// ==========================================================================
//  Squidex Headless CMS
// ==========================================================================
//  Copyright (c) Squidex UG (haftungsbeschraenkt)
//  All rights reserved. Licensed under the MIT license.
// ==========================================================================

using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using Squidex.Config;
using Squidex.Domain.Users;
using Squidex.Infrastructure;
using Squidex.Infrastructure.Security;
using Squidex.Infrastructure.Translations;
using Squidex.Shared.Identity;
using Squidex.Shared.Users;
using Squidex.Web;

namespace Squidex.Areas.IdentityServer.Controllers.Account
{
    public sealed class AccountController : IdentityServerController
    {
        private readonly IUserService userService;
        private readonly MyIdentityOptions identityOptions;

        public AccountController(
            IUserService userService,
            IOptions<MyIdentityOptions> identityOptions)
        {
            this.identityOptions = identityOptions.Value;
            this.userService = userService;
        }

        [HttpGet]
        [Route("account/error/")]
        public IActionResult LoginError()
        {
            throw new InvalidOperationException();
        }

        [HttpGet]
        [Route("account/forbidden/")]
        public IActionResult Forbidden()
        {
            throw new DomainForbiddenException(T.Get("users.userLocked"));
        }

        [HttpGet]
        [Route("account/lockedout/")]
        public IActionResult LockedOut()
        {
            return View();
        }

        [HttpGet]
        [Route("account/accessdenied/")]
        public IActionResult AccessDenied()
        {
            return View();
        }

        [HttpGet]
        [Route("account/logout-completed/")]
        public IActionResult LogoutCompleted()
        {
            return View();
        }

        [HttpGet]
        [Route("account/consent/")]
        public IActionResult Consent(string? returnUrl = null)
        {
            return View(new ConsentVM { PrivacyUrl = identityOptions.PrivacyUrl, ReturnUrl = returnUrl });
        }

        [HttpPost]
        [Route("account/consent/")]
        public async Task<IActionResult> Consent(ConsentModel model, string? returnUrl = null)
        {
            // We ask new users to agree to the cookie and privacy agreements and show and error if they do not agree.
            if (!model.ConsentToCookies)
            {
                ModelState.AddModelError(nameof(model.ConsentToCookies), T.Get("users.consent.needed"));
            }

            if (!model.ConsentToPersonalInformation)
            {
                ModelState.AddModelError(nameof(model.ConsentToPersonalInformation), T.Get("users.consent.needed"));
            }

            if (!ModelState.IsValid)
            {
                var vm = new ConsentVM { PrivacyUrl = identityOptions.PrivacyUrl, ReturnUrl = returnUrl };

                return View(vm);
            }

            var user = await userService.GetAsync(User, HttpContext.RequestAborted);

            // There is almost no case where this could have happened.
            if (user == null)
            {
                throw new DomainException(T.Get("users.userNotFound"));
            }

            var update = new UserValues
            {
                Consent = true,
                ConsentForEmails = model.ConsentToAutomatedEmails
            };

            await userService.UpdateAsync(user.Id, update, ct: HttpContext.RequestAborted);

            return RedirectToReturnUrl(returnUrl);
        }

        [HttpGet]
        [Route("account/logout/")]
        public async Task<IActionResult> Logout(string logoutId)
        {
            await SignInManager.SignOutAsync();

            return Redirect("~/../");
        }

        [HttpGet]
        [Route("account/logout-redirect/")]
        public async Task<IActionResult> LogoutRedirect()
        {
            await SignInManager.SignOutAsync();

            return RedirectToAction(nameof(LogoutCompleted));
        }

        [HttpGet]
        [Route("account/signup/")]
        public Task<IActionResult> Signup(string? returnUrl = null)
        {
            return LoginViewAsync(returnUrl, false, false);
        }

        [HttpGet]
        [Route("account/login/")]
        [ClearCookies]
        public Task<IActionResult> Login(string? returnUrl = null)
        {
            return LoginViewAsync(returnUrl, true, false);
        }

        [HttpPost]
        [Route("account/login/")]
        public async Task<IActionResult> Login(LoginModel model, string? returnUrl = null)
        {
            if (!ModelState.IsValid)
            {
                return await LoginViewAsync(returnUrl, true, true);
            }

            var result = await SignInManager.PasswordSignInAsync(model.Email, model.Password, true, true);

            if (!result.Succeeded && result.IsLockedOut)
            {
                return View(nameof(LockedOut));
            }
            else if (!result.Succeeded)
            {
                return await LoginViewAsync(returnUrl, true, true);
            }
            else
            {
                return RedirectToReturnUrl(returnUrl);
            }
        }

        private async Task<IActionResult> LoginViewAsync(string? returnUrl, bool isLogin, bool isFailed)
        {
            // If password authentication is enabled we always show the page.
            var allowPasswordAuth = identityOptions.AllowPasswordAuth;

            var externalProviders = await SignInManager.GetExternalProvidersAsync();

