[API] add endpoint to check notifications [Extend #9488] (#9595)

* introduce GET /notifications/new

* add TEST

* use Sprintf instead of path.Join

* Error more verbose

* return number of notifications if unreaded exist

* 200 http status for available notifications

routers/api/v1/api.go

@@ -518,6 +518,7 @@ func RegisterRoutes(m *macaron.Macaron) {
 			m.Combo("").
 				Get(notify.ListNotifications).
 				Put(notify.ReadNotifications)
+			m.Get("/new", notify.NewAvailable)
 			m.Combo("/threads/:id").
 				Get(notify.GetThread).
 				Patch(notify.ReadThread)

routers/api/v1/notify/notifications.go

@@ -0,0 +1,33 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package notify
+
+import (
+	"net/http"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/context"
+	api "code.gitea.io/gitea/modules/structs"
+)
+
+// NewAvailable check if unread notifications exist
+func NewAvailable(ctx *context.APIContext) {
+	// swagger:operation GET /notifications/new notification notifyNewAvailable
+	// ---
+	// summary: Check if unread notifications exist
+	// responses:
+	//   "200":
+	//    "$ref": "#/responses/NotificationCount"
+	//   "204":
+	//     description: No unread notification
+
+	count := models.CountUnread(ctx.User)
+
+	if count > 0 {
+		ctx.JSON(http.StatusOK, api.NotificationCount{New: count})
+	} else {
+		ctx.Status(http.StatusNoContent)
+	}
+}

routers/api/v1/swagger/notify.go

@@ -21,3 +21,10 @@ type swaggerNotificationThreadList struct {
 	// in:body
 	Body []api.NotificationThread `json:"body"`
 }
+
+// Number of unread notifications
+// swagger:response NotificationCount
+type swaggerNotificationCount struct {
+	// in:body
+	Body api.NotificationCount `json:"body"`
+}