/*******************************************************************************
 * Copyright (c) 2005, 2014 springside.github.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *******************************************************************************/
package com.cjs.site.util.redis;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;

import com.cjs.site.util.redis.JedisTemplate.JedisAction;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.exceptions.JedisDataException;
import redis.clients.util.Pool;

/**
 * 装载并执行Lua Script，如果服务器上因为集群多台服务器或重启等原因没有装载script，会自动重新装载后重试。
 */
public class JedisScriptExecutor {
    private static Logger logger = LoggerFactory.getLogger(JedisScriptExecutor.class);

    private JedisTemplate jedisTemplate;

    private String        script;
    private String        sha1;

    public JedisScriptExecutor(Pool<Jedis> jedisPool) {
        this.jedisTemplate = new JedisTemplate(jedisPool);
    }

    public JedisScriptExecutor(JedisTemplate jedisTemplate) {
        this.jedisTemplate = jedisTemplate;
    }

    /**
     * 装载Lua Script。
     * 如果Script出错，抛出JedisDataException。
     */
    public void load(final String scriptContent) throws JedisDataException {
        sha1 = jedisTemplate.execute(new JedisTemplate.JedisAction<String>() {
            @Override
            public String action(Jedis jedis) {
                return jedis.scriptLoad(scriptContent);
            }
        });
        script = scriptContent;

        logger.debug("Script \"{}\" had been loaded as {}", scriptContent, sha1);
    }

    /**
     * 从文件加载Lua Script, 文件路径格式为Spring Resource的格式.
     */
    public void loadFromFile(final String scriptPath) throws JedisDataException {
        String scriptContent;
        try {
            Resource resource = new DefaultResourceLoader().getResource(scriptPath);
            scriptContent = FileUtils.readFileToString(resource.getFile());
        } catch (IOException e) {
            throw new IllegalArgumentException(scriptPath + " is not exist.", e);
        }

        load(scriptContent);
    }

    /**
     * 执行Lua Script, 如果Redis服务器上还没装载Script则自动装载并重试。
     * keys与args不允许为null.
     */
    public Object execute(final String[] keys,
                          final String[] args) throws IllegalArgumentException {
        Validate.notNull(keys, "keys can't be null.");
        Validate.notNull(args, "args can't be null.");

        return execute(Arrays.asList(keys), Arrays.asList(args));
    }

    /**
     * 执行Lua Script, 如果Redis服务器上还没装载Script则自动装载并重试。
     * keys与args不允许为null.
     */
    public Object execute(final List<String> keys,
                          final List<String> args) throws IllegalArgumentException {
        Validate.notNull(keys, "keys can't be null.");
        Validate.notNull(args, "args can't be null.");

        return jedisTemplate.execute(new JedisAction<Object>() {
            @Override
            public Object action(Jedis jedis) {
                try {
                    return jedis.evalsha(sha1, keys, args);
                } catch (JedisDataException e) {
                    logger.warn(
                        "Script {} is not loaded in server yet or the script is wrong, try to reload and run it again.",
                        script, e);
                    return jedis.eval(script, keys, args);
                }
            }
        });
    }
}