


def _get_model_initialization_kwargs(
        model_class: Type[nn.Module], lora_config: Optional[LoRAConfig],
        vision_language_config: Optional[VisionLanguageConfig]
) -> Dict[str, Any]:
    """Get extra kwargs for model initialization."""
    extra_kwargs = {}
    if hasattr(model_class, "supported_lora_modules"):
        extra_kwargs["lora_config"] = lora_config
    elif lora_config:
        raise ValueError(
            f"Model {model_class.__name__} does not support LoRA, "
            "but LoRA is enabled. Support for this model may "
            "be added in the future. If this is important to you, "
            "please open an issue on github.")
    elif model_class in _VISION_MODEL_CLASSES:
        extra_kwargs["vision_language_config"] = vision_language_config
    return extra_kwargs


def _initialize_model(
        model_config: ModelConfig, load_config: LoadConfig,
        lora_config: Optional[LoRAConfig],
        vision_language_config: Optional[VisionLanguageConfig]) -> nn.Module:
    """Initialize a model with the given configurations."""
    model_class = get_model_architecture(model_config)[0]
    linear_method = _get_linear_method(model_config, load_config)

    return model_class(config=model_config.hf_config,
                       linear_method=linear_method,
                       **_get_model_initialization_kwargs(
                           model_class, lora_config, vision_language_config))


class BaseModelLoader(ABC):
    """Base class for model loaders."""

    def __init__(self, load_config: LoadConfig):
        self.load_config = load_config

    @abstractmethod
    def load_model(self, *, model_config: ModelConfig,
                   device_config: DeviceConfig,
                   lora_config: Optional[LoRAConfig],
                   vision_language_config: Optional[VisionLanguageConfig],
                   parallel_config: ParallelConfig,
                   scheduler_config: SchedulerConfig) -> nn.Module:
        """Load a model with the given configurations."""
        ...


class DefaultModelLoader(BaseModelLoader):
    """Model loader that can load different file types from disk."""

    def __init__(self, load_config: LoadConfig):
        super().__init__(load_config)
        if load_config.model_loader_extra_config:
            raise ValueError(f"Model loader extra config is not supported for "
                             f"load format {load_config.load_format}")

    def _maybe_download_from_modelscope(
            self, model: str, revision: Optional[str]) -> Optional[str]:
        """Download model from ModelScope hub if VLLM_USE_MODELSCOPE is True.
        
        Returns the path to the downloaded model, or None if the model is not
        downloaded from ModelScope."""
        if VLLM_USE_MODELSCOPE:
            # download model from ModelScope hub,
            # lazy import so that modelscope is not required for normal use.
            # pylint: disable=C.
            from modelscope.hub.snapshot_download import snapshot_download

            if not os.path.exists(model):
                model_path = snapshot_download(
                    model_id=model,
                    cache_dir=self.load_config.download_dir,
                    revision=revision)
            else:
                model_path = model
            return model_path
        return None

    def _prepare_weights(self, model_name_or_path: str,
                         revision: Optional[str],
                         fall_back_to_pt: bool) -> Tuple[str, List[str], bool]:
        """Prepare weights for the model.

        If the model is not local, it will be downloaded."""
        model_name_or_path = self._maybe_download_from_modelscope(
            model_name_or_path, revision) or model_name_or_path

        is_local = os.path.isdir(model_name_or_path)
        load_format = self.load_config.load_format
        use_safetensors = False
        # Some quantized models use .pt files for storing the weights.
        if load_format == LoadFormat.AUTO:
            allow_patterns = ["*.safetensors", "*.bin"]
        elif load_format == LoadFormat.SAFETENSORS:
            use_safetensors = True
            allow_patterns = ["*.safetensors"]
        elif load_format == LoadFormat.PT:
            allow_patterns = ["*.pt"]
        elif load_format == LoadFormat.NPCACHE:
            allow_patterns = ["*.bin"]
        else:
            raise ValueError(f"Unknown load_format: {load_format}")

        if fall_back_to_pt:
            allow_patterns += ["*.pt"]

        if not is_local:
            hf_folder = download_weights_from_hf(model_name_or_path,
                                                 self.load_config.download_dir,
                                                 allow_patterns)
        else:
            hf_folder = model_name_or_path

        hf_weights_files: List[str] = []
        for pattern in allow_patterns:
            hf_weights_files += glob.glob(os.path.join(hf_folder, pattern))
            if len(hf_weights_files) > 0:
                if pattern == "*.safetensors":
                    use_safetensors = True
                break

        if not use_safetensors:
            hf_weights_files = filter_files_not_needed_for_inference(
                hf_weights_files)

        if len(hf_weights_files) == 0:
            raise RuntimeError(
                f"Cannot find any model weights with `{model_name_or_path}`")

        return hf_folder, hf_weights_files, use_safetensors

    def _get_weights_iterator(
        self, model_name_or_path: str, revision: Optional[str],
        fall_back_to_pt: bool
    ) -> Generator[Tuple[str, torch.Tensor], None, None]:
        """Get an iterator for the model weights based on the load format."""
        hf_folder, hf_weights_files, use_safetensors = self._prepare_weights(
            model_name_or_path, revision, fall_back_to_pt)
        if self.load_config.load_format == LoadFormat.NPCACHE:
            # Currently np_cache only support *.bin checkpoints
            assert use_safetensors is False
            return np_cache_weights_iterator(model_name_or_path,
                                             self.load_config.download_dir,
                                             hf_folder, hf_weights_files)
        if use_safetensors:
            return safetensors_weights_iterator(hf_weights_files)
        return pt_weights_iterator(hf_weights_files)

