/**

 * WinPR: Windows Portable Runtime

 * System.Collections.Queue

 *

 * Copyright 2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>

 *

 * Licensed 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.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <winpr/crt.h>

#include <winpr/collections.h>

/**

 * C equivalent of the C# Queue Class:

 * http://msdn.microsoft.com/en-us/library/system.collections.queue.aspx

 */

/**

 * Properties

 */

/**

 * Gets the number of elements contained in the Queue.

 */

int Queue_Count(wQueue* queue)

{

	int ret;

	if (queue->synchronized)

		EnterCriticalSection(&queue->lock);

	ret = queue->size;

	if (queue->synchronized)

		LeaveCriticalSection(&queue->lock);

	return ret;

}

/**

 * Lock access to the ArrayList

 */

void Queue_Lock(wQueue* queue)

{

	EnterCriticalSection(&queue->lock);

}

/**

 * Unlock access to the ArrayList

 */

void Queue_Unlock(wQueue* queue)

{

	LeaveCriticalSection(&queue->lock);

}

/**

 * Gets an event which is set when the queue is non-empty

 */

HANDLE Queue_Event(wQueue* queue)

{

	return queue->event;

}

/**

 * Methods

 */

/**

 * Removes all objects from the Queue.

 */

void Queue_Clear(wQueue* queue)

{

	int index;

	if (queue->synchronized)

		EnterCriticalSection(&queue->lock);

	for (index = queue->head; index != queue->tail; index = (index + 1) % queue->capacity)

	{

		if (queue->object.fnObjectFree)

			queue->object.fnObjectFree(queue->array[index]);

		queue->array[index] = NULL;

	}

	queue->size = 0;

	queue->head = queue->tail = 0;

	if (queue->synchronized)

		LeaveCriticalSection(&queue->lock);

}

/**

 * Determines whether an element is in the Queue.

 */

BOOL Queue_Contains(wQueue* queue, void* obj)

{

	int index;

	BOOL found = FALSE;

	if (queue->synchronized)

		EnterCriticalSection(&queue->lock);

	for (index = 0; index < queue->tail; index++)

	{

		if (queue->object.fnObjectEquals(queue->array[index], obj))

		{

			found = TRUE;

			break;

		}

	}

	if (queue->synchronized)

		LeaveCriticalSection(&queue->lock);

	return found;

}

/**

 * Adds an object to the end of the Queue.

 */

BOOL Queue_Enqueue(wQueue* queue, void* obj)

{

	BOOL ret = TRUE;

	if (queue->synchronized)

		EnterCriticalSection(&queue->lock);

	if (queue->size == queue->capacity)

	{

		int old_capacity;

		int new_capacity;

		void** newArray;

		old_capacity = queue->capacity;

		new_capacity = queue->capacity * queue->growthFactor;

		newArray = (void**)realloc(queue->array, sizeof(void*) * new_capacity);

		if (!newArray)

		{

			ret = FALSE;

			goto out;

		}

		queue->capacity = new_capacity;

		queue->array = newArray;

		ZeroMemory(&(queue->array[old_capacity]), (new_capacity - old_capacity) * sizeof(void*));

		/* rearrange wrapped entries */

		if (queue->tail <= queue->head)

		{

			CopyMemory(&(queue->array[old_capacity]), queue->array, queue->tail * sizeof(void*));

			queue->tail += old_capacity;

		}

	}

	queue->array[queue->tail] = obj;

	queue->tail = (queue->tail + 1) % queue->capacity;

	queue->size++;

	SetEvent(queue->event);

out:

	if (queue->synchronized)

		LeaveCriticalSection(&queue->lock);

	return ret;

}

/**

 * Removes and returns the object at the beginning of the Queue.

 */

void* Queue_Dequeue(wQueue* queue)

{

	void* obj = NULL;

	if (queue->synchronized)

		EnterCriticalSection(&queue->lock);

	if (queue->size > 0)

	{

		obj = queue->array[queue->head];

		queue->array[queue->head] = NULL;

		queue->head = (queue->head + 1) % queue->capacity;

		queue->size--;

	}

	if (queue->size < 1)

		ResetEvent(queue->event);

	if (queue->synchronized)

		LeaveCriticalSection(&queue->lock);

	return obj;

}

/**

 * Returns the object at the beginning of the Queue without removing it.

 */

void* Queue_Peek(wQueue* queue)

{

	void* obj = NULL;

	if (queue->synchronized)

		EnterCriticalSection(&queue->lock);

	if (queue->size > 0)

		obj = queue->array[queue->head];

	if (queue->synchronized)

		LeaveCriticalSection(&queue->lock);

	return obj;

}

static BOOL default_queue_equals(const void* obj1, const void* obj2)

{

	return (obj1 == obj2);

}

/**

 * Construction, Destruction

 */

wQueue* Queue_New(BOOL synchronized, int capacity, int growthFactor)

{

	wQueue* queue = NULL;

	queue = (wQueue*)calloc(1, sizeof(wQueue));

	if (!queue)

		return NULL;

	queue->capacity = 32;

	queue->growthFactor = 2;

	queue->synchronized = synchronized;

	if (capacity > 0)

		queue->capacity = capacity;

	if (growthFactor > 0)

		queue->growthFactor = growthFactor;

	queue->array = (void**)calloc(queue->capacity, sizeof(void*));

	if (!queue->array)

		goto out_free;

	queue->event = CreateEvent(NULL, TRUE, FALSE, NULL);

	if (!queue->event)

		goto out_free_array;

	if (!InitializeCriticalSectionAndSpinCount(&queue->lock, 4000))

		goto out_free_event;

	queue->object.fnObjectEquals = default_queue_equals;

	return queue;

out_free_event:

	CloseHandle(queue->event);

out_free_array:

	free(queue->array);

out_free:

	free(queue);

	return NULL;

}

void Queue_Free(wQueue* queue)

{

	if (!queue)

		return;

	Queue_Clear(queue);

	CloseHandle(queue->event);

	DeleteCriticalSection(&queue->lock);

	free(queue->array);

	free(queue);

}