import os
import configparser
from typing import Optional


class Config:
    """从 config.ini 读取的应用配置"""

    _config = configparser.ConfigParser()
    _root_dir = os.path.dirname(os.path.dirname(__file__))
    _config_path = os.path.join(_root_dir, 'config', 'config.ini')

    # 在类初始化时加载配置
    if not os.path.exists(_config_path):
        raise FileNotFoundError(
            f"Configuration file not found at: {_config_path}. "
            "Please copy 'config/config.ini.example' to 'config/config.ini' and fill in your details."
        )

    try:
        with open(_config_path, "r", encoding="utf-8") as f:
            _config.read_file(f)
    except UnicodeDecodeError:
        with open(_config_path, "r", encoding="gbk") as f:
            _config.read_file(f)

    # 通用设置
    DEFAULT_MODEL_SECTION: str = _config.get('General', 'DEFAULT_MODEL_SECTION', fallback='gpt-4o')
    MAX_RETRIES: int = _config.getint('General', 'MAX_RETRIES', fallback=3)
    TIMEOUT: int = _config.getint('General', 'TIMEOUT', fallback=30)

    @classmethod
    def get_model_config(cls, section: Optional[str] = None) -> dict:
        """
        获取指定模型配置段。
        若 section 为 None，则使用默认模型配置段。
        """
        if section is None:
            section = cls.DEFAULT_MODEL_SECTION

        if not cls._config.has_section(section):
            raise ValueError(f"Model section '{section}' not found in config.ini")

        config = dict(cls._config.items(section))

        # 确保必需的键存在
        if 'model_name' not in config or 'openai_api_key' not in config:
            raise ValueError(f"Model section '{section}' must contain 'model_name' and 'openai_api_key'")

        return {
            "model": config['model_name'],
            "api_key": config['openai_api_key'],
            "base_url": config.get('url') or config.get('base_url')
        }

    @classmethod
    def get_section(cls, section: str) -> dict:
        """获取指定配置段的键值对（键名会被转为小写）"""
        if not cls._config.has_section(section):
            return {}
        return dict(cls._config.items(section))

    @classmethod
    def validate_config(cls):
        """校验默认模型配置是否存在且有效"""
        try:
            default_config = cls.get_model_config()
            if not default_config.get("api_key") or 'your_openai_api_key_here' in default_config.get("api_key"):
                raise ValueError(f"API key for default model '{cls.DEFAULT_MODEL_SECTION}' is missing or a placeholder.")
        except (ValueError, configparser.Error) as e:
            raise ValueError(f"Configuration validation failed: {e}")


# 如有需要可在导入时做初始校验，
# 但已移到 main.py 以便更可控地执行。
# 如需在导入时校验，可在此调用 Config.validate_config()