/*
  * Copyright (c) 2011 Jonathan Baldwin
  *
  * This file is part of FFmpeg.
  *

  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.

  *

  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
  * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  * PERFORMANCE OF THIS SOFTWARE.

  */
 
 /**
  * @file
  * OpenAL 1.1 capture device for libavdevice
  **/
 
 #include <AL/al.h>
 #include <AL/alc.h>
 
 #include "libavutil/opt.h"

 #include "libavformat/internal.h"

 #include "avdevice.h"
 
 typedef struct {
     AVClass *class;
     /** OpenAL capture device context. **/
     ALCdevice *device;
     /** The number of channels in the captured audio. **/
     int channels;
     /** The sample rate (in Hz) of the captured audio. **/
     int sample_rate;
     /** The sample size (in bits) of the captured audio. **/
     int sample_size;
     /** The OpenAL sample format of the captured audio. **/
     ALCenum sample_format;
     /** The number of bytes between two consecutive samples of the same channel/component. **/
     ALCint sample_step;
     /** If true, print a list of capture devices on this system and exit. **/
     int list_devices;
 } al_data;
 
 typedef struct {
     ALCenum al_fmt;

     enum AVCodecID codec_id;

     int channels;
 } al_format_info;
 
 #define LOWEST_AL_FORMAT FFMIN(FFMIN(AL_FORMAT_MONO8,AL_FORMAT_MONO16),FFMIN(AL_FORMAT_STEREO8,AL_FORMAT_STEREO16))
 
 /**
  * Get information about an AL_FORMAT value.
  * @param al_fmt the AL_FORMAT value to find information about.
  * @return A pointer to a structure containing information about the AL_FORMAT value.
  */
 static inline al_format_info* get_al_format_info(ALCenum al_fmt)
 {
     static al_format_info info_table[] = {

         [AL_FORMAT_MONO8-LOWEST_AL_FORMAT]    = {AL_FORMAT_MONO8, AV_CODEC_ID_PCM_U8, 1},
         [AL_FORMAT_MONO16-LOWEST_AL_FORMAT]   = {AL_FORMAT_MONO16, AV_NE (AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE), 1},
         [AL_FORMAT_STEREO8-LOWEST_AL_FORMAT]  = {AL_FORMAT_STEREO8, AV_CODEC_ID_PCM_U8, 2},
         [AL_FORMAT_STEREO16-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO16, AV_NE (AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE), 2},

     };
 
     return &info_table[al_fmt-LOWEST_AL_FORMAT];
 }
 
 /**
  * Get the OpenAL error code, translated into an av/errno error code.
  * @param device The ALC device to check for errors.
  * @param error_msg_ret A pointer to a char* in which to return the error message, or NULL if desired.
  * @return The error code, or 0 if there is no error.
  */
 static inline int al_get_error(ALCdevice *device, const char** error_msg_ret)
 {
     ALCenum error = alcGetError(device);
     if (error_msg_ret)
         *error_msg_ret = (const char*) alcGetString(device, error);
     switch (error) {
     case ALC_NO_ERROR:
         return 0;
     case ALC_INVALID_DEVICE:
         return AVERROR(ENODEV);
         break;
     case ALC_INVALID_CONTEXT:
     case ALC_INVALID_ENUM:
     case ALC_INVALID_VALUE:
         return AVERROR(EINVAL);
         break;
     case ALC_OUT_OF_MEMORY:
         return AVERROR(ENOMEM);
         break;
     default:
         return AVERROR(EIO);
     }
 }
 
 /**
  * Print out a list of OpenAL capture devices on this system.
  */
 static inline void print_al_capture_devices(void *log_ctx)
 {
     const char *devices;
 
     if (!(devices = alcGetString(NULL, ALC_CAPTURE_DEVICE_SPECIFIER)))
         return;
 
     av_log(log_ctx, AV_LOG_INFO, "List of OpenAL capture devices on this system:\n");
 
     for (; *devices != '\0'; devices += strlen(devices) + 1)
         av_log(log_ctx, AV_LOG_INFO, "  %s\n", devices);
 }
 

 static int read_header(AVFormatContext *ctx)

 {
     al_data *ad = ctx->priv_data;
     static const ALCenum sample_formats[2][2] = {
         { AL_FORMAT_MONO8,  AL_FORMAT_STEREO8  },
         { AL_FORMAT_MONO16, AL_FORMAT_STEREO16 }
     };
     int error = 0;
     const char *error_msg;
     AVStream *st = NULL;
     AVCodecContext *codec = NULL;
 
     if (ad->list_devices) {
         print_al_capture_devices(ctx);
         return AVERROR_EXIT;
     }
 
     ad->sample_format = sample_formats[ad->sample_size/8-1][ad->channels-1];
 
