import { spawn } from 'node:child_process';
import { EventEmitter } from 'node:events';

export const MIC_SAMPLE_RATE = 16_000;
export const MIC_CHANNELS = 1;
export const MIC_FORMAT = 's16';

/** Raw 16 kHz mono capture from PipeWire. The process is deliberately kept
 * outside gnome-shell and has a stable node name for routing in Helvum. */
export class PipeWireCapture extends EventEmitter {
  constructor({ command = 'pw-cat', spawnImpl = spawn, sampleRate = MIC_SAMPLE_RATE, nodeName = 'Jarvis' } = {}) {
    super();
    this.command = command;
    this.spawnImpl = spawnImpl;
    this.sampleRate = sampleRate;
    this.nodeName = nodeName;
    this.process = null;
  }

  start() {
    if (this.process) return this;
    this.process = this.spawnImpl(this.command, [
      '--record', '--raw', '--format', MIC_FORMAT, '--rate', String(this.sampleRate),
      '--channels', String(MIC_CHANNELS), '--name', this.nodeName,
    ], { stdio: ['ignore', 'pipe', 'pipe'] });
    this.process.stdout?.on('data', (chunk) => this.emit('audio', Buffer.from(chunk)));
    this.process.stderr?.on('data', (chunk) => this.emit('diagnostic', String(chunk).trim()));
    this.process.on('error', (error) => this.emit('error', error));
    this.process.on('close', (code, signal) => { this.process = null; this.emit('close', { code, signal }); });
    return this;
  }

  stop() {
    if (!this.process) return;
    this.process.kill('SIGTERM');
    this.process = null;
  }
}

export function pcmRms(chunk) {
  const bytes = Buffer.from(chunk || '');
  if (bytes.length < 2) return 0;
  let sum = 0;
  for (let i = 0; i + 1 < bytes.length; i += 2) {
    const sample = bytes.readInt16LE(i) / 32768;
    sum += sample * sample;
  }
  return Math.sqrt(sum / Math.floor(bytes.length / 2));
}