/*
 * Licensed under the Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
 * See https://github.com/openiddict/openiddict-core for more information concerning
 * the license and the contributors participating to this project.
 */

using System;
using System.Security.Claims;
using System.Threading;
using System.Threading.Tasks;
using AspNet.Security.OpenIdConnect.Extensions;
using AspNet.Security.OpenIdConnect.Server;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http.Authentication;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Mvc.Server.Models;
using Mvc.Server.ViewModels.Authorization;
using Mvc.Server.ViewModels.Shared;
using OpenIddict;

namespace Mvc.Server {
    public class AuthorizationController : Controller {
        private readonly OpenIddictApplicationManager<OpenIddictApplication<Guid>> _applicationManager;
        private readonly SignInManager<ApplicationUser> _signInManager;
        private readonly OpenIddictUserManager<ApplicationUser> _userManager;

        public AuthorizationController(
            OpenIddictApplicationManager<OpenIddictApplication<Guid>> applicationManager,
            SignInManager<ApplicationUser> signInManager,
            OpenIddictUserManager<ApplicationUser> userManager) {
            _applicationManager = applicationManager;
            _signInManager = signInManager;
            _userManager = userManager;
        }

        // Note: to support interactive flows like the code flow,
        // you must provide your own authorization endpoint action:

        [Authorize, HttpGet, Route("~/connect/authorize")]
        public async Task<IActionResult> Authorize() {
            // Extract the authorization request from the ASP.NET environment.
            var request = HttpContext.GetOpenIdConnectRequest();

            // Retrieve the application details from the database.
            var application = await _applicationManager.FindByClientIdAsync(request.ClientId);
            if (application == null) {
                return View("Error", new ErrorViewModel {
                    Error = OpenIdConnectConstants.Errors.InvalidClient,
                    ErrorDescription = "Details concerning the calling client application cannot be found in the database"
                });
            }

            // Flow the request_id to allow OpenIddict to restore
            // the original authorization request from the cache.
            return View(new AuthorizeViewModel {
                ApplicationName = application.DisplayName,
                RequestId = request.RequestId,
                Scope = request.Scope
            });
        }

        [Authorize, HttpPost("~/connect/authorize/accept"), ValidateAntiForgeryToken]
        public async Task<IActionResult> Accept() {
            // Extract the authorization request from the ASP.NET environment.
            var request = HttpContext.GetOpenIdConnectRequest();

            // Retrieve the profile of the logged in user.
            var user = await _userManager.GetUserAsync(User);
            if (user == null) {
                return View("Error", new ErrorViewModel {
                    Error = OpenIdConnectConstants.Errors.ServerError,
                    ErrorDescription = "An internal error has occurred"
                });
            }

            // Create a new ClaimsIdentity containing the claims that
            // will be used to create an id_token, a token or a code.
            var identity = await _userManager.CreateIdentityAsync(user, request.GetScopes());

            // Create a new authentication ticket holding the user identity.
            var ticket = new AuthenticationTicket(
                new ClaimsPrincipal(identity),
                new AuthenticationProperties(),
                OpenIdConnectServerDefaults.AuthenticationScheme);

            ticket.SetResources(request.GetResources());
            ticket.SetScopes(request.GetScopes());

            // Returning a SignInResult will ask OpenIddict to issue the appropriate access/identity tokens.
            return SignIn(ticket.Principal, ticket.Properties, ticket.AuthenticationScheme);
        }

        [Authorize, HttpPost("~/connect/authorize/deny"), ValidateAntiForgeryToken]
        public IActionResult Deny() {
            // Notify OpenIddict that the authorization grant has been denied by the resource owner
            // to redirect the user agent to the client application using the appropriate response_mode.
            return Forbid(OpenIdConnectServerDefaults.AuthenticationScheme);
        }

        [HttpGet("~/connect/logout")]
        public IActionResult Logout() {
            // Extract the authorization request from the ASP.NET environment.
            var request = HttpContext.GetOpenIdConnectRequest();

