import {
  computed,
  defineComponent,
  onBeforeUnmount,
  onMounted,
  onUpdated,
  ref,
  Text,
  watch,
  watchEffect,
} from 'vue';
import Wave from '../_util/wave';
import buttonTypes from './buttonTypes';
import { flattenChildren, initDefaultProps } from '../_util/props-util';
import useConfigInject from '../_util/hooks/useConfigInject';
import devWarning from '../vc-util/devWarning';
import LoadingIcon from './LoadingIcon';

import type { ButtonType } from './buttonTypes';
import type { VNode, Ref } from 'vue';

type Loading = boolean | number;

const rxTwoCNChar = /^[\u4e00-\u9fa5]{2}$/;
const isTwoCNChar = rxTwoCNChar.test.bind(rxTwoCNChar);

function isUnborderedButtonType(type: ButtonType | undefined) {
  return type === 'text' || type === 'link';
}

export default defineComponent({
  name: 'AButton',
  inheritAttrs: false,
  __ANT_BUTTON: true,
  props: initDefaultProps(buttonTypes(), { type: 'default' }),
  slots: ['icon'],
  emits: ['click', 'mousedown'],
  setup(props, { slots, attrs, emit }) {
    const { prefixCls, autoInsertSpaceInButton, direction, size } = useConfigInject('btn', props);

    const buttonNodeRef = ref<HTMLElement>(null);
    const delayTimeoutRef = ref(undefined);
    let isNeedInserted = false;

    const innerLoading: Ref<Loading> = ref(false);
    const hasTwoCNChar = ref(false);

    const autoInsertSpace = computed(() => autoInsertSpaceInButton.value !== false);

    // =============== Update Loading ===============
    const loadingOrDelay = computed(() =>
      typeof props.loading === 'object' && props.loading.delay
        ? props.loading.delay || true
        : !!props.loading,
    );

    watch(
      loadingOrDelay,
      val => {
        clearTimeout(delayTimeoutRef.value);
        if (typeof loadingOrDelay.value === 'number') {
          delayTimeoutRef.value = setTimeout(() => {
            innerLoading.value = val;
          }, loadingOrDelay.value);
        } else {
          innerLoading.value = val;
        }
      },
      {
        immediate: true,
      },
    );

    const classes = computed(() => {
      const { type, shape = 'default', ghost, block, danger } = props;
      const pre = prefixCls.value;

      const sizeClassNameMap = { large: 'lg', small: 'sm', middle: undefined };
      const sizeFullname = size.value;
      const sizeCls = sizeFullname ? sizeClassNameMap[sizeFullname] || '' : '';

      return {
        [`${pre}`]: true,
        [`${pre}-${type}`]: type,
        [`${pre}-${shape}`]: shape !== 'default' && shape,
        [`${pre}-${sizeCls}`]: sizeCls,
        [`${pre}-loading`]: innerLoading.value,
        [`${pre}-background-ghost`]: ghost && !isUnborderedButtonType(type),
        [`${pre}-two-chinese-chars`]: hasTwoCNChar.value && autoInsertSpace.value,
        [`${pre}-block`]: block,
        [`${pre}-dangerous`]: !!danger,
        [`${pre}-rtl`]: direction.value === 'rtl',
      };
    });

    const fixTwoCNChar = () => {
      // Fix for HOC usage like <FormatMessage />
      const node = buttonNodeRef.value!;
      if (!node || autoInsertSpaceInButton.value === false) {
        return;
      }
      const buttonText = node.textContent;

      if (isNeedInserted && isTwoCNChar(buttonText)) {
        if (!hasTwoCNChar.value) {
          hasTwoCNChar.value = true;
        }
      } else if (hasTwoCNChar.value) {
        hasTwoCNChar.value = false;
      }
    };
    const handleClick = (event: Event) => {
      // https://github.com/ant-design/ant-design/issues/30207
      if (innerLoading.value || props.disabled) {
        event.preventDefault();
        return;
      }
      emit('click', event);
    };

    const insertSpace = (child: VNode, needInserted: boolean) => {
      const SPACE = needInserted ? ' ' : '';
      if (child.type === Text) {
        let text = (child.children as string).trim();
        if (isTwoCNChar(text)) {
          text = text.split('').join(SPACE);
        }
        return <span>{text}</span>;
      }
      return child;
    };

    watchEffect(() => {
      devWarning(
        !(props.ghost && isUnborderedButtonType(props.type)),
        'Button',
        "`link` or `text` button can't be a `ghost` button.",
      );
    });

    onMounted(fixTwoCNChar);
    onUpdated(fixTwoCNChar);

    onBeforeUnmount(() => {
      delayTimeoutRef.value && clearTimeout(delayTimeoutRef.value);
    });

    return () => {
      const { icon = slots.icon?.() } = props;
      const children = flattenChildren(slots.default?.());

      isNeedInserted = children.length === 1 && !icon && !isUnborderedButtonType(props.type);

      const { type, htmlType, disabled, href, title, target } = props;

      const iconType = innerLoading.value ? 'loading' : icon;
      const buttonProps = {
        ...attrs,
        title,
        disabled,
        class: [
          classes.value,
          attrs.class,
          { [`${prefixCls.value}-icon-only`]: children.length === 0 && !!iconType },
        ],
        onClick: handleClick,
      };
      // https://github.com/vueComponent/ant-design-vue/issues/4930
      if (!disabled) {
        delete buttonProps.disabled;
      }

      const iconNode =
        icon && !innerLoading.value ? (
          icon
        ) : (
          <LoadingIcon
            existIcon={!!icon}
            prefixCls={prefixCls.value}
            loading={!!innerLoading.value}
          />
        );

      const kids = children.map(child =>
        insertSpace(child, isNeedInserted && autoInsertSpace.value),
      );

      if (href !== undefined) {
        return (
          <a {...buttonProps} href={href} target={target} ref={buttonNodeRef}>
            {iconNode}
            {kids}
          </a>
        );
      }

      const buttonNode = (
        <button {...buttonProps} ref={buttonNodeRef} type={htmlType}>
          {iconNode}
          {kids}
        </button>
      );

      if (isUnborderedButtonType(type)) {
        return buttonNode;
      }

      return (
        <Wave ref="wave" disabled={!!innerLoading.value}>
          {buttonNode}
        </Wave>
      );
    };
  },
});