// Transforms an array of entries like this:
//
// [
//   'baz.tar.gz',
//   'foo/bar/lol.txt',
//   'foo/bar/kaka/perro/siete/lol.txt'
// ]
//
// into this one:
//
// baz.tar.gz:
//   size: 10
// foo:
//   size: 3
//   entries:
//     bar:
//       size: 3
//       entries:
//         lol.txt:
//           size: 7
//         kaka:
//           size: 4
//           entries:
//             perro:
//               size: 5
//               entries:
//                 siete:
//                   size: 5
//                   entries:
//                     lol.txt:
//                       size: 7

const entries = [
  'baz.tar.gz',
  'foo/bar/lol.txt',
  'foo/bar/kaka/perro/siete/lol.txt'
];

function printTree(tree, padding = '') {
  if (typeof tree !== 'object') {
    return ` ${tree}`;
  }

  return Object.keys(tree).reduce((output, key) => {
    return `${output}\n${padding}${key}:${printTree(tree[key], `${padding}  `)}`;
  }, '');
}

function mergeEntryTrees(tree = {}, otherTree = {}) {
  if (typeof tree !== 'object' && typeof otherTree !== 'object') {
    return tree;
  }

  const allKeys = [...new Set([...Object.keys(tree), ...Object.keys(otherTree)])];

  return allKeys.reduce((partialTree, key) => {
    if (tree[key] && !otherTree[key]) {
      partialTree[key] = tree[key];
    }

    if (!tree[key] && otherTree[key]) {
      partialTree[key] = otherTree[key];
    }

    if (tree[key] && otherTree[key]) {
      partialTree[key] = mergeEntryTrees(tree[key], otherTree[key]);
    }

    return partialTree;
  }, {});
}

entries
  .map((entry) => {
    return entry.split('/').reduceRight((partialTree, part) => {
      return {
        [part]: {
          size: part.length,
          entries: partialTree,
        },
      };
    }, {});
   })
  .reduce((tree, partialTree) => {
    return mergeEntryTrees(tree, partialTree);
  }, {});