# WindowsApp-CleanDowngrade.ps1
# Downgrade Windows App to 2.0.964.0
# Clears cached authentication, WebView2 runtime data, and reinstalls Windows App

$OutputEncoding = [System.Text.Encoding]::UTF8

$Url = "https://res.cdn.office.net/remote-desktop-windows-client/870e08dc-f2e8-47cb-93ee-d0d3743a8bb6/WindowsApp_x64_Release_2.0.964.0.msix"

$Folder = "C:\Temp\WinApp964"
$Msix = "$Folder\WindowsApp_2.0.964.0.msix"

New-Item -ItemType Directory -Force -Path $Folder | Out-Null

Write-Host ""
Write-Host "==================================================="
Write-Host " Windows App Cleanup and Downgrade"
Write-Host "==================================================="
Write-Host ""

# --------------------------------------------------
# Stop running processes
# --------------------------------------------------

Write-Host "Stopping Windows App processes..."

Get-Process `
    msrdc, `
    WindowsApp, `
    RemoteDesktop, `
    msedgewebview2 `
    -ErrorAction SilentlyContinue |
    Stop-Process -Force -ErrorAction SilentlyContinue

Start-Sleep 3

# --------------------------------------------------
# Remove Windows App packages
# --------------------------------------------------

Write-Host "Removing Windows App packages..."

Get-AppxPackage |
Where-Object {
    $_.Name -match "Windows365|WindowsApp"
} |
ForEach-Object {

    Write-Host "Removing $($_.Name) $($_.Version)"

    try {
        Remove-AppxPackage `
            -Package $_.PackageFullName `
            -ErrorAction Stop
    }
    catch {
        Write-Warning $_.Exception.Message
    }
}

# --------------------------------------------------
# Remove local caches
# --------------------------------------------------

Write-Host "Removing local cache..."

$CleanupFolders = @(
    "$env:LOCALAPPDATA\Packages\MicrosoftCorporationII.Windows365_8wekyb3d8bbwe",
    "$env:LOCALAPPDATA\Packages\MicrosoftCorporationII.WindowsApp_8wekyb3d8bbwe",
    "$env:LOCALAPPDATA\Microsoft\IdentityCache",
    "$env:LOCALAPPDATA\Microsoft\TokenBroker",
    "$env:LOCALAPPDATA\Microsoft\EdgeWebView",
    "$env:LOCALAPPDATA\Microsoft\OneAuth"
)

foreach ($Path in $CleanupFolders) {

    if (Test-Path $Path) {

        Write-Host "Removing $Path"

        Remove-Item `
            $Path `
            -Recurse `
            -Force `
            -ErrorAction SilentlyContinue
    }
}

# --------------------------------------------------
# DNS Cleanup
# --------------------------------------------------

Write-Host "Flushing DNS cache..."

ipconfig /flushdns | Out-Null

# --------------------------------------------------
# Download package
# --------------------------------------------------

Write-Host "Downloading Windows App 2.0.964.0..."

if (Test-Path $Msix) {
    Remove-Item $Msix -Force -ErrorAction SilentlyContinue
}

Start-BitsTransfer `
    -Source $Url `
    -Destination $Msix

# --------------------------------------------------
# Install package
# --------------------------------------------------

Write-Host "Installing Windows App..."

Add-AppxPackage `
    -Path $Msix `
    -ForceApplicationShutdown

Start-Sleep 10

# --------------------------------------------------
# Verify installation
# --------------------------------------------------

$WindowsApp = Get-AppxPackage |
Where-Object {
    $_.PackageFamilyName -like "*Windows365*"
} |
Sort-Object Version -Descending |
Select-Object -First 1

Write-Host ""
Write-Host "==================================================="

if ($WindowsApp) {

    Write-Host "Installation Complete" -ForegroundColor Green
    Write-Host "Version Installed: $($WindowsApp.Version)"

}
else {

    Write-Host "Installation Failed" -ForegroundColor Red
}

Write-Host "==================================================="
Write-Host ""