using System.Globalization;
using System.Net;
using System.Security.Claims;
using System.Security.Principal;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Umbraco.Cms.Core;
using Umbraco.Cms.Core.Cache;
using Umbraco.Cms.Core.Configuration.Grid;
using Umbraco.Cms.Core.Configuration.Models;
using Umbraco.Cms.Core.Hosting;
using Umbraco.Cms.Core.Manifest;
using Umbraco.Cms.Core.Models;
using Umbraco.Cms.Core.Security;
using Umbraco.Cms.Core.Serialization;
using Umbraco.Cms.Core.Services;
using Umbraco.Cms.Core.WebAssets;
using Umbraco.Cms.Infrastructure.WebAssets;
using Umbraco.Cms.Web.BackOffice.ActionResults;
using Umbraco.Cms.Web.BackOffice.Filters;
using Umbraco.Cms.Web.BackOffice.Install;
using Umbraco.Cms.Web.BackOffice.Security;
using Umbraco.Cms.Web.Common.ActionsResults;
using Umbraco.Cms.Web.Common.Attributes;
using Umbraco.Cms.Web.Common.Authorization;
using Umbraco.Cms.Web.Common.Controllers;
using Umbraco.Cms.Web.Common.Filters;
using Umbraco.Extensions;
using SignInResult = Microsoft.AspNetCore.Identity.SignInResult;

namespace Umbraco.Cms.Web.BackOffice.Controllers;

[DisableBrowserCache]
[UmbracoRequireHttps]
[PluginController(Constants.Web.Mvc.BackOfficeArea)]
[IsBackOffice]
public class BackOfficeController : UmbracoController
{
    private readonly AppCaches _appCaches;
    private readonly IBackOfficeSecurityAccessor _backofficeSecurityAccessor;
    private readonly BackOfficeServerVariables _backOfficeServerVariables;
    private readonly IBackOfficeTwoFactorOptions _backOfficeTwoFactorOptions;
    private readonly IBackOfficeExternalLoginProviders _externalLogins;
    private readonly IGridConfig _gridConfig;
    private readonly IHostingEnvironment _hostingEnvironment;
    private readonly IHttpContextAccessor _httpContextAccessor;
    private readonly IJsonSerializer _jsonSerializer;
    private readonly ILogger<BackOfficeController> _logger;
    private readonly IManifestParser _manifestParser;
    private readonly IRuntimeMinifier _runtimeMinifier;
    private readonly IRuntimeState _runtimeState;
    private readonly IOptions<SecuritySettings> _securitySettings;
    private readonly ServerVariablesParser _serverVariables;
    private readonly IBackOfficeSignInManager _signInManager;

    private readonly ILocalizedTextService _textService;
    // See here for examples of what a lot of this is doing: https://github.com/dotnet/aspnetcore/blob/main/src/Identity/samples/IdentitySample.Mvc/Controllers/AccountController.cs
    // along with our AuthenticationController

    // NOTE: Each action must either be explicitly authorized or explicitly [AllowAnonymous], the latter is optional because
    // this controller itself doesn't require authz but it's more clear what the intention is.

    private readonly IBackOfficeUserManager _userManager;
    private readonly GlobalSettings _globalSettings;


