/*  Copyright (C) 2008-2016 Peter Palotas, Jeffrey Jangli, Alexandr Normuradov
 *  
 *  Permission is hereby granted, free of charge, to any person obtaining a copy 
 *  of this software and associated documentation files (the "Software"), to deal 
 *  in the Software without restriction, including without limitation the rights 
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
 *  copies of the Software, and to permit persons to whom the Software is 
 *  furnished to do so, subject to the following conditions:
 *  
 *  The above copyright notice and this permission notice shall be included in 
 *  all copies or substantial portions of the Software.
 *  
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
 *  THE SOFTWARE. 
 */

using System;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using System.Security;
using System.Text;

namespace Alphaleonis.Win32.Security
{
   /// <summary>Represents a privilege for an access token. The privileges available on the local machine are available as 
   /// static instances from this class. To create a <see cref="Privilege"/> representing a privilege on another system,
   /// use the constructor specifying a system name together with one of these static instances.
   /// </summary>
   /// <seealso cref="PrivilegeEnabler"/>
   [ImmutableObject(true)]
   public class Privilege : IEquatable<Privilege>
   {
      #region System Privileges

      #region AssignPrimaryToken

      /// <summary>Required to assign the primary token of a process. User Right: Replace a process-level token.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege AssignPrimaryToken = new Privilege("SeAssignPrimaryTokenPrivilege");

      #endregion // AssignPrimaryToken

      #region Audit

      /// <summary>Required to generate audit-log entries. Give this privilege to secure servers. User Right: Generate security audits.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege Audit = new Privilege("SeAuditPrivilege");

      #endregion // Audit

      #region Backup

      /// <summary>Required to perform backup operations. This privilege causes the system to grant all read access control to any file, regardless of the access control list (ACL) specified for the file. Any access request other than read is still evaluated with the ACL. User Right: Back up files and directories.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege Backup = new Privilege("SeBackupPrivilege");

      #endregion // Backup

      #region ChangeNotify

      /// <summary>Required to receive notifications of changes to files or directories. This privilege also causes the system to skip all traversal access checks. It is enabled by default for all users. User Right: Bypass traverse checking.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege ChangeNotify = new Privilege("SeChangeNotifyPrivilege");

      #endregion // ChangeNotify

      #region CreateGlobal

      /// <summary>Required to create named file mapping objects in the global namespace during Terminal Services sessions. This privilege is enabled by default for administrators, services, and the local system account. User Right: Create global objects.</summary>
      /// <remarks>Windows XP/2000:  This privilege is not supported. Note that this value is supported starting with Windows Server 2003, Windows XP SP2, and Windows 2000 SP4.</remarks>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege CreateGlobal = new Privilege("SeCreateGlobalPrivilege");

      #endregion // CreateGlobal

      #region CreatePagefile

      /// <summary>Required to create a paging file. User Right: Create a pagefile.</summary>
      [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Pagefile")]
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege CreatePagefile = new Privilege("SeCreatePagefilePrivilege");

      #endregion // CreatePagefile

      #region CreatePermanent

      /// <summary>Required to create a permanent object. User Right: Create permanent shared objects.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege CreatePermanent = new Privilege("SeCreatePermanentPrivilege");

      #endregion // CreatePermanent

      #region CreateSymbolicLink

      /// <summary>Required to create a symbolic link. User Right: Create symbolic links.</summary>           
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege CreateSymbolicLink = new Privilege("SeCreateSymbolicLinkPrivilege");

      #endregion // CreateSymbolicLink

      #region CreateToken

      /// <summary>Required to create a primary token. User Right: Create a token object.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege CreateToken = new Privilege("SeCreateTokenPrivilege");

      #endregion // CreateToken

      #region Debug

      /// <summary>Required to debug and adjust the memory of a process owned by another account. User Right: Debug programs.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege Debug = new Privilege("SeDebugPrivilege");

      #endregion // Debug

      #region EnableDelegation

      /// <summary>Required to mark user and computer accounts as trusted for delegation. User Right: Enable computer and user accounts to be trusted for delegation.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege EnableDelegation = new Privilege("SeEnableDelegationPrivilege");

