# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import dataclasses
import glob
import os
import time
from collections.abc import Generator, Iterable
from typing import Optional, cast

import huggingface_hub
import torch
from torch import nn
from transformers.utils import SAFE_WEIGHTS_INDEX_NAME

from vllm import envs
from vllm.config import LoadConfig, LoadFormat, ModelConfig
from vllm.logger import init_logger
from vllm.model_executor.model_loader.base_loader import BaseModelLoader
from vllm.model_executor.model_loader.weight_utils import (
    download_safetensors_index_file_from_hf, download_weights_from_hf,
    fastsafetensors_weights_iterator, filter_duplicate_safetensors_files,
    filter_files_not_needed_for_inference, get_lock, np_cache_weights_iterator,
    pt_weights_iterator, safetensors_weights_iterator)
from vllm.platforms import current_platform

logger = init_logger(__name__)


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

    @dataclasses.dataclass
    class Source:
        """A source for weights."""

        model_or_path: str
        """The model ID or path."""

        revision: Optional[str]
        """The optional model revision."""

        prefix: str = ""
        """A prefix to prepend to all weights."""

        fall_back_to_pt: bool = True
        """Whether .pt weights can be used."""

        allow_patterns_overrides: Optional[list[str]] = None
        """If defined, weights will load exclusively using these patterns."""

    counter_before_loading_weights: float = 0.0
    counter_after_loading_weights: float = 0.0

    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 envs.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):
                # Use file lock to prevent multiple processes from
                # downloading the same model weights at the same time.
                with get_lock(model, self.load_config.download_dir):
                    model_path = snapshot_download(
                        model_id=model,
                        cache_dir=self.load_config.download_dir,
                        local_files_only=huggingface_hub.constants.
                        HF_HUB_OFFLINE,
                        revision=revision,
                        ignore_file_pattern=self.load_config.ignore_patterns,
                    )
            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,
        allow_patterns_overrides: Optional[list[str]],
    ) -> 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
        index_file = SAFE_WEIGHTS_INDEX_NAME
        # Some quantized models use .pt files for storing the weights.
        if load_format == LoadFormat.AUTO:
            allow_patterns = ["*.safetensors", "*.bin"]
        elif (load_format == LoadFormat.SAFETENSORS
              or load_format == LoadFormat.FASTSAFETENSORS):
            use_safetensors = True
            allow_patterns = ["*.safetensors"]
        elif load_format == LoadFormat.MISTRAL:
            use_safetensors = True
            allow_patterns = ["consolidated*.safetensors"]
            index_file = "consolidated.safetensors.index.json"
        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 allow_patterns_overrides is not None:
            allow_patterns = allow_patterns_overrides

        if not is_local:
            hf_folder = download_weights_from_hf(
                model_name_or_path,
                self.load_config.download_dir,
                allow_patterns,
                revision,
                ignore_patterns=self.load_config.ignore_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 use_safetensors:
            # For models like Mistral-7B-Instruct-v0.3
            # there are both sharded safetensors files and a consolidated
            # safetensors file. Using both breaks.
            # Here, we download the `model.safetensors.index.json` and filter
            # any files not found in the index.
            if not is_local:
                download_safetensors_index_file_from_hf(
                    model_name_or_path,
                    index_file,
                    self.load_config.download_dir,
                    revision,
                )
            hf_weights_files = filter_duplicate_safetensors_files(
                hf_weights_files, hf_folder, index_file)
        else:
            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, source: "Source"
    ) -> 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(
            source.model_or_path, source.revision, source.fall_back_to_pt,
            source.allow_patterns_overrides)
        if self.load_config.load_format == LoadFormat.NPCACHE:
            # Currently np_cache only support *.bin checkpoints
            assert use_safetensors is False
            weights_iterator = np_cache_weights_iterator(
                source.model_or_path,
                self.load_config.download_dir,
                hf_folder,
                hf_weights_files,
                self.load_config.use_tqdm_on_load,
            )
        elif use_safetensors:
            if self.load_config.load_format == LoadFormat.FASTSAFETENSORS:
                weights_iterator = fastsafetensors_weights_iterator(
                    hf_weights_files,
                    self.load_config.use_tqdm_on_load,
                )
            else:
                weights_iterator = safetensors_weights_iterator(
                    hf_weights_files,
                    self.load_config.use_tqdm_on_load,
                )
        else:
            weights_iterator = pt_weights_iterator(
                hf_weights_files,
                self.load_config.use_tqdm_on_load,
                self.load_config.pt_load_map_location,
            )

        if current_platform.is_tpu():
            # In PyTorch XLA, we should call `xm.mark_step` frequently so that
            # not too many ops are accumulated in the XLA program.
            import torch_xla.core.xla_model as xm

            def _xla_weights_iterator(iterator: Generator):
                for weights in iterator:
                    yield weights
                    xm.mark_step()

            weights_iterator = _xla_weights_iterator(weights_iterator)

        if self.counter_before_loading_weights == 0.0:
            self.counter_before_loading_weights = time.perf_counter()
        # Apply the prefix.
        return ((source.prefix + name, tensor)
                for (name, tensor) in weights_iterator)

    def get_all_weights(
        self,
        model_config: ModelConfig,
        model: nn.Module,
    ) -> Generator[tuple[str, torch.Tensor], None, None]:
        primary_weights = DefaultModelLoader.Source(
            model_config.model,
            model_config.revision,
            prefix="",
            fall_back_to_pt=getattr(model, "fall_back_to_pt_during_load",
                                    True),
            allow_patterns_overrides=getattr(model, "allow_patterns_overrides",
                                             None),
        )
        yield from self._get_weights_iterator(primary_weights)

        secondary_weights = cast(
            Iterable[DefaultModelLoader.Source],
            getattr(model, "secondary_weights", ()),
        )
        for source in secondary_weights:
            yield from self._get_weights_iterator(source)

    def download_model(self, model_config: ModelConfig) -> None:
        self._prepare_weights(model_config.model,
                              model_config.revision,
                              fall_back_to_pt=True,
                              allow_patterns_overrides=None)

    def load_weights(self, model: nn.Module,
                     model_config: ModelConfig) -> None:
        weights_to_load = {name for name, _ in model.named_parameters()}
        loaded_weights = model.load_weights(
            self.get_all_weights(model_config, model))
        self.counter_after_loading_weights = time.perf_counter()
        logger.info(
            "Loading weights took %.2f seconds",
            self.counter_after_loading_weights -
            self.counter_before_loading_weights)
        # We only enable strict check for non-quantized models
        # that have loaded weights tracking currently.
        if model_config.quantization is None and loaded_weights is not None:
            weights_not_loaded = weights_to_load - loaded_weights
            if weights_not_loaded:
                raise ValueError("Following weights were not initialized from "
                                 f"checkpoint: {weights_not_loaded}")
