"""数据库连接管理 - 使用上下文管理器，避免全局单例连接泄漏"""
import os
import aiosqlite
from contextlib import asynccontextmanager
from typing import AsyncIterator
from app.core.config import settings
from app.core.log import logger


DB_PATH = os.path.join(settings.base_dir, settings.db_path)


def ensure_db_dir():
    db_dir = os.path.dirname(DB_PATH)
    if db_dir and not os.path.exists(db_dir):
        os.makedirs(db_dir, exist_ok=True)


async def _apply_connection_pragmas(db: aiosqlite.Connection) -> None:
    await db.execute("PRAGMA journal_mode=WAL")
    await db.execute("PRAGMA synchronous=NORMAL")
    await db.execute("PRAGMA busy_timeout=30000")


# aiosqlite/sqlite3：等待锁的最长时间（秒），与高并发验证写入配合
_SQLITE_CONNECT_TIMEOUT = 30.0


async def init_db():
    """初始化数据库表结构（支持迁移）"""
    ensure_db_dir()
    async with aiosqlite.connect(DB_PATH, timeout=_SQLITE_CONNECT_TIMEOUT) as db:
        await _apply_connection_pragmas(db)
        await db.execute("PRAGMA cache_size=-64000")
        await db.execute("PRAGMA temp_store=MEMORY")

        await db.execute("""
            CREATE TABLE IF NOT EXISTS proxies (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                ip TEXT NOT NULL,
                port INTEGER NOT NULL,
                protocol TEXT DEFAULT 'http',
                score INTEGER DEFAULT 10,
                response_time_ms REAL,
                last_check TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
                UNIQUE(ip, port)
            )
        """)

        # 迁移：如果旧表缺少 response_time_ms 列，则添加
        try:
            await db.execute("SELECT response_time_ms FROM proxies LIMIT 1")
        except Exception:
            await db.execute("ALTER TABLE proxies ADD COLUMN response_time_ms REAL")
            logger.info("Migrated: added response_time_ms column")

        # 迁移：如果旧表缺少 created_at 列，则添加
        try:
            await db.execute("SELECT created_at FROM proxies LIMIT 1")
        except Exception:
            await db.execute("ALTER TABLE proxies ADD COLUMN created_at TIMESTAMP")
            await db.execute("UPDATE proxies SET created_at = CURRENT_TIMESTAMP WHERE created_at IS NULL")
            logger.info("Migrated: added created_at column")

        # 迁移：validated 0=待验证 1=已验证入池（参与分数维护）
        try:
            await db.execute("SELECT validated FROM proxies LIMIT 1")
        except Exception:
            await db.execute(
                "ALTER TABLE proxies ADD COLUMN validated INTEGER NOT NULL DEFAULT 0"
            )
            await db.execute(
                "UPDATE proxies SET validated = 1 WHERE score > 0"
            )
            logger.info("Migrated: added validated column")

        try:
            await db.execute("SELECT use_count FROM proxies LIMIT 1")
        except Exception:
            await db.execute(
                "ALTER TABLE proxies ADD COLUMN use_count INTEGER NOT NULL DEFAULT 0"
            )
            logger.info("Migrated: added use_count column")

        await db.execute("CREATE INDEX IF NOT EXISTS idx_score ON proxies(score)")
        await db.execute("CREATE INDEX IF NOT EXISTS idx_protocol ON proxies(protocol)")
        await db.execute("CREATE INDEX IF NOT EXISTS idx_last_check ON proxies(last_check)")
        await db.execute("CREATE INDEX IF NOT EXISTS idx_ip_port ON proxies(ip, port)")
        await db.execute("CREATE INDEX IF NOT EXISTS idx_validated ON proxies(validated)")

        # 插件设置表
        await db.execute("""
            CREATE TABLE IF NOT EXISTS plugin_settings (
                plugin_id TEXT PRIMARY KEY,
                enabled INTEGER DEFAULT 1,
                config_json TEXT DEFAULT '{}',
                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
                updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
            )
        """)

        # 迁移：为旧版 plugin_settings 表增加 config_json 列
        try:
            await db.execute("SELECT config_json FROM plugin_settings LIMIT 1")
        except Exception:
            await db.execute("ALTER TABLE plugin_settings ADD COLUMN config_json TEXT DEFAULT '{}'")
            logger.info("Migrated: added config_json column to plugin_settings")

        # 迁移：为旧版 plugin_settings 表增加 stats_json 列
        try:
            await db.execute("SELECT stats_json FROM plugin_settings LIMIT 1")
        except Exception:
            await db.execute("ALTER TABLE plugin_settings ADD COLUMN stats_json TEXT DEFAULT '{}'")
            logger.info("Migrated: added stats_json column to plugin_settings")

        # 验证任务队列表已废弃，不再创建；旧表保留在数据库中不影响功能

        # 系统设置表
        await db.execute("""
            CREATE TABLE IF NOT EXISTS settings (
                key TEXT PRIMARY KEY,
                value TEXT NOT NULL,
                updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
            )
        """)
        # 仅移除已废弃设置键，不碰 proxies 表数据
        await db.execute(
            "DELETE FROM settings WHERE key IN ('crawl_timeout', 'max_retries')"
        )

        await db.commit()
    logger.info("Database initialized")


@asynccontextmanager
async def get_db() -> AsyncIterator[aiosqlite.Connection]:
    """获取数据库连接的异步上下文管理器"""
    ensure_db_dir()
    db = await aiosqlite.connect(DB_PATH, timeout=_SQLITE_CONNECT_TIMEOUT)
    try:
        await _apply_connection_pragmas(db)
        yield db
    finally:
        await db.close()


@asynccontextmanager
async def get_db_connection() -> AsyncIterator[aiosqlite.Connection]:
    """与 get_db 相同 pragma/超时；保留别名供需「长连接」语义处使用。"""
    ensure_db_dir()
    db = await aiosqlite.connect(DB_PATH, timeout=_SQLITE_CONNECT_TIMEOUT)
    try:
        await _apply_connection_pragmas(db)
        yield db
    finally:
        await db.close()


@asynccontextmanager
async def transaction() -> AsyncIterator[aiosqlite.Connection]:
    """获取带有显式事务控制的数据库连接
    
    用法：
        async with transaction() as db:
            await repo.update(db, ...)
            # 如果抛出异常，自动 rollback
    """
    ensure_db_dir()
    db = await aiosqlite.connect(DB_PATH, timeout=_SQLITE_CONNECT_TIMEOUT)
    try:
        await _apply_connection_pragmas(db)
        await db.execute("BEGIN")
        yield db
        await db.commit()
    except Exception:
        await db.rollback()
        raise
    finally:
        await db.close()