MM-24694: Add getGroupsByUserId to API layer (#14443)

* add getGroupsByUserId to API layer

* update for lint errors

* add check for contextId = userId or ManageSystem Permission

Co-authored-by: mattermod <mattermod@users.noreply.github.com>

api4/group.go

@@ -55,6 +55,10 @@ func (api *API) InitGroup() {
 	api.BaseRoutes.Groups.Handle("/{group_id:[A-Za-z0-9]+}/members",
 		api.ApiSessionRequired(getGroupMembers)).Methods("GET")
 
+	// GET /api/v4/users/:user_id/groups?page=0&per_page=100
+	api.BaseRoutes.Users.Handle("/{user_id:[A-Za-z0-9]+}/groups",
+		api.ApiSessionRequired(getGroupsByUserId)).Methods("GET")
+
 	// GET /api/v4/channels/:channel_id/groups?page=0&per_page=100
 	api.BaseRoutes.Channels.Handle("/{channel_id:[A-Za-z0-9]+}/groups",
 		api.ApiSessionRequired(getGroupsByChannel)).Methods("GET")
@@ -505,6 +509,37 @@ func getGroupMembers(c *Context, w http.ResponseWriter, r *http.Request) {
 	w.Write(b)
 }
 
+func getGroupsByUserId(c *Context, w http.ResponseWriter, r *http.Request) {
+	c.RequireUserId()
+	if c.Err != nil {
+		return
+	}
+
+	if c.App.Session().UserId != c.Params.UserId && !c.App.SessionHasPermissionTo(*c.App.Session(), model.PERMISSION_MANAGE_SYSTEM) {
+		c.SetPermissionError(model.PERMISSION_MANAGE_SYSTEM)
+		return
+	}
+
+	if c.App.License() == nil || !*c.App.License().Features.LDAPGroups {
+		c.Err = model.NewAppError("Api4.getGroupsByUserId", "api.ldap_groups.license_error", nil, "", http.StatusNotImplemented)
+		return
+	}
+
+	groups, err := c.App.GetGroupsByUserId(c.Params.UserId)
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	b, marshalErr := json.Marshal(groups)
+	if marshalErr != nil {
+		c.Err = model.NewAppError("Api4.getGroupsByUserId", "api.marshal_error", nil, marshalErr.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	w.Write(b)
+}
+
 func getGroupsByChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.RequireChannelId()
 	if c.Err != nil {