marechai/Marechai/Areas/Identity/Pages/Account/ForgotPassword.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 class ForgotPasswordModel : PageModel
    {
        readonly IEmailSender                 _emailSender;
        readonly UserManager<ApplicationUser> _userManager;

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

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

        public async Task<IActionResult> OnPostAsync()
        {
            if(ModelState.IsValid)
            {
                ApplicationUser user = await _userManager.FindByEmailAsync(Input.Email);

                if(user == null ||
                   !await _userManager.IsEmailConfirmedAsync(user))
                {
                    // Don't reveal that the user does not exist or is not confirmed
                    return RedirectToPage("./ForgotPasswordConfirmation");
                }

                // For more information on how to enable account confirmation and password reset please 
                // visit https://go.microsoft.com/fwlink/?LinkID=532713
                string code = await _userManager.GeneratePasswordResetTokenAsync(user);
                code = WebEncoders.Base64UrlEncode(Encoding.UTF8.GetBytes(code));

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

                await _emailSender.SendEmailAsync(Input.Email, "Reset Password",
                                                  $"Please reset your password by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");

                return RedirectToPage("./ForgotPasswordConfirmation");
            }

            return Page();
        }

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