    [ActivatorUtilitiesConstructor]
    public BackOfficeController(
        IBackOfficeUserManager userManager,
        IRuntimeState runtimeState,
        IRuntimeMinifier runtimeMinifier,
        IOptionsSnapshot<GlobalSettings> globalSettings,
        IHostingEnvironment hostingEnvironment,
        ILocalizedTextService textService,
        IGridConfig gridConfig,
        BackOfficeServerVariables backOfficeServerVariables,
        AppCaches appCaches,
        IBackOfficeSignInManager signInManager,
        IBackOfficeSecurityAccessor backofficeSecurityAccessor,
        ILogger<BackOfficeController> logger,
        IJsonSerializer jsonSerializer,
        IBackOfficeExternalLoginProviders externalLogins,
        IHttpContextAccessor httpContextAccessor,
        IBackOfficeTwoFactorOptions backOfficeTwoFactorOptions,
        IManifestParser manifestParser,
        ServerVariablesParser serverVariables,
        IOptions<SecuritySettings> securitySettings)
    {
        _userManager = userManager;
        _runtimeState = runtimeState;
        _runtimeMinifier = runtimeMinifier;
        _globalSettings = globalSettings.Value;
        _hostingEnvironment = hostingEnvironment;
        _textService = textService;
        _gridConfig = gridConfig ?? throw new ArgumentNullException(nameof(gridConfig));
        _backOfficeServerVariables = backOfficeServerVariables;
        _appCaches = appCaches;
        _signInManager = signInManager;
        _backofficeSecurityAccessor = backofficeSecurityAccessor;
        _logger = logger;
        _jsonSerializer = jsonSerializer;
        _externalLogins = externalLogins;
        _httpContextAccessor = httpContextAccessor;
        _backOfficeTwoFactorOptions = backOfficeTwoFactorOptions;
        _manifestParser = manifestParser;
        _serverVariables = serverVariables;
        _securitySettings = securitySettings;
    }

    [HttpGet]
    [AllowAnonymous]
    public async Task<IActionResult> Default()
    {
        // Check if we not are in an run state, if so we need to redirect
        if (_runtimeState.Level != RuntimeLevel.Run)
        {
            if (_runtimeState.Level == RuntimeLevel.Upgrade)
            {
                return RedirectToAction(nameof(AuthorizeUpgrade), routeValues: new RouteValueDictionary()
                {
                    ["redir"] = _globalSettings.GetBackOfficePath(_hostingEnvironment),
                });
            }
            return Redirect("/");
        }

        // force authentication to occur since this is not an authorized endpoint
        AuthenticateResult result = await this.AuthenticateBackOfficeAsync();

        var viewPath = Path.Combine(Constants.SystemDirectories.Umbraco, Constants.Web.Mvc.BackOfficeArea, nameof(Default) + ".cshtml")
            .Replace("\\", "/"); // convert to forward slashes since it's a virtual path

        return await RenderDefaultOrProcessExternalLoginAsync(
            result,
            () => View(viewPath),
            () => View(viewPath));
    }

    [HttpGet]
    [AllowAnonymous]
    public async Task<IActionResult> VerifyInvite(string invite)
    {
        AuthenticateResult authenticate = await this.AuthenticateBackOfficeAsync();

        //if you are hitting VerifyInvite, you're already signed in as a different user, and the token is invalid
        //you'll exit on one of the return RedirectToAction(nameof(Default)) but you're still logged in so you just get
        //dumped at the default admin view with no detail
        if (authenticate.Succeeded)
        {
            await _signInManager.SignOutAsync();
        }

        if (invite == null)
        {
            _logger.LogWarning("VerifyUser endpoint reached with invalid token: NULL");
            return RedirectToAction(nameof(Default));
        }

        var parts = WebUtility.UrlDecode(invite).Split('|');

        if (parts.Length != 2)
        {
            _logger.LogWarning("VerifyUser endpoint reached with invalid token: {Invite}", invite);
            return RedirectToAction(nameof(Default));
        }

        var token = parts[1];

        var decoded = token.FromUrlBase64();
        if (decoded.IsNullOrWhiteSpace())
        {
            _logger.LogWarning("VerifyUser endpoint reached with invalid token: {Invite}", invite);
            return RedirectToAction(nameof(Default));
        }

        var id = parts[0];

        BackOfficeIdentityUser? identityUser = await _userManager.FindByIdAsync(id);
        if (identityUser == null)
        {
            _logger.LogWarning("VerifyUser endpoint reached with non existing user: {UserId}", id);
            return RedirectToAction(nameof(Default));
        }

        IdentityResult result = await _userManager.ConfirmEmailAsync(identityUser, decoded!);

        if (result.Succeeded == false)
        {
            _logger.LogWarning("Could not verify email, Error: {Errors}, Token: {Invite}", result.Errors.ToErrorMessage(), invite);
            return new RedirectResult(Url.Action(nameof(Default)) + "#/login/false?invite=3");
        }

