/*!
 * Jodit Editor (https://xdsoft.net/jodit/)
 * License GNU General Public License version 2 or later;
 * Copyright 2013-2019 Valeriy Chupurnov https://xdsoft.net
 */

import { JoditObject } from './JoditObject';
import { JoditArray } from './JoditArray';
import { type } from './type';
import { isPlainObject } from './checker/isPlainObject';

/**
 * Copy the values of all of the enumerable own properties from one or more source objects to a
 * target object. Returns the target object.
 * @param target The target object to copy to.
 * @param source The source object from which to copy properties.
 */
export function extend<T, U>(target: T, source: U): T & U;
export function extend<U, V>(deep: true, source1: U, source2: V): U & V;

/**
 * Copy the values of all of the enumerable own properties from one or more source objects to a
 * target object. Returns the target object.
 * @param target The target object to copy to.
 * @param source1 The first source object from which to copy properties.
 * @param source2 The second source object from which to copy properties.
 */
export function extend<T, U, V>(target: T, source1: U, source2: V): T & U & V;
export function extend<T, U, V>(
    deep: true,
    target: T,
    source1: U,
    source2: V
): T & U & V;

/**
 * Copy the values of all of the enumerable own properties from one or more source objects to a
 * target object. Returns the target object.
 * @param target The target object to copy to.
 * @param source1 The first source object from which to copy properties.
 * @param source2 The second source object from which to copy properties.
 * @param source3 The third source object from which to copy properties.
 */
export function extend<T, U, V, W>(
    target: T,
    source1: U,
    source2: V,
    source3: W
): T & U & V & W;
export function extend<T, U, V, W>(
    deep: true,
    target: T,
    source1: U,
    source2: V,
    source3: W
): T & U & V & W;

/**
 * Copy the values of all of the enumerable own properties from one or more source objects to a
 * target object. Returns the target object.
 * @param target The target object to copy to.
 * @param sources One or more source objects from which to copy properties
 */
export function extend(target: object, ...sources: any[]): any;
export function extend(deep: true, target: object, ...sources: any[]): any;

export function extend(this: any, ...args: any[]): any {
    const length = args.length;
    let options,
        name,
        src,
        copy,
        copyIsArray,
        clone,
        target: boolean | any = args[0] || {},
        i = 1,
        j,
        keys,
        deep = false;

    if (typeof target === 'boolean') {
        deep = target;
        target = args[i] || {};
        i += 1;
    }

    if (typeof target !== 'object' && type(target) === 'function') {
        target = {};
    }

    if (i === length) {
        target = this;
        i += 1;
    }

    for (i; i < length; i += 1) {
        options = args[i];
        if (options !== null && options !== undefined) {
            keys = Object.keys(options);
            for (j = 0; j < keys.length; j += 1) {
                name = keys[j];
                src = target[name];
                copy = options[name];

                if (target === copy) {
                    continue;
                }

                if (
                    deep &&
                    copy &&
                    ((isPlainObject(copy) && !(copy instanceof JoditObject)) ||
                        (Array.isArray(copy) && !(copy instanceof JoditArray)))
                ) {
                    copyIsArray = Array.isArray(copy);

                    if (copyIsArray) {
                        copyIsArray = false;
                        clone = src && Array.isArray(src) ? src : [];
                    } else {
                        clone = src && isPlainObject(src) ? src : {};
                    }
                    target[name] = extend(deep, clone, copy);
                } else if (copy !== undefined) {
                    target[name] = copy;
                }
            }
        }
    }

    return target;
}