      #endregion // EnableDelegation

      #region Impersonate

      /// <summary>Required to impersonate. User Right: Impersonate a client after authentication.</summary>
      /// <remarks>Windows XP/2000:  This privilege is not supported. Note that this value is supported starting with Windows Server 2003, Windows XP SP2, and Windows 2000 SP4.</remarks>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege Impersonate = new Privilege("SeImpersonatePrivilege");

      #endregion // Impersonate

      #region IncreaseBasePriority

      /// <summary>Required to increase the base priority of a process. User Right: Increase scheduling priority.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege IncreaseBasePriority = new Privilege("SeIncreaseBasePriorityPrivilege");

      #endregion // IncreaseBasePriority

      #region IncreaseQuota

      /// <summary>Required to increase the quota assigned to a process. User Right: Adjust memory quotas for a process.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege IncreaseQuota = new Privilege("SeIncreaseQuotaPrivilege");

      #endregion // IncreaseQuota

      #region IncreaseWorkingSet

      /// <summary>Required to allocate more memory for applications that run in the context of users. User Right: Increase a process working set.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege IncreaseWorkingSet = new Privilege("SeIncreaseWorkingSetPrivilege");

      #endregion // IncreaseWorkingSet

      #region LoadDriver

      /// <summary>Required to load or unload a device driver. User Right: Load and unload device drivers.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege LoadDriver = new Privilege("SeLoadDriverPrivilege");

      #endregion // LoadDriver

      #region LockMemory

      /// <summary>Required to lock physical pages in memory. User Right: Lock pages in memory.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege LockMemory = new Privilege("SeLockMemoryPrivilege");

      #endregion // LockMemory

      #region MachineAccount

      /// <summary>Required to create a computer account. User Right: Add workstations to domain.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege MachineAccount = new Privilege("SeMachineAccountPrivilege");

      #endregion // MachineAccount

      #region ManageVolume

      /// <summary>Required to enable volume management privileges. User Right: Manage the files on a volume.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege ManageVolume = new Privilege("SeManageVolumePrivilege");

      #endregion // ManageVolume

      #region ProfileSingleProcess

      /// <summary>Required to gather profiling information for a single process. User Right: Profile single process.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege ProfileSingleProcess = new Privilege("SeProfileSingleProcessPrivilege");

      #endregion // ProfileSingleProcess

      #region Relabel

      /// <summary>Required to modify the mandatory integrity level of an object. User Right: Modify an object label.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Relabel")]
      public static readonly Privilege Relabel = new Privilege("SeRelabelPrivilege");

      #endregion // Relabel

      #region RemoteShutdown

      /// <summary>Required to shut down a system using a network request. User Right: Force shutdown from a remote system.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege RemoteShutdown = new Privilege("SeRemoteShutdownPrivilege");

      #endregion // RemoteShutdown

      #region Restore

      /// <summary>Required to perform restore operations. This privilege causes the system to grant all write access control to any file, regardless of the ACL specified for the file. Any access request other than write is still evaluated with the ACL. Additionally, this privilege enables you to set any valid user or group SID as the owner of a file. User Right: Restore files and directories.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege Restore = new Privilege("SeRestorePrivilege");

      #endregion // Restore

      #region Security

      /// <summary>Required to perform a number of security-related functions, such as controlling and viewing audit messages. This privilege identifies its holder as a security operator. User Right: Manage auditing and security log.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege Security = new Privilege("SeSecurityPrivilege");

      #endregion // Security

      #region Shutdown

      /// <summary>Required to shut down a local system. User Right: Shut down the system.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege Shutdown = new Privilege("SeShutdownPrivilege");

      #endregion // Shutdown

      #region SyncAgent

      /// <summary>Required for a domain controller to use the LDAP directory synchronization services. This privilege enables the holder to read all objects and properties in the directory, regardless of the protection on the objects and properties. By default, it is assigned to the Administrator and LocalSystem accounts on domain controllers. User Right: Synchronize directory service data.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege SyncAgent = new Privilege("SeSyncAgentPrivilege");

