/*
   This file is part of GNUnet
   Copyright (C) 2013 GNUnet e.V.

   GNUnet is free software: you can redistribute it and/or modify it
   under the terms of the GNU Affero General Public License as published
   by the Free Software Foundation, either version 3 of the License,
   or (at your option) any later version.

   GNUnet is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Affero General Public License for more details.

   You should have received a copy of the GNU Affero General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

/**
 * @author Simon Dieterle
 * @author Andreas Fuchs
 * @author Christian Grothoff
 *
 * @file
 * API to access an audio speaker; provides access to hardware speakers
 *
 * @defgroup speaker  Speaker service
 * Access hardware audio speakers.
 * @{
 */
#ifndef GNUNET_SPEAKER_SERVICE_H
#define GNUNET_SPEAKER_SERVICE_H

#ifdef __cplusplus
extern "C"
{
#if 0                           /* keep Emacsens' auto-indent happy */
}
#endif
#endif

#include "gnunet_util_lib.h"

/**
 * Function that enables a speaker.
 *
 * @param cls closure
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
typedef int (*GNUNET_SPEAKER_EnableCallback)(void *cls);

/**
 * Function that disables a speaker.
 *
 * @param cls closure
 */
typedef void (*GNUNET_SPEAKER_DisableCallback)(void *cls);

/**
 * Function to destroy a speaker.
 *
 * @param cls closure
 */
typedef void (*GNUNET_SPEAKER_DestroyCallback)(void *cls);

/**
 * Function to cause a speaker to play audio data.
 *
 * @param cls closure
 * @param data_size number of bytes in @a data
 * @param data audio data to play, format is
 *        opaque to the API but should be OPUS.
 */
typedef void (*GNUNET_SPEAKER_PlayCallback)(void *cls,
                                            size_t data_size,
                                            const void *data);


/**
 * A speaker is a device that can play or record audio data.
 */
struct GNUNET_SPEAKER_Handle
{
  /**
   * Turn on the speaker.
   */
  GNUNET_SPEAKER_EnableCallback enable_speaker;

  /**
   * Play audio.
   */
  GNUNET_SPEAKER_PlayCallback play;

  /**
   * Turn the speaker off.
   */
  GNUNET_SPEAKER_DisableCallback disable_speaker;

  /**
   * Destroy the speaker.  Called by #GNUNET_SPEAKER_destroy.
   */
  GNUNET_SPEAKER_DestroyCallback destroy_speaker;

  /**
   * Closure for the callbacks.
   */
  void *cls;
};


/**
 * Create a speaker that corresponds to the speaker hardware
 * of our system.
 *
 * @param cfg configuration to use
 * @return NULL on error
 */
struct GNUNET_SPEAKER_Handle *
GNUNET_SPEAKER_create_from_hardware (const struct
                                     GNUNET_CONFIGURATION_Handle *cfg);


/**
 * Destroy a speaker.
 *
 * @param speaker speaker to destroy
 */
void
GNUNET_SPEAKER_destroy (struct GNUNET_SPEAKER_Handle *speaker);


#if 0                           /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif

#endif

/** @} */ /* end of group */

/* end of gnunet_speaker_lib.h */