# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import os
from collections.abc import Generator

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

from vllm.config import ModelConfig
from vllm.config.load import LoadConfig
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,
    runai_safetensors_weights_iterator,
)
from vllm.transformers_utils.runai_utils import is_runai_obj_uri, list_safetensors


class RunaiModelStreamerLoader(BaseModelLoader):
    """
    Model loader that can load safetensors
    files from local FS or S3 bucket.
    """

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

        self._is_distributed = False
        if load_config.model_loader_extra_config:
            extra_config = load_config.model_loader_extra_config

            if "distributed" in extra_config and isinstance(
                extra_config.get("distributed"), bool
            ):
                self._is_distributed = extra_config.get("distributed")

            if "concurrency" in extra_config and isinstance(
                extra_config.get("concurrency"), int
            ):
                os.environ["RUNAI_STREAMER_CONCURRENCY"] = str(
                    extra_config.get("concurrency")
                )

            if "memory_limit" in extra_config and isinstance(
                extra_config.get("memory_limit"), int
            ):
                os.environ["RUNAI_STREAMER_MEMORY_LIMIT"] = str(
                    extra_config.get("memory_limit")
                )

            runai_streamer_s3_endpoint = os.getenv("RUNAI_STREAMER_S3_ENDPOINT")
            aws_endpoint_url = os.getenv("AWS_ENDPOINT_URL")
            if runai_streamer_s3_endpoint is None and aws_endpoint_url is not None:
                os.environ["RUNAI_STREAMER_S3_ENDPOINT"] = aws_endpoint_url

    def _prepare_weights(
        self, model_name_or_path: str, revision: str | None
    ) -> list[str]:
        """Prepare weights for the model.

        If the model is not local, it will be downloaded."""

        is_object_storage_path = is_runai_obj_uri(model_name_or_path)
        is_local = os.path.isdir(model_name_or_path)
        safetensors_pattern = "*.safetensors"
        index_file = SAFE_WEIGHTS_INDEX_NAME

        hf_folder = (
            model_name_or_path
            if (is_local or is_object_storage_path)
            else download_weights_from_hf(
                model_name_or_path,
                self.load_config.download_dir,
                [safetensors_pattern],
                revision,
                ignore_patterns=self.load_config.ignore_patterns,
            )
        )
        hf_weights_files = list_safetensors(path=hf_folder)

        if not is_local and not is_object_storage_path:
            download_safetensors_index_file_from_hf(
                model_name_or_path, index_file, self.load_config.download_dir, revision
            )

        if not hf_weights_files:
            raise RuntimeError(
                f"Cannot find any safetensors model weights with `{model_name_or_path}`"
            )

        return hf_weights_files

    def _get_weights_iterator(
        self, model_or_path: str, revision: str
    ) -> Generator[tuple[str, torch.Tensor], None, None]:
        """Get an iterator for the model weights based on the load format."""
        hf_weights_files = self._prepare_weights(model_or_path, revision)
        return runai_safetensors_weights_iterator(
            hf_weights_files, self.load_config.use_tqdm_on_load, self._is_distributed
        )

    def download_model(self, model_config: ModelConfig) -> None:
        """Download model if necessary"""
        self._prepare_weights(model_config.model, model_config.revision)

    def load_weights(self, model: nn.Module, model_config: ModelConfig) -> None:
        """Load weights into a model."""
        model_weights = model_config.model
        if model_weights_override := model_config.model_weights:
            model_weights = model_weights_override
        model.load_weights(
            self._get_weights_iterator(model_weights, model_config.revision)
        )
