/* Copyright (C) 2017-2018 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
{
    /// <summary>
    /// [MS-FSCC] 2.4.40 - FileStreamInformation data element
    /// </summary>
    public class FileStreamEntry
    {
        public const int FixedLength = 24;

        public uint NextEntryOffset;
        private uint StreamNameLength;
        public long StreamSize;
        public long StreamAllocationSize;
        public string StreamName = String.Empty;

        public FileStreamEntry()
        {
        }

        public FileStreamEntry(byte[] buffer, int offset)
        {
            NextEntryOffset = LittleEndianConverter.ToUInt32(buffer, offset + 0);
            StreamNameLength = LittleEndianConverter.ToUInt32(buffer, offset + 4);
            StreamSize = LittleEndianConverter.ToInt64(buffer, offset + 8);
            StreamAllocationSize = LittleEndianConverter.ToInt64(buffer, offset + 16);
            StreamName = ByteReader.ReadUTF16String(buffer, offset + 24, (int)StreamNameLength / 2);
        }

        public void WriteBytes(byte[] buffer, int offset)
        {
            StreamNameLength = (uint)(StreamName.Length * 2);
            LittleEndianWriter.WriteUInt32(buffer, offset + 0, NextEntryOffset);
            LittleEndianWriter.WriteUInt32(buffer, offset + 4, StreamNameLength);
            LittleEndianWriter.WriteInt64(buffer, offset + 8, StreamSize);
            LittleEndianWriter.WriteInt64(buffer, offset + 16, StreamAllocationSize);
            ByteWriter.WriteUTF16String(buffer, offset + 24, StreamName);
        }

        public int Length
        {
            get
            {
                return FixedLength + StreamName.Length * 2;
            }
        }

        /// <summary>
        /// [MS-FSCC] When multiple FILE_STREAM_INFORMATION data elements are present in the buffer, each MUST be aligned on an 8-byte boundary
        /// </summary>
        public int PaddedLength
        {
            get
            {
                int length = this.Length;
                int padding = (8 - (length % 8)) % 8;
                return length + padding;
            }
        }
    }
}