SDL/SDL/Classes/cFiskaltrustClient.vb

Imports System.Net.Http
Imports System.Text
Imports Newtonsoft.Json
Imports System.Threading

Public Class cFiskaltrustClient

    Private ReadOnly _baseUrl As String
    Private ReadOnly _cashboxId As String
    Private ReadOnly _accessToken As String
    Private ReadOnly _country As String

    Private Shared ReadOnly _httpClient As New HttpClient()

    Public Sub New(baseUrl As String, cashboxId As String, accessToken As String, country As String)
        _baseUrl = baseUrl.TrimEnd("/"c)
        _cashboxId = cashboxId
        _accessToken = accessToken
        _country = country
    End Sub

    ' ================================
    ' PUBLIC API
    ' ================================
    Public Async Function SignReceiptAsync(amount As Double, vat As Double, POS As List(Of EABelegPositionen)) As Task(Of String)

        Dim payload = BuildPayload(amount, vat, POS)
        Dim endpoint = GetEndpoint("payment")

        Return Await SendAsync(endpoint, payload)

    End Function


    Public Async Function Echo() As Task(Of String)

        Dim payload = "TEST"
        Dim endpoint = GetEndpoint("test")

        Return Await SendAsync(endpoint, payload)

    End Function

    ' Optional: Storno Beispiel
    Public Async Function CancelReceiptAsync(reference As String) As Task(Of String)

        Dim payload = New With {
            .ftCashBoxID = _cashboxId,
            .ftPosSystemId = "POS-1",
            .cbTerminalID = "T1",
            .cbReceiptReference = reference,
            .cbReceiptMoment = DateTime.UtcNow.ToString("o"),
            .ftReceiptCase = 4919338172267102210 ' Storno
        }

        Return Await SendAsync(GetEndpoint("payment"), payload)

    End Function

    ' ================================
    ' CORE HTTP LOGIC (RETRY!)
    ' ================================
    Private Async Function SendAsync(endpoint As String, payload As Object) As Task(Of String)

        Dim exToThrow As Exception = Nothing

        Dim json As String = JsonConvert.SerializeObject(payload)
        Dim url = _baseUrl & endpoint

        Dim retries As Integer = 3
        Dim delayMs As Integer = 500

        For attempt = 1 To retries

            Try
                Using request As New HttpRequestMessage(HttpMethod.Post, url)

                    request.Headers.Add("cashboxid", _cashboxId)
                    request.Headers.Add("accesstoken", _accessToken)

                    Select Case _country
                        Case "AT"
                            request.Content = New StringContent(json, Encoding.UTF8, "text/xml")
                        Case Else
                            request.Content = New StringContent(json, Encoding.UTF8, "application/json")
                    End Select

                    Dim response = Await _httpClient.SendAsync(request)
                    Dim result = Await response.Content.ReadAsStringAsync()

                    ' Logging Hook
                    Log($"[{DateTime.Now}] Response ({response.StatusCode}): {result}")

                    If response.IsSuccessStatusCode Then
                        Return result
                    End If

                    ' Retry only on transient errors
                    If CType(response.StatusCode, Integer) >= 500 Then
                        Throw New Exception("Server error: " & result)
                    Else
                        ' Client error → no retry
                        Throw New Exception("Client error: " & result)
                    End If

                End Using

            Catch ex As Exception

                Log($"[{DateTime.Now}] Attempt {attempt} failed: {ex.Message}")

                If attempt = retries Then
                    exToThrow = ex
                End If

            End Try


        Next


        If exToThrow IsNot Nothing Then
            Await Task.Delay(1000) ' ✅ jetzt OK
            Throw exToThrow
        End If

        Throw New Exception("Unexpected error")

    End Function




    ' ================================
    ' PAYLOAD BUILDER
    ' ================================
    Private Function BuildPayload(amount As Double, vat As Double, POS As List(Of EABelegPositionen)) As Object

        ' ChargeItems Liste vorbereiten
        Dim chargeItems = New List(Of Object)

        For Each p In POS
            chargeItems.Add(New With {
            .Quantity = p.Anzahl,
            .Amount = p.Preis,
            .VATRate = vat,
            .Description = p.LeistungsBez,
            .ftChargeItemCase = 4919338167972134929
        })
        Next

        ' Payload Objekt erstellen
        Dim payload = New With {
        .ftCashBoxID = _cashboxId,
        .ftPosSystemId = "POS-1",
        .cbTerminalID = "T1",
        .cbReceiptReference = Guid.NewGuid().ToString(),
        .cbReceiptMoment = DateTime.UtcNow.ToString("o"),
        .cbChargeItems = chargeItems,
        .cbPayItems = New Object() {
            New With {
                .Quantity = 1.0,
                .Amount = amount,
                .Description = "Cash",
                .ftPayItemCase = 4919338167972134913
            }
        },
        .ftReceiptCase = 4919338172267102209
    }

        Return payload

    End Function

    ' ================================
    ' ENDPOINT SWITCH
    ' ================================
    Private Function GetEndpoint(type As String) As String

        If type = "payment" Then


            Select Case _country
                Case "DE"
                    Return "/json/v1/Sign"
                Case "AT"
                    Return "/json/Sign"
                Case Else
                    Throw New Exception("Unsupported country")
            End Select

        ElseIf type = "test" Then

            Select Case _country
                Case "DE"
                    Return "/json/v1/Echo"
                Case "AT"
                    Return "/json/Echo"
                Case Else
                    Throw New Exception("Unsupported country")
            End Select

        End If





    End Function

    ' ================================
    ' LOGGING (REPLACE IN PROD!)
    ' ================================
    Private Sub Log(message As String)
        ' 👉 Hier anschließen:
        ' - Datei
        ' - Datenbank
        ' - Serilog / NLog
        Console.WriteLine(message)
    End Sub

End Class