using Fengling.AuthService.Data;
using Fengling.AuthService.Models;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using OpenIddict.Abstractions;
using OpenIddict.Server.AspNetCore;
using System.Security.Claims;
using Fengling.AuthService.ViewModels;
using Microsoft.AspNetCore;
using Microsoft.Extensions.Primitives;
using static OpenIddict.Abstractions.OpenIddictConstants;

namespace Fengling.AuthService.Controllers;

[ApiController]
[Route("connect")]
public class AuthorizationController(
    IOpenIddictApplicationManager applicationManager,
    IOpenIddictAuthorizationManager authorizationManager,
    IOpenIddictScopeManager scopeManager,
    SignInManager<ApplicationUser> signInManager,
    UserManager<ApplicationUser> userManager,
    ILogger<AuthorizationController> logger)
    : Controller
{

    [HttpGet("authorize")]
    [HttpPost("authorize")]
    public async Task<IActionResult> Authorize()
    {
        var request = HttpContext.GetOpenIddictServerRequest() ??
                      throw new InvalidOperationException("The OpenID Connect request cannot be retrieved.");

        // If prompt=login was specified by the client application,
        // immediately return the user agent to the login page.
        if (request.HasPromptValue(OpenIddictConstants.PromptValues.Login))
        {
            // To avoid endless login -> authorization redirects, the prompt=login flag
            // is removed from the authorization request payload before redirecting the user.
            var prompt = string.Join(" ", request.GetPromptValues().Remove(OpenIddictConstants.PromptValues.Login));

            var parameters = Request.HasFormContentType
                ? Request.Form.Where(parameter => parameter.Key != OpenIddictConstants.Parameters.Prompt).ToList()
                : Request.Query.Where(parameter => parameter.Key != OpenIddictConstants.Parameters.Prompt).ToList();

            parameters.Add(KeyValuePair.Create(OpenIddictConstants.Parameters.Prompt, new StringValues(prompt)));

            return Challenge(
                authenticationSchemes: IdentityConstants.ApplicationScheme,
                properties: new AuthenticationProperties
                {
                    RedirectUri = Request.PathBase + Request.Path + QueryString.Create(parameters)
                });
        }

        // Retrieve the user principal stored in the authentication cookie.
        // If a max_age parameter was provided, ensure that the cookie is not too old.
        // If the user principal can't be extracted or the cookie is too old, redirect the user to the login page.
        var result = await HttpContext.AuthenticateAsync(IdentityConstants.ApplicationScheme);
        if (result is not { Succeeded: true } || (request.MaxAge != null && result.Properties?.IssuedUtc != null &&
                                                  DateTimeOffset.UtcNow - result.Properties.IssuedUtc >
                                                  TimeSpan.FromSeconds(request.MaxAge.Value)))
        {
            // If the client application requested promptless authentication,
            // return an error indicating that the user is not logged in.
            if (request.HasPromptValue(OpenIddictConstants.PromptValues.None))
            {
                return Forbid(
                    authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
                    properties: new AuthenticationProperties(new Dictionary<string, string>
                    {
                        [OpenIddictServerAspNetCoreConstants.Properties.Error] =
                            OpenIddictConstants.Errors.LoginRequired,
                        [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] = "The user is not logged in."
                    }!));
            }

            return Challenge(
                authenticationSchemes: IdentityConstants.ApplicationScheme,
                properties: new AuthenticationProperties
                {
                    RedirectUri = Request.PathBase + Request.Path + QueryString.Create(
                        Request.HasFormContentType ? Request.Form.ToList() : Request.Query.ToList())
                });
        }

        // Retrieve the profile of the logged in user.
        var user = await userManager.GetUserAsync(result.Principal) ??
                   throw new InvalidOperationException("The user details cannot be retrieved.");

        // Retrieve the application details from the database.
        var application = await applicationManager.FindByClientIdAsync(request.ClientId!) ??
                          throw new InvalidOperationException(
                              "Details concerning the calling client application cannot be found.");

