Proof-of-concept: independent menu section providers

- Replace god-class resolvers with a service that populates the menus from lists of injectable providers
- Static menu sections are resolved at the root route ~ `resolveStatic`
- Route-dependent menu sections can be declared in the same structure, but are resolved on-demand ~ `resolveRoute`
- More and more easily customizable
  - Parts can be moved between menus, removed, replaced or extended individually
  - The dependencies of each provider are independent of each other
  - Order of providers determines the order of each menu → single source of truth for the order

src/app/shared/menu/menu-section.model.ts

@@ -1,15 +1,82 @@
-import { MenuItemModel } from './menu-item/models/menu-item.model';
+import { MenuItemType } from './menu-item-type.model';
+import { AltmetricMenuItemModel } from './menu-item/models/altmetric.model';
+import { ExternalLinkMenuItemModel } from './menu-item/models/external-link.model';
+import { LinkMenuItemModel } from './menu-item/models/link.model';
+import { OnClickMenuItemModel } from './menu-item/models/onclick.model';
+import { SearchMenuItemModel } from './menu-item/models/search.model';
+import { TextMenuItemModel } from './menu-item/models/text.model';
 
-/**
- * Represents the state of a single menu section in the store
- */
-export class MenuSection {
-  id: string;
-  parentID?: string;
-  visible: boolean;
-  active: boolean;
-  model: MenuItemModel;
-  index?: number;
-  icon?: string;
-  shouldPersistOnRouteChange? = false;
+export type MenuItemModels =
+  LinkMenuItemModel
+  | AltmetricMenuItemModel
+  | ExternalLinkMenuItemModel
+  | OnClickMenuItemModel
+  | SearchMenuItemModel
+  | TextMenuItemModel;
+
+function itemModelFactory(type: MenuItemType): MenuItemModels {
+  switch (type) {
+    case MenuItemType.TEXT:
+      return new TextMenuItemModel();
+    case MenuItemType.LINK:
+      return new LinkMenuItemModel();
+    case MenuItemType.ALTMETRIC:
+      return new AltmetricMenuItemModel();
+    case MenuItemType.SEARCH:
+      return new SearchMenuItemModel();
+    case MenuItemType.ONCLICK:
+      return new OnClickMenuItemModel();
+    case MenuItemType.EXTERNAL:
+      return new ExternalLinkMenuItemModel();
+    default: {
+      throw new Error(`No such menu item type: ${type}`);
+    }
+  }
+}
+
+export interface MenuSection {
+  /**
+   * The identifier for this section
+   */
+  id: string;
+
+  /**
+   * Whether this section should be visible.
+   */
+  visible: boolean;
+
+  /**
+   *
+   */
+  model: MenuItemModels;
+
+  /**
+   * The identifier of this section's parent section (optional).
+   */
+  parentID?: string;
+
+  /**
+   * The index of this section in its menu.
+   */
+  index?: number;
+
+  /**
+   * Whether this section is currently active.
+   * Newly created sections are inactive until toggled.
+   */
+  active?: boolean;
+
+  /**
+   * Whether this section is independent of the route (default: true).
+   * This value should be set explicitly for route-dependent sections.
+   */
+  shouldPersistOnRouteChange?: boolean;
+
+
+  /**
+   * An optional icon for this section.
+   * Must correspond to a FontAwesome icon class save for the `.fa-` prefix.
+   * Note that not all menus may render icons.
+   */
+  icon?: string;
 }