makedrive/lib/sync-path-resolver.js

Webmaker Filesystem

/**
 * Sync path resolver is a library that provides
 * functionality to determine 'syncable' paths
 * It exposes the following methods:
 *
 * resolve          - This method takes two paths as arguments.
 *                    The goal is to find the most common ancestor
 *                    between them. For e.g. the most common ancestor
 *                    between '/dir' and '/dir/file.txt' is '/dir' while
 *                    between '/dir' and '/file.txt' would be '/'.
 *
 * resolveFromArray - This method works exactly like resolve but works for arrays of paths instead
*/

var pathResolver = {};
var dirname = require('./filer').Path.dirname;

function getDepth(path) {
  if(path === '/') {
    return 0;
  }

  return 1 + getDepth(dirname(path));
}

function commonAncestor(path1, depth1, path2, depth2) {
  if(path1 === path2) {
    return path1;
  }

  // Regress the appropriate path
  if(depth1 === depth2) {
    path1 = dirname(path1);
    depth1--;
    path2 = dirname(path2);
    depth2--;
  } else if(depth1 > depth2) {
    path1 = dirname(path1);
    depth1--;
  } else {
    path2 = dirname(path2);
    depth2--;
  }

  return commonAncestor(path1, depth1, path2, depth2);
}

pathResolver.resolve = function(path1, path2) {
  if(!path1 && !path2) {
    return '/';
  }

  if(!path1 || !path2) {
    return path1 || path2;
  }

  var path1Depth = getDepth(path1);
  var path2Depth = getDepth(path2);

  return commonAncestor(path1, path1Depth, path2, path2Depth);
};

pathResolver.resolveFromArray = function(paths) {
  if(!paths) {
    return '/';
  }

  var resolvedPath, i;

  for(i = 1, resolvedPath = paths[0]; i < paths.length; i++) {
    resolvedPath = pathResolver.resolve(resolvedPath, paths[i]);
  }

  return resolvedPath;
};

module.exports = pathResolver;