using System.ComponentModel.DataAnnotations;
using System.Text;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Marechai.Database.Models;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI.Services;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.WebUtilities;

namespace Marechai.Areas.Identity.Pages.Account.Manage
{
    public class EmailModel : PageModel
    {
        readonly IEmailSender                   _emailSender;
        readonly SignInManager<ApplicationUser> _signInManager;
        readonly UserManager<ApplicationUser>   _userManager;

        public EmailModel(UserManager<ApplicationUser> userManager, SignInManager<ApplicationUser> signInManager,
                          IEmailSender emailSender)
        {
            _userManager   = userManager;
            _signInManager = signInManager;
            _emailSender   = emailSender;
        }

        public string Username { get; set; }

        public string Email { get; set; }

        public bool IsEmailConfirmed { get; set; }

        [TempData]
        public string StatusMessage { get; set; }

        [BindProperty]
        public InputModel Input { get; set; }

        async Task LoadAsync(ApplicationUser user)
        {
            string email = await _userManager.GetEmailAsync(user);
            Email = email;

            Input = new InputModel
            {
                NewEmail = email
            };

            IsEmailConfirmed = await _userManager.IsEmailConfirmedAsync(user);
        }

        public async Task<IActionResult> OnGetAsync()
        {
            ApplicationUser user = await _userManager.GetUserAsync(User);

            if(user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }

            await LoadAsync(user);

            return Page();
        }

        public async Task<IActionResult> OnPostChangeEmailAsync()
        {
            ApplicationUser user = await _userManager.GetUserAsync(User);

            if(user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }

            if(!ModelState.IsValid)
            {
                await LoadAsync(user);

                return Page();
            }

            string email = await _userManager.GetEmailAsync(user);

            if(Input.NewEmail != email)
            {
                string userId = await _userManager.GetUserIdAsync(user);
                string code   = await _userManager.GenerateChangeEmailTokenAsync(user, Input.NewEmail);

                string callbackUrl = Url.Page("/Account/ConfirmEmailChange", null, new
                {
                    userId,
                    email = Input.NewEmail,
                    code
                }, Request.Scheme);

                await _emailSender.SendEmailAsync(Input.NewEmail, "Confirm your email",
                                                  $"Please confirm your account by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");

                StatusMessage = "Confirmation link to change email sent. Please check your email.";

                return RedirectToPage();
            }

            StatusMessage = "Your email is unchanged.";

            return RedirectToPage();
        }

        public async Task<IActionResult> OnPostSendVerificationEmailAsync()
        {
            ApplicationUser user = await _userManager.GetUserAsync(User);

            if(user == null)
            {
                return NotFound($"Unable to load user with ID '{_userManager.GetUserId(User)}'.");
            }

            if(!ModelState.IsValid)
            {
                await LoadAsync(user);

                return Page();
            }

            string userId = await _userManager.GetUserIdAsync(user);
            string email  = await _userManager.GetEmailAsync(user);
            string code   = await _userManager.GenerateEmailConfirmationTokenAsync(user);
            code = WebEncoders.Base64UrlEncode(Encoding.UTF8.GetBytes(code));

            string callbackUrl = Url.Page("/Account/ConfirmEmail", null, new
            {
                area = "Identity",
                userId,
                code
            }, Request.Scheme);

            await _emailSender.SendEmailAsync(email, "Confirm your email",
                                              $"Please confirm your account by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");

            StatusMessage = "Verification email sent. Please check your email.";

            return RedirectToPage();
        }

        public class InputModel
        {
            [Required, EmailAddress, Display(Name = "New email")]
            public string NewEmail { get; set; }
        }
    }
}