import Taro from '@tarojs/taro'

let scrollTop = 0

const isWeapp =  Taro.getEnv() === Taro.ENV_TYPE.WEAPP

const isWeb = Taro.getEnv() === Taro.ENV_TYPE.WEB

function handleTouchScroll (flag: any): void {
  if (!isWeb) {
    return
  }
  if (flag) {
    // eslint-disable-next-line prefer-destructuring
    scrollTop = document.documentElement.scrollTop

    // 使body脱离文档流
    document.body.classList.add('at-frozen')

    // 把脱离文档流的body拉上去！否则页面会回到顶部！
    document.body.style.top = `${-scrollTop}px`
  } else {
    document.body.style.top = ''
    document.body.classList.remove('at-frozen')

    document.documentElement.scrollTop = scrollTop
  }
}

/**
 * 合并 style
 * @param {Object|String} style1
 * @param {Object|String} style2
 * @returns {String}
 */
function mergeStyle (
  style1: object | string,
  style2: object | string
): object | string {
  if (
    style1 &&
    typeof style1 === 'object' &&
    style2 &&
    typeof style2 === 'object'
  ) {
    return { ...style1, ...style2 }
  }
  return objectToString(style1) + objectToString(style2)
}

function pxTransform (size: number): string {
  if (!size) return ''
  const designWidth = 750
  const deviceRatio = {
    640: 2.34 / 2,
    750: 1,
    828: 1.81 / 2
  }
  if (isWeb) {
    return 16 / 750 * size + 'rem'
  }
  return `${size / deviceRatio[designWidth]}rpx`
}

function objectToString (style: object | string): string {
  if (style && typeof style === 'object') {
    let styleStr = ''
    Object.keys(style).forEach(key => {
      const lowerCaseKey = key.replace(/([A-Z])/g, '-$1').toLowerCase()
      styleStr += `${lowerCaseKey}:${style[key]};`
    })
    return styleStr
  } else if (style && typeof style === 'string') {
    return style
  }
  return ''
}

/**
 * 
 * 
 */

function isTest (): boolean {
  return process.env.NODE_ENV === 'test'
}

/**
 * 
 * 
 * 随机选取 len 长度的字符
 * 
*/
function uuid (len = 8, radix = 16): string {
  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('')
  const value: string[] = []
  let i = 0
  const radix2 = radix || chars.length

  if (len) {
    // Compact form
    for (i = 0; i < len; i ++) value[i] = chars[0 | (Math.random() * radix2)]
  } else {
    // rfc4122, version 4 form
    let r

    // rfc4122 requires these characters
    /* eslint-disable-next-line */
    value[8] = value[13] = value[18] = value[23] = '-'
    value[14] = '4'

    // Fill in random data.  At i==19 set the high bits of clock sequence as
    // per rfc4122, sec. 4.1.5
    for (i = 0; i < 36; i ++) {
      if (!value[i]) {
        r = 0 | (Math.random() * 16)
        value[i] = chars[i === 19 ? (r & 0x3) | 0x8 : r]
      }
    }
  }
  return value.join('')
}

function getDateUTC (value:any) {
  if (value) return new Date(value.replace(/-/g, '/'))
  return new Date(new Date().getTime() + 5 * 60 * 1000)
}

const regex = new RegExp(/[A-Z]/g)
const kebabCase = (str) => str.replace(regex, v => `-${v.toLowerCase()}`)

function transformationString (cssProperties) {
  const finalResult = Object.keys(cssProperties).reduce((accumulator, key) => {
    const cssKey = kebabCase(key)
    const cssValue = cssProperties[key].replace("'", "")
    return `${accumulator}${cssKey}:${cssValue};`
  }, '')
  return finalResult
}


export {
  handleTouchScroll,
  mergeStyle,
  pxTransform,
  isTest,
  uuid,
  transformationString,
  objectToString,
  getDateUTC,
  isWeapp,
  isWeb
}