function Set-AppTierGMSAAccounts {
<#
.SYNOPSIS
    Sets App Tier GMS Accounts.
#>

    [CmdletBinding()]
    Param(
        [Parameter(Mandatory = $true)]
        [Alias("PodGMSAAccount")]
        [string]$podGMSAAccountParent
    )

    $DEFAULTVALUE = "DEFAULTVALUE"

    Write-Host "If a warning happens next for [The AppSetting with Key Environment.UserPrefix could not be found], you can ignore that completely"
    ## We want to set the value if it does not exist, because eventually all machines should have this configured.
    ## This pairs with Alkami.PowerShell.Configuration\Get-AppServiceAccountName to go in the local web.config or app.config
    ## Only write it as we consume it.
    if ($null -eq (Get-AppSetting -appSettingKey "Environment.UserPrefix")) {
        Write-Verbose "Adding Environment.UserPrefix to match this function"
        Set-AppSetting -key "Environment.UserPrefix" -Value $podGMSAAccountParent
        ## This is so we can use this later as ($domain)\(Get-AppSetting -appSettingKey "Environment.UserPrefix").$MatrixLookup[appName]$
        ## see also Get-AppServiceAccountName
    }

    $applicationsDictionary = @{
        'AuditService' = 'fh\DEFAULTVALUE.audit$';
        'BankService' = 'fh\DEFAULTVALUE.bank$';
        'ContentService' = 'fh\DEFAULTVALUE.content$';
        'CoreService' = 'fh\DEFAULTVALUE.core$';
        'ExceptionService' = 'fh\DEFAULTVALUE.exception$';
        'MessageCenterService' = 'fh\DEFAULTVALUE.msgctr$';
        'NagConfigurationService' = 'fh\DEFAULTVALUE.nag$';
        'NotificationService' = 'fh\DEFAULTVALUE.notify$';
        'RP-STS' = 'fh\DEFAULTVALUE.rpsts$';
        'SchedulerService' = 'fh\DEFAULTVALUE.schedule$';
        'SecurityManagementService' = 'fh\DEFAULTVALUE.secmgr$';
        'STSConfiguration' = 'fh\DEFAULTVALUE.stsconf$';
        'SymConnectMultiplexer' = 'fh\DEFAULTVALUE.multiplx$';
        'Alkami Radium Scheduler Service' = 'fh\DEFAULTVALUE.radium$';
        'Alkami Nag Service' = 'fh\DEFAULTVALUE.nag$';
    }

    foreach ($appTierApplication in $appTierApplications) {
        $appName = $appTierApplication.Name
        $newUserName = $applicationsDictionary[$appName] -replace $DEFAULTVALUE,$podGMSAAccountParent
        $appTierApplication.User = $newUserName
        Write-Host "$($appTierApplication.Name) : $($appTierApplication.User)"
    }

    foreach ($appTierService in (Get-AppTierServices)) {
        $appName = $appTierService.Name
        $newUserName = $applicationsDictionary[$appName] -replace $DEFAULTVALUE,$podGMSAAccountParent
        $appTierService.User = $newUserName
        Write-Host "$($appTierService.Name) : $($appTierService.User)"
    }
}