import { Key, FlattenNode } from "../interface";

//Find Expanded Nodes Keys
const findExpandedKeys = (prev: Key[] = [], next: Key[] = []) => {
  const prevLen = prev.length;
  const nextLen = next.length;

  if (Math.abs(prevLen - nextLen) !== 1) {
    return { add: false, key: null };
  }
  const find = (shorter: Key[], longer: Key[]) => {
    const cache: Map<Key, boolean> = new Map();
    shorter.forEach(key => {
      cache.set(key, true);
    });

    const keys = longer.filter(key => !cache.has(key));

    return keys.length === 1 ? keys[0] : null;
  };
  if (prevLen < nextLen) {
    return {
      add: true,
      key: find(prev, next)
    };
  }
  return {
    add: false,
    key: find(next, prev)
  };
};

//Get Expand Node Range
const getExpandRange = (
  shorter: FlattenNode[],
  longer: FlattenNode[],
  key: Key
) => {
  const shorterStartIndex = shorter.findIndex(({ data }) => data.key === key);
  const shorterEndNode = shorter[shorterStartIndex + 1];
  const longerStartIndex = longer.findIndex(({ data }) => data.key === key);

  if (shorterEndNode) {
    const longerEndIndex = longer.findIndex(
      ({ data }) => data.key === shorterEndNode.data.key
    );
    return longer.slice(longerStartIndex + 1, longerEndIndex);
  }
  return longer.slice(longerStartIndex + 1);
};

export { getExpandRange, findExpandedKeys };
