Facebook.DateTimeConvertor.ToUnixTime C# (CSharp) Method

        public static double ToUnixTime(DateTime dateTime)
        {
            return Math.Round((dateTime.ToUniversalTime() - Epoch).TotalSeconds);
        }

        /// <summary>
        /// Creates a Facebook session from a signed request.
        /// </summary>
        /// <param name="appSecret">
        /// The app secret.
        /// </param>
        /// <param name="signedRequest">
        /// The signed request.
        /// </param>
        /// <returns>
        /// The Facebook session.
        /// </returns>
        internal static FacebookSession Create(IFacebookApplication settings, FacebookSignedRequest signedRequest)
        {
            if (settings == null)
            {
                throw new ArgumentNullException("settings");
            }

            if (signedRequest == null)
            {
                return(null);
            }

            var data = (IDictionary <string, object>)signedRequest.Data;

            if (data == null)
            {
                return(null);
            }

            if (!data.ContainsKey("code") && string.IsNullOrEmpty(signedRequest.AccessToken))
            {
                return(null);
            }

            var dictionary = new JsonObject
            {
                { "uid", signedRequest.UserId.ToString() }
            };

            if (!string.IsNullOrEmpty(signedRequest.AccessToken))
            {
                dictionary["access_token"] = signedRequest.AccessToken;
            }

            if (data.ContainsKey("code"))
            {
                foreach (var key in data.Keys)
                {
                    dictionary[key] = data[key];
                }
            }
            else
            {
                if (signedRequest.Expires == DateTime.MaxValue)
                {
                    dictionary["expires"] = 0;
                }
                else if (signedRequest.Expires != DateTime.MinValue)
                {
                    dictionary["expires"] = DateTimeConvertor.ToUnixTime(signedRequest.Expires);
                }

                if (settings != null && !string.IsNullOrEmpty(settings.AppSecret))
                {
                    dictionary["sig"] = GenerateSessionSignature(settings.AppSecret, dictionary);
                }
            }

            return(new FacebookSession(dictionary, settings));
        }