"""
快取輔助函數
用於提升應用程式效能
"""
from functools import wraps
from flask import request, current_app
from app import cache
import hashlib
import json

def cache_key(*args, **kwargs):
    """生成快取鍵值"""
    key_data = {
        'args': args,
        'kwargs': kwargs,
        'user_id': getattr(request, 'user_id', 'anonymous'),
        'path': request.path if hasattr(request, 'path') else ''
    }
    key_string = json.dumps(key_data, sort_keys=True, default=str)
    return hashlib.md5(key_string.encode('utf-8')).hexdigest()

def cached_route(timeout=300):
    """路由快取裝飾器"""
    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            if not current_app.config.get('CACHE_TYPE') or current_app.debug:
                return f(*args, **kwargs)
            
            key = f"route:{f.__name__}:{cache_key(*args, **kwargs)}"
            
            # 嘗試從快取獲取
            cached_result = cache.get(key)
            if cached_result is not None:
                current_app.logger.debug(f"快取命中: {key}")
                return cached_result
            
            # 執行函數並快取結果
            result = f(*args, **kwargs)
            cache.set(key, result, timeout=timeout)
            current_app.logger.debug(f"快取設定: {key}")
            
            return result
        return decorated_function
    return decorator

def cached_query(timeout=300):
    """資料庫查詢快取裝飾器"""
    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            if not current_app.config.get('CACHE_TYPE') or current_app.debug:
                return f(*args, **kwargs)
            
            key = f"query:{f.__name__}:{cache_key(*args, **kwargs)}"
            
            # 嘗試從快取獲取
            cached_result = cache.get(key)
            if cached_result is not None:
                current_app.logger.debug(f"查詢快取命中: {key}")
                return cached_result
            
            # 執行查詢並快取結果
            result = f(*args, **kwargs)
            cache.set(key, result, timeout=timeout)
            current_app.logger.debug(f"查詢快取設定: {key}")
            
            return result
        return decorated_function
    return decorator

def invalidate_cache(pattern):
    """清除快取"""
    try:
        if hasattr(cache, 'delete_many'):
            # Redis backend
            keys = cache.cache._read_clients.keys(f"flask_cache_{pattern}*")
            if keys:
                cache.delete_many(*keys)
                current_app.logger.info(f"清除快取: {len(keys)} 個項目")
        else:
            # Simple cache backend
            cache.clear()
            current_app.logger.info("清除所有快取")
    except Exception as e:
        current_app.logger.error(f"清除快取失敗: {e}")

# 快取統計
def cache_stats():
    """獲取快取統計資訊"""
    try:
        if hasattr(cache.cache, 'info'):
            return cache.cache.info()
        else:
            return {"status": "simple cache", "info": "無統計資訊"}
    except Exception as e:
        return {"error": str(e)}