using System.Globalization;
using Events.FilesAPI.Infrastructure.Options;
using Events.WebAPI.Handlers.EF.Data.Postgres;
using Events.WebAPI.Handlers.EF.Models;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;

namespace Events.FilesAPI.Features.Certificates.Synchronize;

public sealed class CertificateFileGenerator(
  EventsContext context,
  IHostEnvironment hostEnvironment,
  IOptions<GeneratedFilesOptions> generatedFilesOptions,
  ILogger<CertificateFileGenerator> logger)
{
  public async Task GenerateAsync(int eventId, int personId, CancellationToken cancellationToken)
  {
    var registrations = await context.Set<Registration>()
      .AsNoTracking()
      .Where(r => r.EventId == eventId && r.PersonId == personId)
      .OrderBy(r => r.Sport.Name)
      .Select(r => new CertificateRegistrationData
      {
        EventId = r.EventId,
        EventName = r.Event.Name,
        EventDate = r.Event.EventDate,
        PersonId = r.PersonId,
        FirstName = r.Person.FirstName,
        LastName = r.Person.LastName,
        FirstNameTranscription = r.Person.FirstNameTranscription,
        LastNameTranscription = r.Person.LastNameTranscription,
        SportName = r.Sport.Name
      })
      .ToListAsync(cancellationToken);

    string certificatePath = GetCertificatePath(eventId, personId);
    if (registrations.Count == 0)
    {
      DeleteCertificateIfExists(certificatePath);
      return;
    }

    Directory.CreateDirectory(Path.GetDirectoryName(certificatePath)!);

    byte[] pdfBytes = CertificatePdfDocumentWriter.CreateCertificate(BuildModel(registrations));
    await File.WriteAllBytesAsync(certificatePath, pdfBytes, cancellationToken);

    logger.LogInformation(
      "Registration certificate generated for event #{EventId}, person #{PersonId} at {Path}",
      eventId,
      personId,
      certificatePath);
  }

  private string GetCertificatePath(int eventId, int personId)
  {
    string rootPath = Path.IsPathRooted(generatedFilesOptions.Value.OutputPath)
      ? generatedFilesOptions.Value.OutputPath
      : Path.GetFullPath(Path.Combine(hostEnvironment.ContentRootPath, generatedFilesOptions.Value.OutputPath));

    return Path.Combine(rootPath, eventId.ToString(CultureInfo.InvariantCulture), $"{eventId}-{personId}.pdf");
  }

  private void DeleteCertificateIfExists(string certificatePath)
  {
    DeleteFileIfExists(certificatePath, "Registration certificate deleted at {Path}");

    string? directory = Path.GetDirectoryName(certificatePath);
    if (!string.IsNullOrWhiteSpace(directory) &&
        Directory.Exists(directory) &&
        !Directory.EnumerateFileSystemEntries(directory).Any())
    {
      Directory.Delete(directory);
    }
  }

  private void DeleteFileIfExists(string path, string logMessage)
  {
    if (!File.Exists(path))
      return;

    File.Delete(path);
    logger.LogInformation(logMessage, path);
  }

  private static CertificatePdfModel BuildModel(IReadOnlyList<CertificateRegistrationData> registrations)
  {
    CertificateRegistrationData first = registrations[0];
    string originalFullName = $"{first.FirstName} {first.LastName}".Trim();
    string transcriptionFullName = $"{first.FirstNameTranscription} {first.LastNameTranscription}".Trim();

    var sports = registrations
      .Select(r => r.SportName)
      .Distinct(StringComparer.OrdinalIgnoreCase)
      .OrderBy(name => name, StringComparer.OrdinalIgnoreCase)
      .ToList();

    return new CertificatePdfModel
    {
      Title = "Certificate of participation",
      PersonFullName = originalFullName,
      PersonFullNameTranscription = transcriptionFullName,
      EventName = first.EventName,
      EventDate = first.EventDate,
      EventId = first.EventId,
      PersonId = first.PersonId,
      SportNames = sports
    };
  }

  private sealed class CertificateRegistrationData
  {
    public int EventId { get; init; }
    public string EventName { get; init; } = string.Empty;
    public DateOnly EventDate { get; init; }
    public int PersonId { get; init; }
    public string? FirstName { get; init; } = string.Empty;
    public string? LastName { get; init; } = string.Empty;
    public string FirstNameTranscription { get; init; } = string.Empty;
    public string LastNameTranscription { get; init; } = string.Empty;
    public string SportName { get; init; } = string.Empty;
  }
}