Update code to typescript

src/tts/google.ts

@@ -0,0 +1,78 @@
+import { existsSync } from "node:fs";
+import { writeFile } from "node:fs/promises";
+import textToSpeech from "@google-cloud/text-to-speech";
+import type { TextToSpeechClient } from "@google-cloud/text-to-speech";
+import { config } from "../config.js";
+import { BaseEngine, type VoiceParams } from "./BaseEngine.js";
+
+interface GoogleVoiceMeta {
+  name: string;
+  lang: string;
+}
+
+export class GoogleEngine extends BaseEngine {
+  private client: TextToSpeechClient | undefined;
+  protected override voices: Record<string, GoogleVoiceMeta> = {};
+
+  constructor() {
+    super("google", "Google Cloud TTS", "wav");
+    void this.populateVoiceList();
+  }
+
+  override getDefaultVoice(): string {
+    return "en-us-wavenet-a";
+  }
+
+  private credentialsAvailable(): boolean {
+    return (
+      !!config.GOOGLE_APPLICATION_CREDENTIALS &&
+      existsSync(config.GOOGLE_APPLICATION_CREDENTIALS)
+    );
+  }
+
+  private getClient(): TextToSpeechClient {
+    if (!this.credentialsAvailable()) {
+      throw new Error(
+        "Google Cloud TTS unavailable: GOOGLE_APPLICATION_CREDENTIALS must point to a readable file",
+      );
+    }
+    this.client ??= new textToSpeech.TextToSpeechClient();
+    return this.client;
+  }
+
+  private async populateVoiceList(): Promise<void> {
+    if (!this.credentialsAvailable()) return;
+    try {
+      const [result] = await this.getClient().listVoices({});
+      for (const voice of result.voices ?? []) {
+        if (!voice.name || !voice.languageCodes?.[0]) continue;
+        this.voices[voice.name.toLowerCase()] = {
+          name: voice.name,
+          lang: voice.languageCodes[0],
+        };
+      }
+    } catch (err) {
+      console.error("Google Cloud TTS: failed to populate voice list:", err);
+    }
+  }
+
+  override async getSpeechFile(
+    text: string,
+    filepath: string,
+    voice: string = this.getDefaultVoice(),
+    _params: VoiceParams = {},
+  ): Promise<string> {
+    const meta = this.voices[voice];
+    if (!meta) throw new Error(`Google: unknown voice "${voice}"`);
+    const [response] = await this.getClient().synthesizeSpeech({
+      input: { text },
+      voice: { name: meta.name, languageCode: meta.lang },
+      audioConfig: { audioEncoding: "LINEAR16" },
+    });
+    if (!response.audioContent) {
+      throw new Error("Google: synthesizeSpeech returned no audioContent");
+    }
+    await writeFile(filepath, response.audioContent);
+    return filepath;
+  }
+}