/*
This file is part of web3.js.

web3.js is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

web3.js is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with web3.js.  If not, see <http://www.gnu.org/licenses/>.
*/

import { TypedArray } from '@theqrl/web3-types';
import { isNullish } from '@theqrl/web3-validator';

const isIterable = (item: unknown): item is Record<string, unknown> =>
	typeof item === 'object' &&
	!isNullish(item) &&
	!Array.isArray(item) &&
	!(item instanceof TypedArray);

// The following code is a derivative work of the code from the "LiskHQ/lisk-sdk" project,
// which is licensed under Apache version 2.
/**
 * Deep merge two objects.
 * @param destination - The destination object.
 * @param sources - An array of source objects.
 * @returns - The merged object.
 */
const FORBIDDEN_KEYS = new Set(['__proto__', 'constructor', 'prototype']);

export const mergeDeep = (
	destination: Record<string, unknown>,
	...sources: Record<string, unknown>[]
): Record<string, unknown> => {
	if (!isIterable(destination)) {
		return destination;
	}
	const result = { ...destination };
	for (const src of sources) {
		// eslint-disable-next-line no-restricted-syntax
		for (const key in src) {
			if (FORBIDDEN_KEYS.has(key) || !Object.hasOwnProperty.call(src, key)) {
				continue;
			}
			if (isIterable(src[key])) {
				if (!result[key]) {
					result[key] = {};
				}
				result[key] = mergeDeep(
					result[key] as Record<string, unknown>,
					src[key] as Record<string, unknown>,
				);
			} else if (!isNullish(src[key])) {
				if (Array.isArray(src[key]) || src[key] instanceof TypedArray) {
					// eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion
					result[key] = (src[key] as unknown[]).slice(0);
				} else {
					result[key] = src[key];
				}
			}
		}
	}
	return result;
};