namespace DXApp.TemplateKitProject.Services;

using DXApp.TemplateKitProject.Models;
using System.Xml.Linq;

public class ZugferdParserService
{
    // ZUGFeRD v2 / Factur-X Namespaces
    private static readonly XNamespace Ram = "urn:un:unece:uncefact:data:standard:ReusableAggregateBusinessInformationEntity:100";

    private static readonly XNamespace Rsm = "urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100";
    private static readonly XNamespace Udt = "urn:un:unece:uncefact:data:standard:UnqualifiedDataType:100";

    public ZugferdInvoice Parse(string xml)
    {
        var doc = XDocument.Parse(xml);
        var root = doc.Root!;

        var header = root.Element(Rsm + "ExchangedDocument");
        var trade = root.Element(Rsm + "SupplyChainTradeTransaction");

        var agreement = trade?.Element(Ram + "ApplicableHeaderTradeAgreement");
        var settlement = trade?.Element(Ram + "ApplicableHeaderTradeSettlement");

        return new ZugferdInvoice
        {
            InvoiceNumber = header?.Element(Ram + "ID")?.Value ?? string.Empty,
            InvoiceDate = ParseDate(header?.Element(Ram + "IssueDateTime")
                                             ?.Element(Udt + "DateTimeString")?.Value),

            SellerName = agreement?.Element(Ram + "SellerTradeParty")
                                    ?.Element(Ram + "Name")?.Value ?? string.Empty,
            SellerTaxId = agreement?.Element(Ram + "SellerTradeParty")
                                    ?.Element(Ram + "SpecifiedTaxRegistration")
                                    ?.Element(Ram + "ID")?.Value ?? string.Empty,
            BuyerName = agreement?.Element(Ram + "BuyerTradeParty")
                                    ?.Element(Ram + "Name")?.Value ?? string.Empty,

            CurrencyCode = settlement?.Element(Ram + "InvoiceCurrencyCode")?.Value ?? "EUR",
            TotalAmount = ParseDecimal(settlement?.Element(Ram + "SpecifiedTradeSettlementHeaderMonetarySummation")
                                                   ?.Element(Ram + "GrandTotalAmount")?.Value),
            TaxAmount = ParseDecimal(settlement?.Element(Ram + "SpecifiedTradeSettlementHeaderMonetarySummation")
                                                   ?.Element(Ram + "TaxTotalAmount")?.Value),
            Iban = settlement?.Element(Ram + "SpecifiedTradeSettlementPaymentMeans")
                                      ?.Element(Ram + "PayeePartyCreditorFinancialAccount")
                                      ?.Element(Ram + "IBANID")?.Value ?? string.Empty,
            RawXml = xml,
            ImportedAt = DateTime.UtcNow
        };
    }

    private static DateTime ParseDate(string? value)
    {
        if (string.IsNullOrWhiteSpace(value)) return DateTime.MinValue;
        return DateTime.TryParseExact(value, "yyyyMMdd",
            System.Globalization.CultureInfo.InvariantCulture,
            System.Globalization.DateTimeStyles.None, out var dt) ? dt : DateTime.MinValue;
    }

    private static decimal ParseDecimal(string? value)
        => decimal.TryParse(value,
            System.Globalization.NumberStyles.Any,
            System.Globalization.CultureInfo.InvariantCulture, out var d) ? d : 0m;
}