using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Authentication;
using System.Text;
using System.Threading.Tasks;
using Tango.Transport.Web;

namespace Tango.Web.Security
{
    public class TokensManager<T> where T : IEquatable<T>
    {
        private Dictionary<String, TokenWrapper> _tokens;

        private class TokenWrapper : IEquatable<TokenWrapper>
        {
            public WebToken WebToken { get; set; }

            public T Value { get; set; }

            public bool Equals(TokenWrapper other)
            {
                return Value.Equals(other.Value);
            }
        }

        public TokensManager()
        {
            _tokens = new Dictionary<string, TokenWrapper>();
            ExpirationTime = TimeSpan.FromHours(1);
        }

        public TimeSpan ExpirationTime { get; set; }

        public WebToken GetOrCreate(T tokenObject)
        {
            var existing_token = _tokens.FirstOrDefault(x => x.Value.Value.Equals(tokenObject));

            if (existing_token.Key != null)
            {
                return existing_token.Value.WebToken;
            }
            else
            {
                String token = Guid.NewGuid().ToString();
                TokenWrapper wrapper = new TokenWrapper()
                {
                    Value = tokenObject,
                    WebToken = new WebToken()
                    {
                        //AccessToken = token,
                        //Expiration = DateTime.UtcNow.Add(ExpirationTime)
                    },
                };

                _tokens.Add(token, wrapper);
                return wrapper.WebToken;
            }
        }

        public void Validate(String token)
        {
            GetTokenObject(token);
        }

        public T GetTokenObject(String token)
        {
            if (!_tokens.ContainsKey(token))
            {
                throw new AuthenticationException("Invalid token.");
            }

            if (DateTime.UtcNow > _tokens[token].WebToken.Expiration)
            {
                _tokens.Remove(token);
                throw new TokenExpiredException("Session Expired.");
            }

            return _tokens[token].Value;
        }
    }
}