class ScoreManager {

	constructor() {
		this.score = 0;
		this.highScore = 0;

		this.onChangeScoreFunctions = [];
		this.onChangeHighScoreFunctions = [];
	}

	addOnChangeScoreFunctions(onChangeFunction) {
		this.onChangeScoreFunctions.push(onChangeFunction);
	}

	removeOnChangeScoreFunctions(onChangeFunction) {
		let itemIndex = this.onChangeScoreFunctions.indexOf(onChangeFunction);
		if(itemIndex > -1)
			this.onChangeScoreFunctions.splice(itemIndex, 1);
	}

	addOnChangeHighScoreFunctions(onChangeHighScoreFunction) {
		this.onChangeHighScoreFunctions.push(onChangeHighScoreFunction);
	}

	removeOnChangeHighScoreFunctions(onChangeHighScoreFunction) {
		let itemIndex = this.onChangeHighScoreFunctions.indexOf(onChangeHighScoreFunction);
		if(itemIndex > -1)
			this.onChangeHighScoreFunctions.splice(itemIndex, 1);
	}

	removeAllFunctions() {
		this.onChangeScoreFunctions = [];
		this.onChangeHighScoreFunctions = [];
	}


	getScore() {
		return this.score;
	}

	getHighScore() {
		return this.highScore;
	}


	plusScore(amount) {
		this.setScore(this.score + amount);
	}

	minusScore(amount) {
		this.plusScore(-1 * amount);
	}

	setScore(value) {
		let beforeScore = this.score;
		this.score = value;

		// update score
		if(beforeScore !== this.score) {
			if(this.onChangeScoreFunctions.length > 0) {
				for(let i = 0; i < this.onChangeScoreFunctions.length; i++) {
					this.onChangeScoreFunctions[i](this.score);
				}
			}
		}

		// update high score
		if(this.score > this.highScore) {
			this.highScore = this.score;

			if(this.onChangeHighScoreFunctions.length > 0) {
				for(let i = 0; i < this.onChangeHighScoreFunctions.length; i++) {
					this.onChangeHighScoreFunctions[i](this.highScore);
				}
			}
		}
	}

}