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 NORMAL_HEADER_SIZE = 240;
        public const int EX_HEADER_SIZE = 256;
        public const int LEGACY_HEADER_SIZE = 160;

        public const int UNIQUE_ID_SIZE = 32;
        public const int HARDWARE_ID_SIZE = 16;
        public const int MAX_CONTENTS = 8;
        public const int NUM_OF_SECTION = 11;
        public const int TMD_RESERVED_SIZE = 62;
        public const int RESERVED_SIZE = 13;

        // for WithPrivateSave
        public const int RESERVED_SIZE_FOR_WPS = 12;

        // for Legacy
        public const int RESERVED_SIZE_FOR_LEGACY = 4;
        public const int NUM_OF_SECTION_LEGACY = 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 readonly UInt32[] contentId;
        public readonly UInt16[] contentIndex;
        public readonly TmdReserved tmdReserved;
        public Byte headerVersion;
        public readonly Byte[] reserved;

        // for WithPrivateSave
        public UInt32 privateSaveForWPS;
        public readonly Byte[] reservedForWPS;

        // for Legacy
        public UInt32 contentIdForLegacy;
        public UInt16 contentIndexForLegacy;

        private BkpType type;
        private int headerSize;

        public HeaderBody(byte[] data, BkpType type)
        {
            this.type = type;
            switch (this.type)
            {
                case BkpType.NORMAL:
                    headerSize = NORMAL_HEADER_SIZE;
                    break;
                case BkpType.WITH_PRIVATE_SAVE:
                    headerSize = EX_HEADER_SIZE;
                    break;
                case BkpType.LEGACY:
                    headerSize = LEGACY_HEADER_SIZE;
                    break;
            }

            if (data == null)
            {
                throw new ArgumentNullException("data");
            }
            if (data.Length != headerSize)
            {
                string message = string.Format("data.Length % {0} != 0 (data.Length:{1})", headerSize, data.Length);
                throw new ArgumentException("data", message);
            }

            uniqueId = new Byte[UNIQUE_ID_SIZE];
            hardwareId = new Byte[HARDWARE_ID_SIZE];
            if (type != BkpType.LEGACY)
            {
                fileSizes = new UInt32[NUM_OF_SECTION];
                contentId = new UInt32[MAX_CONTENTS];
                contentIndex = new UInt16[MAX_CONTENTS];
                reserved = new Byte[RESERVED_SIZE];
            }
            else
            {
                fileSizes = new UInt32[NUM_OF_SECTION_LEGACY];
                reserved = new Byte[RESERVED_SIZE_FOR_LEGACY];
            }
            tmdReserved = new TmdReserved();
            if (type == BkpType.WITH_PRIVATE_SAVE)
            {
                reservedForWPS = new Byte[RESERVED_SIZE_FOR_WPS];
            }

            SetBytes(data);
        }

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

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

        /// <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 >= headerSize)
            {
                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 >= headerSize)
            {
                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[headerSize];

            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);
                }
                if (type != BkpType.LEGACY)
                {
                    foreach (UInt32 e in contentId)
                    {
                        bw.Write(e);
                    }
                }
                else
                {
                    bw.Write(contentIdForLegacy);
                }
                if (type != BkpType.LEGACY)
                {
                    foreach (UInt16 e in contentIndex)
                    {
                        bw.Write(e);
                    }
                }
                bw.Write(tmdReserved.GetBytes());
                if (type == BkpType.LEGACY)
                {
                    bw.Write(contentIndexForLegacy);
                }
                if (type != BkpType.LEGACY)
                {
                    bw.Write(headerVersion);
                }
                bw.Write(reserved);
                if (type == BkpType.WITH_PRIVATE_SAVE)
                {
                    bw.Write(privateSaveForWPS);
                    bw.Write(reservedForWPS);
                }

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

            return bytes;
        }

        public override void SetBytes(byte[] bytes)
        {
            if (bytes == null)
            {
                throw new ArgumentNullException("bytes");
            }
            if (bytes.Length != headerSize)
            {
                string message = string.Format("bytes.Length != {0} (bytes.Length:{1})", headerSize, 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);
                if (type != BkpType.LEGACY)
                {
                    br.Read(contentId);
                }
                else
                {
                    br.Read(ref contentIdForLegacy);
                }
                if (type != BkpType.LEGACY)
                {
                    br.Read(contentIndex);
                }
                {
                    byte[] tmdReservedBytes = new byte[TMD_RESERVED_SIZE];
                    br.Read(tmdReservedBytes);
                    tmdReserved.SetBytes(tmdReservedBytes);
                }
                if (type == BkpType.LEGACY)
                {
                    br.Read(ref contentIndexForLegacy);
                }
                if (type != BkpType.LEGACY)
                {
                    br.Read(ref headerVersion);
                }
                br.Read(reserved);
                if (type == BkpType.WITH_PRIVATE_SAVE)
                {
                    br.Read(ref privateSaveForWPS);
                    br.Read(reservedForWPS);
                }

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

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