# Copyright 2024 Bytedance Ltd. and/or its affiliates
#
# 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.
"""
Utilities to check if packages are available.
We assume package availability won't change during runtime.
"""

from functools import cache
from typing import List, Optional


@cache
def is_megatron_core_available():
    try:
        from megatron.core import parallel_state as mpu
        return True
    except ImportError:
        return False


@cache
def is_vllm_available():
    try:
        import vllm
        from verl.third_party.vllm import parallel_state as vllm_ps
        return True
    except (ImportError, ValueError):
        return False


@cache
def is_sglang_available():
    try:
        import sglang
        return True
    except ImportError:
        return False


def import_external_libs(external_libs=None):
    if external_libs is None:
        return
    if not isinstance(external_libs, List):
        external_libs = [external_libs]
    import importlib
    for external_lib in external_libs:
        importlib.import_module(external_lib)


def load_extern_type(file_path: Optional[str], type_name: Optional[str]):
    """Load a external data type based on the file path and type name"""
    import importlib.util, os

    if not file_path:
        return None

    if not os.path.exists(file_path):
        raise FileNotFoundError(f"Custom type file '{file_path}' not found.")

    spec = importlib.util.spec_from_file_location("custom_module", file_path)
    module = importlib.util.module_from_spec(spec)
    try:
        spec.loader.exec_module(module)
    except Exception as e:
        raise RuntimeError(f"Error loading module from '{file_path}': {e}")

    if not hasattr(module, type_name):
        raise AttributeError(f"Custom type '{type_name}' not found in '{file_path}'.")

    return getattr(module, type_name)