import {TtsSession} from '@mintplex-labs/piper-tts-web';
import {trackModelDownload} from './piper-download-progress.mjs';
import {localPiperModelUrl} from './piper-model-routing.mjs';
import {createOnnxWasmPaths} from './piper-onnx-config.mjs';

const VOICE_ID = 'sv_SE-nst-medium';
const ASSET_ROOT = '/static/piper-wasm-v1';
const localFetch = self.fetch.bind(self);

function reportStage(id, stage) {
  if (Number.isSafeInteger(id)) self.postMessage({id, type: 'progress', progress: {stage}});
}

// Keep the TTS library's OPFS cache logic, but serve models/config from the
// same-origin static asset service instead of its built-in external model URL.
self.fetch = async (resource, options) => {
  const requestedUrl = resource instanceof Request ? resource.url : String(resource);
  const localModelUrl = localPiperModelUrl(requestedUrl, self.location.origin);
  if (!localModelUrl) {
    if (activeRequestId && requestedUrl.includes('/static/piper-wasm-v1/onnx/')) {
      reportStage(activeRequestId, 'loading-runtime-assets');
    }
    return localFetch(resource, options);
  }
  const isModel = localModelUrl.endsWith('.onnx');
  if (activeRequestId) reportStage(activeRequestId, isModel ? 'loading-model' : 'loading-model-info');
  const redirected = resource instanceof Request ? new Request(localModelUrl, resource) : localModelUrl;
  const response = await localFetch(redirected, options);
  if (!activeRequestId || !isModel) return response;
  reportStage(activeRequestId, 'reading-model');
  return trackModelDownload(response, {
    id: activeRequestId,
    postMessage: message => self.postMessage(message),
  });
};

let sessionPromise;
let inferenceQueue = Promise.resolve();
let activeRequestId = null;

async function getSession() {
  if (!sessionPromise) {
    sessionPromise = TtsSession.create({
      voiceId: VOICE_ID,
      wasmPaths: {
        onnxWasm: createOnnxWasmPaths(self.location.origin),
        piperData: `${ASSET_ROOT}/piper/piper_phonemize.data`,
        piperWasm: `${ASSET_ROOT}/piper/piper_phonemize.wasm`,
      },
    }).catch(error => {
      sessionPromise = null;
      throw error;
    });
  }
  return sessionPromise;
}

async function synthesizeMessage(event) {
  const {id, text} = event.data || {};
  if (!Number.isSafeInteger(id) || typeof text !== 'string') return;
  activeRequestId = id;
  reportStage(id, 'loading-runtime');
  try {
    const session = await getSession();
    reportStage(id, 'model-ready');
    const blob = await session.predict(text);
    const audio = await blob.arrayBuffer();
    self.postMessage({id, type: 'audio', audio}, [audio]);
  } catch (error) {
    self.postMessage({id, type: 'error', error: String(error?.message || error)});
  } finally {
    activeRequestId = null;
  }
}

self.addEventListener('message', event => {
  inferenceQueue = inferenceQueue.then(() => synthesizeMessage(event));
});