/**
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of and a contribution to the lwIP TCP/IP stack.
 *
 * Credits go to Adam Dunkels (and the current maintainers) of this software.
 *
 * Christiaan Simons rewrote this file to get a more stable echo application.
 *
 **/

 /* This file was modified by ST */


#include "lwip/debug.h"
#include "lwip/stats.h"
#include "lwip/tcp.h"
#include <string.h>

#include "OwnCode\Ethernet.h"
#include "Owncode\UARTDebug.h"

#define TCP_SERVER_PORT		52360   /* define the UDP local connection port */
#define PBUF_NUM			5

#if LWIP_TCP

static struct tcp_pcb *tcp_server_pcb;

static struct pbuf *txPBUF[PBUF_NUM];
uint8_t txPBUF_count = 0;

// OWN USER VARIABLE
uint8_t payloadbuffer[PBUF_MAXLENGTH]; // Buffer to copy the packet into - 1000 bytes

/* protocol states */
enum tcp_server_states
{
  ES_NONE = 0,
  ES_ACCEPTED,
  ES_RECEIVED,
  ES_CLOSING
};

/* structure for maintaining connection infos to be passed as argument
   to LwIP callbacks*/
struct tcp_server_struct
{
  u8_t state;             /* current connection state */
  u8_t retries;
  struct tcp_pcb *pcb;    /* pointer on the current tcp_pcb */
  struct pbuf *p;         /* pointer on the received/to be transmitted pbuf */
};


static err_t tcp_server_accept(void *arg, struct tcp_pcb *newpcb, err_t err);
static err_t tcp_server_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err);
static void tcp_server_error(void *arg, err_t err);
static err_t tcp_server_poll(void *arg, struct tcp_pcb *tpcb);
static err_t tcp_server_sent(void *arg, struct tcp_pcb *tpcb, u16_t len);
static void tcp_server_send(struct tcp_pcb *tpcb, struct tcp_server_struct *es);
static void tcp_server_connection_close(struct tcp_pcb *tpcb, struct tcp_server_struct *es);


/**
  * @brief  Initializes the tcp server
  * @param  None
  * @retval None
  */
void tcp_server_init(void)
{
  /* create new tcp pcb */
  tcp_server_pcb = tcp_new();

  if (tcp_server_pcb != NULL)
  {
    err_t err;

    err = tcp_bind(tcp_server_pcb, IP_ADDR_ANY, TCP_SERVER_PORT);

    if (err == ERR_OK)
    {
      /* start tcp listening for pcb */
      tcp_server_pcb = tcp_listen(tcp_server_pcb);

      /* initialize LwIP tcp_accept callback function */
      tcp_accept(tcp_server_pcb, tcp_server_accept);
    }
    else
    {
      /* deallocate the pcb */
      memp_free(MEMP_TCP_PCB, tcp_server_pcb);
    }
  }

  for (uint8_t i = 0; i < PBUF_NUM; i++) {
	  txPBUF[i] = pbuf_alloc(PBUF_TRANSPORT, PBUF_MAXLENGTH, PBUF_RAM); // Allocate pbuf in RAM with enough length
  }
}

/**
  * @brief  This function is the implementation of tcp_accept LwIP callback
  * @param  arg: not used
  * @param  newpcb: pointer on tcp_pcb struct for the newly created tcp connection
  * @param  err: not used
  * @retval err_t: error status
  */
static err_t tcp_server_accept(void *arg, struct tcp_pcb *newpcb, err_t err)
{
  err_t ret_err;
  struct tcp_server_struct *es;

  LWIP_UNUSED_ARG(arg);
  LWIP_UNUSED_ARG(err);

  /* set priority for the newly accepted tcp connection newpcb */
  tcp_setprio(newpcb, TCP_PRIO_MIN);

  /* allocate structure es to maintain tcp connection informations */
  es = (struct tcp_server_struct *)mem_malloc(sizeof(struct tcp_server_struct));
  if (es != NULL)
  {
    es->state = ES_ACCEPTED;
    es->pcb = newpcb;
    es->retries = 0;
    es->p = NULL;

    /* pass newly allocated es structure as argument to newpcb */
    tcp_arg(newpcb, es);