        //sign the user in
        DateTime? previousLastLoginDate = identityUser.LastLoginDateUtc;
        await _signInManager.SignInAsync(identityUser, false);
        //reset the lastlogindate back to previous as the user hasn't actually logged in, to add a flag or similar to BackOfficeSignInManager would be a breaking change
        identityUser.LastLoginDateUtc = previousLastLoginDate;
        await _userManager.UpdateAsync(identityUser);

        return new RedirectResult(Url.Action(nameof(Default)) + "#/login/false?invite=1");
    }

    /// <summary>
    ///     This Action is used by the installer when an upgrade is detected but the admin user is not logged in. We need to
    ///     ensure the user is authenticated before the install takes place so we redirect here to show the standard login
    ///     screen.
    /// </summary>
    /// <returns></returns>
    [HttpGet]
    [StatusCodeResult(HttpStatusCode.ServiceUnavailable)]
    [AllowAnonymous]
    public async Task<IActionResult> AuthorizeUpgrade()
    {
        // force authentication to occur since this is not an authorized endpoint
        AuthenticateResult result = await this.AuthenticateBackOfficeAsync();
        if (result.Succeeded)
        {
            // Redirect to installer if we're already authorized
            var installerUrl = Url.Action(nameof(InstallController.Index), ControllerExtensions.GetControllerName<InstallController>(), new { area = Cms.Core.Constants.Web.Mvc.InstallArea }) ?? "/";
            return new LocalRedirectResult(installerUrl);
        }

        var viewPath = Path.Combine(Constants.SystemDirectories.Umbraco, Constants.Web.Mvc.BackOfficeArea, nameof(AuthorizeUpgrade) + ".cshtml");

        return await RenderDefaultOrProcessExternalLoginAsync(
            result,
            //The default view to render when there is no external login info or errors
            () => View(viewPath),
            //The IActionResult to perform if external login is successful
            () => Redirect("/"));
    }

    /// <summary>
    ///     Returns the JavaScript main file including all references found in manifests
    /// </summary>
    /// <returns></returns>
    [MinifyJavaScriptResult(Order = 0)]
    [HttpGet]
    [AllowAnonymous]
    public async Task<IActionResult> Application()
    {
        var result = await _runtimeMinifier.GetScriptForLoadingBackOfficeAsync(
            _globalSettings,
            _hostingEnvironment,
            _manifestParser);

        return new JavaScriptResult(result);
    }

    /// <summary>
    ///     Get the json localized text for a given culture or the culture for the current user
    /// </summary>
    /// <param name="culture"></param>
    /// <returns></returns>
    [HttpGet]
    [AllowAnonymous]
    public async Task<Dictionary<string, Dictionary<string, string>>> LocalizedText(string? culture = null)
    {
        CultureInfo? cultureInfo = null;
        if (string.IsNullOrWhiteSpace(culture))
        {
            // Force authentication to occur since this is not an authorized endpoint, we need this to get a user.
            AuthenticateResult authenticationResult = await this.AuthenticateBackOfficeAsync();
            // We have to get the culture from the Identity, we can't rely on thread culture
            // It's entirely likely for a user to have a different culture in the backoffice, than their system.
            IIdentity? user = authenticationResult.Principal?.Identity;

            if (authenticationResult.Succeeded && user is not null)
            {
                cultureInfo = user.GetCulture();
            }

            cultureInfo ??= CultureInfo.GetCultureInfo(_globalSettings.DefaultUILanguage);
        }
        else
        {
            cultureInfo = CultureInfo.GetCultureInfo(culture);
        }

        IDictionary<string, string> allValues = _textService.GetAllStoredValues(cultureInfo!);
        var pathedValues = allValues.Select(kv =>
        {
            var slashIndex = kv.Key.IndexOf('/');
            var areaAlias = kv.Key[..slashIndex];
            var valueAlias = kv.Key[(slashIndex + 1)..];
            return new { areaAlias, valueAlias, value = kv.Value };
        });

        var nestedDictionary = pathedValues
            .GroupBy(pv => pv.areaAlias)
            .ToDictionary(pv => pv.Key, pv =>
                pv.ToDictionary(pve => pve.valueAlias, pve => pve.value));

        return nestedDictionary;
    }

    [Authorize(Policy = AuthorizationPolicies.BackOfficeAccess)]
    [AngularJsonOnlyConfiguration]
    [HttpGet]
    public IEnumerable<IGridEditorConfig> GetGridConfig() => _gridConfig.EditorsConfig.Editors;

