import os
import json
import hashlib
from typing import Any, Optional
from collections import OrderedDict

class LRUCache:
    """LRU缓存实现"""
    
    def __init__(self, capacity: int = 100):
        self.capacity = capacity
        self.cache = OrderedDict()
        
    def get(self, key: str) -> Optional[Any]:
        """获取缓存值"""
        if key in self.cache:
            # 移动到末尾表示最近使用
            self.cache.move_to_end(key)
            return self.cache[key]
        return None
        
    def put(self, key: str, value: Any):
        """设置缓存值"""
        if key in self.cache:
            # 更新现有值
            self.cache.move_to_end(key)
        elif len(self.cache) >= self.capacity:
            # 删除最久未使用的项
            self.cache.popitem(last=False)
            
        self.cache[key] = value
        
    def delete(self, key: str):
        """删除缓存项"""
        if key in self.cache:
            del self.cache[key]

class CacheManager:
    """多级缓存管理器"""
    
    def __init__(self, memory_capacity: int = 100, disk_cache_dir: str = "cache"):
        self.memory_cache = LRUCache(memory_capacity)
        self.disk_cache_dir = disk_cache_dir
        
        # 创建磁盘缓存目录
        if not os.path.exists(disk_cache_dir):
            os.makedirs(disk_cache_dir)
    
    def _get_disk_cache_path(self, key: str) -> str:
        """获取磁盘缓存文件路径"""
        # 使用哈希值作为文件名避免特殊字符问题
        key_hash = hashlib.md5(key.encode()).hexdigest()
        return os.path.join(self.disk_cache_dir, f"{key_hash}.cache")
    
    def get(self, key: str) -> Optional[Any]:
        """获取缓存值"""
        # 首先从内存缓存获取
        value = self.memory_cache.get(key)
        if value is not None:
            return value
            
        # 然后从磁盘缓存获取
        disk_path = self._get_disk_cache_path(key)
        if os.path.exists(disk_path):
            try:
                with open(disk_path, 'r', encoding='utf-8') as f:
                    data = json.load(f)
                    # 放入内存缓存
                    self.memory_cache.put(key, data)
                    return data
            except (json.JSONDecodeError, IOError):
                # 磁盘缓存损坏，删除文件
                try:
                    os.remove(disk_path)
                except OSError:
                    pass
                    
        return None
    
    def put(self, key: str, value: Any):
        """设置缓存值"""
        # 放入内存缓存
        self.memory_cache.put(key, value)
        
        # 同时写入磁盘缓存
        disk_path = self._get_disk_cache_path(key)
        try:
            with open(disk_path, 'w', encoding='utf-8') as f:
                json.dump(value, f, ensure_ascii=False, indent=2)
        except IOError:
            # 磁盘写入失败，不影响内存缓存
            pass
    
    def delete(self, key: str):
        """删除缓存项"""
        # 从内存缓存删除
        self.memory_cache.delete(key)
        
        # 从磁盘缓存删除
        disk_path = self._get_disk_cache_path(key)
        if os.path.exists(disk_path):
            try:
                os.remove(disk_path)
            except OSError:
                pass
    
    def clear(self):
        """清空所有缓存"""
        # 清空内存缓存
        self.memory_cache.cache.clear()
        
        # 清空磁盘缓存
        for filename in os.listdir(self.disk_cache_dir):
            file_path = os.path.join(self.disk_cache_dir, filename)
            try:
                if os.path.isfile(file_path):
                    os.remove(file_path)
            except OSError:
                pass

# 创建全局缓存管理器实例
cache_manager = CacheManager()