//  Copyright 2016 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">Duplicate an object to a new handle. Optionally specify processes to duplicate to.</para>
    /// <para type="description">This cmdlet duplicates an object either in the same process or between processes. If you duplicate to another process the cmdlet will return a handle value rather than an object.
    /// </para>
    /// </summary>
    /// <example>
    ///   <code>Copy-NtObject -Object $obj</code>
    ///   <para>Duplicate an object to another in the current process with same access rights.</para>
    /// </example>
    /// <example>
    ///   <code>Copy-NtObject -Object $obj -DestinationProcess $proc</code>
    ///   <para>Duplicate an object to another process. If the desintation process is the current process an object is returned, otherwise a handle is returned.</para>
    /// </example>
    /// <example>
    ///   <code>Copy-NtObject -Handle 1234 -SourceProcess $proc</code>
    ///   <para>Duplicate an object from another process to the current process.</para>
    /// </example>
    [Cmdlet(VerbsCommon.Copy, "NtObject")]
    [OutputType(typeof(NtObject))]
    public sealed class CopyNtObjectCmdlet : PSCmdlet
    {
        /// <summary>
        /// <para type="description">Specify the object to duplicate in the current process.</para>
        /// </summary>
        [Parameter(Mandatory = true, Position = 0, ParameterSetName = "FromObject", ValueFromPipeline = true)]
        public NtObject[] Object { get; set; }

        /// <summary>
        /// <para type="description">Specify the object to duplicate as a handle.</para>
        /// </summary>
        [Parameter(Mandatory = true, Position = 0, ParameterSetName = "FromHandle")]
        public IntPtr[] SourceHandle { get; set; }

        /// <summary>
        /// <para type="description">Specify the process to duplicate from.</para>
        /// </summary>
        [Parameter(ParameterSetName = "FromHandle")]
        public NtProcess SourceProcess { get; set; }

        /// <summary>
        /// <para type="description">Specify the process to duplicate to. Defaults to current process.</para>
        /// </summary>
        [Parameter]
        public NtProcess DestinationProcess { get; set; }

        /// <summary>
        /// <para type="description">The desired access for the duplication.</para>
        /// </summary>
        [Parameter]
        public GenericAccessRights? DesiredAccess { get; set; }

        /// <summary>
        /// <para type="description">The desired access for the duplication as an access mask.</para>
        /// </summary>
        [Parameter]
        public AccessMask? DesiredAccessMask { get; set; }

        /// <summary>
        /// <para type="description">Specify the no rights upgrade flags.</para>
        /// </summary>
        [Parameter]
        public SwitchParameter NoRightsUpgrade { get; set; }

        /// <summary>
        /// <para type="description">The desired object attribute flags for the duplication.</para>
        /// </summary>
        [Parameter]
        public AttributeFlags? ObjectAttributes { get; set; }

        /// <summary>
        /// <para type="description">Close the source handle.</para>
        /// </summary>
        [Parameter(ParameterSetName = "FromHandle")]
        public SwitchParameter CloseSource { get; set; }

        /// <summary>
        /// Constructor.
        /// </summary>
        public CopyNtObjectCmdlet()
        {
            SourceProcess = NtProcess.Current;
            DestinationProcess = NtProcess.Current;
        }

        private DuplicateObjectOptions GetOptions()
        {
            DuplicateObjectOptions options = DuplicateObjectOptions.None;
            if (!DesiredAccess.HasValue && !DesiredAccessMask.HasValue)
            {
                options |= DuplicateObjectOptions.SameAccess;
            }

            if (!ObjectAttributes.HasValue)
            {
                options |= DuplicateObjectOptions.SameAttributes;
            }

            if (CloseSource)
            {
                options |= DuplicateObjectOptions.CloseSource;
            }

            if (NoRightsUpgrade)
            {
                options |= DuplicateObjectOptions.NoRightsUpgrade;
            }

            return options;
        }

        private GenericAccessRights GetDesiredAccess()
        {
            if (DesiredAccess.HasValue)
            {
                return DesiredAccess.Value;
            }
            if (DesiredAccessMask.HasValue)
            {
                return DesiredAccessMask.Value.ToGenericAccess();
            }
            return GenericAccessRights.None;
        }

        private object GetObject(IntPtr handle)
        {
            using (var dup_obj = NtGeneric.DuplicateFrom(SourceProcess, handle, 
                GetDesiredAccess(), ObjectAttributes ?? 0, GetOptions()))
            {
                return dup_obj.ToTypedObject();
            }
        }

        private object GetHandle(IntPtr handle)
        {
            return NtObject.DuplicateHandle(SourceProcess, handle, DestinationProcess, 
                GetDesiredAccess(), ObjectAttributes ?? 0, GetOptions());
        }

        private object GetObject(NtObject obj)
        {
            return obj.DuplicateObject(GetDesiredAccess(), ObjectAttributes ?? 0, GetOptions());
        }

        private object GetHandle(NtObject obj)
        {
            return GetHandle(obj.Handle.DangerousGetHandle());
        }

        /// <summary>
        /// Process record.
        /// </summary>
        protected override void ProcessRecord()
        {
            if (ParameterSetName == "FromObject")
            {
                Func<NtObject, object> func;
                if (DestinationProcess.ProcessId == NtProcess.Current.ProcessId)
                {
                    func = GetObject;
                }
                else
                {
                    func = GetHandle;
                }

                foreach (var obj in Object)
                {
                    WriteObject(func(obj));
                }
            }
            else
            {
                Func<IntPtr, object> func;
                if (DestinationProcess.ProcessId == NtProcess.Current.ProcessId)
                {
                    func = GetObject;
                }
                else
                {
                    func = GetHandle;
                }

                foreach (var handle in SourceHandle)
                {
                    WriteObject(func(handle));
                }
            }
        }
    }
}
