// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.ComponentModel.DataAnnotations;
using System.Security.Claims;
using System.Threading.Tasks;
using Identity.ExternalClaims.Data;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.Extensions.Logging;
 
namespace Identity.ExternalClaims.Pages.Account;
 
public class ExternalLoginModel : PageModel
{
    private readonly SignInManager<ApplicationUser> _signInManager;
    private readonly UserManager<ApplicationUser> _userManager;
    private readonly ILogger<ExternalLoginModel> _logger;
 
    public ExternalLoginModel(
        SignInManager<ApplicationUser> signInManager,
        UserManager<ApplicationUser> userManager,
        ILogger<ExternalLoginModel> logger)
    {
        _signInManager = signInManager;
        _userManager = userManager;
        _logger = logger;
    }
 
    [BindProperty]
    public InputModel Input { get; set; }
 
    public string LoginProvider { get; set; }
 
    public string ReturnUrl { get; set; }
 
    [TempData]
    public string ErrorMessage { get; set; }
 
    public class InputModel
    {
        [Required]
        [EmailAddress]
        public string Email { get; set; }
    }
 
    public IActionResult OnGetAsync()
    {
        return RedirectToPage("./Login");
    }
 
    public IActionResult OnPost(string provider, string returnUrl = null)
    {
        // Request a redirect to the external login provider.
        var redirectUrl = Url.Page("./ExternalLogin", pageHandler: "Callback", values: new { returnUrl });
        var properties = _signInManager.ConfigureExternalAuthenticationProperties(provider, redirectUrl);
        return new ChallengeResult(provider, properties);
    }
 
    public async Task<IActionResult> OnGetCallbackAsync(string returnUrl = null, string remoteError = null)
    {
        if (remoteError != null)
        {
            ErrorMessage = $"Error from external provider: {remoteError}";
            return RedirectToPage("./Login");
        }
        var info = await _signInManager.GetExternalLoginInfoAsync();
        if (info == null)
        {
            return RedirectToPage("./Login");
        }
 
        // Sign in the user with this external login provider if the user already has a login.
        var result = await _signInManager.ExternalLoginSignInAsync(info.LoginProvider, info.ProviderKey, isPersistent: false, bypassTwoFactor: true);
        if (result.Succeeded)
        {
            // Store the access token and resign in so the token is included in the cookie
            var user = await _userManager.FindByLoginAsync(info.LoginProvider, info.ProviderKey);
            var props = new AuthenticationProperties();
            props.StoreTokens(info.AuthenticationTokens);
            await _signInManager.SignInAsync(user, props, info.LoginProvider);
 
            _logger.LogInformation("{Name} logged in with {LoginProvider} provider.", info.Principal.Identity.Name, info.LoginProvider);
            return LocalRedirect(Url.GetLocalUrl(returnUrl));
        }
        if (result.IsLockedOut)
        {
            return RedirectToPage("./Lockout");
        }
        else
        {
            // If the user does not have an account, then ask the user to create an account.
            ReturnUrl = returnUrl;
            LoginProvider = info.LoginProvider;
            if (info.Principal.HasClaim(c => c.Type == ClaimTypes.Email))
            {
                Input = new InputModel
                {
                    Email = info.Principal.FindFirstValue(ClaimTypes.Email)
                };
            }
            return Page();
        }
    }
 
    public async Task<IActionResult> OnPostConfirmationAsync(string returnUrl = null)
    {
        if (ModelState.IsValid)
        {
            // Get the information about the user from the external login provider
            var info = await _signInManager.GetExternalLoginInfoAsync();
            if (info == null)
            {
                throw new ApplicationException("Error loading external login information during confirmation.");
            }
            var user = new ApplicationUser { UserName = Input.Email, Email = Input.Email };
            var result = await _userManager.CreateAsync(user);
            if (result.Succeeded)
            {
                result = await _userManager.AddLoginAsync(user, info);
                if (result.Succeeded)
                {
                    // Copy over the gender claim as well
                    await _userManager.AddClaimAsync(user, info.Principal.FindFirst(ClaimTypes.Gender));
 
                    // Include the access token in the properties
                    var props = new AuthenticationProperties();
                    props.StoreTokens(info.AuthenticationTokens);
 
                    await _signInManager.SignInAsync(user, props, authenticationMethod: info.LoginProvider);
                    _logger.LogInformation("User created an account using {Name} provider.", info.LoginProvider);
                    return LocalRedirect(Url.GetLocalUrl(returnUrl));
                }
            }
            foreach (var error in result.Errors)
            {
                ModelState.AddModelError(string.Empty, error.Description);
            }
        }
 
        ReturnUrl = returnUrl;
        return Page();
    }
}