param(
    [Parameter(Mandatory=$true)]
    [string[]]$Members,

    [Parameter(Mandatory=$false)]
    [string]$DistroGroupName = "GWStorageMonitoringUsers",

    # Exchange params â mandatory in Standalone sets only
    [string]$ExchangeCertificatePath,

    [string]$ExchangeAppId,

    [string]$ExchangeOrganization,

    # Optional local/interactive login via UPN instead of cert
    [string]$UserPrincipalName,

    # Standalone switch â present in Halo, assumed Standalone if absent
    [switch]$Halo
)

if (-not $Halo)
{
    Write-Host("Starting Glasswall Outlook Banner synchronization...")

    if (-not (Get-Module -ListAvailable -Name ExchangeOnlineManagement)) {
        Write-Warning "EXO module not found. Installing..."
        Install-Module -Name ExchangeOnlineManagement -Scope CurrentUser -Force
    }

    if (-not (Get-Module -Name ExchangeOnlineManagement)) {
        Write-Verbose "Importing EXO module..."
        Import-Module ExchangeOnlineManagement
    }

    try {
        Get-OrganizationConfig -ErrorAction Stop | Out-Null
        Write-Host "Connected to Exchange Online" -ForegroundColor Green
    } catch {
        Write-Verbose "Not connected to Exchange Online. Initiating connection..."
        if ($UserPrincipalName) {
            Write-Host "Opening browser login for $UserPrincipalName..."
            Connect-ExchangeOnline -UserPrincipalName $UserPrincipalName `
                                -ShowBanner:$false
        } else {
            Write-Warning "No UserPrincipalName provided, falling back to certificate authentication. Please ensure certificate parameters are provided..."
            $parametersMissing = $false
            if (-not $ExchangeCertificatePath) { Write-Error "-ExchangeCertificatePath is required"; $parametersMissing = $true }
            if (-not $ExchangeAppId) { Write-Error "-ExchangeAppId is required"; $parametersMissing = $true }
            if (-not $ExchangeOrganization) { Write-Error "-ExchangeOrganization is required"; $parametersMissing = $true }

            if ($parametersMissing) {
                Write-Error "One or more Exchange parameters are missing - see previous errors. Alternatively, please provide a valid email login for UserPrincipalName"
                exit 1
            }

            Write-Host "Connecting to Exchange Online via certificate authentication..."
            Connect-ExchangeOnline -AppId $ExchangeAppId `
                                -CertificateFilePath $ExchangeCertificatePath `
                                -Organization $ExchangeOrganization `
                                -ShowBanner:$false
        }

        Write-Host "Connected to Exchange Online" -ForegroundColor Green
    }
}

try {
    foreach ($member in $Members) {
        Remove-DistributionGroupMember -Identity $DistroGroupName -Member $member -Confirm:$false -ErrorAction SilentlyContinue
        Write-Verbose "Success: Member was removed Distribution Group and will no longer receive monitoring banners"
    }
} catch {
    Write-Warning "Some or all members were unable to be removed from the Distribution Group. $Error"
}