    /// <summary>
    ///     Returns the JavaScript object representing the static server variables javascript object
    /// </summary>
    [Authorize(Policy = AuthorizationPolicies.BackOfficeAccess)]
    [MinifyJavaScriptResult(Order = 1)]
    public async Task<JavaScriptResult> ServerVariables()
    {
        // cache the result if debugging is disabled
        var serverVars = await _serverVariables.ParseAsync(await _backOfficeServerVariables.GetServerVariablesAsync());
        var result = _hostingEnvironment.IsDebugMode
            ? serverVars
            : _appCaches.RuntimeCache.GetCacheItem(
                typeof(BackOfficeController) + "ServerVariables",
                () => serverVars,
                new TimeSpan(0, 10, 0));

        return new JavaScriptResult(result);
    }

    [HttpPost]
    [AllowAnonymous]
    public ActionResult ExternalLogin(string provider, string? redirectUrl = null)
    {
        if (redirectUrl == null || Uri.TryCreate(redirectUrl, UriKind.Absolute, out _))
        {
            redirectUrl = Url.Action(nameof(Default), this.GetControllerName());
        }

        // Configures the redirect URL and user identifier for the specified external login
        AuthenticationProperties properties =
            _signInManager.ConfigureExternalAuthenticationProperties(provider, redirectUrl);

        return Challenge(properties, provider);
    }

    /// <summary>
    ///     Called when a user links an external login provider in the back office
    /// </summary>
    /// <param name="provider"></param>
    /// <returns></returns>
    [Authorize(Policy = AuthorizationPolicies.BackOfficeAccess)]
    [HttpPost]
    public ActionResult LinkLogin(string provider)
    {
        // Request a redirect to the external login provider to link a login for the current user
        var redirectUrl = Url.Action(nameof(ExternalLinkLoginCallback), this.GetControllerName());

        // Configures the redirect URL and user identifier for the specified external login including xsrf data
        AuthenticationProperties properties =
            _signInManager.ConfigureExternalAuthenticationProperties(provider, redirectUrl, _userManager.GetUserId(User));

        return Challenge(properties, provider);
    }

    [HttpGet]
    [AllowAnonymous]
    public async Task<IActionResult> ValidatePasswordResetCode([Bind(Prefix = "u")] int userId, [Bind(Prefix = "r")] string resetCode)
    {
        BackOfficeIdentityUser? user = await _userManager.FindByIdAsync(userId.ToString(CultureInfo.InvariantCulture));
        if (user != null)
        {
            var result = await _userManager.VerifyUserTokenAsync(user, "Default", "ResetPassword", resetCode);
            if (result)
            {
                //Add a flag and redirect for it to be displayed
                TempData[ViewDataExtensions.TokenPasswordResetCode] =
                    _jsonSerializer.Serialize(
                        new ValidatePasswordResetCodeModel { UserId = userId, ResetCode = resetCode });
                return RedirectToLocal(Url.Action(nameof(Default), this.GetControllerName()));
            }
        }

        //Add error and redirect for it to be displayed
        TempData[ViewDataExtensions.TokenPasswordResetCode] =
            new[] { _textService.Localize("login", "resetCodeExpired") };
        return RedirectToLocal(Url.Action(nameof(Default), this.GetControllerName()));
    }

    /// <summary>
    ///     Callback path when the user initiates a link login request from the back office to the external provider from the
    ///     <see cref="LinkLogin(string)" /> action
    /// </summary>
    /// <remarks>
    ///     An example of this is here
    ///     https://github.com/dotnet/aspnetcore/blob/main/src/Identity/samples/IdentitySample.Mvc/Controllers/AccountController.cs#L155
    ///     which this is based on
    /// </remarks>
    [Authorize(Policy = AuthorizationPolicies.BackOfficeAccess)]
    [HttpGet]
    public async Task<IActionResult> ExternalLinkLoginCallback()
    {
        BackOfficeIdentityUser? user = await _userManager.GetUserAsync(User);
        if (user == null)
        {
            // ... this should really not happen
            TempData[ViewDataExtensions.TokenExternalSignInError] = new[] { "Local user does not exist" };
            return RedirectToLocal(Url.Action(nameof(Default), this.GetControllerName()));
        }

