fix(Browser history): fixed NPE when navigating a study via browser history and history navigation is now available via the navigateHistory command (#3337)

* fix(Browser history):
- fixed an NPE when navigating to a different study via the URL
- exposed browser history navigation via a command

* Added documentation for the navigateHistory command.
Moved the history object from UI to viewer.

extensions/default/src/commandsModule.ts

@@ -11,6 +11,8 @@ import findViewportsByPosition, {
 } from './findViewportsByPosition';
 
 import { ContextMenuProps } from './CustomizeableContextMenu/types';
+import { NavigateHistory } from './types/commandModuleTypes';
+import { history } from '@ohif/viewer';
 
 const { subscribeToNextViewportGridChange } = utils;
 
@@ -480,6 +482,28 @@ const commandsModule = ({
       }
     },
 
+    /**
+     * Exposes the browser history navigation used by OHIF. This command can be used to either replace or
+     * push a new entry into the browser history. For example, the following will replace the current
+     * browser history entry with the specified relative URL which changes the study displayed to the
+     * study with study instance UID 1.2.3. Note that as a result of using `options.replace = true`, the
+     * page prior to invoking this command cannot be returned to via the browser back button.
+     *
+     * navigateHistory({
+     *   to: 'viewer?StudyInstanceUIDs=1.2.3',
+     *   options: { replace: true },
+     * });
+     *
+     * @param historyArgs - arguments for the history function;
+     *                      the `to` property is the URL;
+     *                      the `options.replace` is a boolean indicating if the current browser history entry
+     *                      should be replaced or a new entry pushed onto the history (stack); the default value
+     *                      for `replace` is false
+     */
+    navigateHistory(historyArgs: NavigateHistory) {
+      history.navigate(historyArgs.to, historyArgs.options);
+    },
+
     openDICOMTagViewer() {
       const { activeViewportIndex, viewports } = viewportGridService.getState();
       const activeViewportSpecificData = viewports[activeViewportIndex];
@@ -540,6 +564,11 @@ const commandsModule = ({
       storeContexts: [],
       options: {},
     },
+    navigateHistory: {
+      commandFn: actions.navigateHistory,
+      storeContexts: [],
+      options: {},
+    },
     nextStage: {
       commandFn: actions.deltaStage,
       storeContexts: [],

extensions/default/src/types/commandModuleTypes.tsx

@@ -0,0 +1,6 @@
+export type NavigateHistory = {
+  to: string; // the URL to navigate to
+  options?: {
+    replace?: boolean; // replace or add/push to history?
+  };
+};