            // Flow the request_id to allow OpenIddict to restore
            // the original logout request from the distributed cache.
            return View(new LogoutViewModel {
                RequestId = request.RequestId
            });
        }

        [HttpPost("~/connect/logout"), ValidateAntiForgeryToken]
        public async Task<IActionResult> Logout(CancellationToken cancellationToken) {
            // Ask ASP.NET Core Identity to delete the local and external cookies created
            // when the user agent is redirected from the external identity provider
            // after a successful authentication flow (e.g Google or Facebook).
            await _signInManager.SignOutAsync();

            // Returning a SignOutResult will ask OpenIddict to redirect the user agent
            // to the post_logout_redirect_uri specified by the client application.
            return SignOut(OpenIdConnectServerDefaults.AuthenticationScheme);
        }

        // Note: to support non-interactive flows like password,
        // you must provide your own token endpoint action:

        [HttpPost("~/connect/token")]
        [Produces("application/json")]
        public async Task<IActionResult> Exchange() {
            var request = HttpContext.GetOpenIdConnectRequest();

            if (request.IsPasswordGrantType()) {
                var user = await _userManager.FindByNameAsync(request.Username);
                if (user == null) {
                    return BadRequest(new OpenIdConnectResponse {
                        Error = OpenIdConnectConstants.Errors.InvalidGrant,
                        ErrorDescription = "The username/password couple is invalid."
                    });
                }

                // Ensure the user is allowed to sign in.
                if (!await _signInManager.CanSignInAsync(user)) {
                    return BadRequest(new OpenIdConnectResponse {
                        Error = OpenIdConnectConstants.Errors.InvalidGrant,
                        ErrorDescription = "The specified user is not allowed to sign in."
                    });
                }

                // Reject the token request if two-factor authentication has been enabled by the user.
                if (_userManager.SupportsUserTwoFactor && await _userManager.GetTwoFactorEnabledAsync(user)) {
                    return BadRequest(new OpenIdConnectResponse {
                        Error = OpenIdConnectConstants.Errors.InvalidGrant,
                        ErrorDescription = "The specified user is not allowed to sign in."
                    });
                }

                // Ensure the user is not already locked out.
                if (_userManager.SupportsUserLockout && await _userManager.IsLockedOutAsync(user)) {
                    return BadRequest(new OpenIdConnectResponse {
                        Error = OpenIdConnectConstants.Errors.InvalidGrant,
                        ErrorDescription = "The username/password couple is invalid."
                    });
                }

                // Ensure the password is valid.
                if (!await _userManager.CheckPasswordAsync(user, request.Password)) {
                    if (_userManager.SupportsUserLockout) {
                        await _userManager.AccessFailedAsync(user);
                    }

                    return BadRequest(new OpenIdConnectResponse {
                        Error = OpenIdConnectConstants.Errors.InvalidGrant,
                        ErrorDescription = "The username/password couple is invalid."
                    });
                }

                if (_userManager.SupportsUserLockout) {
                    await _userManager.ResetAccessFailedCountAsync(user);
                }

                var identity = await _userManager.CreateIdentityAsync(user, request.GetScopes());

                // Create a new authentication ticket holding the user identity.
                var ticket = new AuthenticationTicket(
                    new ClaimsPrincipal(identity),
                    new AuthenticationProperties(),
                    OpenIdConnectServerDefaults.AuthenticationScheme);

                ticket.SetResources(request.GetResources());
                ticket.SetScopes(request.GetScopes());

                return SignIn(ticket.Principal, ticket.Properties, ticket.AuthenticationScheme);
            }

            return BadRequest(new OpenIdConnectResponse {
                Error = OpenIdConnectConstants.Errors.UnsupportedGrantType,
                ErrorDescription = "The specified grant type is not supported."
            });
        }
    }
}