        ExternalLoginInfo? info =
            await _signInManager.GetExternalLoginInfoAsync(await _userManager.GetUserIdAsync(user));

        if (info == null)
        {
            //Add error and redirect for it to be displayed
            TempData[ViewDataExtensions.TokenExternalSignInError] =
                new[] { "An error occurred, could not get external login info" };
            return RedirectToLocal(Url.Action(nameof(Default), this.GetControllerName()));
        }

        IdentityResult addLoginResult = await _userManager.AddLoginAsync(user, info);
        if (addLoginResult.Succeeded)
        {
            // Update any authentication tokens if succeeded
            await _signInManager.UpdateExternalAuthenticationTokensAsync(info);

            return RedirectToLocal(Url.Action(nameof(Default), this.GetControllerName()));
        }

        //Add errors and redirect for it to be displayed
        TempData[ViewDataExtensions.TokenExternalSignInError] = addLoginResult.Errors;
        return RedirectToLocal(Url.Action(nameof(Default), this.GetControllerName()));
    }

    /// <summary>
    ///     Used by Default and AuthorizeUpgrade to render as per normal if there's no external login info,
    ///     otherwise process the external login info.
    /// </summary>
    /// <returns></returns>
    private async Task<IActionResult> RenderDefaultOrProcessExternalLoginAsync(
        AuthenticateResult authenticateResult,
        Func<IActionResult> defaultResponse,
        Func<IActionResult> externalSignInResponse)
    {
        if (defaultResponse is null)
        {
            throw new ArgumentNullException(nameof(defaultResponse));
        }

        if (externalSignInResponse is null)
        {
            throw new ArgumentNullException(nameof(externalSignInResponse));
        }

        ViewData.SetUmbracoPath(_globalSettings.GetUmbracoMvcArea(_hostingEnvironment));

        //check if there is the TempData or cookies with the any token name specified, if so, assign to view bag and render the view
        if (ViewData.FromBase64CookieData<BackOfficeExternalLoginProviderErrors>(
                _httpContextAccessor.HttpContext,
                ViewDataExtensions.TokenExternalSignInError,
                _jsonSerializer) ||
            ViewData.FromTempData(TempData, ViewDataExtensions.TokenExternalSignInError) || ViewData.FromTempData(TempData, ViewDataExtensions.TokenPasswordResetCode))
        {
            return defaultResponse();
        }

        //First check if there's external login info, if there's not proceed as normal
        ExternalLoginInfo? loginInfo = await _signInManager.GetExternalLoginInfoAsync();

        if (loginInfo == null || loginInfo.Principal == null)
        {
            // if the user is not logged in, check if there's any auto login redirects specified
            if (!authenticateResult.Succeeded)
            {
                var oauthRedirectAuthProvider = _externalLogins.GetAutoLoginProvider();
                if (!oauthRedirectAuthProvider.IsNullOrWhiteSpace())
                {
                    return ExternalLogin(oauthRedirectAuthProvider!);
                }
            }

            return defaultResponse();
        }

        //we're just logging in with an external source, not linking accounts
        return await ExternalSignInAsync(loginInfo, externalSignInResponse);
    }

    private async Task<IActionResult> ExternalSignInAsync(ExternalLoginInfo loginInfo, Func<IActionResult> response)
    {
        if (loginInfo == null)
        {
            throw new ArgumentNullException(nameof(loginInfo));
        }

        if (response == null)
        {
            throw new ArgumentNullException(nameof(response));
        }

        // Sign in the user with this external login provider (which auto links, etc...)
        SignInResult result = await _signInManager.ExternalLoginSignInAsync(loginInfo, false, _securitySettings.Value.UserBypassTwoFactorForExternalLogins);

        var errors = new List<string>();

        if (result == SignInResult.Success)
        {
            // Update any authentication tokens if succeeded
            await _signInManager.UpdateExternalAuthenticationTokensAsync(loginInfo);

