//  Copyright 2020 Google Inc. All Rights Reserved.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

using NtApiDotNet;
using System;
using System.Management.Automation;

namespace NtObjectManager.Cmdlets.Object
{
    /// <summary>
    /// <para type="synopsis">Set a NT token on a process or thread.</para>
    /// <para type="description">This cmdlet sets a token on a process or thread.</para>
    /// </summary>
    /// <example>
    ///   <code>Set-NtToken -Token $token -Process $process</code>
    ///   <para>Set a process' primary token.</para>
    /// </example>
    /// <example>
    ///   <code>Set-NtToken -Token $token -Process $process -Duplicate</code>
    ///   <para>Set a process' primary token, duplicating it before use.</para>
    /// </example>
    /// <example>
    ///   <code>Set-NtToken -Token $token -ProcessId 1234</code>
    ///   <para>Set a process' primary token from its PID.</para>
    /// </example>
    /// <example>
    ///   <code>Set-NtToken -Token $token -Thread $thread</code>
    ///   <para>Set a thread's impersonation token.</para>
    /// </example>
    /// <example>
    ///   <code>Set-NtToken -Token $token -Thread $thread -Duplicate -ImpersonationLevel Identification</code>
    ///   <para>Set a thread's impersonation token, duplicating as an Identification level token first..</para>
    /// </example>
    /// <example>
    ///   <code>Set-NtToken -Token $token -ThreadId 1234</code>
    ///   <para>Set a thread's impersonation token from its TID.</para>
    /// </example>
    /// <para type="link">about_ManagingNtObjectLifetime</para>
    [Cmdlet(VerbsCommon.Set, "NtToken", DefaultParameterSetName = "Process")]
    public class SetNtTokenCmdlet : PSCmdlet
    {
        /// <summary>
        /// <para type="description">Specify the process to set the token on.</para>
        /// </summary>
        [Parameter(Mandatory = true, Position = 1, ParameterSetName = "Process")]
        public NtProcess Process { get; set; }

        /// <summary>
        /// <para type="description">Specify the process to set the token on.as a PID.</para>
        /// </summary>
        [Parameter(Mandatory = true, Position = 1, ParameterSetName = "ProcessId"), Alias("pid")]
        public int ProcessId { get; set; }

        /// <summary>
        /// <para type="description">Specify the thread to set the token on.</para>
        /// </summary>
        [Parameter(Mandatory = true, Position = 1, ParameterSetName = "Thread")]
        public NtThread Thread { get; set; }

        /// <summary>
        /// <para type="description">Specify the thread to set the token on as a TID.</para>
        /// </summary>
        [Parameter(Mandatory = true, ParameterSetName = "ThreadId"), Alias("tid")]
        public int ThreadId { get; set; }

        /// <summary>
        /// <para type="description">Duplicate the token before setting it.</para>
        /// </summary>
        [Parameter]
        public SwitchParameter Duplicate { get; set; }

        /// <summary>
        /// <para type="description">Specify the token to set.</para>
        /// </summary>
        [Parameter(Mandatory = true, Position = 0)]
        public NtToken Token { get; set; }

        /// <summary>
        /// <para type="description">Specify the impersonation level of the token to assign if -Duplicate is specified.</para>
        /// </summary>
        [Parameter(ParameterSetName = "Thread"), Parameter(ParameterSetName = "ThreadId")]
        public SecurityImpersonationLevel ImpersonationLevel { get; set; }

        /// <summary>
        /// <para type="description">Specify the integrity level of the token to set if -Duplicate is specified.</para>
        /// </summary>
        [Parameter]
        public TokenIntegrityLevel? IntegrityLevel { get; set; }

        private bool IsProcess()
        {
            switch (ParameterSetName)
            {
                case "Process":
                case "ProcessId":
                    return true;
                case "Thread":
                case "ThreadId":
                    return false;
                default:
                    throw new ArgumentException("Invalid parameter set.");
            }
        }

        private NtToken GetToken()
        {
            if (!Duplicate)
                return Token.Duplicate();

            TokenType type = IsProcess() ? TokenType.Primary : TokenType.Impersonation;

            using (var token = Token.DuplicateToken(type, ImpersonationLevel, TokenAccessRights.MaximumAllowed))
            {
                if (IntegrityLevel.HasValue)
                {
                    token.IntegrityLevel = IntegrityLevel.Value;
                }
                return token.Duplicate();
            }
        }

        private NtProcess GetProcess()
        {
            if (ParameterSetName == "Process")
                return Process.Duplicate(ProcessAccessRights.SetInformation);
            return NtProcess.Open(ProcessId, ProcessAccessRights.SetInformation);
        }

        private NtThread GetThread()
        {
            if (ParameterSetName == "Thread")
                return Thread.Duplicate(ThreadAccessRights.Impersonate);
            return NtThread.Open(ThreadId, ThreadAccessRights.Impersonate);
        }

        /// <summary>
        /// Overridden ProcessRecord method.
        /// </summary>
        protected override void ProcessRecord()
        {
            using (var token = GetToken())
            {
                if (IsProcess())
                {
                    using (var proc = GetProcess())
                    {
                        proc.SetToken(token);
                    }
                }
                else
                {
                    using (var thread = GetThread())
                    {
                        thread.Impersonate(token);
                    }
                }
            }
        }
    }
}
