/* 3. Vježba
Napraviti funkcije za rad s uređenom jednostruko povezanom listom struktura
u radnoj memoriji (dodavanje, traženje, brisanje, ispis).  Strukturu zapisa
i dio zapisa koji predstavlja ključ definirati po volji.
Napisati potprograme za izmjenu ključa elementa liste uz očuvanje uređenja:
a) zamjenom sadržaja elemenata
b) uporabom funkcija za brisanje i dodavanje elementa
U glavnom programu treba kreirati uređenu listu podataka prethodno
pohranjenih u slijednoj formatiziranoj datoteci, a zatim interaktivno
tražiti elemente i mijenjati vrijednost ključa uz provjeru sadržaja liste.

Dodatak: Prilagoditi podatkovne strukture i napisati potprogram koji
postojeću listu, uz osnovni ključ, uređuje po nekom drugom ključu (lista s
više ključeva). */

//(c) kreator '97
//travelling through the time, moving slowly in the sand
//knowledge is the weapon against the hunger in the land.

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

struct item_type
{
    //structure type..
	char name[20+1];
	int score;
};

struct list_item
{
    //structure of node
	struct item_type item;
	struct list_item *next;
};

typedef struct list_item node;

int create(node *record, FILE *input) //create linked list without key
{
	struct item_type item;
	int flag=0;
	while ((fscanf(input, "%s %d", &item.name, &item.score)!=EOF))
	{
		flag=1;
		record->item=item; //copy item to current node
		record->next=(node *)malloc(sizeof(node)); //allocate space for next node
		if (!record->next) break; //stop adding.. it's end
		if (!create(record->next, input)) record->next=0; //create next node
	}
	return flag;
}

void display(node *record) //display linked list
{
	printf("%s %d\n", record->item.name, record->item.score);
	if (record->next) display(record->next);
	return;
}

node *locate(node *record, char *target)
{
	if (!strcmpi(record->next->item.name,target)) return(record); //found
		else if (!record->next->next) return 0; //end of list
			else locate(record->next, target); //try next node
}

node *delet(node *first) //add 1 record, ret ptr to start of altered list
{
	node *tag;
	node *tmp;
	char target[20+1];
	printf("Delete item [s]: ");
	scanf("%s", &target);
	if (!(strcmpi(first->item.name,target)))
	{
		tmp=first->next;
		free(first);
		first=tmp;
	}
	else //insert node after existing
	{
		tag=locate(first, target);
		if (!tag) printf("Not found!\n");
		else
		{
			tmp=tag->next->next;
			free(tag->next);
			tag->next=tmp;
		}
	}
	return(first);
}

node *insert(node *first) //add 1 record, ret ptr to start of altered list
{
	node *newrecord; //new node
	node *tag; //node before target node
	struct item_type newitem; //new data item
	char target[20+1]; //data item following the new entry
	printf("New data item [s] [d]: ");
	scanf("%s %d", &newitem.name, &newitem.score);
	printf("Place it before [s]: ");
	scanf("%s", &target);
	if (!(strcmpi(first->item.name,target))) //new node is first in the list
	{
		newrecord=(node *)malloc(sizeof(node));
		newrecord->item=newitem;
		newrecord->next=first;
		first=newrecord;
	}
	else //insert node after existing
	{
		tag=locate(first, target);
		if (!tag) printf("Not found!\n");
		else
		{
			newrecord=(node *)malloc(sizeof(node));
			newrecord->item=newitem;
			newrecord->next=tag->next;
			tag->next=newrecord;
		}
	}
	return(first);
}

node *create2(node *start, FILE *input)
{
	node *tmp=start, *newitem, *tmp2;
	struct item_type item;

	fscanf(input, "%s %d", &item.name, &item.score);
	start->item=item;
	start->next=0;

	while (fscanf(input, "%s %d", &item.name, &item.score)!=EOF)
	{
		newitem=(node *)malloc(sizeof(node));
		newitem->item=item;
		newitem->next=0;
		if (tmp->item.score>=item.score)
		{
			//to the beginning
			newitem->next=start;
			start=newitem;
		}
		else
		{
			//find where to put it
            tmp2=start; //init values.. in fact start searching from head->next
			tmp=start->next;
			while (tmp&&tmp->item.score<item.score)
			{
				tmp2=tmp;
				tmp=tmp->next;
			}
			tmp2->next=newitem; //link prev with new
			newitem->next=tmp; //link new with fol
		}
		tmp=start;
	}
	return start;
}

void change (node *first)
{
	node *tag;
	struct item_type item;

	char target[20+1];
	printf("change item [s]: ");
	scanf("%s", &target);
	if (!strcmpi(first->item.name,target))
	{ //it's head..
		printf("Enter new values [s] [d]: ");
		scanf("%s %d", &item.name, &item.score);
		first->item=item;
	}
	else
    { //seek and destroy ;)
		tag=locate(first, target);
		if (!tag) printf("Not found!\n");
		else
		{
			printf("Enter new values [s] [d]: ");
			scanf("%s %d", &item.name, &item.score);
			tag->next->item=item;
		}
	}
}


void main(void)
{
	FILE *input;
	node *start=(node *)malloc(sizeof(node));
	char choice;

	clrscr();
	if (!(input=fopen("INPUT.TXT", "rt")))
	{
		printf("Input error!\n");
		exit(1);
	}

while (1)
	{
		clrscr();
		printf("1) sort_liste\n2) unsort_list\n3) add\n4) delete\n5) change\n6) exit\n");
		choice=getch();
		switch(choice)
		{
			case '1': start=create2(start, input); display(start); getch(); break;
			case '2': create(start, input); display(start); getch(); break;
			case '3': display(start); start=insert(start); display(start); getch(); break;
			case '4': display(start); start=delet(start); display(start); getch(); break;
			case '5': display(start); change(start); display(start); getch(); break;
			case '6': fclose(input); exit(0);
			default: printf("Wrong choice!\n"); getch();
		}
	rewind(input);
	}
}