// 封装异步加载资源的方法

/**
 * 加载外部资源
 * @param url 地址 例如 https://xx.com/xx.js
 * @param type js 或 css
 * @returns {Promise<unknown>}
 */
export function loadExternalResource (url, type) {
  return new Promise((resolve, reject) => {
    let tag

    if (type === 'css') {
      tag = document.createElement('link')
      tag.rel = 'stylesheet'
      tag.href = url
    } else if (type === 'js') {
      tag = document.createElement('script')
      tag.src = url
    }
    if (tag) {
      tag.onload = () => resolve(url)
      tag.onerror = () => reject(url)
      document.head.appendChild(tag)
    }
  })
}

/**
 * 查询url中的query参数
 * @param {}} variable
 * @returns
 */
export function getQueryVariable (variable) {
  const query = window.location.search.substring(1)
  const vars = query.split('&')
  for (let i = 0; i < vars.length; i++) {
    const pair = vars[i].split('=')
    if (pair[0] === variable) { return pair[1] }
  }
  return (false)
}

/**
 * 深度合并两个对象
 * @param target
 * @param sources
 */
export function mergeDeep (target, ...sources) {
  if (!sources.length) return target
  const source = sources.shift()

  if (isObject(target) && isObject(source)) {
    for (const key in source) {
      if (isObject(source[key])) {
        if (!target[key]) Object.assign(target, { [key]: {} })
        mergeDeep(target[key], source[key])
      } else {
        Object.assign(target, { [key]: source[key] })
      }
    }
  }
  return mergeDeep(target, ...sources)
}

/**
 * 对象检查
 * @param item
 * @returns {boolean}
 */
export function isObject (item) {
  return (item && typeof item === 'object' && !Array.isArray(item))
}