[MM-16934] Add API endpoint to update channel privacy (#11993)

* Add API endpoint to update channel privacy setting

* Fix language files

* Improve tests by making sure channel has been updated correctly

* Improve tests

api4/channel.go

@@ -35,6 +35,7 @@ func (api *API) InitChannel() {
 	api.BaseRoutes.Channel.Handle("", api.ApiSessionRequired(updateChannel)).Methods("PUT")
 	api.BaseRoutes.Channel.Handle("/patch", api.ApiSessionRequired(patchChannel)).Methods("PUT")
 	api.BaseRoutes.Channel.Handle("/convert", api.ApiSessionRequired(convertChannelToPrivate)).Methods("POST")
+	api.BaseRoutes.Channel.Handle("/privacy", api.ApiSessionRequired(updateChannelPrivacy)).Methods("PUT")
 	api.BaseRoutes.Channel.Handle("/restore", api.ApiSessionRequired(restoreChannel)).Methods("POST")
 	api.BaseRoutes.Channel.Handle("", api.ApiSessionRequired(deleteChannel)).Methods("DELETE")
 	api.BaseRoutes.Channel.Handle("/stats", api.ApiSessionRequired(getChannelStats)).Methods("GET")
@@ -229,6 +230,54 @@ func convertChannelToPrivate(c *Context, w http.ResponseWriter, r *http.Request)
 	w.Write([]byte(rchannel.ToJson()))
 }
 
+func updateChannelPrivacy(c *Context, w http.ResponseWriter, r *http.Request) {
+	c.RequireChannelId()
+	if c.Err != nil {
+		return
+	}
+
+	props := model.StringInterfaceFromJson(r.Body)
+	privacy, ok := props["privacy"].(string)
+	if !ok || (privacy != model.CHANNEL_OPEN && privacy != model.CHANNEL_PRIVATE) {
+		c.SetInvalidParam("privacy")
+		return
+	}
+
+	channel, err := c.App.GetChannel(c.Params.ChannelId)
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	if !c.App.SessionHasPermissionToTeam(c.App.Session, channel.TeamId, model.PERMISSION_MANAGE_TEAM) {
+		c.SetPermissionError(model.PERMISSION_MANAGE_TEAM)
+		return
+	}
+
+	if channel.Name == model.DEFAULT_CHANNEL && privacy == model.CHANNEL_PRIVATE {
+		c.Err = model.NewAppError("updateChannelPrivacy", "api.channel.update_channel_privacy.default_channel_error", nil, "", http.StatusBadRequest)
+		return
+	}
+
+	user, err := c.App.GetUser(c.App.Session.UserId)
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	channel.Type = privacy
+
+	updatedChannel, err := c.App.UpdateChannelPrivacy(channel, user)
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	c.LogAudit("name=" + updatedChannel.Name)
+
+	w.Write([]byte(updatedChannel.ToJson()))
+}
+
 func patchChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.RequireChannelId()
 	if c.Err != nil {