Invoke-TeamsMachineWideReinstall.ps1

[CmdletBinding(SupportsShouldProcess)]
param(

)

#The download URL for the Teams Machine-Wide Installer for x64 systems.
$teamsInstallDownloadUri = "https://teams.microsoft.com/downloads/desktopurl?env=production&plat=windows&arch=x64&managedInstaller=true&download=true"

# -- Begin searching for a current install of Teams --
Write-Verbose "Looking for a current installation of Teams Machine-Wide Installer."
$uninstallRegKeyPaths = @(
    "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall",
    "HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall"
)

#Loop through both of the 'Uninstall' keys and get their data.
$uninstallRegKeys = [System.Collections.Generic.List[pscustomobject]]::new()
foreach ($uninstallRegKeyPath in $uninstallRegKeyPaths) {
    $regKeys = Get-ChildItem -Path $uninstallRegKeyPath
    foreach ($regKey in $regKeys) {
        $keyData = Get-ItemProperty -Path $regKey.PSPath
        $uninstallRegKeys.Add(
            [pscustomobject]@{
                "Name"    = $regKey.PSChildName;
                "Path"    = $regKey.PSPath;
                "KeyData" = $keyData;
            }
        )
    }
}

#Filter the registry keys found for "Teams Machine-Wide Installer"
$msTeamsUninstallKey = $uninstallRegKeys | Where-Object { $PSItem.KeyData.DisplayName -eq "Teams Machine-Wide Installer" }

switch ($null -eq $msTeamsUninstallKey) {
    $false {
        #If a key was found, start the uninstall process.
        Write-Warning "Teams Machine-Wide Installer registry key was found."
        if ($PSCmdlet.ShouldProcess("Teams Machine-Wide Installer", "Uninstall")) {
            Start-Process -FilePath "msiexec" -ArgumentList @("/x" , "$($msTeamsUninstallKey.Name)", "/qn") -NoNewWindow -Wait
        }
        break
    }

    #If no key was found, continue on and try the install.
}

#Build a path for temporarily saving the installer.
$tempDir = [System.IO.Path]::GetTempPath()
$downloadPath = Join-Path -Path $tempDir -ChildPath "Teams_windows_x64.msi"

#Download the Teams Machine-Wide Installer
if ($PSCmdlet.ShouldProcess("Teams_windows_x64.msi", "Download MSI to $($tempDir)")) {
    $ProgressPreference = "SilentlyContinue" #Disable the progress UI from showing. This improves download performance.
    Invoke-WebRequest -Uri $teamsInstallDownloadUri -OutFile $downloadPath -ErrorAction "Stop"
    $ProgressPreference = "Continue"
}

#Install Teams Machine-Wide Installer
if ($PSCmdlet.ShouldProcess("Teams Machine-Wide Installer", "Install")) {
    Start-Process -FilePath "msiexec" -ArgumentList @("/i", "`"$($downloadPath)`"", "/qn", "OPTIONS=`"noAutoStart=true`"", "ALLUSERS=1") -Wait -NoNewWindow
}

#Cleanup the temp file
if ($PSCmdlet.ShouldProcess($downloadPath, "Remove install file")) {
    Remove-Item -Path $downloadPath -Force
}