"""
核心配置

集中管理环境变量和应用配置，遵循 12-factor 原则。
"""

import os
from pathlib import Path
from typing import Optional
from dotenv import load_dotenv

# 仅从项目根目录 .env 加载，作为唯一配置源
BACKEND_DIR = Path(__file__).resolve().parents[2]
PROJECT_ROOT = BACKEND_DIR.parent
load_dotenv(PROJECT_ROOT / ".env", override=False)

# 默认数据库固定到 Docker PostgreSQL，不再提供 SQLite 回落
DEFAULT_DB_HOST = os.getenv("DB_HOST", "127.0.0.1")
DEFAULT_DB_PORT = os.getenv("DB_PORT", "5435")
DEFAULT_DB_NAME = os.getenv("POSTGRES_DB", "pmflow")
DEFAULT_DB_USER = os.getenv("POSTGRES_USER", "pmflow")
DEFAULT_DB_PASSWORD = os.getenv("POSTGRES_PASSWORD", "pmflow_pass")
DEFAULT_DATABASE_URL = (
    f"postgresql+asyncpg://{DEFAULT_DB_USER}:{DEFAULT_DB_PASSWORD}"
    f"@{DEFAULT_DB_HOST}:{DEFAULT_DB_PORT}/{DEFAULT_DB_NAME}"
)


class Settings:
    """应用配置（从环境变量读取）"""

    # 应用
    app_name: str = os.getenv("APP_NAME", "Neural Sync API")
    debug: bool = os.getenv("DEBUG", "false").lower() in ("true", "1", "yes")

    # 数据库
    database_url: str = os.getenv("DATABASE_URL", DEFAULT_DATABASE_URL)
    db_pool_size: int = int(os.getenv("DB_POOL_SIZE", "20"))
    db_max_overflow: int = int(os.getenv("DB_MAX_OVERFLOW", "40"))
    db_pool_timeout: int = int(os.getenv("DB_POOL_TIMEOUT", "30"))
    db_pool_recycle: int = int(os.getenv("DB_POOL_RECYCLE", "1800"))

    # JWT
    secret_key: str = os.getenv("SECRET_KEY", "your-secret-key-change-in-production")
    algorithm: str = os.getenv("JWT_ALGORITHM", "HS256")
    access_token_expire_minutes: int = int(os.getenv("ACCESS_TOKEN_EXPIRE_MINUTES", str(60 * 24 * 7)))

    # CORS
    cors_origins: str = os.getenv("CORS_ORIGINS", "*")

    # LLM
    llm_provider: str = os.getenv("LLM_PROVIDER", "ollama").lower()
    ollama_host: str = os.getenv("OLLAMA_HOST", "http://127.0.0.1:11434")
    business_context: Optional[str] = os.getenv("BUSINESS_CONTEXT")

    # Redis（可选，用于 AI 结果缓存）
    redis_url: Optional[str] = os.getenv("REDIS_URL")

    # 多租户（预留）
    default_tenant_id: str = os.getenv("DEFAULT_TENANT_ID", "default")


# 全局配置实例
settings = Settings()