// src/Webshop.Application/Services/Customers/CustomerService.cs
using Microsoft.AspNetCore.Identity;
using Microsoft.Extensions.Configuration;
using Resend;
using System.Linq;
using System.Threading.Tasks;
using System.Web;
using Webshop.Application.DTOs;
using Webshop.Application.DTOs.Auth;
using Webshop.Application.DTOs.Customers;
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 IResend _resend;

        public CustomerService(ICustomerRepository customerRepository, UserManager<ApplicationUser> userManager, IConfiguration configuration, IResend resend)
        {
            _customerRepository = customerRepository;
            _userManager = userManager;
            _configuration = configuration;
            _resend = resend;
        }

        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.");

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

            customer.FirstName = profileDto.FirstName;
            customer.LastName = profileDto.LastName;
            customer.DefaultShippingAddressId = profileDto.DefaultShippingAddressId;
            customer.DefaultBillingAddressId = profileDto.DefaultBillingAddressId;
            await _customerRepository.UpdateAsync(customer);

            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.");

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

            if (user.Email != newEmail && await _userManager.FindByEmailAsync(newEmail) != null)
            {
                return ServiceResult.Fail(ServiceResultType.Conflict, "Die neue E-Mail-Adresse ist bereits registriert.");
            }

            var token = await _userManager.GenerateChangeEmailTokenAsync(user, newEmail);
            var clientUrl = _configuration["App:ClientUrl"]!;
            var confirmationLink = $"{clientUrl}/confirm-email-change?userId={user.Id}&newEmail={HttpUtility.UrlEncode(newEmail)}&token={HttpUtility.UrlEncode(token)}";

            var message = new EmailMessage();
            message.From = _configuration["Resend:FromEmail"]!;
            message.To.Add(newEmail);
            message.Subject = "Bestätigen Sie Ihre neue E-Mail-Adresse";
            message.HtmlBody = $"<h1>E-Mail-Änderung Bestätigung</h1><p>Bitte klicken Sie auf den folgenden Link, um Ihre neue E-Mail-Adresse zu bestätigen:</p><p><a href='{confirmationLink}'>Neue E-Mail-Adresse bestätigen</a></p>";
            await _resend.EmailSendAsync(message);

            // Die Erfolgsmeldung wird hier als Teil des "Ok"-Results übermittelt
            return ServiceResult.Ok("Bestätigungs-E-Mail wurde an die neue Adresse gesendet. Bitte prüfen Sie Ihr Postfach.");
        }
    }
}