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

#define DEBUG(P) printf("%d\n", (P)->val);
//Linked list.
struct node {
	int val;
	struct node *next;
};

void init_head(struct node **head) {
	(*head)->val = 0;
	(*head)->next = NULL;
}

void add_first(struct node **head, int val) {
	struct node *node_t = (struct node *)malloc(sizeof(struct node));
	node_t->val = val;
	node_t->next = *head;
	*head = node_t;
}

void add_last(struct node *head, int val) {
	struct node *ptr = head;
	while (ptr->next != NULL)
		ptr = ptr->next;

	ptr->next = (struct node *)malloc(sizeof(struct node));
	ptr->next->val = val;
	ptr->next->next = NULL;
}

void print_list(struct node *head) {
	struct node *ptr = head;
	while (ptr != NULL) {
		printf("Value: %d\n", ptr->val);
		ptr = ptr->next;
	}
}

void delete_first_node(struct node **head) {
	struct node *ptr = *head;
	*head = ptr->next;
	free(ptr);
}

void delete_last_node(struct node *head) {
	struct node *ptr = head;
	struct node *t = NULL;
	while (ptr->next != NULL) {
		t = ptr;
		ptr = ptr->next;
	}
	free(ptr);
	t->next = NULL;
}
void free_mem_list(struct node *head) {
	struct node *ptr_node;
	while ((ptr_node = head) != NULL) {
		head = head->next;
		free(ptr_node);
	}
}

void remove_node(struct node **head, int _val) {
	struct node *ptr = *head;
	struct node *temp_ptr = ptr;
	while (ptr != NULL) {
		if (ptr->val == _val) {
			if (ptr == *head) {
				temp_ptr = *head;
				ptr = ptr->next;
				*head = (*head)->next;
				free(temp_ptr);
				temp_ptr = ptr;
			} else if (ptr->next == NULL) {
				delete_last_node(*head);
				return;
			} else {
				temp_ptr->next = ptr->next;
				free(ptr);
				ptr = temp_ptr->next; // RESTORE PTR , (IS THE RIGHT WAY(?))
			}
		}else{
			temp_ptr = ptr;
			ptr = ptr->next;
		}
	}
}

int main(int argc, char **argv) {
	struct node *head = (struct node *)malloc(sizeof(struct node));
	init_head(&head);
	add_first(&head, 15);
	add_last(head, 13);
	add_last(head, 15);
	remove_node(&head, 15);
	print_list(head);
	free_mem_list(head);

	return 0;
}