    /* initialize lwip tcp_recv callback function for newpcb  */
    tcp_recv(newpcb, tcp_server_recv);

    /* initialize lwip tcp_err callback function for newpcb  */
    tcp_err(newpcb, tcp_server_error);

    /* initialize lwip tcp_poll callback function for newpcb */
    tcp_poll(newpcb, tcp_server_poll, 0);

    /* initialize lwip tcp_sent callback function for newpcb */
    tcp_sent(newpcb, tcp_server_sent);

    ret_err = ERR_OK;
  }
  else
  {
    /*  close tcp connection */
    tcp_server_connection_close(newpcb, es);
    /* return memory error */
    ret_err = ERR_MEM;
  }
  return ret_err;
}


/**
  * @brief  This function is the implementation for tcp_recv LwIP callback
  * @param  arg: pointer on a argument for the tcp_pcb connection
  * @param  tpcb: pointer on the tcp_pcb connection
  * @param  pbuf: pointer on the received pbuf
  * @param  err: error information regarding the reveived pbuf
  * @retval err_t: error code
  */
static err_t tcp_server_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err)
{
  struct tcp_server_struct *es;
  err_t ret_err;

  LWIP_ASSERT("arg != NULL",arg != NULL);

  es = (struct tcp_server_struct *)arg;

  /* if we receive an empty tcp frame from client => close connection */
  if (p == NULL)
  {
    /* remote host closed connection */
    es->state = ES_CLOSING;
    if(es->p == NULL)
    {
       /* we're done sending, close connection */
       tcp_server_connection_close(tpcb, es);
    }
    else
    {
      /* send remaining data*/
      tcp_server_send(tpcb, es);
    }
    ret_err = ERR_OK;
  }
  /* else : a non empty frame was received from client but for some reason err != ERR_OK */
  else if(err != ERR_OK)
  {
    /* free received pbuf*/
    if (p != NULL)
    {
      pbuf_free(p);
    }
    ret_err = err;
  }
  else if(es->state == ES_ACCEPTED)
  {
    /* first data chunk in p->payload */
    es->state = ES_RECEIVED;

    /* store reference to incoming pbuf (chain) */
    es->p = p;

    /* send back the data */
    tcp_server_send(tpcb, es);

    ret_err = ERR_OK;
  }
  else if (es->state == ES_RECEIVED)
  {
    /* more data received from client and previous data has been already sent*/
    if(es->p == NULL)
    {
      es->p = p;

      /* send back data */
      tcp_server_send(tpcb, es);
    }
    else
    {
      struct pbuf *ptr;

      /* chain pbufs to the end of what we recv'ed previously  */
      ptr = es->p;
      pbuf_cat(ptr,p);
    }
    ret_err = ERR_OK;
  }
  else
  {
    /* unknown es->state, trash data  */
    tcp_recved(tpcb, p->tot_len);
    es->p = NULL;
    pbuf_free(p);
    ret_err = ERR_OK;
  }
  return ret_err;
}

/**
  * @brief  This function implements the tcp_err callback function (called
  *         when a fatal tcp_connection error occurs.
  * @param  arg: pointer on argument parameter
  * @param  err: not used
  * @retval None
  */
static void tcp_server_error(void *arg, err_t err)
{
  struct tcp_server_struct *es;

  LWIP_UNUSED_ARG(err);

  es = (struct tcp_server_struct *)arg;
  if (es != NULL)
  {
    /*  free es structure */
    mem_free(es);
  }
}

/**
  * @brief  This function implements the tcp_poll LwIP callback function
  * @param  arg: pointer on argument passed to callback
  * @param  tpcb: pointer on the tcp_pcb for the current tcp connection
  * @retval err_t: error code
  */
static err_t tcp_server_poll(void *arg, struct tcp_pcb *tpcb)
{
  err_t ret_err;
  struct tcp_server_struct *es;

  es = (struct tcp_server_struct *)arg;
  if (es != NULL)
  {
    if (es->p != NULL)
    {
      /* there is a remaining pbuf (chain) , try to send data */
      tcp_server_send(tpcb, es);
    }
    else
    {
      /* no remaining pbuf (chain)  */
      if(es->state == ES_CLOSING)
      {
        /*  close tcp connection */
        tcp_server_connection_close(tpcb, es);
      }
    }
    ret_err = ERR_OK;
  }
  else
  {
    /* nothing to be done */
    tcp_abort(tpcb);
    ret_err = ERR_ABRT;
  }
  return ret_err;
}

