using System.IO;


namespace ProtoCSStruct
{
    /// <summary>
    /// 定义接口，方便代码使用
    /// </summary>
    public interface IStructMessage
    {
        void ReadFrom(CodedInputStream input);
        void WriteTo(CodedOutputStream output);
        int CalculateSize();//打包后的大小
        void Clear();
        string GetName();
        string ToString();
        int StructSizeof(); //结构体内存大小(估算，不完全正确)
    }

    public interface IStructMessage<T> : IStructMessage where T : struct, IStructMessage<T>
    {

    }

    public interface IStructMessageParser
    {
        void ParseFrom(byte[] data, int length);
        string GetMessageString();
        string GetMessageName();
        IStructMessageParser Clone();
        int GetStructSizeof();
    }

    public class StructMessageParser<T> : IStructMessageParser where T : struct, IStructMessage<T>
    {
        /// <summary>
        /// 线程不安全，请逻辑层自己注意!!!
        /// </summary>
        T structData;

        CodedInputStream input;

        public void ParseFrom(byte[] data, int length)
        {
            if(input != null)
            {
                input.Init(data, 0, length);
            }
            else
            {
                input = new CodedInputStream(data, 0, length);
            }

            structData.Clear();
            structData.ReadFrom(input);
            return;
        }

        public string GetMessageString()
        {
            return structData.ToString();
        }

        public string GetMessageName()
        {
            return structData.GetName();
        }

        public ref T GetMessage()
        {
            return ref structData;
        }

        public ref T GetMessageClear()
        {
            structData.Clear();
            return ref structData;
        }

        public IStructMessageParser Clone()
        {
            var cloneParser = new StructMessageParser<T>();
            cloneParser.structData = this.structData;

            return cloneParser;
        }

        public int GetStructSizeof()
        {
            return structData.StructSizeof();
        }

    }

    /// <summary>
    /// parse 整个buffer
    /// </summary>
    public static class StructMessageParseUtils
    {
        public static void ParseFrom<T>(ref T message, byte[] buffer )
             where T : struct, IStructMessage<T>
        {
            CodedInputStream input = new CodedInputStream(buffer);
            message.ReadFrom(input);
        }

        public static byte[] ToByteArray<T>(ref T message)
             where T : struct, IStructMessage<T>
        {
            int size = message.CalculateSize();
            if (size == 0) return new byte[0];
            byte[] buffer = new byte[size];

            CodedOutputStream output = new CodedOutputStream(buffer);

            message.WriteTo(output);
            //return buffer.Skip(0).Take(size).ToArray();
            return buffer;
        }
    }

    
}