微信公众支付（H5）工具类

import request from '@/utils/request'

// 微信支付(未调用后台接口)
export function wxPay(url, param, methodType, successCallBack, failCallBack) {
    if (!isWechat()) return
    const promise = initiateRequest(url, param, methodType)
    if (promise) {
        promise.then(res => {
            if (res) {
                initAndInvokeWxJSBridge(res, successCallBack, failCallBack)
            }
        })
    }
}

// 微信支付(已调用后台接口，paySign为后台接口返回数据)
export function wxPayByPaySign(paySign, successCallBack, failCallBack) {
    if (!isWechat()) return
    if (paySign) {
        initAndInvokeWxJSBridge(paySign, successCallBack, failCallBack)
    }
}

function invokeWxPay(resData, successCallBack, failCallBack) {
    WeixinJSBridge.invoke('getBrandWCPayRequest', resData,
        res => {
            const msg = res.err_msg ? res.err_msg : res.errMsg;
            switch (msg) {
                case 'get_brand_wcpay_request:ok':
                    if(successCallBack) {
                        successCallBack(res)
                    }
                    break
                default:
                    WeixinJSBridge.log('支付失败!'+msg+',请返回重试.');
                    if(failCallBack){
                        failCallBack(res)
                    }
                    break
            }
        })
}

function initAndInvokeWxJSBridge(resData, successCallBack, failCallBack) {

    if (typeof WeixinJSBridge === 'undefined') {
        if (document.addEventListener) {
            document.addEventListener('WeixinJSBridgeReady', invokeWxPay(resData, successCallBack, failCallBack), false)
        } else if (document.attachEvent) {
            document.attachEvent('WeixinJSBridgeReady', invokeWxPay(resData, successCallBack, failCallBack))
            document.attachEvent('onWeixinJSBridgeReady', invokeWxPay(resData, successCallBack, failCallBack))
        }
    } else {
        invokeWxPay(resData, successCallBack, failCallBack)
    }
}

function isWechat() {
    const ua = window.navigator.userAgent.toLowerCase();
    return ua.match(/micromessenger/i) == 'micromessenger'
}

function initiateRequest(url, param, methodType) {
    if (methodType && url) {
        const t = methodType.toLowerCase()
        switch (t) {
            case 'post':
                return request.post({
                    url: url,
                    params: param
                })
            case 'get':
                return request.get({
                    url: url,
                    params: param
                })
            case 'put':
                return request.put({
                    url: url,
                    params: param,
                    header: {
                        "content-type": "application/x-www-form-urlencoded"
                    }
                })
            default :
                return request.post({
                    url: url,
                    params: param
                })
        }
    }
    return null
}