/**
 * 简易微信SDK。
 *
 * author: Sand
 * since: 1/6/2017
 */
"use strict";

let WechatTokenRepo = require('../repository/mysql/wechat.token.repo.js');

let configFile = require('../include/commons').CONFIG_FILE;
let config = require('../resources/config/' + configFile);
let log = require('./log');
let https = require('https');

class WechatSDK {
    constructor() {
    }

    /**
     * 获取微信access_token
     */
    static getAccessToken(handler) {
        WechatTokenRepo.findOne(function (err, result) {
            if (err) {
                handler(err, null);
                return;
            }

            var data = result && result.length > 0 ? result[0] : null;
            var accessToken = "";

            // 判断access_token是否有效
            if (data) {
                if ((new Date().getTime() - data.add_timestamp) < (data.expires_in * 1000)) {
                    accessToken = data.access_token;
                }
            }

            // access_token为空时从微信新获取并执行回调，否则直接执行回调
            if (!accessToken) {
                var basePath = "https://api.weixin.qq.com/cgi-bin/token?";
                var params = "grant_type=client_credential&appid=" + config.wechatConfig.appId
                    + "&secret=" + config.wechatConfig.appSecret;

                https.get(basePath + params, function (res) {
                    var data = '';
                    res.on('data', (d) => {
                        data += d;
                    });

                    res.on('end', () => {
                        data = data ? JSON.parse(data) : {};
                        if (data.access_token) {
                            accessToken = data.access_token;
                            WechatTokenRepo.save(accessToken, data.expires_in, new Date(), function (err, result) {
                                if (err) {
                                    if (handler) handler(err, null);
                                } else {
                                    if (handler) handler(null, accessToken);
                                }
                            });
                        } else {
                            if (handler) handler(Error("Get access_token from wechat failed"), null);
                        }
                    });
                }).on('error', (e) => {
                    if (handler) handler(Error("Get access_token from wechat failed: " + e.message), null);
                });
            } else {
                if (handler) handler(data, null);
            }
        });
    };

    /**
     * 发送微信模板消息
     */
    static sendTemplateMessage(message, handler) {
        WechatSDK.getAccessToken(function (err, token) {
            if (err) {
                log.error(err);
                handler(err, null);

                return;
            }

            // 发送模板消息
            var messageJSON = JSON.stringify(message);
            var request = https.request({
                    host: 'api.weixin.qq.com',
                    path: '/cgi-bin/message/template/send?access_token=' + token,
                    method: 'POST'
                },
                function (res) {
                    res.setEncoding('utf8');

                    var data = "";
                    res.on('data', (d) => {
                        data += d;
                    });

                    res.on('end', () => {
                        var result = JSON.parse(data);

                        if (result && result.errcode === 0) {
                            log.info("send wechat template message success:" + messageJSON);
                            if (handler) {
                                handler(null, result);
                            }
                        } else {
                            log.error("send wechat template message failed:" + messageJSON);
                            if (handler) {
                                handler(result, null);
                            }
                        }
                    });

                    res.on('error', function (err) {
                        log.error('send wechat template message failed: ' + err.message);
                        if (handler) {
                            handler(err, null);
                        }
                    });
                })
                .on('error', (e) => {
                    log.error("send wechat template message failed:" + e.message);
                    if (handler) {
                        handler(e, null);
                    }
                });

            request.end(messageJSON);
        });
    };
}

module.exports = WechatSDK;