/**
 * Handle virtual list of the TreeNodes.
 */

import { computed, defineComponent, ref, watch } from 'vue';
import VirtualList from '../vc-virtual-list';
import type { FlattenNode, DataEntity, DataNode, ScrollTo } from './interface';
import MotionTreeNode from './MotionTreeNode';
import { nodeListProps } from './props';
import { findExpandedKeys, getExpandRange } from './utils/diffUtil';
import { getTreeNodeProps, getKey } from './utils/treeUtil';

const HIDDEN_STYLE = {
  width: 0,
  height: 0,
  display: 'flex',
  overflow: 'hidden',
  opacity: 0,
  border: 0,
  padding: 0,
  margin: 0,
};

const noop = () => {};

export const MOTION_KEY = `RC_TREE_MOTION_${Math.random()}`;

const MotionNode: DataNode = {
  key: MOTION_KEY,
};

export const MotionEntity: DataEntity = {
  key: MOTION_KEY,
  level: 0,
  index: 0,
  pos: '0',
  node: MotionNode,
};

const MotionFlattenData: FlattenNode = {
  parent: null,
  children: [],
  pos: MotionEntity.pos,
  data: MotionNode,
  title: null,
  key: MOTION_KEY,
  /** Hold empty list here since we do not use it */
  isStart: [],
  isEnd: [],
};

export interface NodeListRef {
  scrollTo: ScrollTo;
  getIndentWidth: () => number;
}

/**
 * We only need get visible content items to play the animation.
 */
export function getMinimumRangeTransitionRange(
  list: FlattenNode[],
  virtual: boolean,
  height: number,
  itemHeight: number,
) {
  if (virtual === false || !height) {
    return list;
  }

  return list.slice(0, Math.ceil(height / itemHeight) + 1);
}

function itemKey(item: FlattenNode) {
  const {
    data: { key },
    pos,
  } = item;
  return getKey(key, pos);
}

function getAccessibilityPath(item: FlattenNode): string {
  let path = String(item.data.key);
  let current = item;

  while (current.parent) {
    current = current.parent;
    path = `${current.data.key} > ${path}`;
  }

  return path;
}

export default defineComponent({
  name: 'NodeList',
  inheritAttrs: false,
  props: nodeListProps,
  setup(props, { expose, attrs }) {
    // =============================== Ref ================================
    const listRef = ref(null);
    const indentMeasurerRef = ref(null);
    expose({
      scrollTo: scroll => {
        listRef.value.scrollTo(scroll);
      },
      getIndentWidth: () => indentMeasurerRef.value.offsetWidth,
    });

    // ============================== Motion ==============================
    const transitionData = ref<FlattenNode[]>(props.data);
    const transitionRange = ref([]);
    const motionType = ref<'show' | 'hide' | null>(null);

    function onMotionEnd() {
      transitionData.value = props.data;
      transitionRange.value = [];
      motionType.value = null;

      props.onListChangeEnd();
    }
    watch(
      [() => [...props.expandedKeys], () => props.data],
      ([expandedKeys, data], [prevExpandedKeys, prevData]) => {
        const diffExpanded = findExpandedKeys(prevExpandedKeys, expandedKeys);

        if (diffExpanded.key !== null) {
          const { virtual, height, itemHeight } = props;
          if (diffExpanded.add) {
            const keyIndex = prevData.findIndex(({ data: { key } }) => key === diffExpanded.key);

            const rangeNodes = getMinimumRangeTransitionRange(
              getExpandRange(prevData, data, diffExpanded.key),
              virtual,
              height,
              itemHeight,
            );

            const newTransitionData: FlattenNode[] = prevData.slice();
            newTransitionData.splice(keyIndex + 1, 0, MotionFlattenData);

            transitionData.value = newTransitionData;
            transitionRange.value = rangeNodes;
            motionType.value = 'show';
          } else {
            const keyIndex = data.findIndex(({ data: { key } }) => key === diffExpanded.key);