            // Check if we are in an upgrade state, if so we need to redirect
            if (_runtimeState.Level == RuntimeLevel.Upgrade)
            {
                // redirect to the the installer
                return Redirect("/");
            }
        }
        else if (result == SignInResult.TwoFactorRequired)
        {
            BackOfficeIdentityUser? attemptedUser = await _userManager.FindByLoginAsync(loginInfo.LoginProvider, loginInfo.ProviderKey);
                if (attemptedUser?.UserName is null)
            {
                return new ValidationErrorResult(
                    $"No local user found for the login provider {loginInfo.LoginProvider} - {loginInfo.ProviderKey}");
            }

            var twofactorView = _backOfficeTwoFactorOptions.GetTwoFactorView(attemptedUser.UserName);
            if (twofactorView.IsNullOrWhiteSpace())
            {
                return new ValidationErrorResult(
                    $"The registered {typeof(IBackOfficeTwoFactorOptions)} of type {_backOfficeTwoFactorOptions.GetType()} did not return a view for two factor auth ");
            }

            // create a with information to display a custom two factor send code view
            var verifyResponse =
                new ObjectResult(new { twoFactorView = twofactorView, userId = attemptedUser.Id })
                {
                    StatusCode = StatusCodes.Status402PaymentRequired
                };

            return verifyResponse;
        }
        else if (result == SignInResult.LockedOut)
        {
            errors.Add(
                $"The local user {loginInfo.Principal.Identity?.Name} for the external provider {loginInfo.ProviderDisplayName} is locked out.");
        }
        else if (result == SignInResult.NotAllowed)
        {
            // This occurs when SignInManager.CanSignInAsync fails which is when RequireConfirmedEmail , RequireConfirmedPhoneNumber or RequireConfirmedAccount fails
            // however since we don't enforce those rules (yet) this shouldn't happen.
            errors.Add(
                $"The user {loginInfo.Principal.Identity?.Name} for the external provider {loginInfo.ProviderDisplayName} has not confirmed their details and cannot sign in.");
        }
        else if (result == SignInResult.Failed)
        {
            // Failed only occurs when the user does not exist
            errors.Add("The requested provider (" + loginInfo.LoginProvider +
                       ") has not been linked to an account, the provider must be linked from the back office.");
        }
        else if (result == ExternalLoginSignInResult.NotAllowed)
        {
            // This occurs when the external provider has approved the login but custom logic in OnExternalLogin has denined it.
            errors.Add(
                $"The user {loginInfo.Principal.Identity?.Name} for the external provider {loginInfo.ProviderDisplayName} has not been accepted and cannot sign in.");
        }
        else if (result == AutoLinkSignInResult.FailedNotLinked)
        {
            errors.Add("The requested provider (" + loginInfo.LoginProvider +
                       ") has not been linked to an account, the provider must be linked from the back office.");
        }
        else if (result == AutoLinkSignInResult.FailedNoEmail)
        {
            errors.Add(
                $"The requested provider ({loginInfo.LoginProvider}) has not provided the email claim {ClaimTypes.Email}, the account cannot be linked.");
        }
        else if (result is AutoLinkSignInResult autoLinkSignInResult && autoLinkSignInResult.Errors.Count > 0)
        {
            errors.AddRange(autoLinkSignInResult.Errors);
        }
        else if (!result.Succeeded)
        {
            // this shouldn't occur, the above should catch the correct error but we'll be safe just in case
            errors.Add($"An unknown error with the requested provider ({loginInfo.LoginProvider}) occurred.");
        }

        if (errors.Count > 0)
        {
            // the external user might actually be signed in at this point, but certain errors (i.e. missing claims)
            // prevents us from applying said user to a back-office session. make sure the sign-in manager does not
            // report the user as being signed in for subsequent requests.
            await _signInManager.SignOutAsync();

            ViewData.SetExternalSignInProviderErrors(
                new BackOfficeExternalLoginProviderErrors(
                    loginInfo.LoginProvider,
                    errors));
        }

        return response();
    }

    private IActionResult RedirectToLocal(string? returnUrl)
    {
        if (Url.IsLocalUrl(returnUrl))
        {
            return Redirect(returnUrl);
        }

        return Redirect("/");
    }
}