// Copyright (c) 2012-2015, The CryptoNote developers, The Bytecoin developers
//
// This file is part of Bytecoin.
//
// Bytecoin is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Bytecoin is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with Bytecoin.  If not, see <http://www.gnu.org/licenses/>.

#include "TcpListener.h"
#include <cassert>
#include <stdexcept>

#include <fcntl.h>
#include <netinet/in.h>
#include <sys/errno.h>
#include <sys/event.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

#include "Dispatcher.h"
#include "TcpConnection.h"
#include <System/InterruptedException.h>
#include <System/Ipv4Address.h>

namespace System {

TcpListener::TcpListener() : dispatcher(nullptr) {
}

TcpListener::TcpListener(Dispatcher& dispatcher, const Ipv4Address& addr, uint16_t port) : dispatcher(&dispatcher) {
  std::string message;
  listener = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (listener == -1) {
    message = "socket() failed, errno=" + std::to_string(errno);
  } else {
    int flags = fcntl(listener, F_GETFL, 0);
    if (flags == -1 || (fcntl(listener, F_SETFL, flags | O_NONBLOCK) == -1)) {
      message = "fcntl() failed errno=" + std::to_string(errno);
    } else {
      int on = 1;
      if (setsockopt(listener, SOL_SOCKET, SO_REUSEADDR, &on, sizeof on) == -1) {
        message = "setsockopt failed, errno=" + std::to_string(errno);
      } else {
        sockaddr_in address;
        address.sin_family = AF_INET;
        address.sin_port = htons(port);
        address.sin_addr.s_addr = htonl(addr.getValue());
        if (bind(listener, reinterpret_cast<sockaddr*>(&address), sizeof address) != 0) {
          message = "bind failed, errno=" + std::to_string(errno);
        } else if (listen(listener, SOMAXCONN) != 0) {
          message = "listen failed, errno=" + std::to_string(errno);
        } else {
          struct kevent event;
          EV_SET(&event, listener, EVFILT_READ, EV_ADD | EV_DISABLE | EV_CLEAR, 0, SOMAXCONN, NULL);

          if (kevent(dispatcher.getKqueue(), &event, 1, NULL, 0, NULL) == -1) {
            message = "kevent() failed, errno=" + std::to_string(errno);
          } else {
            context = nullptr;
            return;
          }
        }
      }
    }

    if (close(listener) == -1) {
      message = "close failed, errno=" + std::to_string(errno);
    }
  }

  throw std::runtime_error("TcpListener::TcpListener, " + message);
}

TcpListener::TcpListener(TcpListener&& other) : dispatcher(other.dispatcher) {
  if (other.dispatcher != nullptr) {
    assert(other.context == nullptr);
    listener = other.listener;
    context = nullptr;
    other.dispatcher = nullptr;
  }
}

TcpListener::~TcpListener() {
  if (dispatcher != nullptr) {
    assert(context == nullptr);
    int result = close(listener);
    assert(result != -1);
  }
}

TcpListener& TcpListener::operator=(TcpListener&& other) {
  if (dispatcher != nullptr) {
    assert(context == nullptr);
    if (close(listener) == -1) {
      throw std::runtime_error("TcpListener::operator=, close failed, errno=" + std::to_string(errno));
    }
  }

  dispatcher = other.dispatcher;
  if (other.dispatcher != nullptr) {
    assert(other.context == nullptr);
    listener = other.listener;
    context = nullptr;
    other.dispatcher = nullptr;
  }

  return *this;
}

TcpConnection TcpListener::accept() {
  assert(dispatcher != nullptr);
  assert(context == nullptr);
  if (dispatcher->interrupted()) {
    throw InterruptedException();
  }

  std::string message;
  OperationContext listenerContext;
  listenerContext.context = dispatcher->getCurrentContext();
  listenerContext.interrupted = false;
  struct kevent event;
  EV_SET(&event, listener, EVFILT_READ, EV_ADD | EV_ENABLE | EV_CLEAR , 0, SOMAXCONN, &listenerContext);
  if (kevent(dispatcher->getKqueue(), &event, 1, NULL, 0, NULL) == -1) {
    message = "kevent() failed, errno=" + std::to_string(errno);
  } else {
    context = &listenerContext;
    dispatcher->getCurrentContext()->interruptProcedure = [&] {
      assert(dispatcher != nullptr);
      assert(context != nullptr);
      OperationContext* listenerContext = static_cast<OperationContext*>(context);
      if (!listenerContext->interrupted) {
        
        struct kevent event;
        EV_SET(&event, listener, EVFILT_READ, EV_DELETE | EV_DISABLE, 0, 0, NULL);
        
        if (kevent(dispatcher->getKqueue(), &event, 1, NULL, 0, NULL) == -1) {
          throw std::runtime_error("TcpListener::stop, kevent() failed, errno=" + std::to_string(errno));
        }
        
        listenerContext->interrupted = true;
        dispatcher->pushContext(listenerContext->context);
      }
    };
    
    dispatcher->dispatch();
    dispatcher->getCurrentContext()->interruptProcedure = nullptr;
    assert(dispatcher != nullptr);
    assert(listenerContext.context == dispatcher->getCurrentContext());
    assert(context == &listenerContext);
    context = nullptr;
    listenerContext.context = nullptr;
    if (listenerContext.interrupted) {
      throw InterruptedException();
    }

    sockaddr inAddr;
    socklen_t inLen = sizeof(inAddr);
    int connection = ::accept(listener, &inAddr, &inLen);
    if (connection == -1) {
      message = "accept() failed, errno=" + std::to_string(errno);
    } else {
      int flags = fcntl(connection, F_GETFL, 0);
      if (flags == -1 || fcntl(connection, F_SETFL, flags | O_NONBLOCK) == -1) {
        message = "fcntl() failed errno=" + std::to_string(errno);
      } else {
        return TcpConnection(*dispatcher, connection);
      }
    }
  }

  throw std::runtime_error("TcpListener::accept, " + message);
}

}