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

#include "linked_list.h"

struct node
{
    elem data;
    position next;
};

int is_empty(list header)
{
    return header->next == NULL;
}

int is_last(position p, list header)
{
    return p->next == NULL;
}

position find(elem x, list header)
{
    position p;
    p = header->next;

    for(; p != NULL; p = p->next) {
        if(p->data == x) return p;
    }

    return NULL;
}

void delete(elem x, list header)
{
    position tmp;
    position pre;

    pre = find_previous(x, header);

    if(!is_last(pre, header)) {
        tmp = pre->next;
        pre->next = pre->next->next;
        free(tmp);
    }

}

position find_previous(elem x, list header)
{
    position p;

    p = header;
    while(p->next != NULL && p->next->data != x)
        p = p->next;

    return p;
}

void insert(elem x, list header, position p)
{
    position tmp;
    
    tmp = malloc(sizeof(struct node));
    
    if(tmp == NULL)
       printf("Out of space!\n"); 

    tmp->data = x;
    tmp->next = p->next;
    p->next = tmp;
}

void delete_list(list header)
{
    position p, tmp;

    p = header->next;
    header->next = NULL;

    while(p != NULL) {
        tmp = p;
        p = p->next;
        free(tmp);
    }
}

void print_list(list header)
{
    position p;

    if(is_empty(header))
       printf("empty list! \n");

    p = header->next;
    for(; p != NULL; p = p->next) 
        printf("%d->", p->data);
    printf("\n");
}

int test()
{
    position p1, p2, p3;
    list l1, l2, l3, l4;
    l1 = malloc(sizeof(struct node));
    l1->next == NULL;

    print_list(l1);

    /* test insert foo */
    insert(5, l1, l1);
    insert(4, l1, l1);
    insert(3, l1, l1);
    insert(2, l1, l1);
    insert(1, l1, l1);
    print_list(l1);


    /* test find foo */
    p1 = find(2, l1);
    printf("%d\n", p1->next->data);

    /* test delete foo */
    delete(3, l1);
    delete(5, l1);
    delete(1, l1);
    print_list(l1);

    /* test delete_list foo */
    delete_list(l1);
    print_list(l1);
}

int main()
{
    test();
    return 0;
}