// tts.service.mjs
export class TTS {
	static QUALITY_PATTERNS = ['Google', 'Microsoft', 'Samantha', 'Premium', 'Natural', 'Neural'];
	static _errorHandlerInstalled = false;
	static _instance = null;

	_currentUtterance = null;
	_voicesLoaded;
	_stoppedUtterances = new WeakSet();
	_rate = 1;
	_pitch = 1;
	_volume = 1;
	_voice;
	_hooks = {
		onSentenceStart: [],
		onSentenceEnd: [],
		onChunk: [],
		onComplete: []
	};

	constructor({ rate, pitch, volume, voice } = {}) {
		TTS.installErrorHandler();
		this._voicesLoaded = this.initializeVoices();
		if (rate !== undefined) this._rate = rate;
		if (pitch !== undefined) this._pitch = pitch;
		if (volume !== undefined) this._volume = volume;
		this._voice = voice === null ? undefined : voice;
	}

	static getInstance(config) {
		if(!this._instance) this._instance = new TTS(config);
		return this._instance;
	}

	static installErrorHandler() {
		if (this._errorHandlerInstalled) return;
		window.addEventListener('unhandledrejection', e => {
			if (e.reason?.error === 'interrupted' && e.reason instanceof SpeechSynthesisErrorEvent) e.preventDefault();
		});
		this._errorHandlerInstalled = true;
	}

	initializeVoices() {
		return new Promise(res => {
			const voices = window.speechSynthesis.getVoices();
			if (voices.length) {
				if (!this._voice) this._voice = TTS.bestVoice();
				res();
			} else {
				const h = () => {
					window.speechSynthesis.removeEventListener('voiceschanged', h);
					if (!this._voice) this._voice = TTS.bestVoice();
					res();
				};
				window.speechSynthesis.addEventListener('voiceschanged', h);
			}
		});
	}

	static bestVoice(lang = 'en') {
		const voices = window.speechSynthesis.getVoices();
		for (const p of this.QUALITY_PATTERNS) {
			const v = voices.find(v => v.name.includes(p) && v.lang.startsWith(lang));
			if (v) return v;
		}
		return voices.find(v => v.lang.startsWith(lang));
	}

	static cleanText(t) {
		return removeEmojis(t).replace(/```[\s\S]*?```/g, ' code block ').replace(/[#*_~`]/g, '');
	}

	on(event, callback) {
		if(this._hooks[event]) this._hooks[event].push(callback);
	}

	off(event, callback) {
		if(this._hooks[event]) this._hooks[event] = this._hooks[event].filter(cb => cb !== callback);
	}

	_emit(event, data) {
		if (this._hooks[event]) {
			this._hooks[event].forEach(cb => {
				try {
					cb(data);
				} catch (err) {
					console.error(`❌ Error in ${event} hook:`, err);
				}
			});
		}
	}

	createUtterance(t) {
		const u = new SpeechSynthesisUtterance(TTS.cleanText(t));
		const v = this._voice || TTS.bestVoice();
		if (v) u.voice = v;
		u.rate = this._rate;
		u.pitch = this._pitch;
		u.volume = this._volume;
		return u;
	}

	async speak(t) {
		if(!t.trim()) return;
		await this._voicesLoaded;
		if(this._currentUtterance && !this._isStreaming) this.stop();
		return new Promise((res, rej) => {
			this._currentUtterance = this.createUtterance(t);
			const u = this._currentUtterance;
			u.onend = () => {
				this._currentUtterance = null;
				res();
			};
			u.onerror = e => {
				console.error('❌ Utterance error:', e);
				this._currentUtterance = null;
				if (this._stoppedUtterances.has(u) && e.error === 'interrupted') res();
				else rej(e);
			};
			window.speechSynthesis.speak(u);
			this._emit('onSentenceStart', {sentence: t});
		}).finally(() => this._emit('onSentenceEnd', {sentence: t}));
	}

	stop() {
		if (this._currentUtterance) this._stoppedUtterances.add(this._currentUtterance);
		window.speechSynthesis.cancel();
		this._currentUtterance = null;
		this._isStreaming = false;
		this._emit('onComplete', {});
	}

	speakStream() {
		this._isStreaming = true;
		let buf = '';
		let sentenceQueue = Promise.resolve();
		const rx = /[^.!?\n]+[.!?\n]+/g;

		return {
			next: t => {
				buf += t;
				this._emit('onChunk', { text: t });
				const ss = buf.match(rx);
				if(ss) {
					ss.forEach(s => {
						const sentence = s.trim();
						sentenceQueue = sentenceQueue.then(async () => this.speak(sentence));
					});
				}
				buf = buf.replace(rx, '');
			},
			done: async () => {
				if (buf.trim()) {
					const sentence = buf.trim();
					sentenceQueue = sentenceQueue.then(async () => this.speak(sentence));
					buf = '';
				}
				await sentenceQueue;
				this._isStreaming = false;
				this._emit('onComplete', {});
			}
		};
	}
}

export function removeEmojis(str) {
	const emojiRegex = /(?:[\u2700-\u27bf]|(?:\ud83c[\udde6-\uddff]){2}|[\ud83c[\udde6-\uddff]|[\ud83d[\ude00-\ude4f]|[\ud83d[\ude80-\udeff]|[\ud83c[\udd00-\uddff]|[\ud83d[\ude50-\ude7f]|[\u2600-\u26ff]|[\u2700-\u27bf]|[\ud83e[\udd00-\uddff]|[\ud83c[\udf00-\uffff]|[\ud83d[\ude00-\udeff]|[\ud83c[\udde6-\uddff])/g;
	return str.replace(emojiRegex, '');
}