fix: platform wx oauth and js config issue. (#302)

* fix: platform wx oauth and js config issue.

fix silenceper/wechat#301.

* fix: platform query auth code error not detected.

* feat: migrate platform oauth and js api.

* fix: func name

openplatform/officialaccount/js/js.go

@@ -0,0 +1,57 @@
+package js
+
+import (
+	"fmt"
+
+	"github.com/silenceper/wechat/v2/credential"
+	"github.com/silenceper/wechat/v2/officialaccount/context"
+	officialJs "github.com/silenceper/wechat/v2/officialaccount/js"
+	"github.com/silenceper/wechat/v2/util"
+)
+
+// Js wx jssdk
+type Js struct {
+	*context.Context
+	credential.JsTicketHandle
+}
+
+//NewJs init
+func NewJs(context *context.Context) *Js {
+	js := new(Js)
+	js.Context = context
+	jsTicketHandle := credential.NewDefaultJsTicket(context.AppID, credential.CacheKeyOfficialAccountPrefix, context.Cache)
+	js.SetJsTicketHandle(jsTicketHandle)
+	return js
+}
+
+//SetJsTicketHandle 自定义js ticket取值方式
+func (js *Js) SetJsTicketHandle(ticketHandle credential.JsTicketHandle) {
+	js.JsTicketHandle = ticketHandle
+}
+
+//GetConfig 第三方平台 - 获取jssdk需要的配置参数
+//uri 为当前网页地址
+func (js *Js) GetConfig(uri, appid string) (config *officialJs.Config, err error) {
+	config = new(officialJs.Config)
+	var accessToken string
+	accessToken, err = js.GetAccessToken()
+	if err != nil {
+		return
+	}
+	var ticketStr string
+	ticketStr, err = js.GetTicket(accessToken)
+	if err != nil {
+		return
+	}
+
+	nonceStr := util.RandomStr(16)
+	timestamp := util.GetCurrTS()
+	str := fmt.Sprintf("jsapi_ticket=%s&noncestr=%s&timestamp=%d&url=%s", ticketStr, nonceStr, timestamp, uri)
+	sigStr := util.Signature(str)
+
+	config.AppID = appid
+	config.NonceStr = nonceStr
+	config.Timestamp = timestamp
+	config.Signature = sigStr
+	return
+}