package com.jsql.util;
   
   import com.jsql.model.InjectionModel;
   import org.apache.commons.lang3.StringUtils;
   import org.apache.logging.log4j.LogManager;
   import org.apache.logging.log4j.Logger;
   
   import java.io.File;
   import java.net.Authenticator;
  import java.net.PasswordAuthentication;
  import java.util.prefs.Preferences;
  
  /**
   * Manage authentication protocols Basic, Digest, NTLM and Kerberos.
   * Java class Authenticator processes Basic, Digest and NTLM, library spnego
   * processes kerberos.
   */
  public class AuthenticationUtil {
      
      private static final Logger LOGGER = LogManager.getRootLogger();
      
      /**
       * True if standard authentication Basic, Digest, NTLM is activated.
       */
      private boolean isAuthentication = false;
  
      /**
       * Login for standard authentication.
       */
      private String usernameAuthentication;
  
      /**
       * Pass for standard authentication.
       */
      private String passwordAuthentication;
      
      /**
       * True if kerberos authentication is activated.
       */
      private boolean isKerberos = false;
  
      /**
       * Path to the kerberos file login.
       */
      private String pathKerberosLogin;
  
      /**
       * Path to the kerberos file krb5.
       */
      private String pathKerberosKrb5;
  
      /**
       * Get new authentication settings from the view, update the utility class,
       * persist settings to the JVM and apply changes to the system.
       * @param isAuthentication true if non-kerberos authentication is activated
       * @param usernameAuthentication login for standard authentication
       * @param passwordAuthentication pass for standard authentication
       * @param isKerberos true if krb authentication is activated
       * @param kerberosKrb5Conf path to the file krb5
       * @param kerberosLoginConf path to the file login
       */
      public boolean set(
          boolean isAuthentication,
          String usernameAuthentication,
          String passwordAuthentication,
          boolean isKerberos,
          String kerberosKrb5Conf,
          String kerberosLoginConf
      ) {
          boolean isRestartRequired = this.initKerberos(isKerberos, kerberosKrb5Conf, kerberosLoginConf);
          this.initSimpleAuthorization(isAuthentication, usernameAuthentication, passwordAuthentication);
          this.setAuthentication();
          return isRestartRequired;
      }
  
      public void initSimpleAuthorization(boolean isAuthentication, String usernameAuthentication, String passwordAuthentication) {
          var preferences = Preferences.userRoot().node(InjectionModel.class.getName());
          preferences.putBoolean("isAuthentication", isAuthentication);
          preferences.put("usernameAuthentication", usernameAuthentication);
          preferences.put("passwordAuthentication", passwordAuthentication);
          // Define proxy settings
          this.isAuthentication = isAuthentication;
          this.usernameAuthentication = usernameAuthentication;
          this.passwordAuthentication = passwordAuthentication;
      }
  
      private boolean initKerberos(boolean isKerberos, String kerberosKrb5Conf, String kerberosLoginConf) {
          // Persist to JVM
          var preferences = Preferences.userRoot().node(InjectionModel.class.getName());
          
          this.isKerberos = isKerberos;
          this.pathKerberosKrb5 = kerberosKrb5Conf;
          this.pathKerberosLogin = kerberosLoginConf;
          
          // Check if krb file has changed
          boolean isRestartRequired = this.isKerberos
              && !new File(this.pathKerberosKrb5).exists()
              && !kerberosKrb5Conf.equals(this.pathKerberosKrb5);
          
         preferences.putBoolean("enableKerberos", this.isKerberos);
         preferences.put("kerberosKrb5Conf", this.pathKerberosKrb5);
         preferences.put("kerberosLoginConf", this.pathKerberosLogin);
         
         // Check krb integrity
         if (this.isKerberos) {
             // Fix #23877: NoClassDefFoundError on java/nio/file/Paths
             if (!new File(this.pathKerberosKrb5).exists()) {
                 LOGGER.log(LogLevelUtil.CONSOLE_ERROR, "Krb5 file not found: {}", this.pathKerberosKrb5);
             }
             if (!new File(this.pathKerberosLogin).exists()) {
                 LOGGER.log(LogLevelUtil.CONSOLE_ERROR, "Login file not found: {}", this.pathKerberosLogin);
             }
         }
         return isRestartRequired;
     }
     
     /**
      * Initialize the utility class with preferences from the JVM
      * and apply environment settings.
      */
     public void setKerberosCifs() {
         // Use Preferences API to persist proxy configuration
         var preferences = Preferences.userRoot().node(InjectionModel.class.getName());
 
         // Default proxy disabled
         this.isAuthentication = preferences.getBoolean("isAuthentication", false);
 
         // Default TOR config
         this.usernameAuthentication = preferences.get("usernameAuthentication", StringUtils.EMPTY);
         this.passwordAuthentication = preferences.get("passwordAuthentication", StringUtils.EMPTY);
         
         this.isKerberos = preferences.getBoolean("enableKerberos", false);
         this.pathKerberosKrb5 = preferences.get("kerberosKrb5Conf", StringUtils.EMPTY);
         this.pathKerberosLogin = preferences.get("kerberosLoginConf", StringUtils.EMPTY);
         
         this.setAuthentication();
     }
     
     /**
      * Apply kerberos authentication to the JVM.
      */
     public void setAuthentication() {
         Authenticator.setDefault(null);
         if (this.isAuthentication) {
             Authenticator.setDefault(new Authenticator() {
                 @Override
                 protected PasswordAuthentication getPasswordAuthentication() {
                     return new PasswordAuthentication (
                         AuthenticationUtil.this.usernameAuthentication,
                         AuthenticationUtil.this.passwordAuthentication.toCharArray()
                     );
                 }
             });
         } else {
             Authenticator.setDefault(null);
         }
         if (this.isKerberos) {
             System.setProperty("java.security.krb5.conf", this.pathKerberosKrb5);
             System.setProperty("java.security.auth.login.config", this.pathKerberosLogin);
             System.setProperty("spnego.krb5.conf", this.pathKerberosKrb5);
             System.setProperty("spnego.login.conf", this.pathKerberosLogin);
         } else {
             System.setProperty("java.security.krb5.conf", StringUtils.EMPTY);
             System.setProperty("java.security.auth.login.config", StringUtils.EMPTY);
             System.setProperty("spnego.krb5.conf", StringUtils.EMPTY);
             System.setProperty("spnego.login.conf", StringUtils.EMPTY);
         }
     }
     
     
     // Getters and setters
 
     public boolean isAuthentEnabled() {
         return this.isAuthentication;
     }
 
     public String getPathKerberosLogin() {
         return this.pathKerberosLogin;
     }
 
     public String getPathKerberosKrb5() {
         return this.pathKerberosKrb5;
     }
 
     public boolean isKerberos() {
         return this.isKerberos;
     }
 
     public String getUsernameAuthentication() {
         return this.usernameAuthentication;
     }
 
     public String getPasswordAuthentication() {
         return this.passwordAuthentication;
     }
     
     
     // Builder
     
     public AuthenticationUtil withAuthenticationEnabled() {
         this.isAuthentication = true;
         return this;
     }
     
     public AuthenticationUtil withUsernameAuthentication(String usernameAuthentication) {
         this.usernameAuthentication = usernameAuthentication;
         return this;
     }
     
     public AuthenticationUtil withPasswordAuthentication(String passwordAuthentication) {
         this.passwordAuthentication = passwordAuthentication;
         return this;
     }
 }