#include "linked_list.h"
#include <stddef.h>
#include <stdlib.h>

void init_linked_list( linked_list_t *p_list ) {
	p_list->p_head = NULL;
	p_list->p_tail = NULL;
	p_list->size = 0;
}

int front( linked_list_t *p_list, bool *p_valid ) {
	int p_front_value = NULL;

	if ( p_list->size == 0 ) {
		*p_valid = false;
	} else {
		*p_valid = true;
		p_front_value = p_list->p_head->value;
	}

	return p_front_value;
}

int back( linked_list_t *p_list, bool *p_valid ) {
	int p_back_value = NULL;

	if ( p_list->size == 0 ) {
		*p_valid = false;
	} else {
		*p_valid = true;
		p_back_value = p_list->p_tail->value;
	}

	return p_back_value;
}

void push_front( linked_list_t *p_list, int new_value ) {
	if ( p_list->size == 0 ) {
		// Allocate memory for a new node
		p_list->p_head = (node_t *)malloc( sizeof( node_t ) );

		// Initialize the new node
		p_list->p_head->value = new_value;
		p_list->p_tail = p_list->p_head;

		p_list->size = 1;
	} else {
		// Allocate memory for a new node
		node_t *p_new_node = (node_t *)malloc( sizeof( node_t ) );

		// Initialize the new node
		p_new_node->value = new_value;
		p_new_node->p_next = p_list->p_head;

		p_list->p_head = p_new_node;
		++( p_list->size );
	}
}

void push_back( linked_list_t *p_list, int new_value ) {
	if ( p_list->size == 0 ) {
		// Let's not repeat ourselves...
		push_front( p_list, new_value );
	} else {
		// Allocate memory for a new node
		p_list->p_tail->p_next = (node_t *)malloc( sizeof( node_t ) );
		p_list->p_tail = p_list->p_tail->p_next;

		// Initialize the new node
		p_list->p_tail->value = new_value;
		p_list->p_tail->p_next = NULL;

		++( p_list->size );
	}
}

void pop_front( linked_list_t *p_list ) {
	if ( p_list->size == 1 ) {
		// Deallocate memory for the one node
		free( p_list->p_head );

		// Reset the linked list
		p_list->p_head = NULL;
		p_list->p_tail = NULL;
		p_list->size = 0;
	} else if ( p_list->size > 1 ) {
		// Store a pointer to the first node
		node_t *p_to_delete = p_list->p_head;

		// Update the linked list
		p_list->p_head = p_list->p_head->p_next;
		--( p_list->size );

		// Deallocate memory for the previous first node
		free( p_to_delete );
	}
}

node_t *find( linked_list_t *p_list, int sought_value ) {
	node_t *p_node;

	for ( p_node = p_list->p_head; p_node != NULL; p_node = p_node->p_next ) {
		if ( p_node->value == sought_value ) {
			break;
		}
	}

	return p_node;
}