/**

 * 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.

 */

#include <winpr/config.h>

#include <winpr/crt.h>

#include <winpr/assert.h>

#include <winpr/collections.h>

struct s_wQueue

{

  size_t capacity;

  size_t growthFactor;

  BOOL synchronized;

  BYTE padding[4];

  size_t head;

  size_t tail;

  size_t size;

  void** array;

  CRITICAL_SECTION lock;

  HANDLE event;

  wObject object;

  BOOL haveLock;

  BYTE padding2[4];

};

/**

 * 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.

 */

size_t Queue_Count(wQueue* queue)

{

  size_t ret;

  Queue_Lock(queue);

  ret = queue->size;

  Queue_Unlock(queue);

  return ret;

}

/**

 * Lock access to the ArrayList

 */

void Queue_Lock(wQueue* queue)

{

  WINPR_ASSERT(queue);

  if (queue->synchronized)

    EnterCriticalSection(&queue->lock);

}

/**

 * Unlock access to the ArrayList

 */

void Queue_Unlock(wQueue* queue)

{

  WINPR_ASSERT(queue);

  if (queue->synchronized)

    LeaveCriticalSection(&queue->lock);

}

/**

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

 */

HANDLE Queue_Event(wQueue* queue)

{

  WINPR_ASSERT(queue);

  return queue->event;

}

wObject* Queue_Object(wQueue* queue)

{

  WINPR_ASSERT(queue);

  return &queue->object;

}

/**

 * Methods

 */

/**

 * Removes all objects from the Queue.

 */

void Queue_Clear(wQueue* queue)

{

  size_t index;

  Queue_Lock(queue);

  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;

  ResetEvent(queue->event);

  Queue_Unlock(queue);

}

/**

 * Determines whether an element is in the Queue.

 */

BOOL Queue_Contains(wQueue* queue, const void* obj)

{

  size_t index;

  BOOL found = FALSE;

  Queue_Lock(queue);

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

  {

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

    {

      found = TRUE;

      break;

    }

  }

  Queue_Unlock(queue);

  return found;

}

static BOOL Queue_EnsureCapacity(wQueue* queue, size_t count)

{

  WINPR_ASSERT(queue);

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

  {

    const size_t old_capacity = queue->capacity;

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

    void** newArray;

    if (new_capacity < queue->size + count)

      new_capacity = queue->size + count;

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

    if (!newArray)

      return FALSE;

    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;

    }

  }

  return TRUE;

}

/**

 * Adds an object to the end of the Queue.

 */

BOOL Queue_Enqueue(wQueue* queue, const void* obj)

{

  BOOL ret = TRUE;

  Queue_Lock(queue);

  if (!Queue_EnsureCapacity(queue, 1))

    goto out;

  if (queue->object.fnObjectNew)

    queue->array[queue->tail] = queue->object.fnObjectNew(obj);

  else

  {

    union

    {

      const void* cv;

      void* v;

    } cnv;

    cnv.cv = obj;

    queue->array[queue->tail] = cnv.v;

  }

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

  queue->size++;

  SetEvent(queue->event);

out:

  Queue_Unlock(queue);

  return ret;

}

/**

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

 */

void* Queue_Dequeue(wQueue* queue)

{

  void* obj = NULL;

  Queue_Lock(queue);

  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);

  Queue_Unlock(queue);

  return obj;

}

/**

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

 */

void* Queue_Peek(wQueue* queue)

{

  void* obj = NULL;

  Queue_Lock(queue);

  if (queue->size > 0)

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

  Queue_Unlock(queue);

  return obj;

}

void Queue_Discard(wQueue* queue)

{

  void* obj;

  Queue_Lock(queue);

  obj = Queue_Dequeue(queue);

  if (queue->object.fnObjectFree)

    queue->object.fnObjectFree(obj);

  Queue_Unlock(queue);

}

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

{

  return (obj1 == obj2);

}

/**

 * Construction, Destruction

 */

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

{

  wObject* obj;

  wQueue* queue = NULL;

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

  if (!queue)

    return NULL;

  queue->synchronized = synchronized;

  queue->growthFactor = 2;

  if (growthFactor > 0)

    queue->growthFactor = (size_t)growthFactor;

  if (capacity <= 0)

    capacity = 32;

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

    goto fail;

  queue->haveLock = TRUE;

  if (!Queue_EnsureCapacity(queue, (size_t)capacity))

    goto fail;

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

  if (!queue->event)

    goto fail;

  obj = Queue_Object(queue);

  obj->fnObjectEquals = default_queue_equals;

  return queue;

fail:

  Queue_Free(queue);

  return NULL;

}

void Queue_Free(wQueue* queue)

{

  if (!queue)

    return;

  if (queue->haveLock)

  {

    Queue_Clear(queue);

    DeleteCriticalSection(&queue->lock);

  }

  CloseHandle(queue->event);

  free(queue->array);

  free(queue);

}