      #endregion // SyncAgent

      #region SystemEnvironment

      /// <summary>Required to modify the nonvolatile RAM of systems that use this type of memory to store configuration information. User Right: Modify firmware environment values.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege SystemEnvironment = new Privilege("SeSystemEnvironmentPrivilege");

      #endregion // SystemEnvironment

      #region SystemProfile

      /// <summary>Required to gather profiling information for the entire system. User Right: Profile system performance.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege SystemProfile = new Privilege("SeSystemProfilePrivilege");

      #endregion // SystemProfile

      #region SystemTime

      /// <summary>Required to modify the system time. User Right: Change the system time.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege SystemTime = new Privilege("SeSystemtimePrivilege");

      #endregion // SystemTime

      #region TakeOwnership

      /// <summary>Required to take ownership of an object without being granted discretionary access. This privilege allows the owner value to be set only to those values that the holder may legitimately assign as the owner of an object. User Right: Take ownership of files or other objects.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege TakeOwnership = new Privilege("SeTakeOwnershipPrivilege");

      #endregion // TakeOwnership

      #region Tcb

      /// <summary>This privilege identifies its holder as part of the trusted computer base. Some trusted protected subsystems are granted this privilege. User Right: Act as part of the operating system.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Tcb")]
      public static readonly Privilege Tcb = new Privilege("SeTcbPrivilege");

      #endregion // Tcb

      #region TimeZone

      /// <summary>Required to adjust the time zone associated with the computer's internal clock. User Right: Change the time zone.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege TimeZone = new Privilege("SeTimeZonePrivilege");

      #endregion // TimeZone

      #region TrustedCredManAccess

      /// <summary>Required to access Credential Manager as a trusted caller. User Right: Access Credential Manager as a trusted caller.</summary>
      [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Cred")]
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege TrustedCredManAccess = new Privilege("SeTrustedCredManAccessPrivilege");

      #endregion // TrustedCredManAccess

      #region Undock

      /// <summary>Required to undock a laptop. User Right: Remove computer from docking station.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege Undock = new Privilege("SeUndockPrivilege");

      #endregion // Undock

      #region UnsolicitedInput

      /// <summary>Required to read unsolicited input from a terminal device. User Right: Not applicable.</summary>
      [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes")]
      public static readonly Privilege UnsolicitedInput = new Privilege("SeUnsolicitedInputPrivilege");

      #endregion // UnsolicitedInput

      #endregion // System Privileges

      #region Privilege

      private readonly string _systemName;

      /// <summary>Create a new <see cref="Privilege"/> representing the specified privilege on the specified system.</summary>
      /// <param name="systemName">Name of the system.</param>
      /// <param name="privilege">The privilege to copy the privilege name from.</param>
      public Privilege(string systemName, Privilege privilege)
      {
         if (Utils.IsNullOrWhiteSpace(systemName))
            throw new ArgumentException(Resources.Privilege_Name_Cannot_Be_Empty, "systemName");

         _systemName = systemName;

         if (privilege != null)
            _name = privilege._name;
      }

      #endregion // Privilege

      #region Name

      private readonly string _name;

      /// <summary>Gets the system name identifying this privilege.</summary>
      /// <value>The system name identifying this privilege.</value>
      public string Name
      {
         get { return _name; }
      }

      #endregion // Name

      #region LookupDisplayName

      /// <summary>Retrieves the display name that represents this privilege.</summary>
      /// <returns>The display name that represents this privilege.</returns>
      [SecurityCritical]
      public string LookupDisplayName()
      {
         const uint initialCapacity = 10;
         uint displayNameCapacity = initialCapacity;
         StringBuilder displayName = new StringBuilder((int) displayNameCapacity);
         uint languageId;

         if (!NativeMethods.LookupPrivilegeDisplayName(_systemName, _name, ref displayName, ref displayNameCapacity, out languageId))
         {
            int lastError = Marshal.GetLastWin32Error();
            if (lastError == Win32Errors.ERROR_INSUFFICIENT_BUFFER)
            {
               displayName = new StringBuilder((int) displayNameCapacity + 1);
               if (!NativeMethods.LookupPrivilegeDisplayName(_systemName, _name, ref displayName, ref displayNameCapacity, out languageId))
                  NativeError.ThrowException(Marshal.GetLastWin32Error());
            }
            else
               NativeError.ThrowException(lastError);
         }
         return displayName.ToString();
      }

