/**
 * express初始化
 */
"use strict";
module.exports = function () {
    let _ = require('lodash'),
        shell = require('shelljs'),
        express = require('express'),
        session = require('express-session'),
        app = express(),
        cookieParser = require('cookie-parser'),
        requestIp = require('request-ip'),
        bodyParser = require('body-parser'),
        methodOverride = require('method-override'),
        original_url_mw = require('kml-original-url-mw'),
        config = require('./config'),
        config_path = config.path,
        logger = require('./log4js-init').system;

    // 定义express body 中间件
    app.use(bodyParser.urlencoded({extended: false}));
    app.use(bodyParser.json());
    // app.use(bodyParser.raw({type: 'application/xml'}));
    app.use(methodOverride());
    app.use(requestIp.mw());

    // 加载用于解析 cookie 的中间件
    app.use(cookieParser());

    // 解析原始请求url
    app.use(original_url_mw());

    const cfg_redis = config.redis;
    if (cfg_redis && cfg_redis.host) {
        let rs = shell.exec(`ping -c 3 -t 5 ${cfg_redis.host}`), sessionMiddleware;

        let session_cfg = {
            name: config.system.project_name + '.sid',
            secret: 'my_secret_treasure',
            resave: true,
            saveUninitialized: false,
            proxy: true
        };

        if (rs.code === 0) {
            // 使用redis存储session
            let RedisStore = require('connect-redis')(session);

            let client = require('./redis-promisify');
            client.on('error', logger.error);

            sessionMiddleware = session(_.merge({
                store: new RedisStore({client, ttl: config.cache.ttl.SESSION_TTL})
            }, session_cfg));
        } else {
            logger.warn(`${cfg_redis.host} can not be connected, we will use default session instead!`);
            sessionMiddleware = session(session_cfg);
        }

        app.use(function (req, res, next) {
            let tries = 3;

            function lookupSession (error) {
                if (error) {
                    return next(error);
                }

                tries--;
                if (req.session !== undefined) {
                    return next();
                }

                if (tries < 0) {
                    return next(new Error('Oops! @_@'));
                }
                sessionMiddleware(req, res, lookupSession);
            }

            lookupSession();
        })
    }

    // 指定一个虚拟路径static挂载静态资源
    app.use('/', express.static(config_path.PUBLIC_PATH));

    return app;
};