    def load_model(self, *, model_config: ModelConfig,
                   device_config: DeviceConfig,
                   lora_config: Optional[LoRAConfig],
                   vision_language_config: Optional[VisionLanguageConfig],
                   parallel_config: ParallelConfig,
                   scheduler_config: SchedulerConfig) -> nn.Module:
        with set_default_torch_dtype(model_config.dtype):
            with torch.device(device_config.device):
                model = _initialize_model(model_config, self.load_config,
                                          lora_config, vision_language_config)
            model.load_weights(
                self._get_weights_iterator(model_config.model,
                                           model_config.revision,
                                           fall_back_to_pt=getattr(
                                               model,
                                               "fall_back_to_pt_during_load",
                                               True)), )
        return model.eval()


class DummyModelLoader(BaseModelLoader):
    """Model loader that will set model weights to random values."""

    def __init__(self, load_config: LoadConfig):
        super().__init__(load_config)
        if load_config.model_loader_extra_config:
            raise ValueError(f"Model loader extra config is not supported for "
                             f"load format {load_config.load_format}")

    def load_model(self, *, model_config: ModelConfig,
                   device_config: DeviceConfig,
                   lora_config: Optional[LoRAConfig],
                   vision_language_config: Optional[VisionLanguageConfig],
                   parallel_config: ParallelConfig,
                   scheduler_config: SchedulerConfig) -> nn.Module:
        with set_default_torch_dtype(model_config.dtype):
            with torch.device(device_config.device):
                model = _initialize_model(model_config, self.load_config,
                                          lora_config, vision_language_config)
            # NOTE(woosuk): For accurate performance evaluation, we assign
            # random values to the weights.
            initialize_dummy_weights(model)
        return model.eval()


class TensorizerLoader(BaseModelLoader):
    """Model loader using CoreWeave's tensorizer library."""

    def __init__(self, load_config: LoadConfig):
        super().__init__(load_config)
        if isinstance(load_config.model_loader_extra_config, TensorizerConfig):
            self.tensorizer_config = load_config.model_loader_extra_config
        else:
            self.tensorizer_config = TensorizerConfig(
                **load_config.model_loader_extra_config)

    def _verify_config(self, model_config: ModelConfig,
                       parallel_config: ParallelConfig):
        self.tensorizer_config.verify_with_model_config(model_config)
        self.tensorizer_config.verify_with_parallel_config(parallel_config)

    def _get_weights_iterator(
            self) -> Generator[Tuple[str, torch.Tensor], None, None]:
        tensorizer_args = self.tensorizer_config._construct_tensorizer_args()
        return tensorizer_weights_iterator(tensorizer_args)

    def _load_model_unserialized(
            self, model_config: ModelConfig, device_config: DeviceConfig,
            lora_config: Optional[LoRAConfig],
            vision_language_config: Optional[VisionLanguageConfig]
    ) -> nn.Module:
        """Load an unserialized model with tensorizer.

        Unserialized here means "not serialized with tensorizer". This
        should still be faster than default HuggingFace loading, but will
        be slower than loading a tensorizer-serialized model.
        """
        with set_default_torch_dtype(model_config.dtype):
            with torch.device(device_config.device):
                model = _initialize_model(model_config, self.load_config,
                                          lora_config, vision_language_config)

            model.load_weights(self._get_weights_iterator())
        return model.eval()

    def _load_model_serialized(
            self, model_config: ModelConfig, device_config: DeviceConfig,
            lora_config: Optional[LoRAConfig],
            vision_language_config: Optional[VisionLanguageConfig]
    ) -> nn.Module:
        """Load a serialized model with tensorizer.

        See the examples/tensorize_vllm_model.py example "
        script for serializing vLLM models."""
        with set_default_torch_dtype(model_config.dtype):
            with torch.device(device_config.device):
                model_class = get_model_architecture(model_config)[0]
                linear_method = _get_linear_method(model_config,
                                                   self.load_config)
                extra_kwargs = _get_model_initialization_kwargs(
                    model_class, lora_config, vision_language_config)
                extra_kwargs["linear_method"] = linear_method

                tensorizer_config = copy.copy(self.tensorizer_config)
                tensorizer_config.model_class = model_class
                tensorizer_config.hf_config = model_config.hf_config
                tensorizer_config.dtype = model_config.dtype

                model = load_with_tensorizer(tensorizer_config, **extra_kwargs)
        return model.eval()

    def load_model(self, *, model_config: ModelConfig,
                   device_config: DeviceConfig,
                   lora_config: Optional[LoRAConfig],
                   vision_language_config: Optional[VisionLanguageConfig],
                   parallel_config: ParallelConfig,
                   scheduler_config: SchedulerConfig) -> nn.Module:
        self._verify_config(model_config, parallel_config)

        if is_vllm_serialized_tensorizer(self.tensorizer_config):
            return self._load_model_serialized(model_config, device_config,
                                               lora_config,
                                               vision_language_config)
        return self._load_model_unserialized(model_config, device_config,
                                             lora_config,
                                             vision_language_config)


def get_model_loader(load_config: LoadConfig) -> BaseModelLoader:
    """Get a model loader based on the load format."""

    if isinstance(load_config.load_format, type):
        return load_config.load_format(load_config)

    if load_config.load_format == LoadFormat.DUMMY:
        return DummyModelLoader(load_config)

    if load_config.load_format == LoadFormat.TENSORIZER:
        return TensorizerLoader(load_config)

    return DefaultModelLoader(load_config)
