"""
统一配置加载：环境变量优先，fallback 到 .env，无 DATABASE_URL 时按 DB_* 拼接。
支持多环境（dev/prod）、容器（DB_HOST=db）、向后兼容。
"""
import os
from pathlib import Path

# 环境变量优先；fallback 到 .env（不覆盖已存在的系统变量）
def _load_dotenv():
    try:
        from dotenv import load_dotenv
    except ImportError:
        return
    env = os.getenv("ENV", "").lower()
    base = Path(__file__).resolve().parent.parent
    if env == "prod":
        load_dotenv(base / ".env.prod", override=False)
    elif env == "dev":
        load_dotenv(base / ".env.dev", override=False)
    load_dotenv(base / ".env", override=False)


_load_dotenv()


def build_database_url_async() -> str:
    """拼接异步数据库 URL（postgresql+asyncpg）。"""
    user = os.getenv("DB_USER", "wecom")
    password = os.getenv("DB_PASSWORD", "password")
    host = os.getenv("DB_HOST", "localhost")
    port = os.getenv("DB_PORT", "5432")
    db = os.getenv("DB_NAME", "wecom_ai")
    return f"postgresql+asyncpg://{user}:{password}@{host}:{port}/{db}"


def build_database_url_sync() -> str:
    """拼接同步数据库 URL（postgresql，Alembic/psycopg2）。"""
    user = os.getenv("DB_USER", "wecom")
    password = os.getenv("DB_PASSWORD", "password")
    host = os.getenv("DB_HOST", "localhost")
    port = os.getenv("DB_PORT", "5432")
    db = os.getenv("DB_NAME", "wecom_ai")
    return f"postgresql://{user}:{password}@{host}:{port}/{db}"


# 优先使用环境变量，否则按 DB_* 拼接（向后兼容）
DATABASE_URL: str = os.getenv("DATABASE_URL") or build_database_url_async()
DATABASE_URL_SYNC: str = os.getenv("DATABASE_URL_SYNC") or build_database_url_sync()