internal/functions/resolve/Resolve-DirectoryRoleDefinition.ps1

function Resolve-DirectoryRoleDefinition
{
    [CmdletBinding()]
    Param (
        [Parameter(Mandatory = $true)]
        [string] $InputReference,
        [switch] $DontFailIfNotExisting,
        [switch] $SearchInDesiredConfiguration,
        [switch] $Expand, # Return object { id, displayName }
        [switch] $DisplayName,
        [System.Management.Automation.PSCmdlet]
        $Cmdlet = $PSCmdlet
    )
    
    begin {
        $InputReference = Resolve-String -Text $InputReference
    }
    process
    {            
        try {
            $detail = $null; $roleDefinition = $null
            if ($InputReference -match $script:guidRegex) {
                $detail = Invoke-MgGraphRequest -Method GET -Uri ("$script:graphBaseUrl/roleManagement/directory/roleDefinitions/{0}?`$select=id,displayName" -f $InputReference)
                $roleDefinition = $detail.id
            } else {
                $detail = (Invoke-MgGraphRequest -Method GET -Uri ("$script:graphBaseUrl/roleManagement/directory/roleDefinitions/?`$filter=displayName eq '{0}'&`$select=id,displayName" -f $InputReference)).value | Select-Object -First 1
                $roleDefinition = $detail.id
            }

            if (-Not $roleDefinition -and $SearchInDesiredConfiguration) {
                if ($InputReference -in $script:desiredConfiguration["roleDefinitions"].displayName) {
                    $roleDefinition = $InputReference
                }
            }

            if (-Not $roleDefinition -and -Not $DontFailIfNotExisting) { throw "Cannot find directoryRole $InputReference." } 
            elseif (-Not $roleDefinition -and $DontFailIfNotExisting) { return }

            if ($roleDefinition.count -gt 1) { throw "Got multiple directory/roleDefinitions for $InputReference" }
            if (-not $Expand) { if ($DisplayName) { return ($detail.displayName) } return $roleDefinition }
            return [pscustomobject]@{ id=$roleDefinition; displayName=$detail.displayName }
        }
        catch {
            Write-PSFMessage -Level Warning -Message ("Cannot resolve DirectoryRoleDefinition resource for input '{0}'. Searched tenant & desired configuration. Error: {1}" -f $InputReference,$_.Exception.Message) -Tag 'failed' -ErrorRecord $_
            $Cmdlet.ThrowTerminatingError($_)                
        }            
    }
}