import { existsSync, mkdirSync } from "node:fs";
import { writeFile } from "node:fs/promises";
import { NextRequest, NextResponse } from "next/server";
import { EdgeTTS } from "edge-tts-universal";
import { getAudioFilePath, getAudioPublicPath } from "@/lib/audio";

export const runtime = "nodejs";
export const dynamic = "force-dynamic";

export async function POST(request: NextRequest) {
  try {
    const body = await request.json();
    const voice = String(body.voice ?? "en-US-EmmaMultilingualNeural");
    const rate = String(body.rate ?? "-10%");
    const text = String(body.text ?? "Hello, welcome to English PK.");

    const audioDirectory = getAudioFilePath("preview");
    if (!existsSync(audioDirectory)) {
      mkdirSync(audioDirectory, { recursive: true });
    }

    const fileName = `tts-preview-${Date.now()}.mp3`;
    const filePath = getAudioFilePath("preview", fileName);
    const publicPath = getAudioPublicPath(`preview/${fileName}`);

    const tts = new EdgeTTS(text, voice, { rate });
    const result = await tts.synthesize();
    const audioBuffer = Buffer.from(await result.audio.arrayBuffer());
    await writeFile(filePath, audioBuffer);

    return NextResponse.json({ audio: publicPath });
  } catch (error) {
    const message = error instanceof Error ? error.message : "试听语音失败";
    return NextResponse.json({ message }, { status: 500 });
  }
}