/**
 * @file resize-sensor.js.
 * @author fex
 */

class EventQueue {
  q: Array<Function> = [];

  add(cb: Function) {
    this.q.push(cb);
  }

  call(...args: Array<any>) {
    this.q.forEach(fn => {
      fn(...args);
    });
  }
}

export function getComputedStyle(element: HTMLElement, prop: string) {
  if ((element as any).currentStyle) {
    return (element as any).currentStyle[prop];
  } else if (window.getComputedStyle) {
    const style = window.getComputedStyle(element, undefined);
    return style ? style.getPropertyValue(prop) : undefined;
  } else {
    return element.style[prop as any];
  }
}

function attachResizeEvent(element: HTMLElement, resized: Function) {
  if (!(element as any).resizedAttached) {
    (element as any).resizedAttached = new EventQueue();
    (element as any).resizedAttached.add(resized);
  } else if ((element as any).resizedAttached) {
    (element as any).resizedAttached.add(resized);
    return;
  }

  const resizeSensor = ((element as any).resizeSensor = document.createElement(
    'div'
  ));
  resizeSensor.className = 'resize-sensor';
  let style =
    'position: absolute; left: 0; top: 0; right: 0; bottom: 0; overflow: scroll; z-index: -1; visibility: hidden;';
  let styleChild = 'position: absolute; left: 0; top: 0;';

  resizeSensor.style.cssText = style;
  resizeSensor.innerHTML = `
  <div class="resize-sensor-expand" style="${style}">
    <div style="${styleChild}"></div>
  </div>
  <div class="resize-sensor-shrink" style="${style}">
    <div style="${styleChild} width: 200%; height: 200%"></div>
  </div>
  <div class="resize-sensor-appear" style="${style}animation-name: apearSensor; animation-duration: 0.2s;"></div>`;
  // 要定义 resizeSensor 这个动画，靠这个监听出现。
  element.appendChild(resizeSensor);
  (element as any).hasInlineStyle = element.hasAttribute('style');
  const position = ((element as any).originPosition = getComputedStyle(
    element,
    'position'
  ));
  if (!~['fixed', 'absolute'].indexOf(position)) {
    element.style.position = 'relative';
  }

  const expand = resizeSensor.children[0] as HTMLElement;
  const expandChild = expand.children[0] as HTMLElement;
  const shrink = resizeSensor.children[1] as HTMLElement;
  // let shrinkChild = shrink.children[0] as HTMLElement;
  const appear = resizeSensor.children[2] as HTMLElement;

  let lastWidth: number, lastHeight: number;

  const reset = function () {
    expandChild.style.width = expand.offsetWidth + 10 + 'px';
    expandChild.style.height = expand.offsetHeight + 10 + 'px';
    expand.scrollLeft = expand.scrollWidth;
    expand.scrollTop = expand.scrollHeight;
    shrink.scrollLeft = shrink.scrollWidth;
    shrink.scrollTop = shrink.scrollHeight;
    lastWidth = element.offsetWidth;
    lastHeight = element.offsetHeight;
  };

  reset();

  let changed = function () {
    if ((element as any).resizedAttached) {
      (element as any).resizedAttached.call();
    }
  };

  let addEvent = function (el: HTMLElement, name: string, cb: Function) {
    if ((el as any).attachEvent) {
      (el as any).attachEvent('on' + name, cb);
    } else {
      el.addEventListener(name, cb as any);
    }
  };

  let onScroll = function (e: Event) {
    if (
      element.offsetWidth != lastWidth ||
      element.offsetHeight != lastHeight
    ) {
      changed();
    }
    reset();
  };

  addEvent(expand, 'scroll', onScroll);
  addEvent(shrink, 'scroll', onScroll);
  addEvent(appear, 'animationstart', reset);
}

function detach(element: HTMLElement) {
  if ((element as any).resizeSensor) {
    if ((element as any).hasInlineStyle) {
      element.style.position = (element as any).originPosition;
    } else {
      element.removeAttribute('style');
    }
    try {
      element.removeChild((element as any).resizeSensor);
    } catch (e) {}
    delete (element as any).resizeSensor;
    delete (element as any).resizedAttached;
    delete (element as any).hasInlineStyle;
    delete (element as any).originPosition;
  }
}

export function resizeSensor(
  element: HTMLElement,
  callback: Function
): () => void;
export function resizeSensor(
  element: HTMLElement,
  callback: Function,
  once: boolean = false
) {
  if (once) {
    attachResizeEvent(element, function (this: any) {
      callback.apply(this, arguments);
      detach(element);
    });
    return;
  }

  attachResizeEvent(element, callback);
  let detached = false;

  return function () {
    if (detached) return;
    detached = true;
    detach(element);
  };
}