"""数据库引擎与会话管理"""

import os
from pathlib import Path
from sqlalchemy import create_engine, event
from sqlalchemy.orm import sessionmaker, declarative_base

PROJECT_ROOT = Path(__file__).resolve().parents[2]
DB_PATH = PROJECT_ROOT / "data" / "web.db"
DB_PATH.parent.mkdir(parents=True, exist_ok=True)
DATABASE_URL = os.getenv("DATABASE_URL", f"sqlite:///{DB_PATH}")

connect_args = (
    {"check_same_thread": False, "timeout": 30}
    if DATABASE_URL.startswith("sqlite")
    else {}
)

engine = create_engine(
    DATABASE_URL,
    connect_args=connect_args,
    echo=False,
)


if DATABASE_URL.startswith("sqlite"):
    @event.listens_for(engine, "connect")
    def _set_sqlite_pragmas(dbapi_connection, connection_record):
        """提升 SQLite 并发写入稳定性。"""
        cursor = dbapi_connection.cursor()
        cursor.execute("PRAGMA journal_mode=WAL")
        cursor.execute("PRAGMA busy_timeout=30000")
        cursor.execute("PRAGMA foreign_keys=ON")
        cursor.close()

SessionLocal = sessionmaker(bind=engine, autocommit=False, autoflush=False)
Base = declarative_base()


def get_db():
    """FastAPI 依赖：提供数据库会话，请求结束自动关闭。"""
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


def init_db():
    """执行数据库迁移 + 写入初始数据。"""
    run_migrations()
    _seed()
    _encrypt_existing_sensitive_data()


def run_migrations():
    """运行 Alembic 迁移到最新版本。"""
    from alembic import command
    from alembic.config import Config

    config = Config(str(PROJECT_ROOT / "alembic.ini"))
    config.set_main_option("script_location", str(PROJECT_ROOT / "web" / "backend" / "migrations"))
    config.set_main_option("sqlalchemy.url", DATABASE_URL)
    command.upgrade(config, "head")


def _seed():
    """写入默认超管账号和角色（账号密码通过环境变量配置）。"""
    from .models import User
    from .security import hash_password

    admin_username = os.getenv("ADMIN_USERNAME", "admin")
    admin_password = os.getenv("ADMIN_PASSWORD", "admin123")

    db = SessionLocal()
    try:
        if not db.query(User).first():
            admin = User(
                username=admin_username,
                password_hash=hash_password(admin_password),
                role="super_admin",
                is_active=True,
                remark="默认超级管理员",
            )
            db.add(admin)
            db.commit()
    finally:
        db.close()


def _encrypt_existing_sensitive_data():
    """启动时把历史明文敏感数据迁移为密文。"""
    from loguru import logger
    from .crypto_storage import encrypt_existing_sensitive_data

    changed = encrypt_existing_sensitive_data(engine)
    if changed:
        logger.info(f"已加密历史敏感字段: {changed} 个值")