            const rangeNodes = getMinimumRangeTransitionRange(
              getExpandRange(data, prevData, diffExpanded.key),
              virtual,
              height,
              itemHeight,
            );

            const newTransitionData: FlattenNode[] = data.slice();
            newTransitionData.splice(keyIndex + 1, 0, MotionFlattenData);

            transitionData.value = newTransitionData;
            transitionRange.value = rangeNodes;
            motionType.value = 'hide';
          }
        } else if (prevData !== data) {
          transitionData.value = data;
        }
      },
    );
    // We should clean up motion if is changed by dragging
    watch(
      () => props.dragging,
      dragging => {
        if (!dragging) {
          onMotionEnd();
        }
      },
    );

    const mergedData = computed(() =>
      props.motion === undefined ? transitionData.value : props.data,
    );

    return () => {
      const {
        prefixCls,
        data,
        selectable,
        checkable,
        expandedKeys,
        selectedKeys,
        checkedKeys,
        loadedKeys,
        loadingKeys,
        halfCheckedKeys,
        keyEntities,
        disabled,

        dragging,
        dragOverNodeKey,
        dropPosition,
        motion,

        height,
        itemHeight,
        virtual,

        focusable,
        activeItem,
        focused,
        tabindex,

        onKeydown,
        onFocus,
        onBlur,
        onActiveChange,

        onListChangeStart,
        onListChangeEnd,

        ...domProps
      } = { ...props, ...attrs };

      const treeNodeRequiredProps = {
        expandedKeys,
        selectedKeys,
        loadedKeys,
        loadingKeys,
        checkedKeys,
        halfCheckedKeys,
        dragOverNodeKey,
        dropPosition,
        keyEntities,
      };
      return (
        <>
          {focused && activeItem && (
            <span style={HIDDEN_STYLE} aria-live="assertive">
              {getAccessibilityPath(activeItem)}
            </span>
          )}

          <div>
            <input
              style={HIDDEN_STYLE}
              disabled={focusable === false || disabled}
              tabindex={focusable !== false ? tabindex : null}
              onKeydown={onKeydown}
              onFocus={onFocus}
              onBlur={onBlur}
              value=""
              onChange={noop}
              aria-label="for screen reader"
            />
          </div>

          <div
            class={`${prefixCls}-treenode`}
            aria-hidden
            style={{
              position: 'absolute',
              pointerEvents: 'none',
              visibility: 'hidden',
              height: 0,
              overflow: 'hidden',
            }}
          >
            <div class={`${prefixCls}-indent`}>
              <div ref={indentMeasurerRef} class={`${prefixCls}-indent-unit`} />
            </div>
          </div>

          <VirtualList
            {...domProps}
            data={mergedData.value}
            itemKey={itemKey as any}
            height={height}
            fullHeight={false}
            virtual={virtual}
            itemHeight={itemHeight}
            prefixCls={`${prefixCls}-list`}
            ref={listRef}
            children={(treeNode: FlattenNode) => {
              const {
                pos,
                data: { ...restProps },
                title,
                key,
                isStart,
                isEnd,
              } = treeNode;
              const mergedKey = getKey(key, pos);
              delete restProps.key;
              delete restProps.children;

              const treeNodeProps = getTreeNodeProps(mergedKey, treeNodeRequiredProps);

              return (
                <MotionTreeNode
                  {...restProps}
                  {...treeNodeProps}
                  title={title}
                  active={!!activeItem && key === activeItem.data.key}
                  pos={pos}
                  data={treeNode.data}
                  isStart={isStart}
                  isEnd={isEnd}
                  motion={motion}
                  motionNodes={key === MOTION_KEY ? transitionRange.value : null}
                  motionType={motionType.value}
                  onMotionStart={onListChangeStart}
                  onMotionEnd={onMotionEnd}
                  treeNodeRequiredProps={treeNodeRequiredProps}
                  onMousemove={() => {
                    onActiveChange(null);
                  }}
                />
              );
            }}
          ></VirtualList>
        </>
      );
    };
  },
});
