export class StorySpeechNarrator {
  private synth: SpeechSynthesis | null = null;
  private currentUtterance: SpeechSynthesisUtterance | null = null;
  private onEndCallback: (() => void) | null = null;
  private onWordCallback: ((wordIndex: number) => void) | null = null;

  constructor() {
    if (typeof window !== 'undefined' && 'speechSynthesis' in window) {
      this.synth = window.speechSynthesis;
    }
  }

  public isAvailable(): boolean {
    return this.synth !== null;
  }

  public speak(
    text: string,
    options?: {
      rate?: number;
      pitch?: number;
      onEnd?: () => void;
      onWord?: (index: number) => void;
    }
  ) {
    if (!this.synth) return;
    this.stop();

    const utterance = new SpeechSynthesisUtterance(text);
    utterance.rate = options?.rate ?? 0.9; // Slightly slower for children's story cadence
    utterance.pitch = options?.pitch ?? 1.05; // Slightly warmer/friendly pitch

    // Find warm friendly voice
    const voices = this.synth.getVoices();
    const naturalVoice = voices.find(v => 
      v.lang.startsWith('en') && 
      (v.name.includes('Natural') || v.name.includes('Samantha') || v.name.includes('Karen') || v.name.includes('Daniel') || v.name.includes('Google'))
    ) || voices.find(v => v.lang.startsWith('en'));

    if (naturalVoice) {
      utterance.voice = naturalVoice;
    }

    this.onEndCallback = options?.onEnd || null;
    this.onWordCallback = options?.onWord || null;

    utterance.onend = () => {
      this.currentUtterance = null;
      if (this.onEndCallback) this.onEndCallback();
    };

    utterance.onerror = () => {
      this.currentUtterance = null;
      if (this.onEndCallback) this.onEndCallback();
    };

    let wordCount = 0;
    utterance.onboundary = (e) => {
      if (e.name === 'word') {
        if (this.onWordCallback) {
          this.onWordCallback(wordCount);
        }
        wordCount++;
      }
    };

    this.currentUtterance = utterance;
    this.synth.speak(utterance);
  }

  public stop() {
    if (!this.synth) return;
    this.synth.cancel();
    this.currentUtterance = null;
  }

  public pause() {
    if (this.synth) {
      this.synth.pause();
    }
  }

  public resume() {
    if (this.synth) {
      this.synth.resume();
    }
  }

  public isSpeaking(): boolean {
    return this.synth ? this.synth.speaking : false;
  }

  public getCurrentUtterance(): SpeechSynthesisUtterance | null {
    return this.currentUtterance;
  }
}

export const speechNarrator = new StorySpeechNarrator();