/* eslint-disable @typescript-eslint/no-unsafe-assignment */
import { UnknownObject } from '../types'

const isObject = (obj: Record<string, unknown>): boolean => !!obj && typeof obj === 'object' && !Array.isArray(obj)

export default function mergeDeep (target: UnknownObject, ...sources: UnknownObject[]): UnknownObject {
  if (!sources.length) return target
  const source = sources.shift()
  if (source === undefined || !isObject(target) || !isObject(source)) return target
  target = { ...target }
  Object.keys(source).forEach((key: string): void => {
    const targetValue = target[key]
    const sourceValue = source[key]

    if (Array.isArray(targetValue) && Array.isArray(sourceValue)) {
      target[key] = sourceValue
    } else if (isObject(targetValue) && isObject(sourceValue)) {
      target[key] = mergeDeep(Object.assign({}, targetValue), sourceValue)
    } else {
      target[key] = sourceValue
    }
  })

  return mergeDeep(target, ...sources)
}