marechai/Marechai/Areas/Identity/Pages/Account/ResendEmailConfirmation.cshtml.cs

using System.ComponentModel.DataAnnotations;
using System.Text;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Marechai.Database.Models;
using Microsoft.AspNetCore.Authorization;
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
{
    [AllowAnonymous]
    public abstract class ResendEmailConfirmationModel : PageModel
    {
        readonly IEmailSender                 _emailSender;
        readonly UserManager<ApplicationUser> _userManager;

        public ResendEmailConfirmationModel(UserManager<ApplicationUser> userManager, IEmailSender emailSender)
        {
            _userManager = userManager;
            _emailSender = emailSender;
        }

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

        public void OnGet() {}

        public async Task<IActionResult> OnPostAsync()
        {
            if(!ModelState.IsValid)
            {
                return Page();
            }

            ApplicationUser user = await _userManager.FindByEmailAsync(Input.Email);

            if(user == null)
            {
                ModelState.AddModelError(string.Empty, "Verification email sent. Please check your email.");

                return Page();
            }

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

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

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

            ModelState.AddModelError(string.Empty, "Verification email sent. Please check your email.");

            return Page();
        }

        public class InputModel
        {
            [Required, EmailAddress]
            public string Email { get; set; }
        }
    }
}