using System;
using System.IO;
using System.Diagnostics;

namespace TwlBackupBlock
{
    /// <summary>
    /// ヘッダブロックのデータ本体。
    /// </summary>
    public class HeaderBody : AbstractBody
    {
        public const int HEADER_SIZE = 160;

        public const int UNIQUE_ID_SIZE = 32;
        public const int HARDWARE_ID_SIZE = 16;
        public const int NUM_OF_SECTION = 4;
        public const int TMD_RESERVED_SIZE = 62;
        public const int RESERVED_SIZE = 4;

        public UInt32 signature;
        public UInt16 companyCode;
        public UInt16 version;
        public readonly Byte[] uniqueId;
        public readonly Byte[] hardwareId;
        public UInt64 titleId;
        public Int64 requiredSize;
        public readonly UInt32[] fileSizes;
        public UInt32 contentId;
        public readonly TmdReserved tmdReserved;
        public UInt16 contentIndex;
        public readonly Byte[] reserved;

        public HeaderBody(byte[] data)
        {
            if (data == null)
            {
                throw new ArgumentNullException("data");
            }
            if (data.Length != HEADER_SIZE)
            {
                string message = string.Format("data.Length % {0} != 0 (data.Length:{1})", HEADER_SIZE, data.Length);
                throw new ArgumentException("data", message);
            }

            uniqueId = new Byte[UNIQUE_ID_SIZE];
            hardwareId = new Byte[HARDWARE_ID_SIZE];
            fileSizes = new UInt32[NUM_OF_SECTION];
            tmdReserved = new TmdReserved();
            reserved = new Byte[RESERVED_SIZE];

            SetBytes(data);
        }

        public override byte this[int index]
        {
            get
            {
                if (index < 0 || index >= HEADER_SIZE)
                {
                    throw new ArgumentException("index");
                }
                return ReadByte(index);
            }
            set
            {
                if (index < 0 || index >= HEADER_SIZE)
                {
                    throw new ArgumentException("index");
                }
                WriteByte(index, value);
            }
        }

        public override int Length
        {
            get
            {
                return HEADER_SIZE;
            }
        }

        /// <summary>
        /// 指定したバイトを取得します。
        /// </summary>
        /// <param name="index">取得したいバイトのインデックス。</param>
        /// <returns><paramref name="index"/>で指定したバイト</returns>
        public byte ReadByte(int index)
        {
            if (index < 0 || index >= HEADER_SIZE)
            {
                throw new ArgumentException("index");
            }
            // TODO 処理が遅ければ効率化
            byte[] bytes = GetBytes();
            return bytes[index];
        }

        /// <summary>
        /// 指定したバイトを書き換えます。
        /// </summary>
        /// <param name="index">書き換えたいバイトのインデックス。</param>
        /// <param name="b">上書きに使うバイト。</param>
        public void WriteByte(int index, byte b)
        {
            if (index < 0 || index >= HEADER_SIZE)
            {
                throw new ArgumentException("index");
            }
            // TODO 処理が遅ければ効率化
            byte[] bytes = GetBytes();
            bytes[index] = b;
            SetBytes(bytes);
        }

        public override byte[] GetBytes()
        {
            byte[] bytes = new byte[HEADER_SIZE];

            using (var ms = new MemoryStream(bytes))
            using (var bw = new BinaryWriter(ms))
            {
                bw.Write(signature);
                bw.Write(companyCode);
                bw.Write(version);
                bw.Write(uniqueId);
                bw.Write(hardwareId);
                bw.Write(titleId);
                bw.Write(requiredSize);
                foreach (UInt32 e in fileSizes)
                {
                    bw.Write(e);
                }
                bw.Write(contentId);
                bw.Write(tmdReserved.GetBytes());
                bw.Write(contentIndex);
                bw.Write(reserved);

                Debug.Assert(ms.Position == HEADER_SIZE);
            }

            return bytes;
        }

        public override void SetBytes(byte[] bytes)
        {
            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }
            if (bytes.Length != HEADER_SIZE)
            {
                string message = string.Format("bytes.Length != {0} (bytes.Length:{1})", HEADER_SIZE, bytes.Length);
                throw new ArgumentException("bytes", message);
            }

            using (var ms = new MemoryStream(bytes))
            using (var br = new ExtBinaryReader(ms))
            {
                br.Read(ref signature);
                br.Read(ref companyCode);
                br.Read(ref version);
                br.Read(uniqueId);
                br.Read(hardwareId);
                br.Read(ref titleId);
                br.Read(ref requiredSize);
                br.Read(fileSizes);
                br.Read(ref contentId);
                {
                    byte[] tmdReservedBytes = new byte[TMD_RESERVED_SIZE];
                    br.Read(tmdReservedBytes);
                    tmdReserved.SetBytes(tmdReservedBytes);
                }
                br.Read(ref contentIndex);
                br.Read(reserved);

                Debug.Assert(ms.Position == HEADER_SIZE);
            }
        }

        public override object Clone()
        {
            return new HeaderBody(GetBytes());
        }
    }

    /// <summary>
    /// ヘッダブロック中のTMDReserved。
    /// </summary>
    public class TmdReserved
    {
        private const int TMD_RESERVED_SIZE = 62;

        public const int RESERVED8_SIZE = 3;
        public const int PARENTAL_CONTROL_SIZE = 16;
        public const int RESERVED_SIZE = 30;

        public UInt32 publicSaveSize;
        public UInt32 privateSaveSize;
        public UInt32 reserved32;
        public Byte flags;
        public readonly Byte[] reserved8;
        public readonly Byte[] parentalControl;
        public readonly Byte[] reserved;

        public TmdReserved()
        {
            reserved8 = new Byte[RESERVED8_SIZE];
            parentalControl = new Byte[PARENTAL_CONTROL_SIZE];
            reserved = new Byte[RESERVED_SIZE];
        }

        public byte[] GetBytes()
        {
            byte[] bytes = new byte[TMD_RESERVED_SIZE];

            using (var ms = new MemoryStream(bytes))
            using (var bw = new BinaryWriter(ms))
            {
                bw.Write(publicSaveSize);
                bw.Write(privateSaveSize);
                bw.Write(reserved32);
                bw.Write(flags);
                bw.Write(reserved8);
                bw.Write(parentalControl);
                bw.Write(reserved);

                Debug.Assert(ms.Position == TMD_RESERVED_SIZE);
            }

            return bytes;
        }

        public void SetBytes(byte[] bytes)
        {
            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }
            if (bytes.Length != TMD_RESERVED_SIZE)
            {
                string message = string.Format("bytes.Length != {0} (bytes.Length:{1})", TMD_RESERVED_SIZE, bytes.Length);
                throw new ArgumentException("bytes", message);
            }

            using (var ms = new MemoryStream(bytes))
            using (var br = new ExtBinaryReader(ms))
            {
                br.Read(ref publicSaveSize);
                br.Read(ref privateSaveSize);
                br.Read(ref reserved32);
                br.Read(ref flags);
                br.Read(reserved8);
                br.Read(parentalControl);
                br.Read(reserved);

                Debug.Assert(ms.Position == TMD_RESERVED_SIZE);
            }
        }
    }
}