/*!
 * Jodit Editor (https://xdsoft.net/jodit/)
 * Licensed under GNU General Public License version 2 or later or a commercial license or MIT;
 * For GPL see LICENSE-GPL.txt in the project root for license information.
 * For MIT see LICENSE-MIT.txt in the project root for license information.
 * For commercial licenses see https://xdsoft.net/jodit/commercial/
 * Copyright (c) 2013-2019 Valeriy Chupurnov. All rights reserved. https://xdsoft.net
 */

import { Config } from '../../Config';
import { IJodit, SnapshotType } from '../../types';
import { Component } from '../Component';
import { debounce } from '../helpers/async';
import { Snapshot } from '../Snapshot';
import { Stack } from '../Stack';
import { Command } from './command';

/**
 * @property{object} observer module settings {@link Observer|Observer}
 * @property{int} observer.timeout=100 Delay on every change
 */
declare module '../../Config' {
	interface Config {
		observer: {
			timeout: number;
		};
	}
}

Config.prototype.observer = {
	timeout: 100
};

/**
 * The module monitors the status of the editor and creates / deletes the required number of Undo / Redo shots .
 * To track changes in use {@link https://developer.mozilla.org/ru/docs/Web/API/MutationObserver|MutationObserver}
 *
 * @module Observer
 * @see {@link Snapshot|Snapshot}
 * @params {Jodit} parent Jodit main object
 */
export class Observer extends Component<IJodit> {
	private __startValue: SnapshotType;
	private __newValue: SnapshotType;

	private onChangeStack = () => {
		this.__newValue = this.snapshot.make();
		if (!Snapshot.equal(this.__newValue, this.__startValue)) {
			this.stack.push(
				new Command(this.__startValue, this.__newValue, this)
			);
			this.__startValue = this.__newValue;
			this.changeStack();
		}
	};

	/**
	 * @property {Stack} stack
	 */
	public stack: Stack;

	/**
	 * @property{Snapshot} snapshot
	 */
	public snapshot: Snapshot;

	/**
	 * Return state of the WYSIWYG editor to step back
	 */
	public redo() {
		if (this.stack.redo()) {
			this.__startValue = this.snapshot.make();
			this.changeStack();
		}
	}

	/**
	 * Return the state of the WYSIWYG editor to step forward
	 */
	public undo() {
		if (this.stack.undo()) {
			this.__startValue = this.snapshot.make();
			this.changeStack();
		}
	}

	public clear() {
		this.__startValue = this.snapshot.make();
		this.stack.clear();
		this.changeStack();
	}

	public changeStack() {
		this.jodit &&
			!this.jodit.isDestructed &&
			this.jodit.events &&
			this.jodit.events.fire('changeStack');
	}

	constructor(editor: IJodit) {
		super(editor);

		this.stack = new Stack();

		this.snapshot = new Snapshot(editor);

		const onChangeStack = debounce(
			this.onChangeStack,
			editor.defaultTimeout
		);

		editor.events.on('afterInit.observer', () => {
			if (this.isDestructed) {
				return;
			}

			this.__startValue = this.snapshot.make();
			editor.events
				// save selection
				.on(
					'changeSelection.observer selectionstart.observer selectionchange.observer mousedown.observer mouseup.observer keydown.observer keyup.observer',
					() => {
						if (
							this.__startValue.html ===
							this.jodit.getNativeEditorValue()
						) {
							this.__startValue = this.snapshot.make();
						}
					}
				)
				.on('change.observer', () => {
					if (!this.snapshot.isBlocked) {
						onChangeStack();
					}
				});
		});
	}
	destruct(): any {
		if (this.jodit.events) {
			this.jodit.events.off('.observer');
		}

		this.snapshot.destruct();
		delete this.snapshot;

		delete this.stack;

		super.destruct();
	}
}