first commit

app/chrome-extension/utils/offscreen-manager.ts

@@ -0,0 +1,108 @@
+/**
+ * Offscreen Document manager
+ * Ensures only one offscreen document is created across the entire extension to avoid conflicts
+ */
+
+export class OffscreenManager {
+  private static instance: OffscreenManager | null = null;
+  private isCreated = false;
+  private isCreating = false;
+  private createPromise: Promise<void> | null = null;
+
+  private constructor() {}
+
+  /**
+   * Get singleton instance
+   */
+  public static getInstance(): OffscreenManager {
+    if (!OffscreenManager.instance) {
+      OffscreenManager.instance = new OffscreenManager();
+    }
+    return OffscreenManager.instance;
+  }
+
+  /**
+   * Ensure offscreen document exists
+   */
+  public async ensureOffscreenDocument(): Promise<void> {
+    if (this.isCreated) {
+      return;
+    }
+
+    if (this.isCreating && this.createPromise) {
+      return this.createPromise;
+    }
+
+    this.isCreating = true;
+    this.createPromise = this._doCreateOffscreenDocument().finally(() => {
+      this.isCreating = false;
+    });
+
+    return this.createPromise;
+  }
+
+  private async _doCreateOffscreenDocument(): Promise<void> {
+    try {
+      if (!chrome.offscreen) {
+        throw new Error('Offscreen API not available. Chrome 109+ required.');
+      }
+
+      const existingContexts = await (chrome.runtime as any).getContexts({
+        contextTypes: ['OFFSCREEN_DOCUMENT'],
+      });
+
+      if (existingContexts && existingContexts.length > 0) {
+        console.log('OffscreenManager: Offscreen document already exists');
+        this.isCreated = true;
+        return;
+      }
+
+      await chrome.offscreen.createDocument({
+        url: 'offscreen.html',
+        reasons: ['WORKERS'],
+        justification: 'Need to run semantic similarity engine with workers',
+      });
+
+      this.isCreated = true;
+      console.log('OffscreenManager: Offscreen document created successfully');
+    } catch (error) {
+      console.error('OffscreenManager: Failed to create offscreen document:', error);
+      this.isCreated = false;
+      throw error;
+    }
+  }
+
+  /**
+   * Check if offscreen document is created
+   */
+  public isOffscreenDocumentCreated(): boolean {
+    return this.isCreated;
+  }
+
+  /**
+   * Close offscreen document
+   */
+  public async closeOffscreenDocument(): Promise<void> {
+    try {
+      if (chrome.offscreen && this.isCreated) {
+        await chrome.offscreen.closeDocument();
+        this.isCreated = false;
+        console.log('OffscreenManager: Offscreen document closed');
+      }
+    } catch (error) {
+      console.error('OffscreenManager: Failed to close offscreen document:', error);
+    }
+  }
+
+  /**
+   * Reset state (for testing)
+   */
+  public reset(): void {
+    this.isCreated = false;
+    this.isCreating = false;
+    this.createPromise = null;
+  }
+}
+
+
+export const offscreenManager = OffscreenManager.getInstance();