from sqlmodel import SQLModel, create_engine
from sqlmodel.ext.asyncio.session import AsyncSession
from sqlalchemy.ext.asyncio import create_async_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy import text
from sqlalchemy.exc import DBAPIError, OperationalError
import os
import logging
from dotenv import load_dotenv

logger = logging.getLogger(__name__)

load_dotenv()

DB_USER = os.getenv("DB_USER")
DB_PASSWORD = os.getenv("DB_PASSWORD")
DB_HOST = os.getenv("DB_HOST")
DB_PORT = os.getenv("DB_PORT", "5432")
DB_NAME = os.getenv("DB_NAME")

DATABASE_URL = f"postgresql+asyncpg://{DB_USER}:{DB_PASSWORD}@{DB_HOST}:{DB_PORT}/{DB_NAME}"

engine = create_async_engine(
    DATABASE_URL,
    echo=True,
    future=True,
    pool_pre_ping=True,
    pool_recycle=180,
    pool_size=5,
    max_overflow=10,
    pool_timeout=30,
)

async def init_db():
    async with engine.begin() as conn:
        # await conn.run_sync(SQLModel.metadata.drop_all)
        await conn.run_sync(SQLModel.metadata.create_all)

        # Migrate: add new columns to existing repairtask table
        migrations = [
            "ALTER TABLE repairtask ADD COLUMN IF NOT EXISTS repair_round INTEGER DEFAULT 1",
            "ALTER TABLE repairtask ADD COLUMN IF NOT EXISTS failure_reason TEXT",
            # Log source support
            "ALTER TABLE errorlog ADD COLUMN IF NOT EXISTS source VARCHAR(20) DEFAULT 'runtime'",
            "ALTER TABLE errorlog ALTER COLUMN file_path DROP NOT NULL",
            "ALTER TABLE errorlog ALTER COLUMN line_number DROP NOT NULL",
            "CREATE INDEX IF NOT EXISTS ix_errorlog_source ON errorlog (source)",
            # ErrorLog failure_reason
            "ALTER TABLE errorlog ADD COLUMN IF NOT EXISTS failure_reason TEXT",
            # Bug severity (1-10 AI评估等级)
            "ALTER TABLE errorlog ADD COLUMN IF NOT EXISTS severity INTEGER",
            "ALTER TABLE errorlog ADD COLUMN IF NOT EXISTS severity_reason TEXT",
            # Seed Project table from existing ErrorLog data
            """INSERT INTO project (project_id, created_at, updated_at)
               SELECT DISTINCT e.project_id, NOW(), NOW()
               FROM errorlog e
               WHERE NOT EXISTS (SELECT 1 FROM project p WHERE p.project_id = e.project_id)""",
        ]
        for sql in migrations:
            try:
                await conn.execute(text(sql))
            except Exception:
                pass  # Already applied

_async_session_factory = sessionmaker(
    engine, class_=AsyncSession, expire_on_commit=False
)

_MAX_RETRIES = 2

async def get_session() -> AsyncSession:
    for attempt in range(_MAX_RETRIES):
        try:
            async with _async_session_factory() as session:
                yield session
                return
        except (DBAPIError, OperationalError, ConnectionResetError, OSError) as e:
            if attempt < _MAX_RETRIES - 1:
                logger.warning("Database connection error (attempt %d/%d): %s", attempt + 1, _MAX_RETRIES, e)
                await engine.dispose()
                continue
            raise