/****************************************************************************
 * apps/examples/tcpecho/tcpecho_main.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/* This code is based upon the poll example from W. Richard Stevens'
 * UNIX Network Programming Book.
 */

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <debug.h>
#include <errno.h>
#include <poll.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <nuttx/net/arp.h>
#include "netutils/netlib.h"

#ifdef CONFIG_EXAMPLES_TCPECHO_DHCPC
#  include <arpa/inet.h>
#endif

/* Here we include the header file for the application(s) we use in
 * our project as defined in the config/<board-name>/defconfig file
 */

/* DHCPC may be used in conjunction with any other feature (or not) */

#ifdef CONFIG_EXAMPLES_TCPECHO_DHCPC
#  include "netutils/dhcpc.h"
#endif

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#define TCPECHO_MAXLINE 64
#define TCPECHO_POLLTIMEOUT 10000

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

static int tcpecho_netsetup(void);
static int tcpecho_server(void);

/****************************************************************************
 * Private Functions
 ****************************************************************************/

static int tcpecho_netsetup()
{
  /* If this task is excecutated as an NSH built-in function, then the
   * network has already been configured by NSH's start-up logic.
   */

#ifndef CONFIG_NSH_NETINIT
  struct in_addr addr;
#if defined(CONFIG_EXAMPLES_TCPECHO_DHCPC) || defined(CONFIG_EXAMPLES_TCPECHO_NOMAC)
  uint8_t mac[IFHWADDRLEN];
#endif
#ifdef CONFIG_EXAMPLES_TCPECHO_DHCPC
  struct dhcpc_state ds;
  void *handle;
#endif

  /* Many embedded network interfaces must have a software assigned MAC */

#ifdef CONFIG_EXAMPLES_TCPECHO_NOMAC
  mac[0] = 0x00;
  mac[1] = 0xe0;
  mac[2] = 0xde;
  mac[3] = 0xad;
  mac[4] = 0xbe;
  mac[5] = 0xef;
  netlib_setmacaddr("eth0", mac);
#endif

  /* Set up our host address */

#ifdef CONFIG_EXAMPLES_TCPECHO_DHCPC
  addr.s_addr = 0;
#else
  addr.s_addr = HTONL(CONFIG_EXAMPLES_TCPECHO_IPADDR);
#endif
  netlib_set_ipv4addr("eth0", &addr);

  /* Set up the default router address */

  addr.s_addr = HTONL(CONFIG_EXAMPLES_TCPECHO_DRIPADDR);
  netlib_set_dripv4addr("eth0", &addr);

  /* Setup the subnet mask */

  addr.s_addr = HTONL(CONFIG_EXAMPLES_TCPECHO_NETMASK);
  netlib_set_ipv4netmask("eth0", &addr);

  /* New versions of netlib_set_ipvXaddr will not bring the network up,
   * So ensure the network is really up at this point.
   */

  netlib_ifup("eth0");

#ifdef CONFIG_EXAMPLES_TCPECHO_DHCPC
  /* Get the MAC address of the NIC */

  netlib_getmacaddr("eth0", mac);

  /* Set up the DHCPC modules */

  handle = dhcpc_open("eth0", &mac, IFHWADDRLEN);

  /* Get an IP address.
   * Note:  there is no logic here for renewing the address in this
   * example.  The address should be renewed in ds.lease_time/2 seconds.
   */

  if (!handle)
    {
      return ERROR;
    }

  if (dhcpc_request(handle, &ds) != OK)
    {
      return ERROR;
    }

  netlib_set_ipv4addr("eth0", &ds.ipaddr);

  if (ds.netmask.s_addr != 0)
    {
      netlib_set_ipv4netmask("eth0", &ds.netmask);
    }

  if (ds.default_router.s_addr != 0)
    {
      netlib_set_dripv4addr("eth0", &ds.default_router);
    }

  if (ds.dnsaddr.s_addr != 0)
    {
      netlib_set_ipv4dnsaddr(&ds.dnsaddr);
    }

  dhcpc_close(handle);
  printf("IP: %s\n", inet_ntoa(ds.ipaddr));

