// ============================================================
// WHISPER WORKER — runs @xenova/transformers in a Web Worker
// Audio never leaves the device. Model cached in IndexedDB.
// ============================================================

importScripts('https://cdn.jsdelivr.net/npm/@xenova/transformers@2.17.2');

var T = self.transformers || transformers;
T.env.allowLocalModels = false;
T.env.useBrowserCache = true;

var _pipe = null;
var _loadedModel = null;

async function load(modelName) {
  if (_pipe && _loadedModel === modelName) return;
  self.postMessage({ type: 'loading', model: modelName });
  _pipe = await T.pipeline('automatic-speech-recognition', modelName, {
    progress_callback: function(p) {
      if (p.status === 'downloading' || p.status === 'progress') {
        self.postMessage({ type: 'progress', file: p.file || '', progress: Math.round(p.progress || 0) });
      }
    }
  });
  _loadedModel = modelName;
  self.postMessage({ type: 'ready', model: modelName });
}

self.addEventListener('message', async function(e) {
  var d = e.data;

  if (d.type === 'load') {
    try { await load(d.model || 'Xenova/whisper-tiny.en'); }
    catch(err) { self.postMessage({ type: 'error', message: err.message }); }
    return;
  }

  if (d.type === 'transcribe') {
    try {
      await load(d.model || 'Xenova/whisper-tiny.en');
      var result = await _pipe(d.audio, {
        language: 'english',
        task: 'transcribe',
        chunk_length_s: 30,
        stride_length_s: 5,
        return_timestamps: false
      });
      self.postMessage({ type: 'result', text: result.text.trim() });
    } catch(err) {
      self.postMessage({ type: 'error', message: err.message });
    }
  }
});