// Author Name: Matt Strapp
// Date: 25 April 2022
// x500: strap012
#include "comms.hpp"

int Send_NonBlocking(int sockFD, BYTE *data, struct CONN_STAT *pStat,
                     struct pollfd *pPeer) {
  while (pStat->nToDo > 0) {
    // pStat keeps tracks of how many bytes have been sent, allowing us to
    // "resume" when a previously non-writable socket becomes writable.
    ftime(&(pStat->lastTime));
    int n =
        send(sockFD, data + pStat->messageLen - pStat->nToDo, pStat->nToDo, 0);
    if (n >= 0) {
      pStat->nToDo -= n;
    } else if (n < 0 && (errno == ECONNRESET || errno == EPIPE)) {
      close(sockFD);
      return -1;
    } else if (n < 0 && (errno == EWOULDBLOCK)) {
      // The socket becomes non-writable. Exit now to prevent blocking.
      // OS will notify us when we can write
      pPeer->events |= POLLWRNORM;
      return 0;
    } else {
      Error("Unexpected send error %d: %s", errno, strerror(errno));
    }
  }

  // out)"); Log("What's currently in there: nBuffered %d, messageLen: %d, nToDo
  // %d", pStat->nBuffered, pStat->messageLen, pStat->nToDo);
  memcpy(data, data + pStat->messageLen, BUF_LEN - pStat->messageLen); // Good
  memset(data + pStat->nBuffered - pStat->messageLen, 0,
         BUF_LEN - pStat->nBuffered + pStat->messageLen);
  pStat->nBuffered -= pStat->messageLen;
  if (pStat->nBuffered > 0) { // start off the next send if one is queued
    Header nextHeader;
    nextHeader.decode(data);
    pStat->messageLen = HEADER_LEN + nextHeader.m_size;
    pStat->nToDo = HEADER_LEN + nextHeader.m_size;
  } else {
    pStat->messageLen = 0;
    pStat->nToDo = 0;
    pPeer->events &= ~POLLWRNORM; // no more bytes to send? Stop listening for
                                  // the writable cue.
  }
  // pStat->nBuffered, pStat->messageLen, pStat->nToDo);

  // Change the connection from a sender to a receiver (used by client)
  if (pStat->changeDirection && (pStat->nToDo == 0)) {
    pStat->direction = (pStat->direction == C2S) ? S2C : C2S;
    pStat->expectingHeader = true;
    pStat->nToDo = HEADER_LEN;
    pStat->changeDirection = false;
    pPeer->events &= ~POLLWRNORM; // stop listening for writable cue
    pPeer->events |= POLLRDNORM;  // start listening for readable cue
  }

  return 0;
}

// TODO: Question: Why isn't the pPeer datastructure used?
int Recv_NonBlocking(int sockFD, BYTE *data, struct CONN_STAT *pStat,
                     struct pollfd *pPeer) {
  // pStat keeps tracks of how many bytes have been rcvd, allowing us to
  // "resume" when a previously non-readable socket becomes readable. Log("Recv:
  // pStat->nToDo %d",pStat->nToDo);
  while (pStat->nToDo > 0) {
    int n = recv(sockFD, data + pStat->nBuffered, pStat->nToDo, 0);
    if (n > 0) {
      pStat->nBuffered += n;
      pStat->nToDo -= n;
    } else if (n == 0 || (n < 0 && errno == ECONNRESET)) {
      close(sockFD);
      return -1;
    } else if (n < 0 && (errno == EWOULDBLOCK)) {
      // The socket becomes non-readable. Exit now to prevent blocking.
      // OS will notify us when we can read
      return 0;
    } else {
      Error("Unexpected recv error %d: %s.", errno, strerror(errno));
    }
  }

  return 0;
}

void SetNonBlockIO(int fd) {
  int val = fcntl(fd, F_GETFL, 0);
  if (fcntl(fd, F_SETFL, val | O_NONBLOCK) != 0) {
    Error("Cannot set nonblocking I/O.");
  }
}

Header::Header() {
  m_direction = C2S;
  m_flag = SUCCESS;
  m_recipient = PUB;
  m_trace = SIGN;
  m_command = INVALID;
  memset(m_name, 0, MAX_USERNAME_LEN + 1);
  m_size = 0;
}

// encode the message to the buffer
void Header::encode(BYTE *buf) {
  memset(buf, 0, HEADER_LEN);
  int index = 0;

  BYTE dir_b = (BYTE)(m_direction << 7);
  BYTE flag_b = (BYTE)(m_flag << 6);
  BYTE recip_b = (BYTE)(m_recipient << 5);
  BYTE trace_b = (BYTE)(m_trace << 4);
  BYTE com_b = (BYTE)m_command & 0x0F;

  buf[index++] = dir_b | flag_b | recip_b | trace_b | com_b;

  memcpy(&buf[index], m_name, 8);
  index += 8;

  LittleEndianToBig(m_size, &buf[index]);
  index += 4;
}

// decode a buffer into a message object
void Header::decode(BYTE *buf) {
  int index = 0;

  m_direction = (enum Direction)((buf[index] >> 7) & 0x01);
  m_flag = (enum Flag)((buf[index] >> 6) & 0x01);
  m_recipient = (enum Recipient)((buf[index] >> 5) & 0x01);
  m_trace = (enum Trace)((buf[index] >> 4) & 0x01);
  m_command = (enum Command)(buf[index] & 0x0F);
  index += 1;

  for (int x = 0; x < MAX_USERNAME_LEN; x++)
    m_name[x] = buf[index++];

  BigEndianToLittle(&buf[index], m_size);
  index += 4;
}

void Header::setFlags(enum Direction direction, enum Flag flag,
                      enum Recipient recipient, enum Trace trace) {
  m_direction = direction;
  m_flag = flag;
  m_recipient = recipient;
  m_trace = trace;
}

// Helper to print contents of class
void Header::displayContents(bool tab = false) {
  Log("%sDirection: %s,  Flag: %s,  Recipient: %s,  Trace: %s", tab ? "\t" : "",
      !m_direction ? "C2S" : "S2C", !m_flag ? "SUCCESS" : "FAIL",
      !m_recipient ? "PUB" : "PRIV", !m_trace ? "SIGN" : "ANNON");
  Log("%sCommand: %s", tab ? "\t" : "", com2str(m_command));
  char name[9] = {0};
  memcpy(name, m_name, MAX_USERNAME_LEN);
  Log("%sUsername: |%s|", tab ? "\t" : "", name);
  Log("%sSize: %d", tab ? "\t" : "", m_size);
}