/**
 *Licensed to the Apache Software Foundation (ASF) under one
 *or more contributor license agreements.  See the NOTICE file
 *distributed with this work for additional information
 *regarding copyright ownership.  The ASF licenses this file
 *to you under the Apache License, Version 2.0 (the
 *"License"); you may not use this file except in compliance
 *with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *Unless required by applicable law or agreed to in writing,
 *software distributed under the License is distributed on an
 *"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 *specific language governing permissions and limitations
 *under the License.
 */
/*
 * linked_list_iterator.c
 *
 *  \date       Jul 16, 2010
 *  \author    	<a href="mailto:dev@celix.apache.org">Apache Celix Project Team</a>
 *  \copyright	Apache License, Version 2.0
 */
#include <stdio.h>
#include <stdlib.h>

#include "linked_list_iterator.h"
#include "linked_list_private.h"

struct linkedListIterator {
	linked_list_entry_pt lastReturned;
	linked_list_entry_pt next;
	int nextIndex;
	linked_list_pt list;
	int expectedModificationCount;
};

linked_list_iterator_pt linkedListIterator_create(linked_list_pt list, unsigned int index) {
	linked_list_iterator_pt iterator;
	if (index > list->size) {
		return NULL;
	}
	iterator = (linked_list_iterator_pt) malloc(sizeof(*iterator));
	iterator->lastReturned = list->header;
	iterator->list = list;
	iterator->expectedModificationCount = list->modificationCount;
	if (index < (list->size >> 1)) {
		iterator->next = iterator->list->header->next;
		for (iterator->nextIndex = 0; iterator->nextIndex < index; iterator->nextIndex++) {
			iterator->next = iterator->next->next;
		}
	} else {
		iterator->next = list->header;
		for (iterator->nextIndex = list->size; iterator->nextIndex > index; iterator->nextIndex--) {
			iterator->next = iterator->next->previous;
		}
	}
	return iterator;
}

void linkedListIterator_destroy(linked_list_iterator_pt iterator) {
	iterator->expectedModificationCount = 0;
	iterator->lastReturned = NULL;
	iterator->list = NULL;
	iterator->next = NULL;
	iterator->nextIndex = 0;
	free(iterator);
}

bool linkedListIterator_hasNext(linked_list_iterator_pt iterator) {
	return iterator->nextIndex != iterator->list->size;
}

void * linkedListIterator_next(linked_list_iterator_pt iterator) {
	if (iterator->list->modificationCount != iterator->expectedModificationCount) {
		return NULL;
	}
	if (iterator->nextIndex == iterator->list->size) {
		return NULL;
	}
	iterator->lastReturned = iterator->next;
	iterator->next = iterator->next->next;
	iterator->nextIndex++;
	return iterator->lastReturned->element;
}

bool linkedListIterator_hasPrevious(linked_list_iterator_pt iterator) {
	return iterator->nextIndex != 0;
}

void * linkedListIterator_previous(linked_list_iterator_pt iterator) {
	if (iterator->nextIndex == 0) {
		return NULL;
	}

	iterator->lastReturned = iterator->next = iterator->next->previous;
	iterator->nextIndex--;

	if (iterator->list->modificationCount != iterator->expectedModificationCount) {
		return NULL;
	}

	return iterator->lastReturned->element;
}

int linkedListIterator_nextIndex(linked_list_iterator_pt iterator) {
	return iterator->nextIndex;
}

int linkedListIterator_previousIndex(linked_list_iterator_pt iterator) {
	return iterator->nextIndex-1;
}

void linkedListIterator_remove(linked_list_iterator_pt iterator) {
	linked_list_entry_pt lastNext;
	if (iterator->list->modificationCount != iterator->expectedModificationCount) {
		return;
	}
	lastNext = iterator->lastReturned->next;
	if (linkedList_removeEntry(iterator->list, iterator->lastReturned) == NULL) {
		return;
	}
	if (iterator->next == iterator->lastReturned) {
		iterator->next = lastNext;
	} else {
		iterator->nextIndex--;
	}
	iterator->lastReturned = iterator->list->header;
	iterator->expectedModificationCount++;
}

void linkedListIterator_set(linked_list_iterator_pt iterator, void * element) {
	if (iterator->lastReturned == iterator->list->header) {
		return;
	}
	if (iterator->list->modificationCount != iterator->expectedModificationCount) {
		return;
	}
	iterator->lastReturned->element = element;
}

void linkedListIterator_add(linked_list_iterator_pt iterator, void * element) {
	if (iterator->list->modificationCount != iterator->expectedModificationCount) {
		return;
	}
	iterator->lastReturned = iterator->list->header;
	linkedList_addBefore(iterator->list, element, iterator->next);
	iterator->nextIndex++;
	iterator->expectedModificationCount++;
}