#endif /* CONFIG_EXAMPLES_TCPECHO_DHCPC */
#endif /* CONFIG_NSH_NETINIT */

  return OK;
}

static int tcpecho_server(void)
{
  int i;
  int maxi;
  int listenfd;
  int connfd;
  int sockfd;
  int nready;
  int ret;
  ssize_t n;
  char buf[TCPECHO_MAXLINE];
  socklen_t clilen;
  bool stop = false;
  struct pollfd client[CONFIG_EXAMPLES_TCPECHO_NCONN];
  struct sockaddr_in cliaddr;
  struct sockaddr_in servaddr;

  listenfd = socket(AF_INET, SOCK_STREAM, 0);

  if (listenfd < 0)
    {
      perror("ERROR: failed to create socket.\n");
      return ERROR;
    }

  memset(&servaddr, 0, sizeof(servaddr));
  servaddr.sin_family      = AF_INET;
  servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
  servaddr.sin_port        = htons(CONFIG_EXAMPLES_TCPECHO_PORT);

  ret = bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
  if (ret < 0)
    {
      perror("ERROR: failed to bind socket.\n");
      return ERROR;
    }

  ninfo("start listening on port: %d\n", CONFIG_EXAMPLES_TCPECHO_PORT);

  ret = listen(listenfd, CONFIG_EXAMPLES_TCPECHO_BACKLOG);
  if (ret < 0)
    {
      perror("ERROR: failed to start listening\n");
      return ERROR;
    }

  client[0].fd = listenfd;
  client[0].events = POLLRDNORM;
  for (i = 1; i < CONFIG_EXAMPLES_TCPECHO_NCONN; i++)
    {
      client[i].fd = -1;        /* -1 indicates available entry */
    }

  maxi = 0;                     /* max index into client[] array */

  while (!stop)
    {
      nready = poll(client, maxi + 1, TCPECHO_POLLTIMEOUT);

      if (client[0].revents & POLLRDNORM)
        {
          /* new client connection */

          clilen = sizeof(cliaddr);
          connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &clilen);

          ninfo("new client: %s\n", inet_ntoa(cliaddr.sin_addr));

          for (i = 1; i < CONFIG_EXAMPLES_TCPECHO_NCONN; i++)
            {
              if (client[i].fd < 0)
                {
                  client[i].fd = connfd;  /* save descriptor */
                  break;
                }
            }

          if (i == CONFIG_EXAMPLES_TCPECHO_NCONN)
            {
              perror("ERROR: too many clients");
              return ERROR;
            }

          client[i].events = POLLRDNORM;
          if (i > maxi)
            {
              maxi = i;    /* max index in client[] array */
            }

          if (--nready <= 0)
            {
              continue;    /* no more readable descriptors */
            }
        }

      for (i = 1; i <= maxi; i++)
        {
          /* check all clients for data */

          if ((sockfd = client[i].fd) < 0)
            {
              continue;
            }

          if (client[i].revents & (POLLRDNORM | POLLERR))
            {
              if ((n = read(sockfd, buf, TCPECHO_MAXLINE)) < 0)
                {
                  if (errno == ECONNRESET)
                    {
                      /* connection reset by client */

                      nwarn("WARNING: client[%d] aborted connection\n", i);

                      close(sockfd);
                      client[i].fd = -1;
                    }
                  else
                    {
                      perror("ERROR: readline error\n");
                      close(sockfd);
                      client[i].fd = -1;
                    }
                }
              else if (n == 0)
                {
                  /* connection closed by client */

                  nwarn("WARNING: client[%d] closed connection\n", i);

                  close(sockfd);
                  client[i].fd = -1;
                }
              else
                {
                  if (strcmp(buf, "exit\r\n") == 0)
                    {
                      nwarn("WARNING: client[%d] closed connection\n", i);
                      close(sockfd);
                      client[i].fd = -1;
                    }
                  else
                    {
                      write(sockfd, buf, n);
                    }
                }

              if (--nready <= 0)
                {
                  break;  /* no more readable descriptors */
                }
            }
        }
    }

  for (i = 0; i <= maxi; i++)
    {
      if (client[i].fd < 0)
        {
          continue;
        }

      close(client[i].fd);
    }

  return ret;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * tcpecho_main
 ****************************************************************************/

int main(int argc, FAR char *argv[])
{
  int ret;

  ret = tcpecho_netsetup();
  if (ret != OK)
    {
      perror("ERROR: failed to setup network\n");
      exit(1);
    }

  printf("Start echo server\n");

  ret = tcpecho_server();

  return ret;
}