I have a list template like this

list = [
    {
      id: "G1",
      text: "Group 1",
      idparent: "",
      children: [
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "1",
          text: "Task 1"
          idparent: "G1",
        },
        {
          start: "2014-10-03",
          end: "2014-10-05",
          id: "2",
          text: "Task 2"
          idparent: "G1",
        }    
      ]
    },
    {
      start: "2014-10-01",
      end: "2014-10-03",
      id: "3",
      text: "Task 3"
      idparent: "",
    },    
  ];

The first item with children is a group of items and the last one is a single item. And the list to be treated is the following

list_to_tree = [
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "G1",
          text: "Group 1"
          id_parent: ""
        },   
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "1",
          text: "Task 1"
          id_parent: "G1"
        },   
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "2",
          text: "Task 2",
          id_parent: "G1"
        },   
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "3",
          text: "Task 3"
          id_parent: ""
        },   
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "G2",
          text: "Group 2"
          id_parent: "G1"
        },
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "4",
          text: "Task 4",
          id_parent: "G2"
        },
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "5",
          text: "Task 5",
          id_parent: ""
        },
        {
          start: "2014-10-01",
          end: "2014-10-03",
          id: "G3",
          text: "Group 3",
          id_parent: ""
        },
   ];

How to sort this list so that it can look like the model above knowing that we can have an infinite number(n) of child spots (group or item). Eg: Task -> subtasks -> n(substasks) if have