const hierarchy = require('./hierarchy');

module.exports = (root, options) => {
  // separate into left and right trees
  const left = hierarchy(root.data, options, true); // root only
  const right = hierarchy(root.data, options, true); // root only
  // automatically
  const treeSize = root.children.length;
  const rightTreeSize = Math.round(treeSize / 2);
  // separate left and right tree by meta data
  const getSide = options.getSide || function(child, index) {
    if (index < rightTreeSize) {
      return 'right';
    }
    return 'left';
  };
  for (let i = 0; i < treeSize; i++) {
    const child = root.children[i];
    const side = getSide(child, i);
    if (side === 'right') {
      right.children.push(child);
    } else {
      left.children.push(child);
    }
  }
  left.eachNode(node => {
    if (!node.isRoot()) {
      node.side = 'left';
    }
  });
  right.eachNode(node => {
    if (!node.isRoot()) {
      node.side = 'right';
    }
  });
  return {
    left,
    right
  };
};