Public/Curanet/Invoicing/Get-CuranetInvoice.ps1

function Get-CuranetInvoice() {
    Param(
        [Parameter(Mandatory)]
        [ValidateSet("3370", "3850")]
        [string]$Account,
        [string]$InvoiceID
    )

    if( ($null -eq (Get-Variable -Name "$($Account)AccessTokenExpire" -Scope Global -ValueOnly -ErrorAction SilentlyContinue)) -or ((Get-Date) -gt (Get-Variable -Name "$($Account)AccessTokenExpire" -Scope Global -ValueOnly -ErrorAction SilentlyContinue)) ) {
        Get-CuranetAccessToken -Account $Account
    }

    $AccessToken = (Get-Variable -Name "$($Account)AccessToken" -Scope Global -ValueOnly -ErrorAction SilentlyContinue).access_token

    $AuthorizationHeader = @{
        Authorization="Bearer $AccessToken"
    }
    try {
        if($InvoiceID) {
            $Invoices = (Invoke-WebRequest -Uri "https://api.curanet.dk/invoicing/v1/Invoices/$($InvoiceID)" -Headers $AuthorizationHeader -UseBasicParsing -Method GET).Content | ConvertFrom-Json
        } else {
            $Invoices = (Invoke-WebRequest -Uri "https://api.curanet.dk/invoicing/v1/Invoices" -Headers $AuthorizationHeader -UseBasicParsing -Method GET).Content | ConvertFrom-Json
        }

    } catch {
        throw "Failed to retreive invoices from Curanet $($Account) API: $_"
    }

    return $Invoices
}