// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
#nullable disable

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Text.Encodings.Web;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Kemkas.Web.Db.Models;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.UI.Services;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Extensions.Logging;

namespace Kemkas.Web.Areas.Identity.Pages.Account
{
    public class RegisterModel : PageModel
    {
        private readonly SignInManager<ApplicationUser> _signInManager;
        private readonly UserManager<ApplicationUser> _userManager;
        private readonly IUserStore<ApplicationUser> _userStore;
        private readonly IUserEmailStore<ApplicationUser> _emailStore;
        private readonly ILogger<RegisterModel> _logger;
        private readonly IEmailSender _emailSender;
        private readonly IWebHostEnvironment _environment;

        public RegisterModel(
            UserManager<ApplicationUser> userManager,
            IUserStore<ApplicationUser> userStore,
            SignInManager<ApplicationUser> signInManager,
            ILogger<RegisterModel> logger,
            IEmailSender emailSender,
            IWebHostEnvironment environment)
        {
            _userManager = userManager;
            _userStore = userStore;
            _emailStore = GetEmailStore();
            _signInManager = signInManager;
            _logger = logger;
            _emailSender = emailSender;
            _environment = environment;
        }

        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        [BindProperty]
        public InputModel Input { get; set; }

        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        public string ReturnUrl { get; set; }

        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        public IList<AuthenticationScheme> ExternalLogins { get; set; }

        /// <summary>
        ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
        ///     directly from your code. This API may change or be removed in future releases.
        /// </summary>
        public class InputModel
        {
            /// <summary>
            ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
            ///     directly from your code. This API may change or be removed in future releases.
            /// </summary>
            [Required]
            [EmailAddress]
            [Display(Name = "Email")]
            public string Email { get; set; }

            /// <summary>
            ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
            ///     directly from your code. This API may change or be removed in future releases.
            /// </summary>
            [Required]
            [StringLength(100, ErrorMessage = "The {0} must be at least {2} and at max {1} characters long.", MinimumLength = 6)]
            [DataType(DataType.Password)]
            [Display(Name = "Password")]
            public string Password { get; set; }

            /// <summary>
            ///     This API supports the ASP.NET Core Identity default UI infrastructure and is not intended to be used
            ///     directly from your code. This API may change or be removed in future releases.
            /// </summary>
            [DataType(DataType.Password)]
            [Display(Name = "Confirm password")]
            [Compare("Password", ErrorMessage = "The password and confirmation password do not match.")]
            public string ConfirmPassword { get; set; }
        }


        public async Task OnGetAsync(string returnUrl = null)
        {
            ReturnUrl = returnUrl;
            ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();
            // Disable not yet approved external login providers in production 
            if (!_environment.IsDevelopment())
            {
                ExternalLogins = ExternalLogins.Where(el => el.Name == "Discord").ToList();
            }
        }

        public async Task<IActionResult> OnPostAsync(string returnUrl = null)
        {
            returnUrl ??= Url.Content("~/");
            ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();
            // Disable not yet approved external login providers in production 
            if (!_environment.IsDevelopment())
            {
                ExternalLogins = ExternalLogins.Where(el => el.Name == "Discord").ToList();
            }
            if (!ModelState.IsValid)
            {
                return Page();
            }
            var user = CreateUser();

            await _userStore.SetUserNameAsync(user, Input.Email, CancellationToken.None);
            await _emailStore.SetEmailAsync(user, Input.Email, CancellationToken.None);
            var result = await _userManager.CreateAsync(user, Input.Password);

            if (!result.Succeeded)
            {
                foreach (var error in result.Errors)
                {
                    ModelState.AddModelError(string.Empty, error.Description);
                }

                return Page();
            }

            _logger.LogInformation("User created a new account with password.");

            var userId = await _userManager.GetUserIdAsync(user);
            var code = await _userManager.GenerateEmailConfirmationTokenAsync(user);
            code = WebEncoders.Base64UrlEncode(Encoding.UTF8.GetBytes(code));
            var callbackUrl = Url.Page(
                "/Account/ConfirmEmail",
                pageHandler: null,
                values: new { area = "Identity", userId = userId, code = code, returnUrl = returnUrl },
                protocol: Request.Scheme);

            try
            {
                await _emailSender.SendEmailAsync(Input.Email, "Confirm your email",
                    $"Please confirm your account by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");
            }
            catch
            {
                await _userManager.DeleteAsync(user); // Delete user to free up the email address for a second registration.
                ModelState.AddModelError("Input.Email", "Failed to send account confirmation email!");
                return Page();
            }

            if (_userManager.Options.SignIn.RequireConfirmedAccount)
            {
                return RedirectToPage("RegisterConfirmation",
                    new { email = Input.Email, returnUrl = returnUrl });
            }

            await _signInManager.SignInAsync(user, isPersistent: false);
            return LocalRedirect(returnUrl);
        }

        private ApplicationUser CreateUser()
        {
            try
            {
                return Activator.CreateInstance<ApplicationUser>();
            }
            catch
            {
                throw new InvalidOperationException($"Can't create an instance of '{nameof(ApplicationUser)}'. " +
                    $"Ensure that '{nameof(ApplicationUser)}' is not an abstract class and has a parameterless constructor, or alternatively " +
                    $"override the register page in /Areas/Identity/Pages/Account/Register.cshtml");
            }
        }

        private IUserEmailStore<ApplicationUser> GetEmailStore()
        {
            if (!_userManager.SupportsUserEmail)
            {
                throw new NotSupportedException("The default UI requires a user store with email support.");
            }
            return (IUserEmailStore<ApplicationUser>)_userStore;
        }
    }
}
