using System;
using System.IO;
using System.Net;
using UnityEngine;
using zlib;

namespace BF
{
    /// <summary>
    /// @TODO GC
    /// </summary>
    internal class NetChannelMessageService : INetChannelMessageService
    {
        private readonly bool isLittleEndian;
        private readonly bool isCompress;

        private NetAesEncrypt encrypt;
        private NetAesEncrypt decrypt;

        /// <summary>
        /// 数据包的头部长度，version + Compress + Seq + Group + Cmd 共8位
        /// </summary>
        private int HeaderLength => 4;

        /// <summary>
        /// 数据包头部长度，使用int类型表示，四个字节
        /// </summary>
        private int HeaderLengthBytesSize => 4;

        public NetChannelMessageService()
        {
            isLittleEndian = BitConverter.IsLittleEndian;
            isCompress = false;
        }

        public void SetEncrypt(NetAesEncrypt encrypt)
        {
            this.encrypt = encrypt;
        }

        public void SetDecrypt(NetAesEncrypt decrypt)
        {
            this.decrypt = decrypt;
        }

        public int ReadBodyLength(CircularBuffer circularBuffer)
        {
            int bodyLength = 0;
            if (circularBuffer.HowManyCanRead >= HeaderLengthBytesSize)
            {
                byte[] head1 = circularBuffer.Read(HeaderLengthBytesSize);
                byte[] head = new byte[4];
                head[0] = head1[3];
                head[1] = head1[2];
                head[2] = head1[1];
                head[3] = head1[0];
                bodyLength = BitConverter.ToInt32(head, 0);
                if (isLittleEndian)
                {
                    bodyLength = IPAddress.NetworkToHostOrder(bodyLength);
                }
                if (bodyLength <= 0)
                {
                    bodyLength = -1;
                }
            }
            return bodyLength;
        }

        public bool Serialize(NetOutgoingMessage message, MemoryStream destination)
        {
            try
            {
                //first write data package size, packageSize = header.length + data.length
                byte[] packageLengthData = null;
                // short packageLength = 0;
                int packageLength = 0;
                if (message.Group != 0)
                {
                    // packageLength = (short)(message.PackDataLength + HeaderLength);
                    packageLength = message.PackDataLength + HeaderLength*2;
                }
                else
                {
                    // packageLength = (short)message.PackDataLength;
                    packageLength = message.PackDataLength;
                }

                if (isLittleEndian)
                {
                    packageLengthData = BitConverter.GetBytes(packageLength);
                }
                else
                {
                    packageLengthData = BitConverter.GetBytes(IPAddress.HostToNetworkOrder(packageLength));
                }

                destination.Write(packageLengthData, 0, packageLengthData.Length);

                var realSendBuffer = SerializeRaw(message);

                //is need encrypt
                if (message.Group != 0)
                {
                    if (encrypt == null)
                    {
                        throw new NotImplementedException("Serialize Error! NetAesEncrypt is null");
                    }
                    encrypt.Encrypt(realSendBuffer, 0, realSendBuffer.Length, realSendBuffer, 0);
                }

                destination.Write(realSendBuffer, 0, realSendBuffer.Length);
                return true;

            }
            catch (Exception)
            {
                return false;
            }
        }

        internal byte[] SerializeRaw(NetOutgoingMessage message)
        {
            if (message.Group != 0)
            {
                byte[] realSendBuffer = new byte[message.PackDataLength + HeaderLength*2];
                byte[] seqBytes = null;
                if (isLittleEndian)
                {
                    seqBytes = BitConverter.GetBytes(message.Seq);
                }
                else
                {
                    seqBytes = BitConverter.GetBytes(IPAddress.HostToNetworkOrder(message.Seq));
                }

                Array.Copy(seqBytes, 0, realSendBuffer, 0, HeaderLength);

