#Requires -RunAsAdministrator

<#
.SYNOPSIS
    Removes Classic Microsoft Teams and Teams Machine-Wide Installer.
.DESCRIPTION
    Stops Classic Teams processes, uninstalls the Machine-Wide Installer via MSI,
    removes per-user Classic Teams installations, cleans residual files/registry run keys,
    and verifies that New Teams (MSTeams) remains intact.
#>

$ErrorActionPreference = "Continue"

Write-Host "Starting Classic Microsoft Teams cleanup..." -ForegroundColor Cyan

# 1. Stop ONLY Classic Teams processes (preserve New Teams)
Get-Process -Name "Teams" -ErrorAction SilentlyContinue | Stop-Process -Force -ErrorAction SilentlyContinue

# Stop Update.exe processes originating specifically from Classic Teams directories
Get-Process -Name "Update" -ErrorAction SilentlyContinue | Where-Object {
    $_.Path -like "*\Microsoft\Teams\Update.exe"
} | Stop-Process -Force -ErrorAction SilentlyContinue

Start-Sleep -Seconds 3

# 2. Remove Teams Machine-Wide Installer from HKLM registry
$uninstallPaths = @(
    "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*",
    "HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*"
)

$machineWideInstallers = foreach ($path in$uninstallPaths) {
    Get-ItemProperty $path -ErrorAction SilentlyContinue \vert{} Where-Object {$_.DisplayName -eq "Teams Machine-Wide Installer"
    }
}

foreach ($app in$machineWideInstallers) {
    Write-Host "Found Teams Machine-Wide Installer: $($app.DisplayName) $($app.DisplayVersion)" -ForegroundColor Yellow

    if ($app.UninstallString -match "\{[A-Fa-f0-9\-]{36}\}") {
        $productCode =$Matches[0]
        Write-Host "Uninstalling Machine-Wide Installer via MSI product code: $productCode" -ForegroundColor Cyan
        Start-Process -FilePath "msiexec.exe" -ArgumentList "/x $productCode /qn /norestart" -Wait -NoNewWindow
    }
    elseif ($app.UninstallString) {
        Write-Host "Uninstalling via UninstallString: $($app.UninstallString)" -ForegroundColor Cyan
        if ($app.UninstallString -match "msiexec") {
            $args =$app.UninstallString -replace "msiexec.exe", "" -replace "/I", "/x"
            Start-Process -FilePath "msiexec.exe" -ArgumentList "$args /qn /norestart" -Wait -NoNewWindow
        } else {
            Start-Process -FilePath "cmd.exe" -ArgumentList "/c `"$($app.UninstallString)`" /quiet /norestart" -Wait -NoNewWindow
        }
    }
}

# 3. Clean per-user Classic Teams installations
$usersRoot = Join-Path$env:SystemDrive "Users"
$userProfiles = Get-ChildItem -Path $usersRoot -Directory -ErrorAction SilentlyContinue \vert{} Where-Object {$_.Name -notin @("Public", "Default", "Default User", "All Users", "defaultuser0")
}

foreach ($profile in$userProfiles) {
    $localTeamsFolder = Join-Path$profile.FullName "AppData\Local\Microsoft\Teams"
    $roamingTeamsFolder = Join-Path$profile.FullName "AppData\Roaming\Microsoft\Teams"
    $updateExe = Join-Path$localTeamsFolder "Update.exe"

    if (Test-Path $updateExe) {
        Write-Host "Uninstalling Classic Teams for profile: $($profile.Name)" -ForegroundColor Cyan
        Start-Process -FilePath $updateExe -ArgumentList "--uninstall -s" -Wait -ErrorAction SilentlyContinue
        Start-Sleep -Seconds 2
    }

    # Remove residual AppData folders (both Local and Roaming)
    foreach ($folder in @($localTeamsFolder,$roamingTeamsFolder)) {
        if (Test-Path $folder) {
            Write-Host "Removing directory: $folder" -ForegroundColor Yellow
            Remove-Item -Path $folder -Recurse -Force -ErrorAction SilentlyContinue
        }
    }
}

# 4. Remove System-Wide ProgramData Leftovers
$leftoverPaths = @(
    "$env:ProgramData\Microsoft\Teams",
    "$env:ProgramData\Microsoft\TeamsMachineInstaller",
    "$env:ProgramData\Microsoft\TeamsCustomData"
)

foreach ($path in$leftoverPaths) {
    if (Test-Path $path) {
        Write-Host "Removing leftover ProgramData path: $path" -ForegroundColor Yellow
        Remove-Item -Path $path -Recurse -Force -ErrorAction SilentlyContinue
    }
}

# 5. Clean Startup Registry Run Keys across loaded user hives
$hkuPath = "Registry::HKEY_USERS"
Get-ChildItem -Path $hkuPath -ErrorAction SilentlyContinue | ForEach-Object {
    $runKey = Join-Path$_.PSPath "Software\Microsoft\Windows\CurrentVersion\Run"
    if (Test-Path $runKey) {
        $val = Get-ItemProperty -Path$runKey -Name "com.squirrel.teams.teams" -ErrorAction SilentlyContinue
        if ($val) {
            Write-Host "Removing Classic Teams startup reg key from hive: $($_.PSChildName)" -ForegroundColor Yellow
            Remove-ItemProperty -Path $runKey -Name "com.squirrel.teams.teams" -ErrorAction SilentlyContinue
        }
    }
}

# 6. Confirm New Teams (MSTeams) status
$newTeams = Get-AppxPackage -Name "MSTeams" -AllUsers -ErrorAction SilentlyContinue

if ($newTeams) {
    Write-Host "New Teams (MSTeams) is installed:" -ForegroundColor Green
    $newTeams | Select-Object Name, Version, PackageFullName | Format-Table -AutoSize | Out-String | Write-Host
} else {
    Write-Host "WARNING: New Teams (MSTeams) was not detected on this device." -ForegroundColor Red
}

# 7. Final Verification
$remainingMachineWide = foreach ($path in$uninstallPaths) {
    Get-ItemProperty $path -ErrorAction SilentlyContinue \vert{} Where-Object {$_.DisplayName -eq "Teams Machine-Wide Installer"
    }
}

$remainingClassicFolders = foreach ($profile in$userProfiles) {
    $localTeamsFolder = Join-Path$profile.FullName "AppData\Local\Microsoft\Teams"
    if (Test-Path $localTeamsFolder) {$localTeamsFolder }
}

if ($remainingMachineWide -or$remainingClassicFolders) {
    Write-Host "Cleanup completed, but some Classic Teams remnants remain." -ForegroundColor Red
    exit 1
} else {
    Write-Host "Classic Teams and Teams Machine-Wide Installer cleanup completed successfully." -ForegroundColor Green
    exit 0
}