#include "Communicate.h"

constexpr unsigned char gHeader[] = {0xFF, 0xFE};
constexpr unsigned char gTail[] = {0xFF, 0xFF};

Communicate::Communicate()
{
}

/*
【 transm TCP 数据协议 】
    header 2 char: 0xFF 0xFE
    from  32 char:
    to    32 char:
    len    4 char:
    data    xxxxx:
    tail   2 char: 0xFF 0xFF
 */
FrameBuffer* Communicate::ParseBuffer(MutBuffer& buffer)
{
    FrameBuffer* frame = nullptr;

    int find = buffer.IndexOf((const char*)gHeader, sizeof(gHeader));
    if (find < 0) {
        return frame;
    }

    int len = 0;
    std::memcpy(&len, buffer.GetData() + find + sizeof(gHeader) + 64, sizeof(len));
    if (buffer.Length() < (find + sizeof(gHeader) + 64 + len + sizeof(len) + sizeof(gTail)) || len < 0) {
        return frame;
    }

    if (std::memcmp(buffer.GetData() + find + sizeof(gHeader) + 64 + sizeof(len) + len, gTail, sizeof(gTail)) != 0) {
        return frame;
    }

    frame = new FrameBuffer();
    frame->fid = std::string(buffer.GetData() + find + sizeof(gHeader), 32);
    frame->tid = std::string(buffer.GetData() + find + sizeof(gHeader) + 32, 32);

    if (len > 0) {
        frame->data = new char[len];
        std::memcpy(frame->data, buffer.GetData() + find + sizeof(gHeader) + 64 + sizeof(len), len);
        frame->len = len;
    }
    buffer.RemoveOf(0, find + sizeof(gHeader) + 64 + len + sizeof(len) + sizeof(gTail));
    return frame;
}

bool Communicate::PackBuffer(FrameBuffer* frame, char** buf, int& len)
{
    if (frame == nullptr) {
        return false;
    }
    if (frame->data == nullptr) {
        frame->len = 0;
    }
    len = sizeof(gHeader) + 64 + sizeof(len) + frame->len + sizeof(gTail);
    *buf = new char[len];
    std::memcpy(*buf, gHeader, sizeof(gHeader));
    std::memcpy(*buf + sizeof(gHeader), frame->fid.c_str(), 32);
    std::memcpy(*buf + sizeof(gHeader) + 32, frame->tid.c_str(), 32);
    std::memcpy(*buf + sizeof(gHeader) + 64, &frame->len, sizeof(len));
    if (frame->len > 0) {
        std::memcpy(*buf + sizeof(gHeader) + 64 + sizeof(len), frame->data, frame->len);
    }
    std::memcpy(*buf + sizeof(gHeader) + 64 + sizeof(len) + frame->len, gTail, sizeof(gTail));
    return true;
}

FrameBuffer::~FrameBuffer()
{
    delete[] data;
    len = 0;
}