/*

* Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:   Base classes for multi-purpose tasks.

*

*/

/**

 * @internal reviewed 30/07/2007 by Simon Brooks

 */

#ifndef C_GLXTNTASK_H

#define C_GLXTNTASK_H

#include "glxtnstd.h"

#include <glxmediaid.h>

#include <e32base.h>

// Forward declarations

class CGlxtnTaskManager;

class MGlxtnThumbnailCreatorClient;

class MGlxtnThumbnailStorage;

/**

 *  Base class for thumbnail tasks.

 *

 * @ingroup glx_thumbnail_creator

 */

NONSHARABLE_CLASS(CGlxtnTask) : public CBase

    {

    friend class CGlxtnTaskManager;

public:

    /**

    * Different state a task can go through

    */

    enum TState 

        {

        EIdle,      /**< Task is not ready to start */

        EStarting,  /**< Task is ready to start */

        ERunning,   /**< Task is currently running */

        ECanceled,  /**< Task has been cancelled, and can be deleted */

        EComplete   /**< Task has finished, and can be deleted */

        };

public:

    CGlxtnTask(const TGlxtnTaskId& aId, const TGlxMediaId& aItemId,

                MGlxtnThumbnailStorage* aStorage);

    ~CGlxtnTask();

    /**

     * Gets the current task specific state

     * @returns TState The task current state.

     */

    inline TState State() const;

    /**

     * Gets the type of task this is.

     * @returns TGlxtnTaskId Task type ID.

     */

    inline TGlxtnTaskId Id() const;

    /**

     * Gets the media ID of the item to which this task relates.

     * @returns TGlxMediaId Media ID.

     */

    inline TGlxMediaId ItemId() const;

    /**

     * Sets the priority of the task. By default it is set to 

     * EPriorityStandard.

     */

    inline void SetPriority(TInt aPriority);

    /**

     * Gets the task priority.

     * @returns TInt Task priority.

     */

	inline TInt Priority() const;

    /**

     * Get thumbnail storage for the task to use, if any.

     * @returns Pointer to thumbnail storage, or NULL if none.

     */

    inline MGlxtnThumbnailStorage* Storage() const;

    /**

     * Provides a pointer to the task manager.

     * @param aManager Pointer to the task manager.

     */

    virtual void SetManager(CGlxtnTaskManager* aManager);

private: // For CGlxTaskManager only

    /**

     * Starts the task 

     */

    void StartL(TRequestStatus& aStatus);

	/**

	 * Cancels the task

	 */

	void Cancel(); 

	/**

	 * Runs a bit of the task

	 */

	void RunL(TRequestStatus& aStatus);

	/**

	 * Handle a leave in StartL or RunL.

	 */

    void RunError(TInt aError);

protected:

    /**

     * Starts the task.

     * @param aStatus Request status for asynchronous operations

     * @returns -ETrue if the task has issued an asyncronous request.

     *			CActive::SetActive() will be called in this case and the 

     *			task state will be ERunning.

     *			-EFalse if the task has not issued a request. 

     *			SetActive will not be called and the task state will be 

     *			EComplete.

     */

    virtual TBool DoStartL(TRequestStatus& aStatus) = 0;

	/**

	 * Cancels the task.  The task's state will be set to ECanceled.

	 */

	virtual void DoCancel() = 0; 

	/**

	 * Runs a bit of the task

     * @param aStatus Request status for asynchronous operations

     * @returns -ETrue if the task has issued an asyncronous request.

     *			CActive::SetActive() will be called in this case and the 

     *			task state will be ERunning.

     *			-EFalse if the task has not issued a request. 

     *			SetActive will not be called and the task state will be 

     *			EComplete.

	 */

	virtual TBool DoRunL(TRequestStatus& aStatus) = 0;

	/**

	 * Handle a leave in StartL or RunL.

     * @param aError The error that occurred.

     * @returns -ETrue if the task has issued an asyncronous request.

     *			CActive::SetActive() will be called in this case and the 

     *			task state will be ERunning.

     *			-EFalse if the task has not issued a request. 

     *			SetActive will not be called and the task state will be 

     *			EComplete.

	 */

    virtual TBool DoRunError(TInt aError) = 0;

protected:

	/**

	 * Issues a request and sets the aStatus as KRequestPending

	 * Use this to make a synchronous operation asynchronous.

	 */

	void SelfComplete(TRequestStatus& aStatus); 

private:

    /** Task state */

    TState iState;

    /** Task id */

    TGlxtnTaskId iId;

    /** Media item id */

    TGlxMediaId iItemId;

    /**

     * Priority of this task. 

     * The task schedule will execute tasks based on this priority

     * When this task is run, the execution priority in CActiveScheduler

     * will be this priority. (So it is comparable to priorities of active 

     * objects in the system.)

     */

    TInt iPriority; 

    /** Thumbnail storage for the task to use (can be NULL) */

    MGlxtnThumbnailStorage* iStorage;

    };

/**

 *  Base class for thumbnail tasks which return results to a client.

 *

 * @ingroup glx_thumbnail_creator

 */

NONSHARABLE_CLASS(CGlxtnClientTask) : public CGlxtnTask

    {

protected:

    CGlxtnClientTask(const TGlxtnTaskId& aId, const TGlxMediaId& aItemId,

                MGlxtnThumbnailCreatorClient& aClient);

    /**

     * Get the client for this task.

     */

    inline MGlxtnThumbnailCreatorClient& Client();

private:

    /** Client for this task */

    MGlxtnThumbnailCreatorClient& iClient;

    };

#include "glxtntask.inl"

#endif // C_GLXTNTASK_H