/*
    * Copyright 2020-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.driver.windows.registry;
   
   import java.util.ArrayList;
   import java.util.List;
   
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.sun.jna.platform.win32.Advapi32Util;
  import com.sun.jna.platform.win32.Advapi32Util.Account;
  import com.sun.jna.platform.win32.Advapi32Util.InfoKey;
  import com.sun.jna.platform.win32.Win32Exception;
  import com.sun.jna.platform.win32.WinNT;
  import com.sun.jna.platform.win32.WinReg;
  import com.sun.jna.platform.win32.WinReg.HKEY;
  
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.software.os.OSSession;
  
  /**
   * Utility to read session data from HKEY_USERS
   */
  @ThreadSafe
  public final class HkeyUserData {
  
      private static final String PATH_DELIMITER = "\\";
      private static final String DEFAULT_DEVICE = "Console";
      private static final String VOLATILE_ENV_SUBKEY = "Volatile Environment";
      private static final String CLIENTNAME = "CLIENTNAME";
      private static final String SESSIONNAME = "SESSIONNAME";
  
      private static final Logger LOG = LoggerFactory.getLogger(HkeyUserData.class);
  
      private HkeyUserData() {
      }
  
      public static List<OSSession> queryUserSessions() {
          List<OSSession> sessions = new ArrayList<>();
          for (String sidKey : Advapi32Util.registryGetKeys(WinReg.HKEY_USERS)) {
              if (!sidKey.startsWith(".") && !sidKey.endsWith("_Classes")) {
                  try {
                      Account a = Advapi32Util.getAccountBySid(sidKey);
                      String name = a.name;
                      String device = DEFAULT_DEVICE;
                      String host = a.domain; // temporary default
                      long loginTime = 0;
                      String keyPath = sidKey + PATH_DELIMITER + VOLATILE_ENV_SUBKEY;
                      if (Advapi32Util.registryKeyExists(WinReg.HKEY_USERS, keyPath)) {
                          HKEY hKey = Advapi32Util.registryGetKey(WinReg.HKEY_USERS, keyPath, WinNT.KEY_READ).getValue();
                          // InfoKey write time is user login time
                          InfoKey info = Advapi32Util.registryQueryInfoKey(hKey, 0);
                          loginTime = info.lpftLastWriteTime.toTime();
                          for (String subKey : Advapi32Util.registryGetKeys(hKey)) {
                              String subKeyPath = keyPath + PATH_DELIMITER + subKey;
                              // Check for session and client name
                              if (Advapi32Util.registryValueExists(WinReg.HKEY_USERS, subKeyPath, SESSIONNAME)) {
                                  String session = Advapi32Util.registryGetStringValue(WinReg.HKEY_USERS, subKeyPath,
                                          SESSIONNAME);
                                  if (!session.isEmpty()) {
                                      device = session;
                                  }
                              }
                              if (Advapi32Util.registryValueExists(WinReg.HKEY_USERS, subKeyPath, CLIENTNAME)) {
                                  String client = Advapi32Util.registryGetStringValue(WinReg.HKEY_USERS, subKeyPath,
                                          CLIENTNAME);
                                  if (!client.isEmpty() && !DEFAULT_DEVICE.equals(client)) {
                                      host = client;
                                  }
                              }
                          }
                          Advapi32Util.registryCloseKey(hKey);
                      }
                      sessions.add(new OSSession(name, device, loginTime, host));
                  } catch (Win32Exception ex) {
                      LOG.warn("Error querying SID {} from registry: {}", sidKey, ex.getMessage());
                  }
              }
          }
          return sessions;
      }
  }