Option to Install Veeam ONE Agent is Unavailable (Greyed Out)

#Check if script is being run on Veeam ONE Server by detecting Veeam ONE Monitoring Service
$onePresent = Get-Service -Name "Veeam ONE Monitoring Service" -ErrorAction SilentlyContinue
if ($onePresent) {
    Write-Host "Veeam ONE detected. Proceeding with checks."
} else {
    Throw "Veeam ONE not detected. This script must be run on the Veeam ONE server."
}

#Check if Veeam ONE Agent service is present.
function Check-VeeamONEAgentStatus {
    $agentPresent = Get-Service -Name "Veeam ONE Agent" -ErrorAction SilentlyContinue
    if (-not $agentPresent) {
        Write-Host "Veeam ONE Agent not detected. Installing..."
        Install-OneAgent
    }
}

#Install Veeam ONE Agent in Master mode.
function Install-OneAgent {
    Write-Host "Installing Veeam ONE Agent in Master mode."
    #Path To VeeamONE.Agent.x64.msi (assuming default C: drive install)
    $msiPath = "C:\Program Files\Veeam\Veeam ONE\Veeam ONE Monitor Server\AgentPackage\VeeamONE.Agent.x64.msi"
	if (Test-Path -Path $msiPath) { } else { Throw "MSI file does not exist at $msiPath" }
    #Get Veeam ONE Monitoring service's log on as account to show user which account credentials should be provided.
    $serviceUsername = (Get-WmiObject -Class Win32_Service -Filter "Name='VeeamDCS'").StartName
    #Prompt user to Specify Veeam ONE Service Account Credentials
    $credentials = Get-Credential -Message "Please enter the credentials for $serviceUsername"
    #Execute Installer and capture exit code
    $installExit = (Start-Process -FilePath "C:\Windows\System32\msiexec.exe" -ArgumentList "/qn", "/i `"$msiPath`"", "ACCEPT_THIRDPARTY_LICENSES=1", "ACCEPT_EULA=1", "ACCEPT_REQUIRED_SOFTWARE=1", "ACCEPT_LICENSING_POLICY=1", "VO_AGENT_TYPE=1", "VO_BUNDLE_INSTALLATION=1", "VO_AGENT_SERVICE_ACCOUNT_NAME=`"$($credentials.UserName)`"", "VO_AGENT_SERVICE_ACCOUNT_PASSWORD=`"$($credentials.GetNetworkCredential().Password)`"" -Wait -Passthru).ExitCode
    #Evaluate Exit Code
    if ($installExit -ne 0) {
        Throw "Veeam ONE Agent Install failed. Check event logs. (Invalid credentials provided?)"
    } else {
        Write-Host "Veeam ONE Agent Installed"
    }
}

#Check which mode Veeam ONE Agent service is running in based on parsing the service log.
function Check-AgentMode {
    $serviceID = Get-AgentServiceID    
    # Check OneAgent.log to determine whether service is running in Master or Worker mode
    $logFilePath = "C:\ProgramData\Veeam\OneAgent\Log\" + $serviceID + "\OneAgent.log"
    $logFileContent = Get-Content $logFilePath | Where-Object { $_ -match "Start actual agent settings:Id=\w+-\w+-\w+-\w+-\w+ AgentType=(Worker|Master) Port=\d+" }
    $agentType = ($logFileContent | Select-Object -Last 1) -replace '.*AgentType=(Worker|Master).*', '$1'
    #Evaluate mode and reinstall Veeam ONE Agent if operating in Worker mode.
    Write-Host "Veeam ONE Agent Mode:" $agentType
    if ([string]::IsNullOrEmpty($agentType)) {
        Write-Host "Agent Mode not detected, restarting Veeam ONE Agent service and trying again."
        Restart-Service VeeamOneAgentSvc
        Check-AgentMode
    } elseif ($agentType -eq "Worker") {
		Reinstall-ONEAgent
    } else {
        Write-Host "Veeam ONE Agent operating in correct mode. Proceeding with checks."
    }
}


