/* Program to use a dynamically allocated linked list
   to implement a queue */

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

#define NAMESIZE 255
#define DEBUG 0


typedef struct node {
	char name[NAMESIZE];
	struct node *next;
} NODE;

/* print_list prints the entire list out to stdout */
void print_list(NODE *head) {

	NODE *current;

	if (DEBUG) printf("In print_list...\n");
	current = head;
	printf("Complete list:\n");

	while (current->next != NULL) {
		printf("%s\n", current->name);
		current = current->next;
	}
	printf("%s\n", current->name);
	printf("\n\n");
}

/* enqueue adds a node to the end of the list */
NODE *enqueue(NODE *head, char *addData) {
	NODE *tail, *new;

	if (DEBUG) printf("In enqueue, addData = %s...\n", addData);
	if (head == NULL) {
		head = (NODE *)malloc(sizeof(NODE));
		head->next = NULL;
		strncpy(head->name, addData, NAMESIZE);
	} else {
		tail = head;
		while (tail->next != NULL)
			tail = tail->next;

		new = (NODE *)malloc(sizeof(NODE));
		tail->next = new;
		strncpy(new->name, addData, NAMESIZE);
		new->next = NULL;
	}
	return(head);

}

/* dequeue removes a node from the front of the list and prints it */
NODE *dequeue(NODE *head) {

	NODE *newHead;

	if (DEBUG) printf("In dequeue, head->name is %s...\n", head->name);
	newHead = head->next;
	printf("dequeue: %s\n", head->name);

        free(head);
	return(newHead);

}

/* main (duh) */
int main()
{

	NODE *head;
	FILE *infile;
	char command[NAMESIZE], name[NAMESIZE];

	if (DEBUG) printf("In main, opening file...\n");
	infile = fopen("queue_input.list", "r");
	if (infile == NULL){
		printf("Error opening input file \"queue_input.list\"\n");
		return(0);
	}

	/* set up an initial list */
	head = NULL;

	/* main loop */
	fscanf(infile, "%s %s", command, name);
	while (!feof(infile)) {
		if (DEBUG) printf("Main loop, read %s %s...\n", command, name);
		if (strcmp(command, "enqueue") == 0) {
			head = enqueue(head, name);
		} else if (strcmp(command, "dequeue") == 0) {
			head = dequeue(head);
		}
		fscanf(infile, "%s %s", command, name);

	}
	
	fclose(infile);

	print_list(head);


}