            // If there is only one external authentication provider, we can redirect just directly.
            if (externalProviders.Count == 1 && !allowPasswordAuth)
            {
                var provider = externalProviders[0].AuthenticationScheme;

                var challengeRedirectUrl = Url.Action(nameof(ExternalCallback));
                var challengeProperties = SignInManager.ConfigureExternalAuthenticationProperties(provider, challengeRedirectUrl);

                // Redirect to the external authentication provider.
                return Challenge(challengeProperties, provider);
            }

            var vm = new LoginVM
            {
                ExternalProviders = externalProviders,
                IsFailed = isFailed,
                IsLogin = isLogin,
                HasPasswordAuth = allowPasswordAuth,
                ReturnUrl = returnUrl
            };

            return View(nameof(Login), vm);
        }

        [HttpPost]
        [Route("account/external/")]
        public IActionResult External(string provider, string? returnUrl = null)
        {
            var challengeRedirectUrl = Url.Action(nameof(ExternalCallback), new { returnUrl });
            var challengeProperties = SignInManager.ConfigureExternalAuthenticationProperties(provider, challengeRedirectUrl);

            return Challenge(challengeProperties, provider);
        }

        [HttpGet]
        [Route("account/external-callback/")]
        public async Task<IActionResult> ExternalCallback(string? returnUrl = null)
        {
            var login = await SignInManager.GetExternalLoginInfoWithDisplayNameAsync();

            if (login == null)
            {
                return RedirectToAction(nameof(Login));
            }

            var result = await SignInManager.ExternalLoginSignInAsync(login.LoginProvider, login.ProviderKey, true);

            if (!result.Succeeded && result.IsLockedOut)
            {
                return View(nameof(LockedOut));
            }

            var isLoggedIn = result.Succeeded;
            var isLocked = false;

            IUser? user = null;

            if (isLoggedIn)
            {
                user = await userService.FindByLoginAsync(login.LoginProvider, login.ProviderKey, HttpContext.RequestAborted);
            }
            else
            {
                var email = login.Principal.GetEmail();

                if (string.IsNullOrWhiteSpace(email))
                {
                    throw new DomainException(T.Get("users.noEmailAddress"));
                }

                user = await userService.FindByEmailAsync(email!, HttpContext.RequestAborted);

                // User might not have a login or password if the user got invited.
                if (user != null && await HasLoginAsync(user))
                {
                    // If we have a login, we reject this user, otherwise you can login to an account you do not own.
                    user = null;
                }

                if (user == null)
                {
                    var values = new UserValues
                    {
                        CustomClaims = login.Principal.Claims.GetSquidexClaims().ToList()
                    };

                    var locked = identityOptions.LockAutomatically;

                    // Try to create a user. If the user exists an exception message is shown to the user.
                    user = await userService.CreateAsync(email!, values, locked, HttpContext.RequestAborted);
                }

                if (user != null)
                {
                    await userService.AddLoginAsync(user.Id, login, HttpContext.RequestAborted);

                    // Login might fail if the user is locked out.
                    (isLoggedIn, isLocked) = await LoginAsync(login);
                }
            }

            if (isLocked)
            {
                return View(nameof(LockedOut));
            }
            else if (!isLoggedIn)
            {
                return RedirectToAction(nameof(Login));
            }
            else if (user != null && !user.Claims.HasConsent() && !identityOptions.NoConsent)
            {
                // This should actually never happen, because user should not be null, when logged in.
                return RedirectToAction(nameof(Consent), new { returnUrl });
            }
            else
            {
                return RedirectToReturnUrl(returnUrl);
            }
        }

        private async Task<bool> HasLoginAsync(IUser user)
        {
            if (await userService.HasPasswordAsync(user, HttpContext.RequestAborted))
            {
                return true;
            }

            var logins = await userService.GetLoginsAsync(user, HttpContext.RequestAborted);

            return logins.Count > 0;
        }

        private async Task<(bool Success, bool Locked)> LoginAsync(UserLoginInfo externalLogin)
        {
            var result = await SignInManager.ExternalLoginSignInAsync(externalLogin.LoginProvider, externalLogin.ProviderKey, true);

            return (result.Succeeded, result.IsLockedOut);
        }
    }
}