Implement brand image endpoints for APIv4 (#5733)

* Implement brand image endpoints for APIv4

* Fix unit test

api4/brand.go

@@ -0,0 +1,70 @@
+// Copyright (c) 2017 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package api4
+
+import (
+	"net/http"
+
+	l4g "github.com/alecthomas/log4go"
+	"github.com/mattermost/platform/app"
+	"github.com/mattermost/platform/model"
+	"github.com/mattermost/platform/utils"
+)
+
+func InitBrand() {
+	l4g.Debug(utils.T("api.brand.init.debug"))
+
+	BaseRoutes.Brand.Handle("/image", ApiHandlerTrustRequester(getBrandImage)).Methods("GET")
+	BaseRoutes.Brand.Handle("/image", ApiSessionRequired(uploadBrandImage)).Methods("POST")
+}
+
+func getBrandImage(c *Context, w http.ResponseWriter, r *http.Request) {
+	// No permission check required
+
+	if img, err := app.GetBrandImage(); err != nil {
+		w.Write(nil)
+	} else {
+		w.Header().Set("Content-Type", "image/png")
+		w.Write(img)
+	}
+}
+
+func uploadBrandImage(c *Context, w http.ResponseWriter, r *http.Request) {
+	if r.ContentLength > *utils.Cfg.FileSettings.MaxFileSize {
+		c.Err = model.NewAppError("uploadBrandImage", "api.admin.upload_brand_image.too_large.app_error", nil, "", http.StatusRequestEntityTooLarge)
+		return
+	}
+
+	if err := r.ParseMultipartForm(*utils.Cfg.FileSettings.MaxFileSize); err != nil {
+		c.Err = model.NewAppError("uploadBrandImage", "api.admin.upload_brand_image.parse.app_error", nil, "", http.StatusBadRequest)
+		return
+	}
+
+	m := r.MultipartForm
+
+	imageArray, ok := m.File["image"]
+	if !ok {
+		c.Err = model.NewAppError("uploadBrandImage", "api.admin.upload_brand_image.no_file.app_error", nil, "", http.StatusBadRequest)
+		return
+	}
+
+	if len(imageArray) <= 0 {
+		c.Err = model.NewAppError("uploadBrandImage", "api.admin.upload_brand_image.array.app_error", nil, "", http.StatusBadRequest)
+		return
+	}
+
+	if !app.SessionHasPermissionTo(c.Session, model.PERMISSION_MANAGE_SYSTEM) {
+		c.SetPermissionError(model.PERMISSION_MANAGE_SYSTEM)
+		return
+	}
+
+	if err := app.SaveBrandImage(imageArray[0]); err != nil {
+		c.Err = err
+		return
+	}
+
+	c.LogAudit("")
+
+	ReturnStatusOK(w)
+}