      #endregion // LookupDisplayName

      #region LookupLuid

      /// <summary>Retrieves the locally unique identifier (LUID) used on to represent this privilege (on the system from which it originates).</summary>
      /// <returns>the locally unique identifier (LUID) used on to represent this privilege (on the system from which it originates).</returns>
      [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Luid")]
      [SecurityCritical]      
      public long LookupLuid()
      {
         Luid luid;

         if (!NativeMethods.LookupPrivilegeValue(_systemName, _name, out luid))
            NativeError.ThrowException(Marshal.GetLastWin32Error());

         return Filesystem.NativeMethods.LuidToLong(luid);
      }

      #endregion // LookupLuid

      #region Equals

      /// <summary>Indicates whether the current object is equal to another object of the same type.</summary>
      /// <param name="other">An object to compare with this object.</param>
      /// <returns><see langword="true"/> if the current object is equal to the <paramref name="other"/> parameter; otherwise, <see langword="false"/>.</returns>
      public bool Equals(Privilege other)
      {
         if (other == null)
            return false;

         return _name.Equals(other._name, StringComparison.OrdinalIgnoreCase) &&
                ((_systemName == null && other._systemName == null) ||
                 (_systemName != null && _systemName.Equals(other._systemName, StringComparison.OrdinalIgnoreCase)));
      }

      /// <summary>Determines whether the specified <see cref="System.Object"/> is equal to the current <see cref="System.Object"/>.</summary>
      /// <param name="obj">The <see cref="System.Object"/> to compare with the current <see cref="System.Object"/>.</param>
      /// <returns><see langword="true"/> if the specified <see cref="System.Object"/> is equal to the current <see cref="System.Object"/>; otherwise, <see langword="false"/>.</returns>
      /// <exception cref="NullReferenceException"/>
      public override bool Equals(object obj)
      {
         Privilege other = obj as Privilege;

         if (other == null)
            return false;

         return _name.Equals(other._name, StringComparison.OrdinalIgnoreCase) &&
                ((_systemName == null && other._systemName == null) ||
                 (_systemName != null && _systemName.Equals(other._systemName, StringComparison.OrdinalIgnoreCase)));
      }

      #endregion // Equals

      #region GetHashCode

      // A random prime number will be picked and added to the HashCode, each time an instance is created.
      [NonSerialized] private readonly int _random = new Random().Next(0, 19);
      [NonSerialized] private static readonly int[] Primes = { 17, 23, 29, 37, 47, 59, 71, 89, 107, 131, 163, 197, 239, 293, 353, 431, 521, 631, 761, 919 };

      /// <summary>Serves as a hash function for a particular type.</summary>
      /// <returns>A hash code for the current Object.</returns>
      public override int GetHashCode()
      {
         unchecked
         {
            int hash = Primes[_random];

            if (!Utils.IsNullOrWhiteSpace(_name))
               hash = hash * Primes[1] + _name.GetHashCode();

            if (!Utils.IsNullOrWhiteSpace(_systemName))
               hash = hash * Primes[1] + _systemName.GetHashCode();

            return hash;
         }
      }

      #endregion // GetHashCode

      #region ToString

      /// <summary>Returns the system name for this privilege.</summary>
      /// <remarks>This is equivalent to <see cref="Privilege.Name"/>.</remarks>
      /// <returns>A <see cref="System.String"/> that represents the current <see cref="System.Object"/>.</returns>
      public override string ToString()
      {
         return _name;
      }

      #endregion // ToString

      #region Privilege

      /// <summary>Initializes a new instance of the <see cref="Privilege"/> class, representing a privilege with the specified name on the local system.</summary>
      /// <param name="name">The name.</param>
      private Privilege(string name)
      {
         if (Utils.IsNullOrWhiteSpace(name))
            throw new ArgumentException(Resources.Privilege_Name_Cannot_Be_Empty, "name");

         _name = name;
      }

      #endregion // Privilege
   }
}