#Extract Veeam ONE Agent service ID from file path specified in service settings.
function Get-AgentServiceID {
    Check-VeeamONEAgentStatus
    #Get Veeam ONE Agent Service ID#
    $serviceID = ([regex]::Match((Get-WmiObject -Class Win32_Service | Where-Object { $_.Name -eq 'VeeamOneAgentSvc' }).PathName, '-id=([a-fA-F0-9-]+)').Groups[1]).Value
    if ([string]::IsNullOrEmpty($serviceID)) {
        Throw "Veeam ONE Agent Service ID Empty."
        }
    return $serviceID
}

#Get PrimaryOneAgentID value from registry. This is set by the Veeam ONE Agent installer and use by Veeam ONE Monitoring service to communicate with Veeam ONE Agent.
function Get-PrimaryOneAgentID {
    $regValue = (Get-ItemProperty -Path 'HKLM:\SOFTWARE\Veeam\Veeam ONE Monitor\Service' -Name "PrimaryOneAgentId").PrimaryOneAgentId
    return $regValue
}

function Reinstall-ONEAgent {
	Write-Host "Veeam ONE Agent wrong mode. Reinstalling..."
        Uninstall-ONEAgent
        Install-OneAgent
        Check-AgentMode
}

#Uninstalls Veeam ONE Agent by pulling the UninstallString from the registry and passing it to msiexec
function Uninstall-ONEAgent {
    Write-Host "Uninstalling Veeam ONE Agent"
    $programName = "Veeam ONE Agent"
    $program = Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Where-Object {$_.DisplayName -eq $programName}
    if ($program) {
      $uninstallCommand = $program.UninstallString
      $start = $uninstallCommand.IndexOf('{')
      $end = $uninstallCommand.IndexOf('}')
      $uninstalGuid = $uninstallCommand.Substring($start, $end - $start + 1)
      $uninstallExit = (Start-Process -FilePath "C:\Windows\System32\msiexec.exe" -ArgumentList "/x `"$uninstalGuid`"" -Wait -Passthru).ExitCode
      if ($uninstallExit -ne 0) {
        Throw "Veeam ONE Agent uninstall failed. Check event logs."
    } else {
        Write-Host "Veeam ONE Agent Uninstalled"
    }
    } else {
    Throw "Veeam ONE Agent uninstall entry in registry not found. Manually uninstall Veeam ONE Agent and rerun script"
    }
}

#Compare the ID value from the Veeam ONE Agent service with the one set in the registry.
function Check-AgentIDs {
    Write-Host "Checking for Agent ID Conflict"
    $serviceID = Get-AgentServiceID
    $regValue = Get-PrimaryOneAgentID
    #Display current values for visual verification.
    Write-Host "Agent Service  ID:" $serviceID
    Write-Host "Agent Registry ID:" $regValue
    if ($serviceID -ne $regValue) {
    Set-PrimaryOneAgentID
    } else {
        Write-Host "No Agent ID mismatch detected." -ForegroundColor Green
    }
}

#Set the PrimaryOneAgentID value in the registry to match the local Veeam ONE Agent service ID.
function Set-PrimaryOneAgentID {
    $serviceID = Get-AgentServiceID
    Set-ItemProperty -Path 'HKLM:\SOFTWARE\Veeam\Veeam ONE Monitor\Service' -Name "PrimaryOneAgentId" -Value $serviceID
    $regValue = Get-PrimaryOneAgentID
    if ($regvalue -eq $serviceID) {
        Write-Host "A value mismatch was detected and has been corrected." -ForegroundColor Green
        Write-Host "PrimaryOneAgentID value set to:" $regValue
    } else {
    Throw "Registry value could not be updated. Check permissions."
    }
}

#Is Veeam ONE Agent installed?
Check-VeeamONEAgentStatus
#Is Veeam ONE Agent running in the correct mode, Master mode?
Check-AgentMode
#Is there a mismatch between the Veeam ONE Agent service ID and the PrimaryONEAgentID in the registry?
Check-AgentIDs