Imports System.Net.Http
Imports System.Text.Json
Imports System.Text.Json.Serialization
Imports System.Text.RegularExpressions
Imports System.Threading.Tasks

' ============================================================
'   CLASES DE MODELO PARA EL JSON DEVUELTO POR VIES (REST)
' ============================================================

Public Class ViesApproximate
    <JsonPropertyName("matchName")>
    Public Property MatchName As Integer

    <JsonPropertyName("matchStreet")>
    Public Property MatchStreet As Integer

    <JsonPropertyName("matchPostalCode")>
    Public Property MatchPostalCode As Integer

    <JsonPropertyName("matchCity")>
    Public Property MatchCity As Integer

    <JsonPropertyName("matchCompanyType")>
    Public Property MatchCompanyType As Integer
End Class

Public Class ViesRestResponse
    <JsonPropertyName("isValid")>
    Public Property IsValid As Boolean

    <JsonPropertyName("requestDate")>
    Public Property RequestDate As Date

    <JsonPropertyName("userError")>
    Public Property UserError As String

    <JsonPropertyName("name")>
    Public Property Name As String

    <JsonPropertyName("address")>
    Public Property Address As String

    <JsonPropertyName("requestIdentifier")>
    Public Property RequestIdentifier As String

    <JsonPropertyName("originalVatNumber")>
    Public Property OriginalVatNumber As String

    <JsonPropertyName("vatNumber")>
    Public Property VatNumber As String

    <JsonPropertyName("viesApproximate")>
    Public Property ViesApproximate As ViesApproximate

    ' Campo adicional para errores locales
    Public Property LocalError As String
End Class


' ============================================================
'   VALIDADOR COMPLETO VAT + VIES REST
' ============================================================

Public Class ValidacionDocumentosIdentidadVIES

    ' -----------------------------
    ' 1) Validación de formato VAT
    ' -----------------------------
    Private Shared ReadOnly Patterns As New Dictionary(Of String, String) From {
        {"AT", "^[A-Z]U[0-9]{8}$"},
        {"BE", "^[0-9]{10}$"},
        {"BG", "^[0-9]{9,10}$"},
        {"CY", "^[0-9]{8}[A-Z]$"},
        {"CZ", "^[0-9]{8,10}$"},
        {"DE", "^[0-9]{9}$"},
        {"DK", "^[0-9]{8}$"},
        {"EE", "^[0-9]{9}$"},
        {"EL", "^[0-9]{9}$"},
        {"ES", "^[A-Z0-9][0-9]{7}[A-Z0-9]$"},
        {"FI", "^[0-9]{8}$"},
        {"FR", "^[A-Z0-9]{2}[0-9]{9}$"},
        {"HR", "^[0-9]{11}$"},
        {"HU", "^[0-9]{8}$"},
        {"IE", "^[0-9]{7}[A-W][A-I]?$"},
        {"IT", "^[0-9]{11}$"},
        {"LT", "^[0-9]{9}|[0-9]{12}$"},
        {"LU", "^[0-9]{8}$"},
        {"LV", "^[0-9]{11}$"},
        {"MT", "^[0-9]{8}$"},
        {"NL", "^[0-9]{9}B[0-9]{2}$"},
        {"PL", "^[0-9]{10}$"},
        {"PT", "^[0-9]{9}$"},
        {"RO", "^[0-9]{2,10}$"},
        {"SE", "^[0-9]{12}$"},
        {"SI", "^[0-9]{8}$"},
        {"SK", "^[0-9]{10}$"},
        {"XI", "^[0-9]{9}$"}
    }

    Public Shared Function IsValidVatFormat(countryCode As String,
                                            vatNumber As String) As Boolean

        countryCode = countryCode.ToUpper().Trim()
        vatNumber = vatNumber.ToUpper().Trim()

        If Not Patterns.ContainsKey(countryCode) Then
            Return False
        End If

        Return Regex.IsMatch(vatNumber, Patterns(countryCode))
    End Function


    ' -----------------------------
    ' 2) Cliente HTTP compartido
    ' -----------------------------
    Private Shared ReadOnly _http As New HttpClient() With {
        .Timeout = TimeSpan.FromSeconds(10)
    }


    ' -----------------------------
    ' 3) Validación VIES vía REST (ASÍNCRONA)
    ' -----------------------------
    Public Shared Async Function ValidateVatAsync(countryCode As String,
                                                  vatNumber As String) As Task(Of ViesRestResponse)

        Dim result As New ViesRestResponse()

        Try
            ' Normalización
            countryCode = countryCode.Trim().ToUpper()
            vatNumber = vatNumber.Trim().ToUpper()

            ' Validación de formato previa
            If Not IsValidVatFormat(countryCode, vatNumber) Then
                result.LocalError = $"Formato VAT inválido para {countryCode}"
                Return result
            End If

            Dim url = $"https://ec.europa.eu/taxation_customs/vies/rest-api/ms/{countryCode}/vat/{vatNumber}"

            Dim json As String = Await _http.GetStringAsync(url).ConfigureAwait(False)

            result = JsonSerializer.Deserialize(Of ViesRestResponse)(json)

        Catch ex As HttpRequestException
            result.LocalError = "Error HTTP: " & ex.Message

        Catch ex As TaskCanceledException
            result.LocalError = "Timeout al consultar VIES"

        Catch ex As Exception
            result.LocalError = "Error inesperado: " & ex.Message
        End Try

        Return result
    End Function


    ' -----------------------------
    ' 4) Validación VIES vía REST (SINCRONA SEGURA PARA WPF)
    ' -----------------------------
    Public Shared Function ValidateVat(countryCode As String,
                                           vatNumber As String) As ViesRestResponse

        Return Task.Run(
            Async Function()
                Return Await ValidateVatAsync(countryCode, vatNumber).ConfigureAwait(False)
            End Function
        ).Result

    End Function

End Class