import {
	InputNode,
	OutputNode,
	ToneAudioNode,
	ToneAudioNodeOptions,
} from "../../core/context/ToneAudioNode.js";
import { Decibels } from "../../core/type/Units.js";
import { optionsFromArguments } from "../../core/util/Defaults.js";
import { Compressor } from "./Compressor.js";
import { Param } from "../../core/context/Param.js";
import { readOnly } from "../../core/util/Interface.js";

export interface LimiterOptions extends ToneAudioNodeOptions {
	threshold: Decibels;
}

/**
 * Limiter will limit the loudness of an incoming signal.
 * Under the hood it's composed of a {@link Compressor} with a fast attack
 * and release and max compression ratio.
 *
 * @example
 * const limiter = new Tone.Limiter(-20).toDestination();
 * const oscillator = new Tone.Oscillator().connect(limiter);
 * oscillator.start();
 * @category Component
 */
export class Limiter extends ToneAudioNode<LimiterOptions> {
	readonly name: string = "Limiter";

	readonly input: InputNode;
	readonly output: OutputNode;

	/**
	 * The compressor which does the limiting
	 */
	private _compressor: Compressor;

	readonly threshold: Param<"decibels">;

	/**
	 * @param threshold The threshold above which the gain reduction is applied.
	 */
	constructor(threshold?: Decibels);
	constructor(options?: Partial<LimiterOptions>);
	constructor() {
		const options = optionsFromArguments(Limiter.getDefaults(), arguments, [
			"threshold",
		]);
		super(options);

		this._compressor =
			this.input =
			this.output =
				new Compressor({
					context: this.context,
					ratio: 20,
					attack: 0.003,
					release: 0.01,
					threshold: options.threshold,
				});

		this.threshold = this._compressor.threshold;
		readOnly(this, "threshold");
	}

	static getDefaults(): LimiterOptions {
		return Object.assign(ToneAudioNode.getDefaults(), {
			threshold: -12,
		});
	}

	/**
	 * A read-only decibel value for metering purposes, representing the current amount of gain
	 * reduction that the compressor is applying to the signal.
	 */
	get reduction(): Decibels {
		return this._compressor.reduction;
	}

	dispose(): this {
		super.dispose();
		this._compressor.dispose();
		this.threshold.dispose();
		return this;
	}
}