Sugiyama algorithm: add fake nodes when needed

addFakeNodes.js

var fakeNodeData = { __fake: true };

sugiyamaService.insertFakeNodeBeforeNext = function(list, currentNode, nextNode) {
  var fakeNode = sugiyamaService.createNode(fakeNodeData);

  sugiyamaService.disconnectNodes(currentNode, nextNode);
  sugiyamaService.connectNodes(fakeNode, nextNode);
  sugiyamaService.connectNodes(currentNode, fakeNode);

  list.push(fakeNode);
};

sugiyamaService.addFakeNodes = function(columns) {
  // check all columns except the last one
  for (var columnIndex = 0; columnIndex < columns.length - 1; columnIndex++) {
    var nextColumn = columns[columnIndex + 1];
    for (var rowIndex = 0; rowIndex < columns[columnIndex].length; rowIndex++) {
      var currentNode = columns[columnIndex][rowIndex];
      for (var nextNodeIndex = 0; nextNodeIndex < currentNode.nextNodes.length; nextNodeIndex++) {
        var nextNode = currentNode.nextNodes[nextNodeIndex];
        if (nextColumn.indexOf(nextNode) === -1) {
          sugiyamaService.insertFakeNodeBeforeNext(columns[columnIndex + 1], currentNode, nextNode);
        }
      }
    }
  }
};