import { EventEmitter } from 'node:events';
import { pcmRms } from './audio-pipewire.js';

export const DEFAULT_VAD = Object.freeze({
  threshold: 0.6,
  minSpeechDurationMs: 300,
  minSilenceDurationMs: 700,
  maxSpeechDurationMs: 15_000,
  speechPadMs: 200,
});

/** A conservative local gate around QVAC's stream. It bounds audio sent to
 * ASR and gives the loop deterministic utterance boundaries in tests. */
export class VadSegmenter extends EventEmitter {
  constructor({ sampleRate = 16_000, frameMs = 20, params = {} } = {}) {
    super();
    this.sampleRate = sampleRate;
    this.frameMs = frameMs;
    this.params = { ...DEFAULT_VAD, ...params };
    this.reset();
  }

  reset() { this.speaking = false; this.buffer = []; this.speechMs = 0; this.silenceMs = 0; }

  push(frame) {
    const chunk = Buffer.from(frame || '');
    const rms = pcmRms(chunk);
    const voiced = rms >= this.params.threshold / 10; // PCM RMS is 0..1; QVAC threshold is posterior-like.
    this.emit('level', rms);
    if (!this.speaking && voiced) {
      this.speaking = true; this.speechMs = 0; this.silenceMs = 0; this.buffer = [];
      this.emit('speechStart');
    }
    if (!this.speaking) return;
    this.buffer.push(chunk);
    if (voiced) { this.speechMs += this.frameMs; this.silenceMs = 0; }
    else { this.silenceMs += this.frameMs; }
    if (this.speechMs >= this.params.maxSpeechDurationMs ||
        (this.speechMs >= this.params.minSpeechDurationMs && this.silenceMs >= this.params.minSilenceDurationMs)) {
      this.end();
    }
  }

  end() {
    if (!this.speaking) return null;
    const audio = Buffer.concat(this.buffer);
    this.reset();
    this.emit('utterance', audio);
    return audio;
  }
}