using System;
using System.Threading.Tasks;
using System.Net.Mail;
using System.IO;
using System.Collections.Generic;
using ComplianceNFs.Core.Entities;
using ComplianceNFs.Core.Ports;
using System.Linq;
using System.Numerics;
using Microsoft.Extensions.Logging;

namespace ComplianceNFs.Core.Application.Services
{
    // Handles ingestion of invoices from mail attachments
    public class InvoiceIngestionService : IInvoiceIngestionService
    {
        private readonly IMailListener _mailListener;
        private readonly IAttachmentRepository _attachmentRepository;
        private readonly IXmlParser _xmlParser;
        private readonly IPdfParser _pdfParser;
        private readonly ILogger<InvoiceIngestionService> _logger;

        public InvoiceIngestionService(IMailListener mailListener, IAttachmentRepository attachmentRepository, IXmlParser xmlParser, IPdfParser pdfParser, ILogger<InvoiceIngestionService> logger)
        {
            _mailListener = mailListener;
            _attachmentRepository = attachmentRepository;
            _xmlParser = xmlParser;
            _pdfParser = pdfParser;
            _logger = logger;
            _mailListener.NewMailReceived += OnNewMailReceived;
        }
        private async void OnNewMailReceived(MailMessage mail)
        {
            _logger.LogInformation("New mail received: {Subject}", mail.Subject);
            try
            {
                // Download attachments, parse, map to EnergyInvoice, save via _attachmentRepository
                foreach (var attachment in mail.Attachments)
                {
                    if (attachment is System.Net.Mail.Attachment att && att.Name != null)
                    {
                        using var stream = new MemoryStream();
                        att.ContentStream.CopyTo(stream);
                        stream.Position = 0;
                        ParsedInvoice parsed = new();
                        if (att.Name.EndsWith(".xml", StringComparison.OrdinalIgnoreCase))
                            parsed = _xmlParser.Parse(stream);
                        else if (att.Name.EndsWith(".pdf", StringComparison.OrdinalIgnoreCase))
                            parsed = _pdfParser.Parse(stream);
                        else
                            continue;
                        var invoice = new EnergyInvoice
                        {
                            MailId = mail.Headers?["Message-ID"] ?? string.Empty,
                            ConversationId = mail.Headers?["Conversation-ID"] ?? string.Empty,
                            SupplierEmail = mail.From != null ? mail.From.Address : string.Empty,
                            ReceivedDate = !string.IsNullOrEmpty(mail.Headers?["Date"]) && DateTime.TryParse(mail.Headers["Date"], out var dt) ? dt : DateTime.Now,
                            InvoiceId = int.TryParse(parsed.NumeroNF, out var nf) ? nf : 0,
                            Filename = att.Name,
                            CnpjComp = parsed.CnpjComp,
                            CnpjVend = parsed.CnpjVend,
                            MontNF = parsed.MontNF,
                            PrecNF = parsed.PrecNF,
                            ValorFinalComImpostos = parsed.ValorFinalComImpostos,
                            RsComp = parsed.RsComp,
                            RsVend = parsed.RsVend,
                            NumeroNF = parsed.NumeroNF,
                            IcmsNF = parsed.IcmsNF,
                            UfComp = parsed.UfComp,
                            UfVend = parsed.UfVend,
                            Status = InvoiceStatus.Pending
                        };
                        await _attachmentRepository.SaveRawAsync(invoice);
                        _logger.LogInformation("Attachment processed: {Filename}", att.Name);
                        if (InvoiceProcessed != null)
                            await InvoiceProcessed.Invoke(invoice);
                    }
                }
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error processing mail: {Subject}", mail.Subject);
            }
        }
        // Change it to an event declaration:
        public event Func<EnergyInvoice, Task>? InvoiceProcessed;
        public Task IngestAsync()
        {
            _mailListener.StartListening();
            return Task.CompletedTask;
        }
    }

    // Handles matching logic for invoices
    public class MatchingService : IMatchingService
    {
        private readonly IAccessDbRepository _accessDbRepository;
        private readonly ILogger<MatchingService> _logger;

        public MatchingService(IAccessDbRepository accessDbRepository, ILogger<MatchingService> logger)
        {
            _accessDbRepository = accessDbRepository;
            _logger = logger;
        }

