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

Public Class VatValidationResult
    Public Property IsValid As Boolean
    Public Property Name As String
    Public Property Address As String
    Public Property RawJson As String
    Public Property ErrorMessage As String
End Class

Public Class ValidacionDocumentosIdentidad

    ' -----------------------------
    ' 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}$"},
        {"XI", "^[0-9]{9}$"} ' Irlanda del Norte
    }

    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 VatValidationResult)

        Dim result As New VatValidationResult()

        Try
            ' Validación de formato previa
            If Not IsValidVatFormat(countryCode, vatNumber) Then
                result.IsValid = False
                result.ErrorMessage = $"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)
            result.RawJson = json

            Dim doc = JsonDocument.Parse(json)
            Dim root = doc.RootElement

            result.IsValid = root.GetProperty("isValid").GetBoolean()

            If result.IsValid Then
                result.Name = root.GetProperty("traderName").GetString()
                result.Address = root.GetProperty("traderAddress").GetString()
            End If

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

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

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

        Return result
    End Function


    ' -----------------------------
    ' 4) Validación VIES vía REST (SINCRONA)
    ' -----------------------------
    Public Shared Function ValidateVat(countryCode As String,
                                       vatNumber As String) As VatValidationResult

        Return ValidateVatAsync(countryCode, vatNumber).GetAwaiter().GetResult()

    End Function

End Class