"""磁盘缓存：SQLite 持久化，重启不丢"""

import json
from datetime import datetime, timedelta
from typing import Optional

from database import get_connection


def get_cache(key: str) -> Optional[str]:
    """获取缓存，过期或不存在返回 None"""
    now = datetime.now().isoformat()
    conn = get_connection()
    try:
        row = conn.execute(
            "SELECT value FROM cache WHERE key = ? AND expires_at > ?",
            (key, now),
        ).fetchone()
        if row:
            return row["value"]
        return None
    finally:
        conn.close()


def set_cache(key: str, value: str, ttl_hours: int = 6):
    """写入缓存，过期时间 = now + ttl_hours"""
    expires_at = (datetime.now() + timedelta(hours=ttl_hours)).isoformat()
    conn = get_connection()
    try:
        conn.execute(
            "INSERT OR REPLACE INTO cache (key, value, expires_at) VALUES (?, ?, ?)",
            (key, value, expires_at),
        )
        conn.commit()
    finally:
        conn.close()


def del_cache(key: str):
    """删除指定缓存"""
    conn = get_connection()
    try:
        conn.execute("DELETE FROM cache WHERE key = ?", (key,))
        conn.commit()
    finally:
        conn.close()


def clean_expired():
    """清理已过期的缓存（可在启动时调用一次）"""
    now = datetime.now().isoformat()
    conn = get_connection()
    try:
        conn.execute("DELETE FROM cache WHERE expires_at <= ?", (now,))
        conn.commit()
    finally:
        conn.close()