#include <stdio.h>
#include <assert.h>
#include <poll.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>


typedef struct linked_list {
	int data;
	struct linked_list *next;
} LL;

typedef struct linked_list Q;

void init_list(LL **head);
int count_list(LL **head);
int add_list(LL **head, int data);
void print_list(LL **head);
int process_data(Q **q);
int add_queue(Q **q, int data);
void init_queue(Q **q);
int count_queue(Q **q);


void init_list(LL **head)
{
	assert(head != NULL);
	*head = NULL;
}

int count_list(LL **head)
{
	assert(head != NULL);
	if (*head == NULL) {
		return 0;
	} else {
		int i = 1;
		LL *ptr;

		ptr = *head;

		while (ptr->next != NULL) {
			ptr = ptr->next;
			i++;
		}

		return i;
	}	
}

int add_list(LL **head, int data)
{
	LL *ptr, *newptr;

	assert(head != NULL);
	ptr = *head;

	newptr = malloc(sizeof(LL));
	if (newptr == NULL) {
		perror("malloc");
		return 0;
	}
	newptr->data = data;
	newptr->next = NULL;

	if (*head == NULL) {
		*head = newptr;
	} else {
		while (ptr->next != NULL)
			ptr = ptr->next;
		ptr->next = newptr;
	}	

	return 1;
}

void print_list(LL **head)
{
	LL *ptr;

	assert(head != NULL);
	ptr = *head;
	while (ptr != NULL) {
		printf("%d\n",ptr->data);
		ptr = ptr->next;
	}
}

int process_data(Q **q)
{
	Q *ptr;

	assert(q != NULL);

	ptr = *q;
	if (ptr == NULL)
		return 0;

	*q = ptr->next;
	printf("processing %d\n",ptr->data);
	free(ptr);
}

int add_queue(Q **q,int data)
{
	assert(q != NULL);

	return add_list(q,data);
}

void init_queue(Q **q)
{

	assert(q != NULL);

	init_list(q);
}

int count_queue(Q **q)
{
	assert(q != NULL);

	return count_list(q);
}

main(int argc, char *argv[])
{
	Q *q;
	FILE *fp;
	char line[200];

	if (argc != 2)
	{
		fprintf(stderr,"usage: %s file\n",basename(argv[0]));
		exit(1);
	}

	fp = fopen(argv[1], "r");
	if (fp == NULL)
	{
		perror("fopen");
		exit(1);
	}

	init_queue(&q);

	fgets(line, sizeof(line), fp);	
	while (!(feof(fp)))
	{
		int data;

		// receive request
		if (line[0] == '?')
		{
			// how many requests in queue
			int num = count_queue(&q);
			printf("queue is %d long\n",num);
			print_list(&q);

		// element in queue
		} else if (line[0] == 'a')
		{
			// new request
			if (1 == sscanf(&line[1],"%d",&data))
				add_queue(&q, data);
			printf("adding %d\n",data);

		} else if (line[0] == 'd')
		{
			// new request
			process_data(&q);

		}

		fgets(line, sizeof(line), fp);	
	}
	fclose(fp);
	exit(0);
}