import type { ExtractPropTypes } from 'vue';
import { defineComponent, computed, ref, watch } from 'vue';
import classNames from '../_util/classNames';
import ListItem from './ListItem';
import Pagination from '../pagination';
import PropTypes from '../_util/vue-types';
import type { TransferItem } from '.';

export const transferListBodyProps = {
  prefixCls: String,
  filteredRenderItems: PropTypes.array.def([]),
  selectedKeys: PropTypes.array,
  disabled: { type: Boolean, default: undefined },
  showRemove: { type: Boolean, default: undefined },
  pagination: PropTypes.any,
  onItemSelect: Function,
  onScroll: Function,
  onItemRemove: Function,
};

export type TransferListBodyProps = Partial<ExtractPropTypes<typeof transferListBodyProps>>;

function parsePagination(pagination) {
  if (!pagination) {
    return null;
  }

  const defaultPagination = {
    pageSize: 10,
    simple: true,
    showSizeChanger: false,
    showLessItems: false,
  };

  if (typeof pagination === 'object') {
    return {
      ...defaultPagination,
      ...pagination,
    };
  }

  return defaultPagination;
}

const ListBody = defineComponent({
  name: 'ListBody',
  inheritAttrs: false,
  props: transferListBodyProps,
  emits: ['itemSelect', 'itemRemove', 'scroll'],
  setup(props, { emit, expose }) {
    const current = ref(1);

    const handleItemSelect = (item: TransferItem) => {
      const { selectedKeys } = props;
      const checked = selectedKeys.indexOf(item.key) >= 0;
      emit('itemSelect', item.key, !checked);
    };

    const handleItemRemove = (item: TransferItem) => {
      emit('itemRemove', item.key);
    };

    const handleScroll = (e: Event) => {
      emit('scroll', e);
    };

    const mergedPagination = computed(() => parsePagination(props.pagination));

    watch(
      [mergedPagination, () => props.filteredRenderItems],
      () => {
        if (mergedPagination.value) {
          // Calculate the page number
          const maxPageCount = Math.ceil(
            props.filteredRenderItems.length / mergedPagination.value.pageSize,
          );

          if (current.value > maxPageCount) {
            current.value = maxPageCount;
          }
        }
      },
      { immediate: true },
    );
    const items = computed(() => {
      const { filteredRenderItems } = props;

      let displayItems = filteredRenderItems;

      if (mergedPagination.value) {
        displayItems = filteredRenderItems.slice(
          (current.value - 1) * mergedPagination.value.pageSize,
          current.value * mergedPagination.value.pageSize,
        );
      }

      return displayItems;
    });

    const onPageChange = (cur: number) => {
      current.value = cur;
    };

    expose({ items });

    return () => {
      const {
        prefixCls,
        filteredRenderItems,
        selectedKeys,
        disabled: globalDisabled,
        showRemove,
      } = props;

      let paginationNode = null;

      if (mergedPagination.value) {
        paginationNode = (
          <Pagination
            simple={mergedPagination.value.simple}
            showSizeChanger={mergedPagination.value.showSizeChanger}
            showLessItems={mergedPagination.value.showLessItems}
            size="small"
            disabled={globalDisabled}
            class={`${prefixCls}-pagination`}
            total={filteredRenderItems.length}
            pageSize={mergedPagination.value.pageSize}
            current={current.value}
            onChange={onPageChange}
          />
        );
      }

      const itemsList = items.value.map(({ renderedEl, renderedText, item }: any) => {
        const { disabled } = item;
        const checked = selectedKeys.indexOf(item.key) >= 0;

        return (
          <ListItem
            disabled={globalDisabled || disabled}
            key={item.key}
            item={item}
            renderedText={renderedText}
            renderedEl={renderedEl}
            checked={checked}
            prefixCls={prefixCls}
            onClick={handleItemSelect}
            onRemove={handleItemRemove}
            showRemove={showRemove}
          />
        );
      });
      return (
        <>
          <ul
            class={classNames(`${prefixCls}-content`, {
              [`${prefixCls}-content-show-remove`]: showRemove,
            })}
            onScroll={handleScroll}
          >
            {itemsList}
          </ul>
          {paginationNode}
        </>
      );
    };
  },
});

export default ListBody;
