"""数据库基础：命名约定、异步引擎与会话。

索引/约束命名按 AGENTS.md 8.6（pk_/uk_/idx_/fk_ + 表名）；
主库统一 PostgreSQL（ADR-024），不提供 SQLite 档。
"""

from collections.abc import AsyncIterator

from sqlalchemy import MetaData
from sqlalchemy.ext.asyncio import (
    AsyncEngine,
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)
from sqlalchemy.orm import DeclarativeBase

from app.core.config import get_settings

naming_convention = {
    "ix": "ix_%(column_0_label)s",
    "uq": "uq_%(table_name)s_%(column_0_name)s",
    "ck": "ck_%(table_name)s_%(constraint_name)s",
    "fk": "fk_%(table_name)s_%(referred_table_name)s",
    "pk": "pk_%(table_name)s",
}


class Base(DeclarativeBase):
    metadata = MetaData(naming_convention=naming_convention)


def create_engine() -> AsyncEngine:
    return create_async_engine(get_settings().database_url, pool_pre_ping=True)


def create_session_factory(engine: AsyncEngine) -> async_sessionmaker[AsyncSession]:
    return async_sessionmaker(engine, expire_on_commit=False)


async def session_scope(
    factory: async_sessionmaker[AsyncSession],
) -> AsyncIterator[AsyncSession]:
    """事务作用域：成功提交、异常回滚（权威状态与 Outbox 同事务，契约第 4.4 节）。"""
    async with factory() as session:
        try:
            yield session
            await session.commit()
        except Exception:
            await session.rollback()
            raise