// excerpts from http://code.google.com/p/muduo/
//
// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (chenshuo at chenshuo dot com)

#include "TcpConnection.h"

#include "logging/Logging.h"
#include "Channel.h"
#include "EventLoop.h"
#include "Socket.h"
#include "SocketsOps.h"

#include <boost/bind.hpp>

#include <errno.h>
#include <stdio.h>

using namespace muduo;

TcpConnection::TcpConnection(EventLoop* loop,
                             const std::string& nameArg,
                             int sockfd,
                             const InetAddress& localAddr,
                             const InetAddress& peerAddr)
  : loop_(CHECK_NOTNULL(loop)),
    name_(nameArg),
    state_(kConnecting),
    socket_(new Socket(sockfd)),
    channel_(new Channel(loop, sockfd)),
    localAddr_(localAddr),
    peerAddr_(peerAddr)
{
  LOG_DEBUG << "TcpConnection::ctor[" <<  name_ << "] at " << this
            << " fd=" << sockfd;
  channel_->setReadCallback(
      boost::bind(&TcpConnection::handleRead, this, _1));
  channel_->setWriteCallback(
      boost::bind(&TcpConnection::handleWrite, this));
  channel_->setCloseCallback(
      boost::bind(&TcpConnection::handleClose, this));
  channel_->setErrorCallback(
      boost::bind(&TcpConnection::handleError, this));
}

TcpConnection::~TcpConnection()
{
  LOG_DEBUG << "TcpConnection::dtor[" <<  name_ << "] at " << this
            << " fd=" << channel_->fd();
}

void TcpConnection::send(const std::string& message)
{
  if (state_ == kConnected) {
    if (loop_->isInLoopThread()) {
      sendInLoop(message);
    } else {
      loop_->runInLoop(
          boost::bind(&TcpConnection::sendInLoop, this, message));
    }
  }
}

void TcpConnection::sendInLoop(const std::string& message)
{
  loop_->assertInLoopThread();
  ssize_t nwrote = 0;
  // if no thing in output queue, try writing directly
  if (!channel_->isWriting() && outputBuffer_.readableBytes() == 0) {
    nwrote = ::write(channel_->fd(), message.data(), message.size());
    if (nwrote >= 0) {
      if (implicit_cast<size_t>(nwrote) < message.size()) {
        LOG_TRACE << "I am going to write more data";
      }
    } else {
      nwrote = 0;
      if (errno != EWOULDBLOCK) {
        LOG_SYSERR << "TcpConnection::sendInLoop";
      }
    }
  }

  assert(nwrote >= 0);
  if (implicit_cast<size_t>(nwrote) < message.size()) {
    outputBuffer_.append(message.data()+nwrote, message.size()-nwrote);
    if (!channel_->isWriting()) {
      channel_->enableWriting();
    }
  }
}

void TcpConnection::shutdown()
{
  // FIXME: use compare and swap
  if (state_ == kConnected)
  {
    setState(kDisconnecting);
    // FIXME: shared_from_this()?
    loop_->runInLoop(boost::bind(&TcpConnection::shutdownInLoop, this));
  }
}

void TcpConnection::shutdownInLoop()
{
  loop_->assertInLoopThread();
  if (!channel_->isWriting())
  {
    // we are not writing
    socket_->shutdownWrite();
  }
}

void TcpConnection::connectEstablished()
{
  loop_->assertInLoopThread();
  assert(state_ == kConnecting);
  setState(kConnected);
  channel_->enableReading();
  connectionCallback_(shared_from_this());
}

void TcpConnection::connectDestroyed()
{
  loop_->assertInLoopThread();
  assert(state_ == kConnected || state_ == kDisconnecting);
  setState(kDisconnected);
  channel_->disableAll();
  connectionCallback_(shared_from_this());

  loop_->removeChannel(get_pointer(channel_));
}

void TcpConnection::handleRead(Timestamp receiveTime)
{
  int savedErrno = 0;
  ssize_t n = inputBuffer_.readFd(channel_->fd(), &savedErrno);
  if (n > 0) {
    messageCallback_(shared_from_this(), &inputBuffer_, receiveTime);
  } else if (n == 0) {
    handleClose();
  } else {
    errno = savedErrno;
    LOG_SYSERR << "TcpConnection::handleRead";
    handleError();
  }
}

void TcpConnection::handleWrite()
{
  loop_->assertInLoopThread();
  if (channel_->isWriting()) {
    ssize_t n = ::write(channel_->fd(),
                        outputBuffer_.peek(),
                        outputBuffer_.readableBytes());
    if (n > 0) {
      outputBuffer_.retrieve(n);
      if (outputBuffer_.readableBytes() == 0) {
        channel_->disableWriting();
        if (state_ == kDisconnecting) {
          shutdownInLoop();
        }
      } else {
        LOG_TRACE << "I am going to write more data";
      }
    } else {
      LOG_SYSERR << "TcpConnection::handleWrite";
    }
  } else {
    LOG_TRACE << "Connection is down, no more writing";
  }
}

void TcpConnection::handleClose()
{
  loop_->assertInLoopThread();
  LOG_TRACE << "TcpConnection::handleClose state = " << state_;
  assert(state_ == kConnected || state_ == kDisconnecting);
  // we don't close fd, leave it to dtor, so we can find leaks easily.
  channel_->disableAll();
  // must be the last line
  closeCallback_(shared_from_this());
}

void TcpConnection::handleError()
{
  int err = sockets::getSocketError(channel_->fd());
  LOG_ERROR << "TcpConnection::handleError [" << name_
            << "] - SO_ERROR = " << err << " " << strerror_tl(err);
}