Function CLogMsg {
    param([Parameter(Mandatory=$true,ValueFromPipeline=$true)][string]$Message)
    If ( $CUSTOM_LOG_AVAILABLE ) { LogMsg $Message } Else { CLogMsg $Message }
}

Function Get-UninstallCodes ([string]$DisplayName) {
    'HKLM:SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall', 'HKLM:SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall' | ForEach-Object {
        Get-ChildItem -Path $_ -ErrorAction SilentlyContinue | ForEach-Object {
            If ( $(Get-ItemProperty -Path $_.PSPath -Name 'DisplayName' -ErrorAction SilentlyContinue) -and ($(Get-ItemPropertyValue -Path $_.PSPath -Name 'DisplayName' -ErrorAction SilentlyContinue) -eq $DisplayName) ) {
                $str = (Get-ItemPropertyValue -Path $_.PSPath -Name 'UninstallString')
                $code = $str.Substring(($str.Length - 37),36)
                CLogMsg "Found    : ${code}"
                $UninstallCodes.Add($code) | Out-Null
            }
        }
    }
}

Function Get-ProductKeys ([string]$ProductName) {
    Get-ChildItem -Path 'HKCR:Installer\Products' | ForEach-Object {
        If ( $(Get-ItemProperty -Path $_.PSPath -Name 'ProductName' -ErrorAction SilentlyContinue) -and ($(Get-ItemPropertyValue -Path $_.PSPath -Name 'ProductName' -ErrorAction SilentlyContinue) -eq $ProductName) ) {
            $prod = $_.PSPath.Substring($_.PSPath.Length - 32)
            CLogMsg "Found    : ${prod}"
            $ProductKeys.Add($prod) | Out-Null
        }
    }
}

Function Get-ServiceStatus ([string]$Name) { (Get-Service -Name $Name -ErrorAction SilentlyContinue).Status }

Function Stop-RunningService ([string]$Name) {
    If ( $(Get-ServiceStatus -Name $Name) -eq "Running" ) { CLogMsg "Stopping : ${Name} service" ; Stop-Service -Name $Name -Force }
}

Function Remove-StoppedService ([string]$Name) {
    $s = (Get-ServiceStatus -Name $Name)
    If ( $s ) {
        If ( $s -eq "Stopped" ) {
            CLogMsg "Deleting : ${Name} service"
            Start-Process "sc.exe" -ArgumentList "delete ${Name}" -Wait
        }
    } Else { CLogMsg "Not Found: ${Name} service" }
}

Function Stop-RunningProcess ([string]$Name) {
    $p = (Get-Process -Name $_ -ErrorAction SilentlyContinue)
    If ( $p ) { CLogMsg "Stopping : ${Name}.exe" ; $p | Stop-Process -Force }
    Else { CLogMsg "Not Found: ${Name}.exe is not running"}
}

Function Remove-Path ([string]$Path) {
    If ( Test-Path $Path ) {
        CLogMsg "Deleting : ${Path}"
        Remove-Item $Path -Recurse -Force
    } Else { CLogMsg "Not Found: ${Path}" }
}

Function Get-AllExeFiles ([string]$Path) {
    If ( Test-Path $Path ) {
        Get-ChildItem -Path $Path -Filter *.exe -Recurse | ForEach-Object { $ExeFiles.Add($_.BaseName) | Out-Null }
    }
}

# Test if the custom function LogMsg is available in the current scope
If ( Get-Command 'LogMsg' -ErrorAction SilentlyContinue ) { $CUSTOM_LOG_AVAILABLE = $true } Else { $CUSTOM_LOG_AVAILABLE = $false }

# Mount HKEY_CLASSES_ROOT registry hive
New-PSDrive -Name HKCR -PSProvider Registry -Root HKEY_CLASSES_ROOT | Out-Null

#######
# START: Information gathering
#######

# Get MSI package codes from the uninstall key
$UninstallCodes = New-Object System.Collections.ArrayList
'AteraAgent' | ForEach-Object { Get-UninstallCodes -DisplayName $_ }

# Get product keys from the list of installed products
$ProductKeys = New-Object System.Collections.ArrayList
'AteraAgent' | ForEach-Object { Get-ProductKeys -ProductName $_ }

# Define all the directories we'll need to cleanup at the end of this script
$Directories = @("${Env:ProgramFiles}\ATERA Networks")

# Get all possible relevant exe files so we can make sure they're closed later on
$ExeFiles = New-Object System.Collections.ArrayList
$Directories | ForEach-Object { Get-AllExeFiles -Path $_ }
$ExeFiles.Add('reg')  | Out-Null

# Define a list of services we need to stop and delete (if necessary)
$ServiceList = @('AteraAgent')

# Define a list of registry keys we'll delete
$RegistryKeys = @('HKLM:SOFTWARE\ATERA Networks')

#######
# END: Information gathering
#######

# Uninstall each MSI package code in $UninstallCodes
$UninstallCodes | ForEach-Object { CLogMsg "Uninstall: ${_}" ; Start-Process "msiexec.exe" -ArgumentList "/X{${_}} /qn" -Wait }

# Stop services if they're still running
$ServiceList | ForEach-Object { Stop-RunningService -Name $_ }

# Terminate all relevant processes that may still be running
$ExeFiles | ForEach-Object { Stop-RunningProcess $_ }

# Delete services if they're still present
$ServiceList | ForEach-Object { Remove-StoppedService -Name $_ }

# Delete products from MSI installer registry
$ProductKeys | ForEach-Object { Remove-Path -Path "HKCR:Installer\Products\${_}" }

# Unmount HKEY_CLASSES_ROOT registry hive
Remove-PSDrive -Name HKCR

# Delete registry keys
$RegistryKeys | ForEach-Object { Remove-Path -Path $_ }

# Delete remaining directories
$Directories | ForEach-Object { Remove-Path -Path $_ }