Refactor card.ts substantially and test.

src/utils/initializer/initializer.ts

@@ -0,0 +1,69 @@
+import { allPromises } from '../basic';
+
+enum InitializationState {
+  INITIALIZING = 'initializing',
+  INITIALIZED = 'initialized',
+}
+
+type InitializationCallback = () => Promise<unknown>;
+
+/**
+ * Manages initialization state & calling initializers.
+ */
+export class Initializer {
+  protected _state: Map<string, InitializationState>;
+
+  constructor() {
+    this._state = new Map();
+  }
+
+  public async initializeMultipleIfNecessary(
+    aspects: Record<string, InitializationCallback>,
+  ): Promise<boolean> {
+    const results = await allPromises(
+      Object.entries(aspects),
+      async ([aspect, options]) => this.initializeIfNecessary(aspect, options),
+    );
+    return results.every(Boolean);
+  }
+
+  /**
+   *
+   * @param aspect The aspect to initialize.
+   * @param initializer The initializer to call.
+   * @returns `true` if the state is confirmed as initialized, `false`
+   * otherwise (i.e. initializing).
+   */
+  public async initializeIfNecessary(
+    aspect: string,
+    initializer?: InitializationCallback,
+  ): Promise<boolean> {
+    const state = this._state.get(aspect);
+    if (state !== InitializationState.INITIALIZED) {
+      if (state !== InitializationState.INITIALIZING) {
+        if (initializer) {
+          this._state.set(aspect, InitializationState.INITIALIZING);
+          await initializer();
+          this._state.set(aspect, InitializationState.INITIALIZED);
+        } else {
+          this._state.set(aspect, InitializationState.INITIALIZED);
+        }
+        return true;
+      }
+      return false;
+    }
+    return true;
+  }
+
+  public uninitialize(aspect: string) {
+    return this._state.delete(aspect);
+  }
+
+  public isInitialized(aspect: string): boolean {
+    return this._state.get(aspect) == InitializationState.INITIALIZED;
+  }
+
+  public isInitializedMultiple(aspects: string[]): boolean {
+    return aspects.every((aspect) => this.isInitialized(aspect));
+  }
+}