DataHelper.vb

Imports System
Imports System.Collections.Generic
Imports System.Data
Imports System.Linq

Namespace TreeViewReport

    Public Class DataHelper

        Private levelField As Integer

        Private nodesCount As Integer

        Private nodesListField As List(Of ParentNode)

        Private rows As List(Of DataRow)

        Private dataTable As DataTable

        Public ReadOnly Property ReportDataSource As DataTable
            Get
                Return dataTable
            End Get
        End Property

        Public Property Level As Integer

        Public ReadOnly Property NodesList As List(Of ParentNode)
            Get
                Return nodesListField
            End Get
        End Property

        Public Sub New(ByVal level As Integer)
            Me.Level = level
            GenerateDataTable()
            nodesListField = New List(Of ParentNode)()
            rows = dataTable.AsEnumerable().ToList()
            nodesCount = dataTable.Rows.Count - 1
            ParseTree(Nothing)
        End Sub

        Private Sub GenerateDataTable()
            dataTable = New DataTable()
            dataTable.Columns.Add("Key", GetType(Object))
            dataTable.Columns.Add("ParentKey", GetType(Object))
            dataTable.Columns.Add("Name", GetType(String))
            dataTable.Columns.Add("Description", GetType(String))
            dataTable.Rows.Add(0, Nothing, "RootNode", "RootNode")
            Dim parentKey As Integer = 0
            Dim currentKey As Integer = 1
            Dim rnd As Random = New Random()
            For levelCount As Integer = 1 To Level
                Dim childCount As Integer = rnd.Next(1, 4)
                For j As Integer = 1 To childCount
                    Dim name As String = String.Format("Child Node {0}", currentKey)
                    Dim description As String = String.Format("Child Node {0} Parent {1}", currentKey, parentKey)
                    dataTable.Rows.Add(currentKey, parentKey, name, description)
                    currentKey += 1
                Next

                parentKey += 1
            Next
        End Sub

        Private Function CreateNewNode(ByVal dataRow As DataRow) As ParentNode
            Dim node As ParentNode = New ParentNode()
            node.NodeKey = dataRow(0)
            node.ParentNodeKey = dataRow(1)
            node.NodeName = dataRow(2).ToString()
            node.NodeDescription = dataRow(3).ToString()
            node.Children = New List(Of ParentNode)()
            Return node
        End Function

        Private Sub ParseTree(ByVal parent As ParentNode)
            If parent IsNot Nothing Then 'create child nodes
                Dim foundRows As List(Of DataRow) = rows.FindAll(Function(x) x.ItemArray(1).Equals(parent.NodeKey))
                For Each row As DataRow In foundRows
                    If nodesCount >= 0 Then
                        Dim node As ParentNode = CreateNewNode(row)
                        parent.Children.Add(node)
                        node.Level = Threading.Interlocked.Increment(levelField)
                        ParseTree(node)
                        nodesCount -= 1
                        levelField -= 1
                    End If
                Next ' create root ParentNode
            Else
                Dim foundRow As DataRow = rows.Find(Function(x) x.ItemArray(1).Equals(DBNull.Value))
                Dim node As ParentNode = CreateNewNode(foundRow)
                node.Level = levelField
                nodesListField.Add(node)
                rows.Remove(foundRow)
                nodesCount -= 1
                ParseTree(node)
            End If
        End Sub
    End Class

    Public Class SimpleNode

        Public Property NodeKey As Object

        Public Property ParentNodeKey As Object

        Public Property NodeName As String

        Public Property NodeDescription As String
    End Class

    Public Class ParentNode
        Inherits SimpleNode

        Public Property Children As List(Of ParentNode)

        Public Property Level As Integer
    End Class
End Namespace