//获取模版文件
var getViewFile = thinkRequire("WriteHtmlCacheBehavior").getViewFile;
var fs = require("fs");
/**
 * 读取HTML缓存
 * @return {[type]} [description]
 */
module.exports = Behavior(function(){
    "use strict";
    return {
        options:{
            'html_cache_on': false, //是否开启缓存
            'html_cache_timeout': 3600, //缓存时间
            'html_cache_rules': {}, //缓存规则
            'html_cache_file_callback': undefined, //生成缓存文件的回调函数
            'html_cache_file_suffix': ".html", //缓存文件扩展名
        },
        run: function(){
            if (!this.options.html_cache_on || isEmpty(this.options.html_cache_rules)) {
                return false;
            }
            var cacheTime = this.getCacheTime();
            if (cacheTime === false) {
                return false;
            }
            if (this.checkCacheTime(cacheTime)) {
                this.responseCacheContent();
                //return a pending promise
                return getDefer().promise;
            }
            return false;
        },
        /**
         * 返回缓存内容
         * @return {[type]} [description]
         */
        responseCacheContent: function(){
            var http = this.http;
            var fileStream = fs.createReadStream(HTML_PATH + "/" + http.html_filename);
            http.setHeader("Content-Type", "text/html");
            http.sendTime("Exec-Time");
            fileStream.pipe(http.res);
            fileStream.on("end", function(){
                http.end();
            });
        },
        /**
         * 获取缓存时间
         * @return {[type]} [description]
         */
        getCacheTime: function(){
            /**
             * rules数据格式
             * {
             *     'index:index': ['index_home', 1800, html_cache_callback]
             * }
             * @type {[type]}
             */
            var rules = this.options.html_cache_rules;
            var group = this.http.group.toLowerCase();
            var controller = this.http.controller.toLowerCase();
            var action = this.http.action.toLowerCase();
            var list = [
                group + ":" + controller + ":" + action,
                controller + ":" + action,
                action,
                "*"
            ];
            var html = [];
            list.some(function(item){
                if (item in rules) {
                    html = rules[item];
                    return true;
                }
            });
            if (isEmpty(html)) {
                return false;
            }
            if (!isArray(html)) {
                html = [html];
            }
            var rule = html[0];
            //将cookie变量传递进去
            var cookiePars = {};
            for(var name in this.http.cookie){
                cookiePars['cookie.' + name] = this.http.cookie[name];
            }
            var pars = extend({}, this.http.get, cookiePars, {
                ":group": group,
                ":controller": controller,
                ":action": action
            });
            rule = rule.replace(/\{([\w\:]+)\}/g, function(a, name){
                return pars[name] || "";
            });
            var callback = html[2] || C('html_cache_file_callback') || this.getCacheFilename;
            var filename = callback(rule, this.http) + this.options.html_cache_file_suffix;
            //静态缓存文件名
            this.http.html_filename = filename;
            var cacheTime = html[1] || this.options.html_cache_timeout;
            return cacheTime;
        },
        /**
         * 
         * @param  {[type]} key [description]
         * @return {[type]}     [description]
         */
        getCacheFilename: function(key){
            var value = md5(key);
            return value.substr(0, 1) + "/" + value;
        },
        /**
         * [checkCacheTime description]
         * @return {[type]} [description]
         */
        checkCacheTime: function(cacheTime){
            var cacheFile = HTML_PATH + "/" + this.http.html_filename;
            if (!isFile(cacheFile)) {
                return false;
            }
            var cacheFileMtime = fs.statSync(cacheFile).mtime.getTime();
            var tplFile = getViewFile(this.http);
            if (tplFile) {
                if (!isFile(tplFile)) {
                    return false;
                }
                var tplFileMtime = fs.statSync(tplFile).mtime.getTime();
                //模版文件有更新
                if (tplFileMtime > cacheFileMtime) {
                    return false;
                }
            }
            if (Date.now() > (cacheFileMtime + cacheTime * 1000)) {
                return false;
            }
            return true;
        }
    };
});