using IdentityServer.PublishedLanguage.Dto;
using IdentityServer.Wrapper.Services;
using Microsoft.AspNetCore.Authentication;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using NDB.Security.Authentication.Identity.Abstractions;
using c = NDB.Security.Authentication.Identity.Constants;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http.Headers;
using System.Security.Claims;
using System.Text.Encodings.Web;
using System.Threading.Tasks;

namespace NDB.Security.Authentication.Identity
{
    public class IdentityAuthenticationHandler : AuthenticationHandler<AuthenticationSchemeOptions>
    {
        private readonly IIdentityService _identityService;
        private readonly IAuthenticationOptions _authenticationOptions;

        public IdentityAuthenticationHandler(IOptionsMonitor<AuthenticationSchemeOptions> options, ILoggerFactory logger, UrlEncoder encoder, ISystemClock clock, IIdentityService identityService, IAuthenticationOptions authenticationOptions)
            : base(options, logger, encoder, clock)
        {
            _identityService = identityService;
            _authenticationOptions = authenticationOptions;
        }

        protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
        {
            var token = GetAuthorizationToken();
            if (token != null)
            {
                TokenCore tokenCore;
                try
                {
                    tokenCore = await _identityService.Authorize(token);
                }
                catch
                {
                    return AuthenticateResult.Fail("Invalid authorization");
                }

                if (tokenCore == null)
                    return AuthenticateResult.Fail("Invalid token");

                var ticket = GetAuthenticationTicket(tokenCore);
                return AuthenticateResult.Success(ticket);
            }

            var authenticateAsGuest = _authenticationOptions.AuthenticateAsGuest?.Invoke(Request) ?? false;
            if (authenticateAsGuest)
            {
                var guestTicket = GetGuestAuthenticationTicket(_authenticationOptions.GuestUserId, _authenticationOptions.GuestUserName);
                return AuthenticateResult.Success(guestTicket);
            }

            return AuthenticateResult.Fail("Missing authorization header");
        }

        private string GetAuthorizationToken()
        {
            if (Request.Headers.ContainsKey("Authorization"))
            {
                var authorizationHeader = AuthenticationHeaderValue.Parse(Request.Headers["Authorization"]);
                var token = authorizationHeader.Parameter;
                return token;
            }

            if (_authenticationOptions.AcceptTokenFromQuery 
                && Request.Query.Count > 0
                && Request.Query.ContainsKey(c.QueryParams.Token))
            {
                var token = Request.Query[c.QueryParams.Token];
                return token.ToString();
            }

            return null;
        }

        private AuthenticationTicket GetGuestAuthenticationTicket(int guestId, string guestName)
        {
            var claims = new[] {
                new Claim(ClaimTypes.NameIdentifier, guestId.ToString()),
                new Claim(ClaimTypes.Name, guestName),
                new Claim(Constants.ClaimTypes.IsGuestUser, bool.TrueString)
            };

            var ticket = GetAuthenticationTicket(claims);
            return ticket;
        }

        private AuthenticationTicket GetAuthenticationTicket(TokenCore tokenCore)
        {
            var claimCollection = new Dictionary<string, string>()
            {
                { ClaimTypes.NameIdentifier, tokenCore.UserId.ToString() },
                { ClaimTypes.Name, tokenCore.UserName },
                { Constants.ClaimTypes.UserName, tokenCore.UserName }
            };

            if (tokenCore.FirstName != null)
                claimCollection.Add(Constants.ClaimTypes.FirstName, tokenCore.FirstName);
            if (tokenCore.LastName != null)
                claimCollection.Add(Constants.ClaimTypes.LastName, tokenCore.LastName);
            if (tokenCore.ProfilePictureUrl != null)
                claimCollection.Add(Constants.ClaimTypes.ProfilePictureUrl, tokenCore.ProfilePictureUrl);
            if (tokenCore.Email != null)
                claimCollection.Add(ClaimTypes.Email, tokenCore.Email);

            if (tokenCore.Claims != null && tokenCore.Claims.Any())
            {
                foreach (var claim in tokenCore.Claims)
                    claimCollection.Add(claim.Key, claim.Value);
            }

            var claims = claimCollection.Select(z => new Claim(z.Key, z.Value)).ToArray();
            var ticket = GetAuthenticationTicket(claims);

            return ticket;
        }

        private AuthenticationTicket GetAuthenticationTicket(Claim[] claims)
        {
            var identity = new ClaimsIdentity(claims, Scheme.Name);
            var principal = new ClaimsPrincipal(identity);
            var ticket = new AuthenticationTicket(principal, Scheme.Name);

            return ticket;
        }
    }
}