        // Retrieve the permanent authorizations associated with the user and the calling client application.
        var authorizations = await authorizationManager.FindAsync(
            subject: await userManager.GetUserIdAsync(user),
            client: (await applicationManager.GetIdAsync(application))!,
            status: OpenIddictConstants.Statuses.Valid,
            type: OpenIddictConstants.AuthorizationTypes.Permanent,
            scopes: request.GetScopes()).ToListAsync();

        switch (await applicationManager.GetConsentTypeAsync(application))
        {
            // If the consent is external (e.g when authorizations are granted by a sysadmin),
            // immediately return an error if no authorization can be found in the database.
            case OpenIddictConstants.ConsentTypes.External when !authorizations.Any():
                return Forbid(
                    authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
                    properties: new AuthenticationProperties(new Dictionary<string, string>
                    {
                        [OpenIddictServerAspNetCoreConstants.Properties.Error] =
                            OpenIddictConstants.Errors.ConsentRequired,
                        [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] =
                            "The logged in user is not allowed to access this client application."
                    }!));

            // If the consent is implicit or if an authorization was found,
            // return an authorization response without displaying the consent form.
            case OpenIddictConstants.ConsentTypes.Implicit:
            case OpenIddictConstants.ConsentTypes.External when authorizations.Any():
            case OpenIddictConstants.ConsentTypes.Explicit
                when authorizations.Any() && !request.HasPromptValue(OpenIddictConstants.PromptValues.Consent):
                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(await scopeManager.ListResourcesAsync(principal.GetScopes()).ToListAsync());

                // Automatically create a permanent authorization to avoid requiring explicit consent
                // for future authorization or token requests containing the same scopes.
                var authorization = authorizations.LastOrDefault();
                if (authorization == null)
                {
                    authorization = await authorizationManager.CreateAsync(
                        principal: principal,
                        subject: await userManager.GetUserIdAsync(user),
                        client: (await applicationManager.GetIdAsync(application))!,
                        type: OpenIddictConstants.AuthorizationTypes.Permanent,
                        scopes: principal.GetScopes());
                }

                principal.SetAuthorizationId(await authorizationManager.GetIdAsync(authorization));

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

                return SignIn(principal, OpenIddictServerAspNetCoreDefaults.AuthenticationScheme);

            // At this point, no authorization was found in the database and an error must be returned
            // if the client application specified prompt=none in the authorization request.
            case OpenIddictConstants.ConsentTypes.Explicit when request.HasPromptValue(OpenIddictConstants.PromptValues.None):
            case OpenIddictConstants.ConsentTypes.Systematic when request.HasPromptValue(OpenIddictConstants.PromptValues.None):
                return Forbid(
                    authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
                    properties: new AuthenticationProperties(new Dictionary<string, string>
                    {
                        [OpenIddictServerAspNetCoreConstants.Properties.Error] =
                            OpenIddictConstants.Errors.ConsentRequired,
                        [OpenIddictServerAspNetCoreConstants.Properties.ErrorDescription] =
                            "Interactive user consent is required."
                    }!));

            // In every other case, render the consent form.
            default:
                return View(new AuthorizeViewModel(await applicationManager.GetDisplayNameAsync(application),request.Scope));
        }
    }
    
    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 OpenIddictConstants.Claims.Name:
                yield return OpenIddictConstants.Destinations.AccessToken;

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

                yield break;

            case OpenIddictConstants.Claims.Email:
                yield return OpenIddictConstants.Destinations.AccessToken;

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

                yield break;

            case OpenIddictConstants.Claims.Role:
                yield return OpenIddictConstants.Destinations.AccessToken;

                if (principal.HasScope(OpenIddictConstants.Permissions.Scopes.Roles))
                    yield return OpenIddictConstants.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 OpenIddictConstants.Destinations.AccessToken;
                yield break;
        }
    }
}