# Download and install New Teams
$ProgressPreference = 'SilentlyContinue'
Invoke-WebRequest -Uri "https://statics.teams.cdn.office.net/production-windows-x64/enterprise/webview2/lkg/MSTeams-x64.msix" -OutFile "$env:temp\MSTeams-x64.msix"
Add-AppxPackage -Path "$env:TEMP\MSTeams-x64.msix"

# Install Teams Outlook add-in
$TeamsDir = (Get-AppxPackage MSTeams).InstallLocation
Start-Process msiexec.exe -Wait -ArgumentList "/i `"$TeamsDir\MicrosoftTeamsMeetingAddinInstaller.msi`" ALLUSERS=1 /qn TARGETDIR=`"C:\Program Files\TeamsMeetingAddin`""

# Register 'msteams' protocol
New-Item -Path "HKLM:\SOFTWARE\Classes\msteams" -Force | Out-Null
New-ItemProperty -Path "HKLM:\SOFTWARE\Classes\msteams" -Name "(Default)" -Value "URL:msteams" -PropertyType String -Force | Out-Null
New-ItemProperty -Path "HKLM:\SOFTWARE\Classes\msteams" -Name "URL Protocol" -Value "" -PropertyType String -Force | Out-Null
New-Item -Path "HKLM:\SOFTWARE\Classes\msteams\shell\open\command" -Force | Out-Null
New-ItemProperty -Path "HKLM:\SOFTWARE\Classes\msteams\shell\open\command" -Name "(Default)" -Value '"ms-teams.exe" "%1"' -PropertyType String -Force | Out-Null

# Retrieve permissions for Teams directory
$TeamsDirAcl= Get-Acl -Path "$TeamsDir"
$TeamsDirSddl = $TeamsDirAcl.sddl
$TeamsDirAcl.SetSecurityDescriptorSddlForm($TeamsDirSddl)

# Create post-activation script to set permissions on Teams directory and register it
$PostActScriptContent = @"
`$Sddl = `'$TeamsDirSddl`'
`$TeamsDir = "C:\Program Files\WindowsApps\" + (Get-ChildItem "C:\Program Files\WindowsApps\MSTeams*" -Directory | Sort-Object LastWriteTime | Select-Object -First 1).Name
`$TeamsDirAcl = Get-Acl -Path "`$TeamsDir"
`$TeamsDirAcl.SetSecurityDescriptorSddlForm(`$sddl)
Set-Acl -Path "`$TeamsDir" -AclObject `$TeamsDirAcl
Add-AppxPackage -DisableDevelopmentMode "`$TeamsDir\AppxManifest.xml" -Register
Start-Process -FilePath "shell:appsFolder\MSTeams_8wekyb3d8bbwe!MSTeams"
"@
$PostActScriptContent | Out-File "$env:USERPROFILE\Desktop\TeamsPostAct.ps1" -Encoding ASCII

# Create post-deactivation script to remove Teams
'Get-AppxPackage -AllUsers | Where-Object { $_.Name -like "*MSTeams*" } | Remove-AppxPackage' | Out-File "$env:USERPROFILE\Desktop\TeamsPostDeact.ps1"

# Grant permissions to Teams folder
$CurrentUser = [System.Security.Principal.WindowsIdentity]::GetCurrent().Name
TakeOwn /F $TeamsDir /A | Out-Null
Icacls $TeamsDir /Grant $CurrentUser`:F | Out-Null

# Disable automatic updates for Teams
New-Item -Path "HKLM:\SOFTWARE\Microsoft\Teams" -Force | Out-Null
New-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Teams" -Name "disableAutoUpdate" -Value "1" -PropertyType Dword -Force | Out-Null
Rename-Item -Path "$TeamsDir\ms-teamsupdate.exe" -NewName "$TeamsDir\ms-teamsupdate.exe.bak" -Force

# Restore permissions to Teams folder
Set-Acl -Path "$TeamsDir" -AclObject $TeamsDirAcl

# Display post-install instructions dialog
Add-Type -AssemblyName PresentationFramework
Add-Type -AssemblyName PresentationCore
$window = New-Object System.Windows.Window
$window.Title = "Next Steps"
$window.Width = 400
$window.Height = 300
$window.WindowStartupLocation = 'CenterScreen'
$window.SizeToContent = 'WidthAndHeight'
$window.ResizeMode = 'NoResize'
$stackPanel = New-Object System.Windows.Controls.StackPanel
$stackPanel.Margin = '10'
$textBlock = New-Object System.Windows.Controls.TextBlock
$textBlock.Text = @"
1. Click 'Finish' to save the package
2. Playback the package
3. Set 'TeamsPostAct.ps1' as a post-activation script (saved to Desktop)
4. Set 'TeamsPostDeAct.ps1' as a post-eactivation script (saved to Desktop)
5. Save the package
6. (Optional) Edit the package metadata to set the icon to 'ms-teams.exe'
"@
$textBlock.Margin = '0,0,0,20'
$textBlock.TextWrapping = 'Wrap'
$stackPanel.Children.Add($textBlock)
$okButton = New-Object System.Windows.Controls.Button
$okButton.Content = 'OK'
$okButton.Width = 75
$okButton.Height = 30
$okButton.HorizontalAlignment = 'Center'
$okButton.Add_Click({
    $window.Close()
})
$stackPanel.Children.Add($okButton)
$window.Content = $stackPanel
$window.ShowDialog()