"""
應用程式設定模組
使用 Pydantic Settings 管理環境變數
"""
from functools import lru_cache
from typing import Literal
from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    """應用程式設定"""
    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=False
    )
    
    # 應用程式
    app_name: str = "每日報導APP"
    app_env: Literal["development", "staging", "production"] = "development"
    debug: bool = Field(
        default=False,  # 預設為 False，更安全
        description="除錯模式，僅開發環境使用"
    )
    secret_key: str = Field(
        default="change-me-in-production",
        description="應用程式密鑰，生產環境必須透過環境變數設定"
    )
    
    # 資料庫
    db_host: str = "localhost"
    db_port: int = 3306
    db_name: str = "daily_news_app"
    db_user: str = "root"
    db_password: str = ""
    
    @property
    def database_url(self) -> str:
        if self.db_host == "sqlite":
            return f"sqlite:///{self.db_name}.db"
        return f"mysql+pymysql://{self.db_user}:{self.db_password}@{self.db_host}:{self.db_port}/{self.db_name}?charset=utf8mb4"
    
    @property
    def async_database_url(self) -> str:
        if self.db_host == "sqlite":
            return f"sqlite+aiosqlite:///{self.db_name}.db"
        return f"mysql+aiomysql://{self.db_user}:{self.db_password}@{self.db_host}:{self.db_port}/{self.db_name}?charset=utf8mb4"
    
    # JWT
    jwt_secret_key: str = Field(
        default="change-me",
        description="JWT 簽章密鑰，生產環境必須透過環境變數設定"
    )
    jwt_algorithm: str = "HS256"
    jwt_access_token_expire_minutes: int = Field(
        default=480,  # 開發環境預設值
        description="JWT Token 過期時間（分鐘），建議生產環境設為 60-120 分鐘"
    )
    
    # LDAP
    ldap_server: str = ""
    ldap_port: int = 389
    ldap_base_dn: str = ""
    ldap_bind_dn: str = ""
    ldap_bind_password: str = ""
    
    # LLM
    llm_provider: Literal["gemini", "openai", "ollama"] = "gemini"
    gemini_api_key: str = ""
    gemini_model: str = "gemini-1.5-pro"
    openai_api_key: str = ""
    openai_model: str = "gpt-4o"
    ollama_endpoint: str = "http://localhost:11434"
    ollama_model: str = "llama3"
    
    # SMTP
    smtp_host: str = ""
    smtp_port: int = 587
    smtp_username: str = ""
    smtp_password: str = ""
    smtp_from_email: str = ""
    smtp_from_name: str = "每日報導系統"
    
    # 爬蟲
    crawl_schedule_time: str = "08:00"
    crawl_request_delay: int = 3
    crawl_max_retries: int = 3
    
    # Digitimes
    digitimes_username: str = ""
    digitimes_password: str = ""
    
    # 資料保留
    data_retention_days: int = 60
    
    # PDF
    pdf_logo_path: str = ""
    pdf_header_text: str = ""
    pdf_footer_text: str = "本報告僅供內部參考使用"
    
    # CORS 設定
    cors_origins: list[str] = Field(
        default=["http://localhost:3000", "http://localhost:8000"],
        description="允許的 CORS 來源列表，生產環境必須明確指定，不能使用 *"
    )

    # 管理員預設密碼
    admin_password: str = Field(
        default="admin123",
        description="管理員預設密碼"
    )


def validate_secrets():
    """驗證生產環境的密鑰設定"""
    if settings.app_env == "production":
        if settings.secret_key == "change-me-in-production":
            raise ValueError("生產環境必須設定 SECRET_KEY 環境變數")
        if settings.jwt_secret_key == "change-me":
            raise ValueError("生產環境必須設定 JWT_SECRET_KEY 環境變數")
        if len(settings.secret_key) < 32:
            raise ValueError("SECRET_KEY 長度必須至少 32 字元")
        if len(settings.jwt_secret_key) < 32:
            raise ValueError("JWT_SECRET_KEY 長度必須至少 32 字元")
        if settings.jwt_access_token_expire_minutes > 120:
            import warnings
            warnings.warn("生產環境 JWT Token 過期時間建議不超過 120 分鐘")


@lru_cache
def get_settings() -> Settings:
    """取得設定實例（快取）"""
    return Settings()


settings = get_settings()