/* Copyright (C) 2017 Tal Aloni <tal.aloni.il@gmail.com>. All rights reserved.
 * 
 * You can redistribute this program and/or modify it under the terms of
 * the GNU Lesser Public License as published by the Free Software Foundation,
 * either version 3 of the License, or (at your option) any later version.
 */
using System;
using System.Collections.Generic;
using Utilities;

namespace SMBLibrary.SMB2
{
    /// <summary>
    /// SMB2 NEGOTIATE Request
    /// </summary>
    public class NegotiateRequest : SMB2Command
    {
        public const int DeclaredSize = 36;

        public ushort StructureSize;
        private ushort DialectCount;
        public SecurityMode SecurityMode;
        public ushort Reserved;
        public ServerCapabilities Capabilities;
        public Guid ClientGuid;
        public DateTime ClientStartTime;
        public List<SMB2Dialect> Dialects = new List<SMB2Dialect>();

        public NegotiateRequest() : base(SMB2CommandName.Negotiate)
        {
            StructureSize = DeclaredSize;
        }

        public NegotiateRequest(byte[] buffer, int offset) : base(buffer, offset)
        {
            StructureSize = LittleEndianConverter.ToUInt16(buffer, offset + SMB2Header.Length + 0);
            DialectCount = LittleEndianConverter.ToUInt16(buffer, offset + SMB2Header.Length + 2);
            SecurityMode = (SecurityMode)LittleEndianConverter.ToUInt16(buffer, offset + SMB2Header.Length + 4);
            Reserved = LittleEndianConverter.ToUInt16(buffer, offset + SMB2Header.Length + 6);
            Capabilities = (ServerCapabilities)LittleEndianConverter.ToUInt32(buffer, offset + SMB2Header.Length + 8);
            ClientGuid = LittleEndianConverter.ToGuid(buffer, offset + SMB2Header.Length + 12);
            ClientStartTime = DateTime.FromFileTimeUtc(LittleEndianConverter.ToInt64(buffer, offset + SMB2Header.Length + 28));

            for (int index = 0; index < DialectCount; index++)
            {
                SMB2Dialect dialect = (SMB2Dialect)LittleEndianConverter.ToUInt16(buffer, offset + SMB2Header.Length + 36 + index * 2);
                Dialects.Add(dialect);
            }
        }

        public override void WriteCommandBytes(byte[] buffer, int offset)
        {
            LittleEndianWriter.WriteUInt16(buffer, offset + 0, StructureSize);
            LittleEndianWriter.WriteUInt16(buffer, offset + 2, DialectCount);
            LittleEndianWriter.WriteUInt16(buffer, offset + 4, (ushort)SecurityMode);
            LittleEndianWriter.WriteUInt16(buffer, offset + 6, Reserved);
            LittleEndianWriter.WriteUInt32(buffer, offset + 8, (uint)Capabilities);
            LittleEndianWriter.WriteGuidBytes(buffer, offset + 12, ClientGuid);
            LittleEndianWriter.WriteInt64(buffer, offset + 28, ClientStartTime.ToFileTimeUtc());
            
            for (int index = 0; index < Dialects.Count; index++)
            {
                SMB2Dialect dialect = Dialects[index];
                LittleEndianWriter.WriteUInt16(buffer, offset + 36 + index * 2, (ushort)dialect);
            }
        }

        public override int CommandLength
        {
            get
            {
                return 36 + Dialects.Count * 2;
            }
        }
    }
}