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

#define MAXSTRING 100
/*Create linked list node structure.*/

struct node {
	char name[MAXSTRING];
	int refcount;
	struct node *next;
};

int calcindex(char j[100]);
struct node * addnode(struct node *j, char k[100], int l);
int lookup(char j[100], struct node *k);
void changeref(char j[100], struct node *k);
void print(struct node *j, FILE *k);

int main(void)
{
	/*Necessary variables.*/
	FILE *ifp, *ofp;
	char item[MAXSTRING];
	char command[MAXSTRING];
	int index;
	int search;
	int i;

	/*Create array[19] of these nodes.*/
	struct node * strarray[19] = {0};
	/*Open input file.*/
	ifp = fopen("inputfile.txt", "r");
	/*Open output file*/
	ofp = fopen("outputfile.txt", "w");
	/*Do until command equals end of input file.*/
	while (fscanf(ifp, "%s", &command) != EOF) {
		/*Get string from file.*/
		fscanf(ifp, "%s", &item);
		/*Print command and string to output file.*/
		fprintf(ofp, "%s	%s", command, item);
		/*Check to see if command is Dec or Use.*/
		/*If the command is Dec:*/
		if (strcmp(command, "DEC") == 0) {
			/*Use calculate index function.*/
			index = calcindex(item);
			/*Check indexed linked list for name by searching list at specific index*/
			search = lookup(item, strarray[index]);
			/*If name exists in list*/
			if (search == 1){
				/*Print error message "***Duplicate Name***" to output file*/
				fprintf(ofp, "	***Duplicate Name***");
				/*Start a new line.*/
				fprintf(ofp, "\n");
			}
			/*If name does not exist in list*/
			else {
				/*Use add node function with proper name, reference count, and pointer.*/
				strarray[index] = addnode(strarray[index], item, strarray[index]->refcount);
				/*Start new line on output file.*/
				fprintf(ofp, "\n");
			}
		}
		/*If the command is Use:*/
		else {
			/*Use calculate index function.*/
			index = calcindex(item);
			/*Check indexed linked list for name by searching list at specific index*/
			search = lookup(item, strarray[index]);
			/*If name exists in list*/
			if (search == 1) {
				/*Reference count +1*/
				changeref(item, strarray[index]);
				/*Start new line on output file.*/
				fprintf(ofp, "\n");
			}
			/*If name does not exist in list*/
			else {
				/*Print error message "***Undefined Name***" to output file*/ 
				fprintf(ofp, "	***Undefined Name***");
				/*Start a new line.*/
				fprintf(ofp, "\n");
			}
		}
	}
	/*Cycle through array.*/
	for (i = 0; i < 19; i++) {
		/*If current linked list is empty*/
		if (strarray[i] == NULL) {
			/*Continue*/
			continue;
		}
		/*If current linked list has data*/
		else {
			/*Print current array field.*/
			fprintf(ofp, "%d	", i);
			/*Use print function*/
			print(strarray[i], ofp);
		}
	}
	/*Close input file.*/
	fclose(ifp);
	/*Close output file.*/
	fclose(ofp);
	/*End program.*/
	return 0;
}

int calcindex(char value[]) {
	int total = 0;
	size_t i;
	/*Until the end of the string*/
	for (i=0; i<strlen(value); i++) {
		/*If current character is a letter*/
		if (isalpha(value[i])) {
			/*If current character is uppercase*/
			if (isupper(value[i])) {
				/*Add to total this value*/
				total = value[i] - 'A' + 1;
			}
			/*If current character is lowercase*/
			else {
				/*Add to total this value*/
				total = value[i] - 'a' + 1;
			}
		}
		/*If current character is a number*/
		else {
			/*Add to total this value*/
			total = value[i] - '0';
		}
	}
	/*Return total*/
	return total;
}

struct node * addnode(struct node *list, char n[], int rc) {
	struct node *pNew = NULL;
	struct node *created_list = NULL;
	/*Creating default node*/
	pNew = malloc(sizeof(struct node));
	strcpy(pNew->name, n);
	pNew->refcount = rc;
	pNew->next = NULL;
	/*If new node is first node in list*/
	created_list = list;
	if (list == NULL)
		return pNew;
	/*If otherwise*/
	while (list->next != NULL)
		list = list->next;
	list->next = pNew;
	/*Return updated list*/
	return created_list;
}

int lookup(char value[], struct node *head) {
	/*If list node is empty, return 0*/
	if (head == NULL)
		return 0;
	/*If list node contains the value, return 1*/
	else if (strcmp(value, head->name) == 0)
		return 1;
	/*Otherwise continue down the list*/
	else
		return(lookup(value, head->next));
}

void changeref(char value[], struct node *head) {
	int rc;
	/*If list node contains the value, raise reference count by 1*/
	if (strcmp(value, head->name) == 0) {
		rc = head->refcount;
		rc += 1;
		head->refcount = rc;
	}
	/*Otherwise continue down the list*/
	else {
		changeref(value, head->next);
	}
}

void print(struct node *list, FILE *ofp) {
	struct node *current = list;
	/*While current node is not empty*/
	while (current != NULL)
	{
		/*Print out the node information*/
		fprintf(ofp, "	%s	%d\n", current->name, current->refcount);
		/*Continue to the next node*/
		current = current->next;
	}
}

.
    fscanf(ifp, "%s", &command)

    fscanf(ifp, "%s", &item);

.
  fscanf(ifp, "%s", command)
  
  fscanf(ifp, "%s", item);

.
  ifp = fopen("inputfile.txt", "r");
  if (!ifp) {
    printf("Can't open input file\n");
    return 0;
  }
  printf("opened input file\n");

  ofp = fopen("outputfile.txt", "w");
  if (!ofp) {
    printf("Can't open output file\n");
    return 0;
  }
  printf("opened output file\n");

  while (fscanf(ifp, "%s", command) == 1) {
    printf("command = %s\n", command);

    if (fscanf(ifp, "%s", item) != 1) {
      printf("fscanf failed for item\n");
      break;
    }
    printf("item = %s\n", item);