Public Class Form1

    Private TodayHistoryList As New HistoryList

    Private YesterDayHistoryList As New HistoryList

    Private ParentToday, ParentYesterDay As TreeNode



    Private Sub Form1_FormClosing(sender As Object, e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing

        TodayHistoryList.WriteFile()

        YesterDayHistoryList.WriteFile()

    End Sub

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load

        'TreeViewの初期化 

        InitTreeView()



        '今日 

        TodayHistoryList = HistoryList.ReadFile(Today)

        If Not IsNothing(TodayHistoryList) Then

            TodayHistoryList.TreeViewColumnsAdd(ParentToday)

        Else

            TodayHistoryList = New HistoryList

        End If



        '昨日 

        YesterDayHistoryList = HistoryList.ReadFile(Today.AddDays(-1))

        If Not IsNothing(YesterDayHistoryList) Then

            YesterDayHistoryList.TreeViewColumnsAdd(ParentYesterDay)

        Else

            YesterDayHistoryList = New HistoryList With {.day = Today.AddDays(-1)}

        End If

    End Sub



    Private Sub WebBrowser1_DocumentCompleted(sender As System.Object, e As System.Windows.Forms.WebBrowserDocumentCompletedEventArgs) Handles WebBrowser1.DocumentCompleted

        Dim NowDate As Date = Today

        '現在の日付と今日の日付が違う場合（日付が変更された） 

        If NowDate <> TodayHistoryList.day Then

            YesterDayHistoryList.WriteFile()

            TodayHistoryList.WriteFile()

            Call Form1_Load(Nothing, Nothing)

        End If



        TodayHistoryList.TreeViewHistoryListColumnAdd(ParentToday, New History With {.Title = WebBrowser1.DocumentTitle,

                                                    .URL = WebBrowser1.Url.AbsoluteUri,

                                                    .ViewDate = Now})

    End Sub



    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click

        WebBrowser1.Navigate(TextBox1.Text)

    End Sub

    Private Sub InitTreeView()

        TreeView1.Nodes.Clear()

        ParentToday = New TreeNode("今日")

        ParentYesterDay = New TreeNode("昨日")

        TreeView1.Nodes.Add(ParentToday)

        TreeView1.Nodes.Add(ParentYesterDay)

    End Sub



    Private Sub TreeView1_DoubleClick(sender As System.Object, e As System.EventArgs) Handles TreeView1.DoubleClick

        WebBrowser1.Navigate(DirectCast(TreeView1.SelectedNode, HistoryTreeViewNode).History.URL)

    End Sub

End Class

Public Class HistoryTreeViewNode

    Inherits TreeNode

    Public Property History As History

End Class