"""Utilities for Huggingface Transformers."""

import json
import os
import warnings
from typing import List, Optional, Tuple, Union

from huggingface_hub import snapshot_download
from transformers import (
    AutoConfig,
    AutoProcessor,
    AutoTokenizer,
    PreTrainedTokenizer,
    PreTrainedTokenizerFast,
)

from sglang.srt.utils import is_multimodal_model


def download_from_hf(model_path: str):
    if os.path.exists(model_path):
        return model_path

    return snapshot_download(model_path, allow_patterns=["*.json", "*.bin", "*.model"])


def get_config_json(model_path: str):
    with open(os.path.join(model_path, "config.json")) as f:
        config = json.load(f)
    return config


def get_config(model: str, trust_remote_code: bool, revision: Optional[str] = None):
    config = AutoConfig.from_pretrained(
        model, trust_remote_code=trust_remote_code, revision=revision
    )
    return config


# Models don't use the same configuration key for determining the maximum
# context length.  Store them here so we can sanely check them.
# NOTE: The ordering here is important. Some models have two of these and we
# have a preference for which value gets used.
CONTEXT_LENGTH_KEYS = [
    "max_sequence_length",
    "seq_length",
    "max_position_embeddings",
    "max_seq_len",
    "model_max_length",
]


def get_context_length(config):
    """Get the context length of a model from a huggingface model config."""
    rope_scaling = getattr(config, "rope_scaling", None)
    if rope_scaling:
        rope_scaling_factor = config.rope_scaling["factor"]
    else:
        rope_scaling_factor = 1

    for key in CONTEXT_LENGTH_KEYS:
        val = getattr(config, key, None)
        if val is not None:
            return int(rope_scaling_factor * val)
    return 2048


# A fast LLaMA tokenizer with the pre-processed `tokenizer.json` file.
_FAST_LLAMA_TOKENIZER = "hf-internal-testing/llama-tokenizer"


def get_tokenizer(
    tokenizer_name: str,
    *args,
    tokenizer_mode: str = "auto",
    trust_remote_code: bool = False,
    tokenizer_revision: Optional[str] = None,
    **kwargs,
) -> Union[PreTrainedTokenizer, PreTrainedTokenizerFast]:
    """Gets a tokenizer for the given model name via Huggingface."""
    if is_multimodal_model(tokenizer_name):
        processor = get_processor(
            tokenizer_name,
            *args,
            trust_remote_code=trust_remote_code,
            tokenizer_revision=tokenizer_revision,
            **kwargs,
        )
        tokenizer = processor.tokenizer
        return tokenizer

    if tokenizer_mode == "slow":
        if kwargs.get("use_fast", False):
            raise ValueError("Cannot use the fast tokenizer in slow tokenizer mode.")
        kwargs["use_fast"] = False

    if (
        "llama" in tokenizer_name.lower()
        and kwargs.get("use_fast", True)
        and tokenizer_name != _FAST_LLAMA_TOKENIZER
    ):
        pass
        # warnings.warn(
        #    "For some LLaMA V1 models, initializing the fast tokenizer may "
        #    "take a long time. To reduce the initialization time, consider "
        #    f"using '{_FAST_LLAMA_TOKENIZER}' instead of the original "
        #    "tokenizer."
        # )
    try:
        tokenizer = AutoTokenizer.from_pretrained(
            tokenizer_name,
            *args,
            trust_remote_code=trust_remote_code,
            tokenizer_revision=tokenizer_revision,
            **kwargs,
        )
    except TypeError as e:
        # The LLaMA tokenizer causes a protobuf error in some environments.
        err_msg = (
            "Failed to load the tokenizer. If you are using a LLaMA V1 model "
            f"consider using '{_FAST_LLAMA_TOKENIZER}' instead of the "
            "original tokenizer."
        )
        raise RuntimeError(err_msg) from e
    except ValueError as e:
        # If the error pertains to the tokenizer class not existing or not
        # currently being imported, suggest using the --trust-remote-code flag.
        if not trust_remote_code and (
            "does not exist or is not currently imported." in str(e)
            or "requires you to execute the tokenizer file" in str(e)
        ):
            err_msg = (
                "Failed to load the tokenizer. If the tokenizer is a custom "
                "tokenizer not yet available in the HuggingFace transformers "
                "library, consider setting `trust_remote_code=True` in LLM "
                "or using the `--trust-remote-code` flag in the CLI."
            )
            raise RuntimeError(err_msg) from e
        else:
            raise e

    if not isinstance(tokenizer, PreTrainedTokenizerFast):
        warnings.warn(
            "Using a slow tokenizer. This might cause a significant "
            "slowdown. Consider using a fast tokenizer instead."
        )
    return tokenizer


def get_processor(
    tokenizer_name: str,
    *args,
    tokenizer_mode: str = "auto",
    trust_remote_code: bool = False,
    tokenizer_revision: Optional[str] = None,
    **kwargs,
):
    processor = AutoProcessor.from_pretrained(
        tokenizer_name,
        *args,
        trust_remote_code=trust_remote_code,
        tokenizer_revision=tokenizer_revision,
        **kwargs,
    )
    return processor
