#include /
#include /
#include /
#include /
#define BUFFER_SIZE 3072

struct sliding_window_buffer{
  int window_start;
  int window_end;
  char *buffer;
}to_application, to_network;

static void init_buffer(struct sliding_window_buffer *swbuffer, int start){
  swbuffer->buffer = (char *)malloc(BUFFER_SIZE);
  assert(swbuffer->buffer);
  swbuffer->window_start = start;
  swbuffer->window_end = swbuffer->window_start;
  for(int i = 0; ibuffer[i] = '\0';
  }
}

static void consume(struct sliding_window_buffer *swbuffer,
		    int bytes, void *ret){
  if(swbuffer->window_start == swbuffer->window_end 
     && swbuffer->buffer[swbuffer->window_start] == '\0' 
     && swbuffer->buffer[swbuffer->window_start+1] == '\0'){
    //IT APPEARS THE BUFFER IS EMPTY, THERE IS NO DATA TO CONSUME
  }
  else{
    //IF THE DATA TO CONSUME DOES NOT CROSS FROM END TO BEGINNING
    if(swbuffer->window_end+bytesbuffer+(swbuffer->window_end%BUFFER_SIZE), bytes);
      //SET THE MOVED DATA TO THE NULL CHARACTER TO EMPTY THE BUFFER
      memset(swbuffer->buffer+(swbuffer->window_end%BUFFER_SIZE), '\0', bytes);
      //MOVE THE END OF THE WINDO TO ITS NEW LOCATION
      swbuffer->window_end = (swbuffer->window_end + bytes)%BUFFER_SIZE;
    }else{
      //THE DATA STARTS AT TH END AND CROSSES TO THE BEGINNING OF THE BUFFER
      //MUST CONSUME IN TWO PARTS AND THEN COMBINE THE PARTS TO RETURN
      void *part_one, *part_two;
      int size_of_part_one = BUFFER_SIZE-swbuffer->window_end;
      int size_of_part_two = bytes-size_of_part_one;
      part_one = malloc(size_of_part_one);
      assert(part_one);
      part_two = malloc(size_of_part_two);
      assert(part_two);
      //GET PEICES
      //THIS RECURSIVE CALL SHOULD TAKE CARE OF MOVING OUR WINDOW
      //AND RESETTING THE BYTES
      consume(swbuffer, size_of_part_one, part_one);
      consume(swbuffer, size_of_part_two, part_two);
      //REASSEMBLE
      memcpy(ret, part_one, size_of_part_one);
      memcpy((char*)ret+size_of_part_one, part_two, size_of_part_two);
      free(part_one);
      free(part_two);
    }
  }
}

static void produce(struct sliding_window_buffer *swbuffer, 
		    int bytes, void *prod){
  //IF THE BYTES TO MOVE ARE NOT TOO LARGE FOR THE BUFFER
  if(byteswindow_start == swbuffer->window_end 
       && swbuffer->buffer[swbuffer->window_start] != '\0' 
       && swbuffer->buffer[swbuffer->window_start+1] != '\0'){
      //IT APPEARS THE BUFFER IS FULL, THERE IS NO ROOM FOR YOUR DATA
    }
    else{
      int space_left;
      //DECIDE HOW TO CALCULATE THE AMOUTN OF SPACE LEFT
      //DEPENDS ON THE ORDER OF THE START AND END OF THE BUFFER
      if(swbuffer->window_end>swbuffer->window_start){
	space_left = swbuffer->window_end-swbuffer->window_start;
      }else{
	space_left = swbuffer->window_end-swbuffer->window_start+BUFFER_SIZE;
      }
      //IF THE BYTES TO MOVE IS GREATER THAN THE SPACE LEFT
      if(bytes > space_left){
	//FIT THE SIZE TO MOVE IN BYTES TO THE SIZE LEFT IN THE BUFFER
	bytes = space_left;
      }
      //IF BYTES WILL FIT BEFORE THE END OF THE BUFFER
      if(bytes+swbuffer->window_startbuffer+swbuffer->window_start, prod, bytes);
      }else{
	//BYTES SPAN FROM END TO BEGIN
	//WILL REQUIRE TWO COPIES
	memcpy(swbuffer->buffer+swbuffer->window_start, 
	       prod, 
	       (BUFFER_SIZE-swbuffer->window_start));
	memcpy(swbuffer->buffer, 
	       (char*)prod+(BUFFER_SIZE-swbuffer->window_start), 
	       bytes-(BUFFER_SIZE-swbuffer->window_start));
      }
      swbuffer->window_start = (swbuffer->window_start+bytes)%BUFFER_SIZE;
    }
  }else{
    printf("ERROR: BYTES ADDED WERE LARGER THAN THE BUFFER");
  }
}

void destroy_buffer(struct sliding_window_buffer *swbuffer){
  free(swbuffer->buffer);
}

int main(){
  //SOME TESTING... NOT STRENUOUS
  init_buffer(&to_application, 200);
  void *half = malloc(strlen("some_bytes")/2);
  consume(&to_application, strlen("some_bytes")/2, half);
  printf("Empty: %s\n", half);  
  void * some_bytes = malloc(strlen("some_bytes"));
  memcpy(some_bytes, "some_bytes", strlen("some_bytes"));
  produce(&to_application, strlen("some_bytes"), some_bytes);
  consume(&to_application, strlen("some_bytes")/2, half);
  printf("first 5: %s\n", half);
  consume(&to_application, strlen("some_bytes")/2, half);
  printf("second 5: %s\n", half);  
  consume(&to_application, strlen("some_bytes")/2, half);
  printf("third 5: %s\n", half);  
  destroy_buffer(&to_application);
  return 0;
}