using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using LogicNP.CryptoLicensing;

namespace Math4Office.Auth
{
    public class Math4OfficeAuth
    {
        //free license case
        private enum appFeature { Measures = LicenseFeatures.Feature1 };
        //CryptoLicense license;
        private string _licenseCode = string.Empty;
        public Math4OfficeAuth(string licenseCode)
        {
            _licenseCode = licenseCode;
        }
        static CryptoLicense license;
        public static bool Authorize()
        {
            if (Math4OfficeAuth.ValidateToken())
            {
                return true;
            }
            else
            {
                // Pop up the login form and ask user to login.
                // Meanwhile return false
                return false;
            }
        }

        public static bool LoginUser()
        {
            // This function should display the login form.
            // Validate user using ValidateLogin function and update the Login
            // pop up based on errors. Return true if the login is successful
            // and return false if the user cancels the login form.
            // If ValidateLogin fails, update the form based on the error.
            LoginForm loginForm = new LoginForm();
            var formResult = loginForm.ShowDialog();
            if (formResult == System.Windows.Forms.DialogResult.Cancel)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        private int ValidateLogin(string userName, string password)
        {
            // return codes can be used to define the type of errors which occurred
            // 1    - Successfull
            // 0    - Unknown error
            // -1   - Invalid username or password
            // -2   - Some fault at server side

            return 1;
        }

        public static void LogoutUser()
        {
            string userAppDataDir = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
            string appDir = Path.Combine(userAppDataDir, "Math4Office");
            string licFileName = Path.Combine(appDir, "token.tok");
            string infoFileName = Path.Combine(appDir, "user.info");

            if (File.Exists(licFileName))
            {
                try
                {
                    File.Delete(licFileName);
                }
                catch
                {
                    if (File.Exists(licFileName))
                    {
                        using (StreamWriter fs = new StreamWriter(licFileName))
                        {
                            fs.WriteLine("");
                        }
                    }
                }
            }
        }

        private static bool ValidateToken()
        {
            bool result = false;

            string userAppDataDir = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
            string appDir = Path.Combine(userAppDataDir, "Math4Office");
            string licFileName = Path.Combine(appDir, "token.tok");

            if (File.Exists(licFileName))
            {
                using (StreamReader fs = new StreamReader(licFileName))
                {
                    string authenticationKey = fs.ReadLine();
                    string validationKey = "AMAAMACmsO3rk5KOGikVV615S52IgdxMMkdswb3e1lmmXDsihncRpqP47NscE8KVcacomy8DAAEAAQ==";
                    license = new CryptoLicense(authenticationKey, validationKey);

                    if (license.Status != LicenseStatus.Valid)
                    {
                        result = false;
                    }
                    else
                    {
                        result = true;
                        //Application.Run(new Form1(lic.ExceptionalFeature()));
                    }

                }

            }

            return result;
        }

        public bool Measures()
        {
            if (license.IsFeaturePresent((LicenseFeatures)appFeature.Measures, false))
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        private static string GenerateToken()
        {
            byte[] time = BitConverter.GetBytes(DateTime.UtcNow.ToBinary());
            byte[] key = Guid.NewGuid().ToByteArray();
            string token = Convert.ToBase64String(time.Concat(key).ToArray());
            return token;
        }
    }
}