     /* Open device for capture */
     ad->device =
         alcCaptureOpenDevice(ctx->filename[0] ? ctx->filename : NULL,
                              ad->sample_rate,
                              ad->sample_format,
                              ad->sample_rate); /* Maximum 1 second of sample data to be read at once */
 
     if (error = al_get_error(ad->device, &error_msg)) goto fail;
 
     /* Create stream */

     if (!(st = avformat_new_stream(ctx, NULL))) {

         error = AVERROR(ENOMEM);
         goto fail;
     }
 
     /* We work in microseconds */

     avpriv_set_pts_info(st, 64, 1, 1000000);

 
     /* Set codec parameters */
     codec = st->codec;
     codec->codec_type = AVMEDIA_TYPE_AUDIO;
     codec->sample_rate = ad->sample_rate;
     codec->channels = get_al_format_info(ad->sample_format)->channels;
     codec->codec_id = get_al_format_info(ad->sample_format)->codec_id;
 
     /* This is needed to read the audio data */
     ad->sample_step = (av_get_bits_per_sample(get_al_format_info(ad->sample_format)->codec_id) *
                        get_al_format_info(ad->sample_format)->channels) / 8;
 
     /* Finally, start the capture process */
     alcCaptureStart(ad->device);
 
     return 0;
 
 fail:
     /* Handle failure */
     if (ad->device)
         alcCaptureCloseDevice(ad->device);
     if (error_msg)
         av_log(ctx, AV_LOG_ERROR, "Cannot open device: %s\n", error_msg);
     return error;
 }
 
 static int read_packet(AVFormatContext* ctx, AVPacket *pkt)
 {
     al_data *ad = ctx->priv_data;
     int error=0;
     const char *error_msg;
     ALCint nb_samples;
 
     /* Get number of samples available */
     alcGetIntegerv(ad->device, ALC_CAPTURE_SAMPLES, (ALCsizei) sizeof(ALCint), &nb_samples);
     if (error = al_get_error(ad->device, &error_msg)) goto fail;
 
     /* Create a packet of appropriate size */
     av_new_packet(pkt, nb_samples*ad->sample_step);
     pkt->pts = av_gettime();
 
     /* Fill the packet with the available samples */
     alcCaptureSamples(ad->device, pkt->data, nb_samples);
     if (error = al_get_error(ad->device, &error_msg)) goto fail;
 
     return pkt->size;
 fail:
     /* Handle failure */
     if (pkt->data)
         av_destruct_packet(pkt);
     if (error_msg)
         av_log(ctx, AV_LOG_ERROR, "Error: %s\n", error_msg);
     return error;
 }
 
 static int read_close(AVFormatContext* ctx)
 {
     al_data *ad = ctx->priv_data;
 
     if (ad->device) {
         alcCaptureStop(ad->device);
         alcCaptureCloseDevice(ad->device);
     }
     return 0;
 }
 
 #define OFFSET(x) offsetof(al_data, x)
 
 static const AVOption options[] = {

     {"channels", "set number of channels",     OFFSET(channels),     AV_OPT_TYPE_INT, {.i64=2},     1, 2,      AV_OPT_FLAG_DECODING_PARAM },
     {"sample_rate", "set sample rate",         OFFSET(sample_rate),  AV_OPT_TYPE_INT, {.i64=44100}, 1, 192000, AV_OPT_FLAG_DECODING_PARAM },
     {"sample_size", "set sample size",         OFFSET(sample_size),  AV_OPT_TYPE_INT, {.i64=16},    8, 16,     AV_OPT_FLAG_DECODING_PARAM },
     {"list_devices", "list available devices", OFFSET(list_devices), AV_OPT_TYPE_INT, {.i64=0},     0, 1,      AV_OPT_FLAG_DECODING_PARAM, "list_devices"  },

     {"true",  "", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
     {"false", "", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },

     {NULL},
 };
 
 static const AVClass class = {
     .class_name = "openal",
     .item_name = av_default_item_name,
     .option = options,
     .version = LIBAVUTIL_VERSION_INT
 };
 
 AVInputFormat ff_openal_demuxer = {
     .name = "openal",
     .long_name = NULL_IF_CONFIG_SMALL("OpenAL audio capture device"),
     .priv_data_size = sizeof(al_data),
     .read_probe = NULL,
     .read_header = read_header,
     .read_packet = read_packet,
     .read_close = read_close,
     .flags = AVFMT_NOFILE,
     .priv_class = &class
 };