"""异步数据库引擎 + 会话。

- engine / SessionLocal:全局单例
- get_session:FastAPI 依赖,按请求注入一个会话
- init_db:启动时建表(MVP 用 create_all;表结构稳定后切 alembic 迁移,对齐 dograh)
"""

from collections.abc import AsyncGenerator
import json

import config
from db.models import Base
from services.interface_catalog import INTERFACE_DEFINITIONS
from sqlalchemy import text
from sqlalchemy.ext.asyncio import (
    AsyncSession,
    async_sessionmaker,
    create_async_engine,
)

engine = create_async_engine(config.DATABASE_URL, echo=False, pool_pre_ping=True)
SessionLocal = async_sessionmaker(engine, expire_on_commit=False)


async def get_session() -> AsyncGenerator[AsyncSession, None]:
    async with SessionLocal() as session:
        yield session


async def init_db() -> None:
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)
        await conn.execute(
            text(
                "ALTER TABLE interface_definitions "
                "ALTER COLUMN field_schema TYPE JSONB USING field_schema::jsonb"
            )
        )
        for definition in INTERFACE_DEFINITIONS:
            await conn.execute(
                text(
                    "INSERT INTO interface_definitions "
                    "(interface_type, name, capability, field_schema, enabled, version) "
                    "VALUES (:interface_type, :name, :capability, CAST(:field_schema AS jsonb), TRUE, 1) "
                    "ON CONFLICT (interface_type) DO UPDATE SET "
                    "name = EXCLUDED.name, capability = EXCLUDED.capability, "
                    "field_schema = EXCLUDED.field_schema, enabled = TRUE, updated_at = now()"
                ),
                {
                    "interface_type": definition["interface_type"],
                    "name": definition["name"],
                    "capability": definition["capability"],
                    "field_schema": json.dumps({"fields": definition["fields"]}),
                },
            )