                //create send buffer
                if (BitConverter.IsLittleEndian)
                {
                    realSendBuffer[7] = (byte)((message.Group >> 24) & 0xFF);
                    realSendBuffer[6] = (byte)((message.Group >> 16) & 0xFF);
                    realSendBuffer[5] = (byte)((message.Group >> 8) & 0xFF);
                    realSendBuffer[4] = (byte)(message.Group & 0xFF);
                }
                else
                {
                    realSendBuffer[4] = (byte)((message.Group >> 24) & 0xFF);
                    realSendBuffer[5] = (byte)((message.Group >> 16) & 0xFF);
                    realSendBuffer[6] = (byte)((message.Group >> 8) & 0xFF);
                    realSendBuffer[7] = (byte)(message.Group & 0xFF);
                }

                //write data
                Array.Copy(message.Data, 0, realSendBuffer, HeaderLength*2, message.PackDataLength);
                return realSendBuffer;
            }
            else
            {
                //create send buffer
                byte[] realSendBuffer = new byte[message.PackDataLength];

                Array.Copy(message.Data, 0, realSendBuffer, 0, message.PackDataLength);

                return realSendBuffer;
            }
        }

        /// <summary>
        /// @TODO Array GC
        /// </summary>
        /// <param name="message"></param>
        /// <returns></returns>
        public bool Deserialize(NetIncomingMessage message, uint receiveSeq)
        {
            try
            {
                decrypt.Decrypt(message.buffer, 0, message.buffer.Length, message.buffer, 0);
                DeserializeRaw(message, receiveSeq);
                if (message.IsCompress)
                {
                    message.buffer = DeCompressBuffer(message.buffer);
                }

                return true;

            }
            catch (Exception)
            {
                return false;
            }
        }

        internal void DeserializeRaw(NetIncomingMessage message, uint receiveSeq)
        {
            //head
            // message.Version = message.buffer[0];
            // message.IsCompress = message.buffer[1] != 0;
            // message.Group = message.buffer[2];
            // message.CMD = message.buffer[3];

            message.Group = (uint)(((message.buffer[7] & 0xFF) << 24)
                    | ((message.buffer[6] & 0xFF) << 16)
                    | ((message.buffer[5] & 0xFF) << 8)
                    | (message.buffer[4] & 0xFF));

            message.CMD = receiveSeq;
            var seq = BitConverter.ToInt32(message.buffer, 0);
            if (isLittleEndian)
            {
                message.Seq = (uint) seq;
            }
            else
            {
                message.Seq = (uint) IPAddress.NetworkToHostOrder(seq);
            }

            //data, @TODO only copy
            Array.Reverse(message.buffer);
            Array.Resize(ref message.buffer, message.buffer.Length - HeaderLength*2);
            Array.Reverse(message.buffer);
        }

        private byte[] DeCompressBuffer(byte[] byteArray)
        {
            using (MemoryStream outMemoryStream = new MemoryStream())
            {
                using (ZOutputStream outZStream = new ZOutputStream(outMemoryStream))
                {
                    using (Stream inMemoryStream = new MemoryStream(byteArray))
                    {
                        byte[] buffer = new byte[inMemoryStream.Length];
                        int len;
                        while ((len = inMemoryStream.Read(buffer, 0, buffer.Length)) > 0)
                        {
                            outZStream.Write(buffer, 0, len);
                        }
                        outZStream.Flush();
                        outZStream.finish();
                        return outMemoryStream.ToArray();
                    }
                }
            }
        }

        private byte[] CompressBuffer(byte[] byteArray)
        {
            using (MemoryStream outMemoryStream = new MemoryStream())
            {
                using (ZInputStream zInputStream = new ZInputStream(outMemoryStream))
                {
                    using (Stream inMemoryStream = new MemoryStream(byteArray))
                    {
                        byte[] buffer = new byte[inMemoryStream.Length];
                        int len;
                        while ((len = inMemoryStream.Read(buffer, 0, buffer.Length)) > 0)
                        {
                            zInputStream.Read(buffer, 0, len);
                        }

                        inMemoryStream.Flush();
                        return outMemoryStream.ToArray();
                    }
                }
            }
        }

    }
}