/*
 * 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.Collections.Generic;
using System.Security.Claims;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Mvc.Server.Helpers;
using Mvc.Server.Models;
using Mvc.Server.ViewModels.Authorization;
using Mvc.Server.ViewModels.Shared;
using OpenIddict.Abstractions;
using OpenIddict.Core;
using OpenIddict.EntityFrameworkCore.Models;
using OpenIddict.Server.AspNetCore;
using static OpenIddict.Abstractions.OpenIddictConstants;

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

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

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

        [Authorize, HttpGet("~/connect/authorize")]
        public async Task<IActionResult> Authorize()
        {
            var request = HttpContext.GetOpenIddictServerRequest();
            if (request == null)
            {
                throw new InvalidOperationException("The OpenID Connect request cannot be retrieved.");
            }

            // Retrieve the application details from the database.
            var application = await _applicationManager.FindByClientIdAsync(request.ClientId);
            if (application == null)
            {
                return View("Error", new ErrorViewModel
                {
                    Error = 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 = await _applicationManager.GetDisplayNameAsync(application),
                Parameters = request.GetFlattenedParameters(),
                Scope = request.Scope
            });
        }

        [Authorize, FormValueRequired("submit.Accept")]
        [HttpPost("~/connect/authorize"), ValidateAntiForgeryToken]
        public async Task<IActionResult> Accept()
        {
            var request = HttpContext.GetOpenIddictServerRequest();
            if (request == null)
            {
                throw new InvalidOperationException("The OpenID Connect request cannot be retrieved.");
            }

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

            var principal = await _signInManager.CreateUserPrincipalAsync(user);

            // Note: in this sample, the granted scopes match the requested scope
            // but you may want to allow the user to uncheck specific scopes.
            // For that, simply restrict the list of scopes before calling SetScopes.
            principal.SetScopes(request.GetScopes());
            principal.SetResources("resource_server");

            foreach (var claim in principal.Claims)
            {
                claim.SetDestinations(GetDestinations(claim, principal));
            }

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

        [Authorize, FormValueRequired("submit.Deny")]
        [HttpPost("~/connect/authorize"), ValidateAntiForgeryToken]
        // 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.
        public IActionResult Deny() => Forbid(OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);

        // Note: the logout action is only useful when implementing interactive
        // flows like the authorization code flow or the implicit flow.

        [HttpGet("~/connect/logout")]
        public IActionResult Logout()
        {
            var request = HttpContext.GetOpenIddictServerRequest();
            if (request == null)
            {
                throw new InvalidOperationException("The OpenID Connect request cannot be retrieved.");
            }

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

        [ActionName(nameof(Logout)), HttpPost("~/connect/logout"), ValidateAntiForgeryToken]
        public async Task<IActionResult> LogoutPost()
        {
            // 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(OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);
        }
        #endregion

        #region Password, authorization code and refresh token flows
        // 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.GetOpenIddictServerRequest();
            if (request == null)
            {
                throw new InvalidOperationException("The OpenID Connect request cannot be retrieved.");
            }

            if (request.IsPasswordGrantType())
            {
                var user = await _userManager.FindByNameAsync(request.Username);
                if (user == null)
                {
                    var properties = new AuthenticationProperties(new Dictionary<string, string>
                    {
                        [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                        [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "The username/password couple is invalid."
                    });

                    return Forbid(properties, OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);
                }

                // Validate the username/password parameters and ensure the account is not locked out.
                var result = await _signInManager.CheckPasswordSignInAsync(user, request.Password, lockoutOnFailure: true);
                if (!result.Succeeded)
                {
                    var properties = new AuthenticationProperties(new Dictionary<string, string>
                    {
                        [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                        [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "The username/password couple is invalid."
                    });

                    return Forbid(properties, OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);
                }

                var principal = await _signInManager.CreateUserPrincipalAsync(user);

                // Note: in this sample, the granted scopes match the requested scope
                // but you may want to allow the user to uncheck specific scopes.
                // For that, simply restrict the list of scopes before calling SetScopes.
                principal.SetScopes(request.GetScopes());
                principal.SetResources("resource_server");

                foreach (var claim in principal.Claims)
                {
                    claim.SetDestinations(GetDestinations(claim, principal));
                }

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

            else if (request.IsAuthorizationCodeGrantType() || request.IsRefreshTokenGrantType())
            {
                // Retrieve the claims principal stored in the authorization code/refresh token.
                var principal = (await HttpContext.AuthenticateAsync(OpenIddictServerAspNetCoreDefaults.AuthenticationScheme)).Principal;

                // Retrieve the user profile corresponding to the authorization code/refresh token.
                // Note: if you want to automatically invalidate the authorization code/refresh token
                // when the user password/roles change, use the following line instead:
                // var user = _signInManager.ValidateSecurityStampAsync(info.Principal);
                var user = await _userManager.GetUserAsync(principal);
                if (user == null)
                {
                    var properties = new AuthenticationProperties(new Dictionary<string, string>
                    {
                        [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                        [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "The token is no longer valid."
                    });

                    return Forbid(properties, OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);
                }

                // Ensure the user is still allowed to sign in.
                if (!await _signInManager.CanSignInAsync(user))
                {
                    var properties = new AuthenticationProperties(new Dictionary<string, string>
                    {
                        [OpenIddictServerAspNetCoreConstants.Properties.Error] = Errors.InvalidGrant,
                        [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "The user is no longer allowed to sign in."
                    });

                    return Forbid(properties, OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);
                }

                foreach (var claim in principal.Claims)
                {
                    claim.SetDestinations(GetDestinations(claim, principal));
                }

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

            throw new InvalidOperationException("The specified grant type is not supported.");
        }
        #endregion

        private IEnumerable<string> GetDestinations(Claim claim, ClaimsPrincipal principal)
        {
            // Note: by default, claims are NOT automatically included in the access and identity tokens.
            // To allow OpenIddict to serialize them, you must attach them a destination, that specifies
            // whether they should be included in access tokens, in identity tokens or in both.

            switch (claim.Type)
            {
                case Claims.Name:
                    yield return Destinations.AccessToken;

                    if (principal.HasScope(Scopes.Profile))
                        yield return Destinations.IdentityToken;

                    yield break;

                case Claims.Email:
                    yield return Destinations.AccessToken;

                    if (principal.HasScope(Scopes.Email))
                        yield return Destinations.IdentityToken;

                    yield break;

                case Claims.Role:
                    yield return Destinations.AccessToken;

                    if (principal.HasScope(Scopes.Roles))
                        yield return Destinations.IdentityToken;

                    yield break;

                // Never include the security stamp in the access and identity tokens, as it's a secret value.
                case "AspNet.Identity.SecurityStamp": yield break;

                default:
                    yield return Destinations.AccessToken;
                    yield break;
            }
        }
    }
}