const STATES = ['ARMED', 'LISTENING', 'THINKING', 'SPEAKING', 'SLEEPING'];
const COMMANDS = new Map([
  ['cancel', 'cancel'], ['stop', 'cancel'], ['never mind', 'cancel'],
  ['hands off', 'cancel'], ['stop clicking', 'cancel'], ["that's enough", 'cancel'],
  ['go to sleep', 'sleep'], ['privacy mode', 'sleep'],
]);

export class VoiceStateMachine {
  constructor({ now = () => Date.now(), idleMs = 30 * 60 * 1000 } = {}) {
    this.now = now;
    this.idleMs = idleMs;
    this.state = 'ARMED';
    this.lastActivity = now();
  }

  transition(next, reason = 'unspecified') {
    if (!STATES.includes(next)) throw new Error(`unknown Jarvis state: ${next}`);
    const allowed = {
      ARMED: ['LISTENING', 'SLEEPING'], LISTENING: ['THINKING', 'ARMED', 'SLEEPING', 'SPEAKING'],
      THINKING: ['SPEAKING', 'ARMED', 'LISTENING'], SPEAKING: ['LISTENING', 'ARMED', 'THINKING'],
      SLEEPING: ['LISTENING', 'ARMED'],
    };
    if (next !== this.state && !allowed[this.state].includes(next)) {
      throw new Error(`invalid state transition ${this.state} -> ${next}`);
    }
    const previous = this.state;
    this.state = next;
    this.lastActivity = this.now();
    return { previous, state: next, reason };
  }

  wake() { return this.transition('LISTENING', 'wake'); }
  utterance() { return this.transition('THINKING', 'utterance'); }
  typedUtterance() {
    if (this.state === 'ARMED' || this.state === 'SLEEPING') this.wake();
    return this.utterance();
  }
  speak() { return this.transition('SPEAKING', 'reply'); }
  finishSpeaking() { return this.transition('LISTENING', 'playback-finished'); }
  cancel() { return this.transition('ARMED', 'cancel'); }
  sleep() { return this.transition('SLEEPING', 'idle-or-privacy'); }

  command(text) {
    const command = COMMANDS.get(String(text || '').trim().toLowerCase());
    if (command === 'cancel') this.cancel();
    if (command === 'sleep') this.sleep();
    return command || null;
  }

  expireIdle() {
    if (['ARMED', 'LISTENING'].includes(this.state) && this.now() - this.lastActivity >= this.idleMs) this.sleep();
    return this.state;
  }
}

export { STATES };