export function debounce(func, wait, immediate) {
	let timeout, args, context, timestamp, result

	const later = function() {
		// 据上一次触发时间间隔
		const last = +new Date() - timestamp

		// 上次被包装函数被调用时间间隔 last 小于设定时间间隔 wait
		if (last < wait && last > 0) {
			timeout = setTimeout(later, wait - last)
		} else {
			timeout = null
			// 如果设定为immediate===true，因为开始边界已经调用过了此处无需调用
			if (!immediate) {
				result = func.apply(context, args)
				if (!timeout) context = args = null
			}
		}
	}

	return function(...args) {
		context = this
		timestamp = +new Date()
		const callNow = immediate && !timeout
		// 如果延时不存在，重新设定延时
		if (!timeout) timeout = setTimeout(later, wait)
		if (callNow) {
			result = func.apply(context, args)
			context = args = null
		}

		return result
	}
}

export default {
  data() {
    return {
      $_sidebarElm: null,
      $_resizeHandler: null
    }
  },
  mounted() {
    this.initListener()
  },
  activated() {
    if (!this.$_resizeHandler) {
      // avoid duplication init
      this.initListener()
    }

    // when keep-alive chart activated, auto resize
    this.resize()
  },
  beforeDestroy() {
    this.destroyListener()
  },
  deactivated() {
    this.destroyListener()
  },
  methods: {
    // use $_ for mixins properties
    // https://vuejs.org/v2/style-guide/index.html#Private-property-names-essential
    $_sidebarResizeHandler(e) {
      if (e.propertyName === 'width') {
        this.$_resizeHandler()
      }
    },
    initListener() {
      this.$_resizeHandler = debounce(() => {
        this.resize()
      }, 100)
      window.addEventListener('resize', this.$_resizeHandler)

      this.$_sidebarElm = document.getElementsByClassName('sidebar-container')[0]
      this.$_sidebarElm && this.$_sidebarElm.addEventListener('transitionend', this.$_sidebarResizeHandler)
    },
    destroyListener() {
      window.removeEventListener('resize', this.$_resizeHandler)
      this.$_resizeHandler = null

      this.$_sidebarElm && this.$_sidebarElm.removeEventListener('transitionend', this.$_sidebarResizeHandler)
    },
    resize() {
      const { chart } = this
      chart && chart.resize()
    }
  }
}
