using Microsoft.AspNetCore.Identity;
using Microsoft.Extensions.Configuration;
using System; // Für Uri
using System.Linq;
using System.Threading.Tasks;
using Webshop.Application; // Für ServiceResult
using Webshop.Application.DTOs.Auth;
using Webshop.Application.DTOs.Customers;
using Webshop.Application.Services.Customers.Interfaces; // Namespace korrigiert
using Webshop.Application.Services.Public.Interfaces; // WICHTIG: Für IEmailService
using Webshop.Domain.Entities;
using Webshop.Domain.Identity;
using Webshop.Domain.Interfaces;

namespace Webshop.Application.Services.Customers
{
    public class CustomerService : ICustomerService
    {
        private readonly ICustomerRepository _customerRepository;
        private readonly UserManager<ApplicationUser> _userManager;
        private readonly IConfiguration _configuration;
        private readonly IEmailService _emailService; // NEU: Statt IResend

        public CustomerService(
            ICustomerRepository customerRepository,
            UserManager<ApplicationUser> userManager,
            IConfiguration configuration,
            IEmailService emailService) // NEU: Injected
        {
            _customerRepository = customerRepository;
            _userManager = userManager;
            _configuration = configuration;
            _emailService = emailService;
        }

        public async Task<ServiceResult<CustomerDto>> GetMyProfileAsync(string userId)
        {
            var customer = await _customerRepository.GetByUserIdAsync(userId);
            if (customer == null)
                return ServiceResult.Fail<CustomerDto>(ServiceResultType.NotFound, "Kundenprofil nicht gefunden.");

            var identityUser = await _userManager.FindByIdAsync(userId);
            if (identityUser == null)
                return ServiceResult.Fail<CustomerDto>(ServiceResultType.NotFound, "Benutzerkonto nicht gefunden.");

            var dto = new CustomerDto
            {
                Id = customer.Id,
                UserId = customer.AspNetUserId,
                FirstName = customer.FirstName,
                LastName = customer.LastName,
                Email = identityUser.Email ?? string.Empty,
                PhoneNumber = identityUser.PhoneNumber,
                DefaultShippingAddressId = customer.DefaultShippingAddressId,
                DefaultBillingAddressId = customer.DefaultBillingAddressId
            };
            return ServiceResult.Ok(dto);
        }

        public async Task<ServiceResult> UpdateMyProfileAsync(string userId, UpdateCustomerDto profileDto)
        {
            var customer = await _customerRepository.GetByUserIdAsync(userId);
            if (customer == null) return ServiceResult.Fail(ServiceResultType.NotFound, "Kundenprofil nicht gefunden.");

            var identityUser = await _userManager.FindByIdAsync(userId);
            if (identityUser == null) return ServiceResult.Fail(ServiceResultType.NotFound, "Benutzerkonto nicht gefunden.");

            // Sicherheitscheck: Passwort prüfen
            if (!await _userManager.CheckPasswordAsync(identityUser, profileDto.CurrentPassword))
            {
                return ServiceResult.Fail(ServiceResultType.InvalidInput, "Das zur Bestätigung eingegebene Passwort ist falsch.");
            }

            // Customer Daten aktualisieren
            customer.FirstName = profileDto.FirstName;
            customer.LastName = profileDto.LastName;
            customer.DefaultShippingAddressId = profileDto.DefaultShippingAddressId;
            customer.DefaultBillingAddressId = profileDto.DefaultBillingAddressId;
            await _customerRepository.UpdateAsync(customer);

            // User Daten (Telefon) aktualisieren
            if (!string.IsNullOrEmpty(profileDto.PhoneNumber) && identityUser.PhoneNumber != profileDto.PhoneNumber)
            {
                identityUser.PhoneNumber = profileDto.PhoneNumber;
                var updateResult = await _userManager.UpdateAsync(identityUser);
                if (!updateResult.Succeeded)
                {
                    var errors = string.Join(" ", updateResult.Errors.Select(e => e.Description));
                    return ServiceResult.Fail(ServiceResultType.Failure, $"Fehler beim Aktualisieren der Telefonnummer: {errors}");
                }
            }
            return ServiceResult.Ok();
        }

        public async Task<ServiceResult> ChangePasswordAsync(string userId, ChangePasswordRequestDto request)
        {
            var user = await _userManager.FindByIdAsync(userId);
            if (user == null) return ServiceResult.Fail(ServiceResultType.NotFound, "Benutzer nicht gefunden.");

            var result = await _userManager.ChangePasswordAsync(user, request.OldPassword, request.NewPassword);
            if (!result.Succeeded)
            {
                var errors = string.Join(" ", result.Errors.Select(e => e.Description));
                return ServiceResult.Fail(ServiceResultType.InvalidInput, errors);
            }
            return ServiceResult.Ok();
        }

        public async Task<ServiceResult> ChangeEmailAsync(string userId, string newEmail, string currentPassword)
        {
            var user = await _userManager.FindByIdAsync(userId);
            if (user == null) return ServiceResult.Fail(ServiceResultType.NotFound, "Benutzer nicht gefunden.");

            // Passwort prüfen
            if (!await _userManager.CheckPasswordAsync(user, currentPassword))
            {
                return ServiceResult.Fail(ServiceResultType.InvalidInput, "Das zur Bestätigung eingegebene Passwort ist falsch.");
            }

            // Prüfen, ob neue Email schon existiert (außer es ist die eigene)
            if (user.Email != newEmail && await _userManager.FindByEmailAsync(newEmail) != null)
            {
                return ServiceResult.Fail(ServiceResultType.Conflict, "Die neue E-Mail-Adresse ist bereits registriert.");
            }

            // Token generieren
            var token = await _userManager.GenerateChangeEmailTokenAsync(user, newEmail);
            var clientUrl = _configuration["App:ClientUrl"]; // Hier stand vorher ! , besser prüfen oder Null-Check

            // Link bauen (Uri.EscapeDataString ist sicherer in URLs als HttpUtility)
            var confirmationLink = $"{clientUrl}/confirm-email-change?userId={user.Id}&newEmail={Uri.EscapeDataString(newEmail)}&token={Uri.EscapeDataString(token)}";

            // --- REFACTORED: Nutzung des EmailService ---
            await _emailService.SendEmailChangeConfirmationAsync(newEmail, confirmationLink);

            // Wir geben die Erfolgsmeldung im Result zurück (passend zu deinem Controller)
            return ServiceResult.Ok("Bestätigungs-E-Mail wurde an die neue Adresse gesendet. Bitte prüfen Sie Ihr Postfach.");
        }
    }
}