        public Task MatchAsync(EnergyInvoice invoice)
        {
            try
            {
                _logger.LogInformation("Matching invoice {InvoiceId}", invoice.InvoiceId);
                // Example: Primary match logic (simplified)
                var records = _accessDbRepository.GetByCnpj(invoice.CnpjComp ?? throw new ArgumentNullException("CnpjComp is required"));
                if (records == null || records.ToList().Count == 0)
                {
                    invoice.Status = InvoiceStatus.NotFound;
                    invoice.DiscrepancyNotes = "No records found for matching";
                    return Task.CompletedTask;
                }
                foreach (var record in records)
                {
                    if (record.CnpjComp == invoice.CnpjComp && record.CnpjVend == invoice.CnpjVend)
                    {
                        var volMatch = Math.Abs(record.MontLO - invoice.MontNF ?? 0) / (record.MontLO == 0 ? 1 : record.MontLO) <= 0.01m;
                        var priceMatch = Math.Abs(record.PrecLO - invoice.PrecNF ?? 0) / (record.PrecLO == 0 ? 1 : record.PrecLO) <= 0.005m;
                        if (volMatch && priceMatch)
                        {
                            invoice.MatchedCodTE = record.CodTE;
                            invoice.Status = InvoiceStatus.Matched;
                            return Task.CompletedTask;
                        }
                    }
                }
                // Fallback: try to match by summing multiple records (multi-invoice sum logic)
                // Only consider records with same CnpjComp and CnpjVend
                var candidateRecords = new List<BuyingRecord>();
                foreach (var record in records)
                {
                    if (record.CnpjComp == invoice.CnpjComp && record.CnpjVend == invoice.CnpjVend)
                    {
                        candidateRecords.Add(record);
                    }
                }
                // Try all combinations of 2 records (can be extended to more)
                for (int i = 0; i < candidateRecords.Count; i++)
                {
                    for (int j = i + 1; j < candidateRecords.Count; j++)
                    {
                        var sumVol = (candidateRecords[i].MontLO ?? 0) + (candidateRecords[j].MontLO ?? 0);
                        var sumPrice = (candidateRecords[i].PrecLO ?? 0) + (candidateRecords[j].PrecLO ?? 0);
                        var volMatch = Math.Abs(sumVol - (invoice.MontNF ?? 0)) / (sumVol == 0 ? 1 : sumVol) <= 0.01m;
                        var priceMatch = Math.Abs(sumPrice - (invoice.PrecNF ?? 0)) / (sumPrice == 0 ? 1 : sumPrice) <= 0.005m;
                        if (volMatch && priceMatch)
                        {
                            invoice.MatchedCodTE = candidateRecords[i].CodTE; // or store both if needed
                            invoice.Status = InvoiceStatus.FallbackMatched;
                            invoice.DiscrepancyNotes = $"Matched by sum of records {candidateRecords[i].CodTE} and {candidateRecords[j].CodTE}";
                            return Task.CompletedTask;
                        }
                    }
                }
                // If no match found
                invoice.Status = InvoiceStatus.NotFound;
                invoice.DiscrepancyNotes = "No matching record found (including fallback sum logic)";
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error matching invoice {InvoiceId}", invoice.InvoiceId);
                throw;
            }
            return Task.CompletedTask;
        }
    }

    // Handles compliance validation
    public class ComplianceService : IComplianceService
    {
        public Task ValidateAsync(EnergyInvoice invoice)
        {
            // Example: Tax compliance check
            if (invoice.Status == InvoiceStatus.Matched || invoice.Status == InvoiceStatus.FallbackMatched)
            {
                decimal? impliedTax = 1 - (invoice.ValorSemImpostos / (invoice.ValorFinalComImpostos == 0 ? 1 : invoice.ValorFinalComImpostos));
                if (Math.Abs(impliedTax - invoice.IcmsNF ?? 0) > 0.01m)
                {
                    invoice.Status = InvoiceStatus.TaxMismatch;
                    invoice.DiscrepancyNotes = $"Tax mismatch: imp={impliedTax:P2}, exp={invoice.IcmsNF:P2}";
                }
                else
                {
                    invoice.Status = InvoiceStatus.Validated;
                }
            }
            return Task.CompletedTask;
        }
    }

    // Handles notifications for mismatches
    public class NotificationService : INotificationService
    {
        public Task NotifyAsync(EnergyInvoice invoice, string message)
        {
            // Example: Send notification (placeholder)
            // In production, use SMTP or other email service
            Console.WriteLine($"Notify {invoice.SupplierEmail}: {message}");
            return Task.CompletedTask;
        }
    }

    // Handles archiving of files
    public class ArchivingService(IFileArchiver fileArchiver) : IArchivingService
    {
        private readonly IFileArchiver _fileArchiver = fileArchiver;

        public Task ArchiveAsync(EnergyInvoice invoice, byte[] rawFile)
        {
            return _fileArchiver.ArchiveAsync(invoice, rawFile);
        }
    }
}