/* @flow */

import React, { Component } from 'react';

const ANIMATION_DURATION = 300;

type Props = {
  isShow: boolean,
  children?: React.Element<any>
};

export default class CollapseTransition extends Component {
  props: Props;

  selfRef: any;
  leaveTimer: any;
  enterTimer: any;

  componentDidMount(): void {
    this.beforeEnter();
    if (this.props.isShow) {
      this.enter();
    }
  }

  componentWillUnmount(): void {
    this.beforeLeave();
    this.leave();
  }

  componentWillReceiveProps(nextProps: any){
    if (this.props.isShow !== nextProps.isShow) this.triggerChange(nextProps.isShow);
  }

  triggerChange(isShow: boolean): void {
    clearTimeout(this.enterTimer);
    clearTimeout(this.leaveTimer);
    if (isShow) {
      this.beforeEnter();
      this.enter();
    } else {
      this.beforeLeave();
      this.leave();
    }
  }

  beforeEnter(): void {
    const el = this.selfRef;
    //prepare
    el.dataset.oldPaddingTop = el.style.paddingTop;
    el.dataset.oldPaddingBottom = el.style.paddingBottom;
    el.dataset.oldOverflow = el.style.overflow;
    el.style.height = '0';
    el.style.paddingTop = 0;
    el.style.paddingBottom = 0;
  }

  enter(): void {
    const el = this.selfRef;
    //start
    el.style.display = 'block';
    if (el.scrollHeight !== 0) {
      el.style.height = el.scrollHeight + 'px';
      el.style.paddingTop = el.dataset.oldPaddingTop;
      el.style.paddingBottom = el.dataset.oldPaddingBottom;
    } else {
      el.style.height = '';
      el.style.paddingTop = el.dataset.oldPaddingTop;
      el.style.paddingBottom = el.dataset.oldPaddingBottom;
    }

    el.style.overflow = 'hidden';

    this.enterTimer = setTimeout(() => this.afterEnter(), ANIMATION_DURATION);
  }

  afterEnter(): void {
    const el = this.selfRef;
    el.style.display = 'block';
    el.style.height = '';
    el.style.overflow = el.dataset.oldOverflow;
  }

  beforeLeave(): void {
    const el = this.selfRef;
    el.dataset.oldPaddingTop = el.style.paddingTop;
    el.dataset.oldPaddingBottom = el.style.paddingBottom;
    el.dataset.oldOverflow = el.style.overflow;

    el.style.display = 'block';
    if (el.scrollHeight !== 0) {
      el.style.height = el.scrollHeight + 'px';
    }
    el.style.overflow = 'hidden';
  }

  leave(): void {
    const el = this.selfRef;
    if (el.scrollHeight !== 0) {
      el.style.height = 0;
      el.style.paddingTop = 0;
      el.style.paddingBottom = 0;
    }
    this.leaveTimer = setTimeout(() => this.afterLeave(), ANIMATION_DURATION);
  }

  afterLeave(): void {
    const el = this.selfRef;
    if (!el) return ;

    el.style.display = 'none';
    el.style.height = '';
    el.style.overflow = el.dataset.oldOverflow;
    el.style.paddingTop = el.dataset.oldPaddingTop;
    el.style.paddingBottom = el.dataset.oldPaddingBottom;
  }

  render(): React.Element<any> {
    return (
      <div
        className="collapse-transition"
        style={{ overflow: 'hidden' }}
        ref={e => this.selfRef = e}
      >
        {this.props.children}
      </div>
    );
  }
}