/**
  * Update the tree according to the list of loaded roots
  *
  * @param roots the list of roots to add to the tree
  * @param uncheckedCommits the map from vcs root to commit identifiers that should be
  *     uncheckedCommits
  */
 private void updateTree(List<Root> roots, Map<VirtualFile, Set<String>> uncheckedCommits) {
   myTreeRoot.removeAllChildren();
   if (roots == null) {
     roots = Collections.emptyList();
   }
   for (Root r : roots) {
     CheckedTreeNode rootNode = new CheckedTreeNode(r);
     Status status = new Status();
     status.root = r;
     rootNode.add(new DefaultMutableTreeNode(status, false));
     Set<String> unchecked =
         uncheckedCommits != null && uncheckedCommits.containsKey(r.root)
             ? uncheckedCommits.get(r.root)
             : Collections.<String>emptySet();
     for (Commit c : r.commits) {
       CheckedTreeNode child = new CheckedTreeNode(c);
       rootNode.add(child);
       child.setChecked(r.remoteName != null && !unchecked.contains(c.commitId()));
     }
     myTreeRoot.add(rootNode);
   }
 }
  private RebaseInfo collectRebaseInfo() {
    final Set<VirtualFile> roots = new HashSet<VirtualFile>();
    final Set<VirtualFile> rootsWithMerges = new HashSet<VirtualFile>();
    final Map<VirtualFile, List<String>> reorderedCommits =
        new HashMap<VirtualFile, List<String>>();
    final Map<VirtualFile, Set<String>> uncheckedCommits = new HashMap<VirtualFile, Set<String>>();
    for (int i = 0; i < myTreeRoot.getChildCount(); i++) {
      CheckedTreeNode node = (CheckedTreeNode) myTreeRoot.getChildAt(i);
      Root r = (Root) node.getUserObject();
      Set<String> unchecked = new HashSet<String>();
      uncheckedCommits.put(r.root, unchecked);
      if (r.commits.size() == 0) {
        if (r.remoteCommits > 0) {
          roots.add(r.root);
        }
        continue;
      }
      boolean seenCheckedNode = false;
      boolean reorderNeeded = false;
      boolean seenMerges = false;
      for (int j = 0; j < node.getChildCount(); j++) {
        if (node.getChildAt(j) instanceof CheckedTreeNode) {
          CheckedTreeNode commitNode = (CheckedTreeNode) node.getChildAt(j);
          Commit commit = (Commit) commitNode.getUserObject();
          seenMerges |= commit.isMerge;
          if (commitNode.isChecked()) {
            seenCheckedNode = true;
          } else {
            unchecked.add(commit.commitId());
            if (seenCheckedNode) {
              reorderNeeded = true;
            }
          }
        }
      }
      if (seenMerges) {
        rootsWithMerges.add(r.root);
      }
      if (r.remoteCommits > 0 || reorderNeeded) {
        roots.add(r.root);
      }
      if (reorderNeeded) {
        List<String> reordered = new ArrayList<String>();
        for (int j = 0; j < node.getChildCount(); j++) {
          if (node.getChildAt(j) instanceof CheckedTreeNode) {
            CheckedTreeNode commitNode = (CheckedTreeNode) node.getChildAt(j);
            if (!commitNode.isChecked()) {
              Commit commit = (Commit) commitNode.getUserObject();
              reordered.add(commit.revision.asString());
            }
          }
        }
        for (int j = 0; j < node.getChildCount(); j++) {
          if (node.getChildAt(j) instanceof CheckedTreeNode) {
            CheckedTreeNode commitNode = (CheckedTreeNode) node.getChildAt(j);
            if (commitNode.isChecked()) {
              Commit commit = (Commit) commitNode.getUserObject();
              reordered.add(commit.revision.asString());
            }
          }
        }
        Collections.reverse(reordered);
        reorderedCommits.put(r.root, reordered);
      }
    }
    final GitVcsSettings.UpdateChangesPolicy p =
        UpdatePolicyUtils.getUpdatePolicy(myStashRadioButton, myShelveRadioButton);
    assert p == GitVcsSettings.UpdateChangesPolicy.STASH
        || p == GitVcsSettings.UpdateChangesPolicy.SHELVE;

    return new RebaseInfo(reorderedCommits, rootsWithMerges, uncheckedCommits, roots, p);
  }