package com.farriver.bwf.service.config.cache;

import io.jsonwebtoken.lang.Assert;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.cache.interceptor.CacheOperationInvocationContext;
import org.springframework.cache.interceptor.CacheResolver;
import org.springframework.lang.Nullable;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

/**
 * 开发者可以通过自定义CacheResolver实现动态选择CacheManager，
 * 如下通过代码实现多种缓存机制：
 * 优先从堆内存读取缓存，堆内存缓存不存在时再从redis读取缓存，
 * redis缓存不存在时最后从mysql读取数据，并将读取到的数据依次写到redis和堆内存中。
 */
public class CustomCacheResolver implements CacheResolver, InitializingBean {
    private static final Logger logger = LoggerFactory.getLogger(CustomCacheResolver.class);

    @Nullable
    private List<CacheManager> cacheManagerList;

    public CustomCacheResolver() {

    }

    public CustomCacheResolver(List<CacheManager> cacheManagerList) {
        this.cacheManagerList = cacheManagerList;
    }

    public void setCacheManagerList(@Nullable List<CacheManager> cacheManagerList) {
        this.cacheManagerList = cacheManagerList;
    }

    public List<CacheManager> getCacheManagerList() {
        return cacheManagerList;
    }

    @Override
    public void afterPropertiesSet() {
        Assert.notNull(this.cacheManagerList, "CacheManager is required");
    }

    @Override
    public Collection<? extends Cache> resolveCaches(CacheOperationInvocationContext<?> cacheOperationInvocationContext) {
        Collection<String> cacheNames = getCacheNames(cacheOperationInvocationContext);
        if (cacheNames == null) {
            return Collections.emptyList();
        }
        Collection<Cache> result = new ArrayList<>();
        for (CacheManager cacheManager : getCacheManagerList()) {
            for (String cacheName : cacheNames) {
                Cache cache = cacheManager.getCache(cacheName);
                if (cache == null) {
                    throw new IllegalArgumentException("Cannot find cache named '" + cacheName + "' for" + cacheOperationInvocationContext.getOperation());
                }

                result.add(cache);
            }
        }

        return result;
    }

    private Collection<String> getCacheNames(CacheOperationInvocationContext<?> cacheOperationInvocationContext) {
        return cacheOperationInvocationContext.getOperation().getCacheNames();
    }
}