The WebView2 Control

' Step 1: Install the NuGet package
' In Visual Studio: Tools → NuGet Package Manager → Manage NuGet Packages
' Search: Microsoft.Web.WebView2
' Install the latest stable version (2.0.x or later)

' Step 2: Add to the Toolbox
' After installing, WebView2 appears in the Toolbox.
' Drag it onto your form like any other control.
' Rename it: wvBrowser (or wv, webView, etc.)

' Step 3: Imports at top of form code
Imports Microsoft.Web.WebView2.WinForms
Imports Microsoft.Web.WebView2.Core

' Step 4: Initialise in Form_Load — ALWAYS Await this first!
Private Async Sub Form1_Load(...) Handles MyBase.Load
    Await wvBrowser.EnsureCoreWebView2Async()   ' starts the browser engine
    wvBrowser.Source = New Uri("https://www.vbtutor.net")
End Sub

' Alternatively, set a home page from settings
Private Async Sub Form1_Load(...) Handles MyBase.Load
    Await wvBrowser.EnsureCoreWebView2Async()
    Dim homePage = My.Settings.HomePage
    If String.IsNullOrWhiteSpace(homePage) Then
        homePage = "https://www.google.com"
    End If
    wvBrowser.CoreWebView2.Navigate(homePage)
End Sub

' --- Navigate to a URL ---
Private Sub btnGo_Click(...) Handles btnGo.Click
    Dim url = txtUrl.Text.Trim()
    If Not url.StartsWith("http") Then url = "https://" & url
    wvBrowser.CoreWebView2.Navigate(url)
End Sub

' Navigate when user presses Enter in the URL bar
Private Sub txtUrl_KeyDown(...) Handles txtUrl.KeyDown
    If e.KeyCode = Keys.Enter Then btnGo.PerformClick()
End Sub

' --- Back / Forward / Reload / Home ---
Private Sub btnBack_Click(...) Handles btnBack.Click
    If wvBrowser.CoreWebView2.CanGoBack Then
        wvBrowser.CoreWebView2.GoBack()
    End If
End Sub

Private Sub btnForward_Click(...) Handles btnForward.Click
    If wvBrowser.CoreWebView2.CanGoForward Then
        wvBrowser.CoreWebView2.GoForward()
    End If
End Sub

Private Sub btnReload_Click(...) Handles btnReload.Click
    wvBrowser.CoreWebView2.Reload()
End Sub

Private Sub btnHome_Click(...) Handles btnHome.Click
    wvBrowser.CoreWebView2.Navigate("https://www.vbtutor.net")
End Sub

' --- NavigationCompleted — update UI after page loads ---
Private Sub wvBrowser_NavigationCompleted(...) Handles wvBrowser.NavigationCompleted
    If e.IsSuccess Then
        txtUrl.Text = wvBrowser.Source.ToString()
        lblStatus.Text = $"Loaded: {wvBrowser.CoreWebView2.DocumentTitle}"
    Else
        lblStatus.Text = $"Error: {e.WebErrorStatus}"
    End If
    btnBack.Enabled    = wvBrowser.CoreWebView2.CanGoBack
    btnForward.Enabled = wvBrowser.CoreWebView2.CanGoForward
End Sub

' --- Load local HTML content (no web server needed) ---
wvBrowser.NavigateToString("<h1>Hello from VB!</h1><p>Local HTML.</p>")

' --- Load a local file ---
Dim htmlPath = Path.Combine(Application.StartupPath, "report.html")
wvBrowser.CoreWebView2.Navigate($"file:///{htmlPath.Replace("\", "/")}")

' --- Blocked domains list ---
Private ReadOnly _blockedDomains As String() = {
    "facebook.com", "twitter.com", "tiktok.com", "youtube.com"
}

Private Sub wvBrowser_NavigationStarting(...) Handles wvBrowser.NavigationStarting
    Dim url = e.Uri.ToLower()

    ' Block listed domains
    For Each domain In _blockedDomains
        If url.Contains(domain) Then
            e.Cancel = True
            lblStatus.Text = $"Blocked: {domain}"
            wvBrowser.NavigateToString(
                $"<h2 style='color:red'>Access Blocked</h2>
                  <p>{domain} is not allowed on this device.</p>")
            Return
        End If
    Next

    ' Allow only HTTPS in production mode
    If chkHttpsOnly.Checked AndAlso Not url.StartsWith("https://") Then
        e.Cancel = True
        lblStatus.Text = "Blocked: HTTP not allowed (HTTPS only mode)"
        Return
    End If

    ' Show the URL being visited in the toolbar
    txtUrl.Text = e.Uri
    lblStatus.Text = $"Loading: {e.Uri}"
End Sub

' --- Get the page title ---
Private Async Sub btnGetTitle_Click(...) Handles btnGetTitle.Click
    Dim result = Await wvBrowser.ExecuteScriptAsync("document.title")
    ' Result is JSON-encoded: "\"VBTutor - Visual Basic Tutorial\""
    lblTitle.Text = result.Trim(""""c)   ' strip surrounding quotes
End Sub