/**
  * @brief  This function implements the tcp_sent LwIP callback (called when ACK
  *         is received from remote host for sent data)
  * @param  None
  * @retval None
  */
static err_t tcp_server_sent(void *arg, struct tcp_pcb *tpcb, u16_t len)
{
  struct tcp_server_struct *es;

  LWIP_UNUSED_ARG(len);

  es = (struct tcp_server_struct *)arg;
  es->retries = 0;

  if(es->p != NULL)
  {
    /* still got pbufs to send */
    tcp_sent(tpcb, tcp_server_sent);
    tcp_server_send(tpcb, es);
  }
  else
  {
    /* if no more data to send and client closed connection*/
    if(es->state == ES_CLOSING)
      tcp_server_connection_close(tpcb, es);
  }
  return ERR_OK;
}


/**
  * @brief  This function is used to send data for tcp connection
  * @param  tpcb: pointer on the tcp_pcb connection
  * @param  es: pointer on state structure
  * @retval None
  */
uint32_t counter = 0;

static void tcp_server_send(struct tcp_pcb *tpcb, struct tcp_server_struct *es)
{
	//---------------------------------------------------------------
	//	ENTIRE FUNCTION REWRITTEN HERE

	//	FunctionDebug(4,0,0);
	uint16_t length = es-> p -> len; // Length of packet
	uint8_t packetType = 0;
	uint8_t free; // Free variable to check when freeing pbufs
	int8_t err;

	if (length == 8 || length == 30 || length == 34) {}
	else {
		printf("Different Length: %lu\n", counter);
 		counter = 0;
	}
	memcpy((char*)payloadbuffer,es-> p -> payload,es-> p -> len); // Copy packet into buffer
	packetType = ValidatePacket(payloadbuffer, length); // Check for checksum and length errors
	if (packetType != 0) {
		length = ProcessPacket(payloadbuffer, packetType);
		if (length != 0) {
			// Copy response packet and place it into LWIP pbuf
			memcpy(txPBUF[txPBUF_count] -> payload, (char*)payloadbuffer, length);
			txPBUF[txPBUF_count] -> len = length;
			txPBUF[txPBUF_count] -> tot_len = length;
			if (txPBUF[txPBUF_count]->len <= tcp_sndbuf(tpcb)) {
				err = tcp_write(tpcb, txPBUF[txPBUF_count]->payload, txPBUF[txPBUF_count]->len, 1); // Queue the data to be sent back and send
				//printf("Write: (%p), err: %i\n", (void *) tpcb -> unsent, err);
				if (err != 0) {
					printf("tcp_write error\n");
				}
				else {
					counter++;
				}
			}
			else {
				printf("length too big\n");
			}
			txPBUF_count++;
			if (txPBUF_count >= PBUF_NUM) {txPBUF_count = 0;}
		} else {}
	} else {}

	tcp_recved(tpcb, es -> p -> len);

	pbuf_ref(es -> p);
	do {
		free = pbuf_free(es -> p);
	} while(free == 0);
	es -> p = NULL;

	//	OWN CODE ENDS HERE
	//---------------------------------------------------------------
}

/**
  * @brief  This functions closes the tcp connection
  * @param  tcp_pcb: pointer on the tcp connection
  * @param  es: pointer on state structure
  * @retval None
  */
static void tcp_server_connection_close(struct tcp_pcb *tpcb, struct tcp_server_struct *es)
{

  /* remove all callbacks */
  tcp_arg(tpcb, NULL);
  tcp_sent(tpcb, NULL);
  tcp_recv(tpcb, NULL);
  tcp_err(tpcb, NULL);
  tcp_poll(tpcb, NULL, 0);

  /* delete es structure */
  if (es != NULL)
  {
    mem_free(es);
  }

  /* close tcp connection */
  tcp_close(tpcb);
}

#endif /* LWIP_TCP */