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

using System.ComponentModel.DataAnnotations;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Text;
using System.Text.Encodings.Web;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Extensions.Logging;

namespace Microsoft.AspNetCore.Identity.UI.V5.Pages.Account.Internal;

/// <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>
[AllowAnonymous]
[IdentityDefaultUI(typeof(RegisterModel<>))]
public abstract class RegisterModel : PageModel
{
    /// <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; } = default!;

    /// <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; } = default!;

        /// <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; } = default!;

        /// <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; }
    }

    /// <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 virtual Task OnGetAsync([StringSyntax(StringSyntaxAttribute.Uri)] string? returnUrl = null) => throw new NotImplementedException();

    /// <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 virtual Task<IActionResult> OnPostAsync([StringSyntax(StringSyntaxAttribute.Uri)] string? returnUrl = null) => throw new NotImplementedException();
}

internal sealed class RegisterModel<TUser> : RegisterModel where TUser : class
{
    private readonly SignInManager<TUser> _signInManager;
    private readonly UserManager<TUser> _userManager;
    private readonly IUserStore<TUser> _userStore;
    private readonly IUserEmailStore<TUser> _emailStore;
    private readonly ILogger<RegisterModel> _logger;
    private readonly IEmailSender<TUser> _emailSender;

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

    public override async Task OnGetAsync(string? returnUrl = null)
    {
        ReturnUrl = returnUrl;
        ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();
    }

    public override async Task<IActionResult> OnPostAsync(string? returnUrl = null)
    {
        returnUrl ??= Url.Content("~/");
        ExternalLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).ToList();
        if (ModelState.IsValid)
        {
            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)
            {
                _logger.LogInformation(LoggerEventIds.UserCreated, "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)!;

                await _emailSender.SendConfirmationLinkAsync(user, Input.Email, HtmlEncoder.Default.Encode(callbackUrl));

                if (_userManager.Options.SignIn.RequireConfirmedAccount)
                {
                    return RedirectToPage("RegisterConfirmation", new { email = Input.Email, returnUrl = returnUrl });
                }
                else
                {
                    await _signInManager.SignInAsync(user, isPersistent: false);
                    return LocalRedirect(returnUrl);
                }
            }
            foreach (var error in result.Errors)
            {
                ModelState.AddModelError(string.Empty, error.Description);
            }
        }

        // If we got this far, something failed, redisplay form
        return Page();
    }

    private TUser CreateUser()
    {
        try
        {
            return Activator.CreateInstance<TUser>();
        }
        catch
        {
            throw new InvalidOperationException($"Can't create an instance of '{nameof(TUser)}'. " +
                $"Ensure that '{nameof(TUser)}' 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<TUser> GetEmailStore()
    {
        if (!_userManager.SupportsUserEmail)
        {
            throw new NotSupportedException("The default UI requires a user store with email support.");
        }
        return (IUserEmailStore<TUser>)_userStore;
    }
}
