import {
  hasOwn
} from 'uni-shared'

const isArray = Array.isArray
const keyList = Object.keys

export default function equal (a, b) {
  if (a === b) return true

  if (a && b && typeof a === 'object' && typeof b === 'object') {
    const arrA = isArray(a)
    const arrB = isArray(b)
    let i, length, key
    if (arrA && arrB) {
      length = a.length
      if (length !== b.length) return false
      for (i = length; i-- !== 0;) {
        if (!equal(a[i], b[i])) return false
      }
      return true
    }
    if (arrA !== arrB) return false

    const dateA = a instanceof Date
    const dateB = b instanceof Date
    if (dateA !== dateB) return false
    if (dateA && dateB) return a.getTime() === b.getTime()

    const regexpA = a instanceof RegExp
    const regexpB = b instanceof RegExp
    if (regexpA !== regexpB) return false
    if (regexpA && regexpB) return a.toString() === b.toString()

    const keys = keyList(a)
    length = keys.length
    if (length !== keyList(b).length) {
      return false
    }
    for (i = length; i-- !== 0;) {
      if (!hasOwn.call(b, keys[i])) return false
    }
    for (i = length; i-- !== 0;) {
      key = keys[i]
      if (!equal(a[key], b[key])) return false
    }

    return true
  }

  return false
}