' --- Get all link hrefs on the page ---
Private Async Sub btnGetLinks_Click(...) Handles btnGetLinks.Click
    Dim script = "JSON.stringify(Array.from(document.links).map(a => a.href))"
    Dim json   = Await wvBrowser.ExecuteScriptAsync(script)
    ' json = '["https://...","https://..."]'
    Dim links  = System.Text.Json.JsonSerializer.Deserialize(Of String())(json)
    lstLinks.Items.Clear()
    For Each link In links
        lstLinks.Items.Add(link)
    Next
End Sub

' --- Scroll the page ---
Private Async Sub btnScrollDown_Click(...) Handles btnScrollDown.Click
    Await wvBrowser.ExecuteScriptAsync("window.scrollBy(0, 400)")
End Sub

' --- Inject CSS: hide ads / dark mode ---
Private Async Sub InjectDarkMode()
    Dim css = "html{filter:invert(1) hue-rotate(180deg)!important}"
    Dim script = $"var s=document.createElement('style');s.textContent='{css}';document.head.appendChild(s)"
    Await wvBrowser.ExecuteScriptAsync(script)
End Sub

' --- Fill a form field programmatically ---
Private Async Sub AutoFillSearch(query As String)
    Dim script = $"document.querySelector('input[name=""q""]').value = '{query}'"
    Await wvBrowser.ExecuteScriptAsync(script)
End Sub

' --- Get computed style value ---
Private Async Sub btnGetBgColor_Click(...) Handles btnGetBgColor.Click
    Dim color = Await wvBrowser.ExecuteScriptAsync(
        "getComputedStyle(document.body).backgroundColor")
    lblBgColor.Text = color.Trim(""""c)
End Sub

' --- VB side: listen for messages from the web page ---
Private Sub Form1_Load(...) Handles MyBase.Load
    Await wvBrowser.EnsureCoreWebView2Async()
    AddHandler wvBrowser.CoreWebView2.WebMessageReceived, AddressOf OnWebMessage
    wvBrowser.NavigateToString(GetPageHtml())
End Sub

Private Sub OnWebMessage(sender As Object, e As CoreWebView2WebMessageReceivedEventArgs)
    Dim msg = e.TryGetWebMessageAsString()   ' simple string message

    ' Or parse JSON: Dim json = e.WebMessageAsJson
    Select Case msg
        Case "btn_clicked" : lblInfo.Text = "User clicked the web button!"
        Case "form_submit" : ProcessWebForm(e.WebMessageAsJson)
        Case Else         : lstLog.Items.Add($"Message: {msg}")
    End Select
End Sub

' --- HTML page side: send message to VB app ---
Private Function GetPageHtml() As String
    Return "<!DOCTYPE html><html><body>
      <h2>Hybrid App Page</h2>
      <button onclick=""window.chrome.webview.postMessage('btn_clicked')"">
        Send Message to VB
      </button>
      <input id='name' placeholder='Your name'>
      <button onclick=""window.chrome.webview.postMessage(
         JSON.stringify({action:'greet', name: document.getElementById('name').value})
      )"">Send Name</button>
    </body></html>"
End Function

' --- VB sends a message TO the web page ---
Private Sub btnSendToPage_Click(...) Handles btnSendToPage.Click
    Dim payload = $"{{""type"":""update"", ""value"":""{txtSend.Text}""}}"
    wvBrowser.CoreWebView2.PostWebMessageAsString(payload)
End Sub

' On the HTML/JS side, receive it:
' window.chrome.webview.addEventListener("message", e => {
'   document.getElementById("output").textContent = e.data;
' });

' --- Build an HTML report from a data table ---
Private Function BuildSalesReport(sales As DataTable) As String
    Dim sb As New Text.StringBuilder
    sb.AppendLine("<!DOCTYPE html><html><head>")
    sb.AppendLine("<style>
      body{font-family:Segoe UI,sans-serif;padding:20px;}
      h1{color:#1a3a6b;}
      table{border-collapse:collapse;width:100%;}
      th{background:#1a3a6b;color:#fff;padding:8px 12px;text-align:left;}
      td{padding:7px 12px;border-bottom:1px solid #eee;}
      tr:nth-child(even){background:#f5f7fa;}
      .total{font-weight:bold;background:#e8f4ff!important;}
    </style></head><body>")
    sb.AppendLine($"<h1>Sales Report — {DateTime.Now:dd MMM yyyy}</h1>")
    sb.AppendLine("<table><tr><th>Product</th><th>Units</th><th>Revenue</th></tr>")

    Dim grandTotal = 0D
    For Each row As DataRow In sales.Rows
        Dim rev = CDec(row("Revenue"))
        grandTotal += rev
        sb.AppendLine($"<tr><td>{row("Product")}</td>
                           <td>{row("Units"):N0}</td>
                           <td>{rev:C2}</td></tr>")
    Next
    sb.AppendLine($"<tr class='total'><td>TOTAL</td><td></td>
                       <td>{grandTotal:C2}</td></tr>")
    sb.AppendLine("</table></body></html>")
    Return sb.ToString()
End Function

' Display in WebView2
Private Sub btnPreview_Click(...) Handles btnPreview.Click
    wvBrowser.NavigateToString(BuildSalesReport(dtSales))
End Sub

' Print directly from WebView2
Private Async Sub btnPrint_Click(...) Handles btnPrint.Click
    Await wvBrowser.ExecuteScriptAsync("window.print()")
End Sub