using System.Linq;
using System.Security.Claims;
using System.Text.Encodings.Web;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Microsoft.Net.Http.Headers;
using WebAPI.Data;

namespace WebAPI.Auth
{
    public class OIDCTokenAuthenticationHandler : AuthenticationHandler<OIDCTokenAuthenticationOptions>
    {
        private readonly OIDCService _oidcService;
        public OIDCTokenAuthenticationHandler(IOptionsMonitor<OIDCTokenAuthenticationOptions> options, ILoggerFactory logger, UrlEncoder encoder, ISystemClock clock, OIDCService oidcService) : base(options, logger, encoder, clock)
        {
            _oidcService = oidcService;
        }

        protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
        {
            var bearerToken = Request.Headers[HeaderNames.Authorization].FirstOrDefault() ?? "";
            if (string.IsNullOrEmpty(bearerToken))
            {
                return AuthenticateResult.Fail("no token");
            }

            var token = bearerToken.Split(" ").ElementAt(1);
            if (!await _oidcService.ValidateAccessToken(token))
            {
                return AuthenticateResult.Fail("failed to validate token");
            }

            var identity = new ClaimsIdentity(new[]
            {
                new Claim(ClaimTypes.Authentication, token)
            }, Scheme.Name);
            var principal = new ClaimsPrincipal(identity);
            return AuthenticateResult.Success(new AuthenticationTicket(principal, Scheme.Name));
        }
    }

    public class OIDCTokenAuthenticationOptions : AuthenticationSchemeOptions
    {
        public string OIDCIntrospectionEndpoint { get; set; }
        public string OIDCClientId { get; set; }
        public string OIDCClientSecret { get; set; }
        
    }

    public class OIDCTokenAuthenticationDefaults
    {
        public static string DefaultScheme => "OIDCAuthentication";
    }
}