import { nextTick } from 'vue';
import { isString } from '@vue/shared';

import { getStyle, addClass, removeClass } from '../../utils/assist';
import {
  createLoadingComponent,
  LoadingInstance,
} from './createLoadingComponent';
import { useZIndex } from '../../utils/helpers';
import isServer from '../../utils/isServer';

// ts
import type { CSSProperties } from 'vue';
import type { LoadingOptions, LoadingOptionsResolved } from './types/loading';

// 全屏展示实例
let fullscreenInstance: LoadingInstance | undefined = undefined;

// 添加样式
const addStyle = async (
  options: LoadingOptionsResolved,
  parent: HTMLElement,
  instance: LoadingInstance
) => {
  const { nextZIndex } = useZIndex();

  // css
  const maskStyle: CSSProperties = {};

  // 开启全屏
  if (options.fullscreen) {
    // 定位
    instance.originalPosition.value = getStyle(document.body, 'position');
    // 隐藏
    instance.originalOverflow.value = getStyle(document.body, 'overflow');
    // zIndex
    maskStyle.zIndex = nextZIndex();
  }
  // 渲染 body
  else if (options.parent === document.body) {
    instance.originalPosition.value = getStyle(document.body, 'position');

    /**
     * await dom render when visible is true in init,
     * because some component's height maybe 0.
     * e.g. table.
     */
    await nextTick();

    // 偏移位置
    for (const property of ['top', 'left']) {
      const scroll = property === 'top' ? 'scrollTop' : 'scrollLeft';

      const position =
        // 元素相对于视窗 top/left
        (options.target as HTMLElement).getBoundingClientRect()[property] +
        // 滚动条位置 scrollTop/scrollLeft
        document.body[scroll] +
        // 滚动条位置 scrollTop/scrollLeft
        document.documentElement[scroll] -
        // body margin
        Number.parseInt(getStyle(document.body, `margin-${property}`), 10);

      // 偏移位置
      maskStyle[property] = `${position}px`;
    }

    // 设置高度
    for (const property of ['height', 'width']) {
      // 元素高度/width
      maskStyle[property] = `${
        (options.target as HTMLElement).getBoundingClientRect()[property]
      }px`;
    }
  }
  // 设置定位
  else {
    instance.originalPosition.value = getStyle(parent, 'position');
  }

  // 设置样式
  for (const [key, value] of Object.entries(maskStyle)) {
    instance.$el.style[key] = value;
  }
};

// 添加 class
const addClassList = (
  options: LoadingOptionsResolved,
  parent: HTMLElement,
  instance: LoadingInstance
) => {
  // 没有定位
  if (
    instance.originalPosition.value !== 'absolute' &&
    instance.originalPosition.value !== 'fixed'
  ) {
    addClass(parent, 'ivue-loading-parent--relative');
  }
  // 删除相对定位
  else {
    removeClass(parent, 'ivue-loading-parent--relative');
  }

  // 全屏 锁定屏幕的滚动 lock
  if (options.fullscreen && options.lock) {
    addClass(parent, 'ivue-loading-parent--hidden');
  }
  // 删除隐藏
  else {
    removeClass(parent, 'ivue-loading-parent--hidden');
  }
};

// 获取选项
const resolveOptions = (options: LoadingOptions): LoadingOptionsResolved => {
  let target: HTMLElement;

  // 获取 document.body
  if (isString(options.target)) {
    target =
      document.querySelector<HTMLElement>(options.target) ?? document.body;
  }
  // 获取 options.target || document.body
  else {
    target = options.target || document.body;
  }

  return {
    parent: target === document.body || options.body ? document.body : target,
    // 遮罩背景色
    background: options.background || '',
    // 显示在加载图标下方的加载文案
    text: options.text || '',
    // 全屏遮罩
    fullscreen: target === document.body && (options.fullscreen ?? true),
    // 锁定屏幕的滚动
    lock: options.lock ?? false,
    // Loading 的自定义类名
    customClass: options.customClass || '',
    // 显示/隐藏
    visible: options.visible ?? true,
    // 自定义加载图标类名
    iconClass: options.iconClass,
    // 自定义加载图标内容
    iconText: options.iconText,
    // 获取当前 target
    target,
    // 自定义旋转图标
    loadingSpinner: options.loadingSpinner,
  };
};

// loading
const Loading = function (options: LoadingOptions = {}): LoadingInstance {
  if (isServer) {
    return undefined;
  }

  // 获取选项
  const resolved = resolveOptions(options);

  // 有全屏
  if (resolved.fullscreen && fullscreenInstance) {
    return fullscreenInstance;
  }

  // 创建组件实例
  const instance = createLoadingComponent({
    ...resolved,
    close: () => {
      // 外部掉用的关闭
      resolved.close?.();

      // 销毁全屏实例
      if (resolved.fullscreen) {
        fullscreenInstance = undefined;
      }
    },
  });

  // 添加样式
  addStyle(resolved, resolved.parent, instance);
  // 添加 class
  addClassList(resolved, resolved.parent, instance);

  // 父级加载样式
  resolved.parent.LoadingAddClassList = () =>
    addClassList(resolved, resolved.parent, instance);

  /**
   * add loading-number to parent.
   * because if a fullscreen loading is triggered when somewhere
   * a v-loading.body was triggered before and it's parent is
   * document.body which with a margin , the fullscreen loading's
   * destroySelf function will remove 'ivue-loading-parent--relative',
   * and then the position of v-loading.body will be error.
   */
  let loadingNumber: string = resolved.parent.getAttribute('loading-number');

  if (!loadingNumber) {
    loadingNumber = '1';
  } else {
    loadingNumber = `${Number.parseInt(loadingNumber) + 1}`;
  }

  resolved.parent.setAttribute('loading-number', loadingNumber);

  // 添加子节点
  resolved.parent.appendChild(instance.$el);

  // 在实例渲染之后，然后修改可见以触发过渡
  nextTick(() => (instance.visible.value = resolved.visible));

  // 开启了全屏
  if (resolved.fullscreen) {
    fullscreenInstance = instance;
  }

  // 返回实例
  return instance;
};

export default Loading;