//
//  audio.cpp
//  interface
//
//  Created by Stephen Birarda on 1/22/13.
//  Copyright (c) 2013 Rosedale Lab. All rights reserved.
//

#include "audio.h"

bool Audio::initialized;
PaError Audio::err;
PaStream *Audio::stream;
Audio::AudioData *Audio::data;


/**
 * Audio callback used by portaudio.
 * Communicates with Audio via a shared pointer to Audio::data.
 * Writes input audio channels (if they exist) into Audio::data->buffer,
 multiplied by Audio::data->inputGain.
 * Then writes Audio::data->buffer into output audio channels, and clears
 the portion of Audio::data->buffer that has been read from for reuse.
 *
 * @param[in]  inputBuffer  A pointer to an internal portaudio data buffer containing data read by portaudio.
 * @param[out] outputBuffer A pointer to an internal portaudio data buffer to be read by the configured output device.
 * @param[in]  frames       Number of frames that portaudio requests to be read/written.
 (Valid size of input/output buffers = frames * number of channels (2) * sizeof data type (float)).
 * @param[in]  timeInfo     Portaudio time info. Currently unused.
 * @param[in]  statusFlags  Portaudio status flags. Currently unused.
 * @param[in]  userData     Pointer to supplied user data (in this case, a pointer to Audio::data).
 Used to communicate with external code (since portaudio calls this function from another thread).
 * @return Should be of type PaStreamCallbackResult. Return paComplete to end the stream, or paContinue to continue (default).
 Can be used to end the stream from within the callback.
 */

int audioCallback (const void *inputBuffer,
                   void *outputBuffer,
                   unsigned long frames,
                   const PaStreamCallbackTimeInfo *timeInfo,
                   PaStreamCallbackFlags statusFlags,
                   void *userData)
{
    Audio::AudioData *data = (Audio::AudioData *) userData;
    int16_t *input = (int16_t *) inputBuffer;
    int16_t *output = (int16_t *) outputBuffer;
    
    // check if we have input data
    if (input != NULL) {
        memcpy(data->buffer, input, data->bufferLength * 2);
    }
    
    memcpy(output, data->buffer, data->bufferLength * 2);

    return paContinue;
}

/**
 * Initialize portaudio and start an audio stream.
 * Should be called at the beginning of program exection.
 * @seealso Audio::terminate
 * @return  Returns true if successful or false if an error occurred.
Use Audio::getError() to retrieve the error code.
 */
bool Audio::init()
{
    return Audio::init(NULL);
}

bool Audio::init(Head* mainHead)
{
    initialized = true;
    
    data = new AudioData();
    data->linkedHead = mainHead;
    
    err = Pa_Initialize();
    if (err != paNoError) goto error;
    
    err = Pa_OpenDefaultStream(&stream,
                               1,       // input channels
                               1,       // output channels
                               paInt16, // sample format
                               22050,   // sample rate (hz)
                               512,     // frames per buffer
                               audioCallback, // callback function
                               (void *) data);  // user data to be passed to callback
    
    if (err != paNoError) goto error;
    
    err = Pa_StartStream(stream);
    if (err != paNoError) goto error;
    
    return paNoError;
error:
    fprintf(stderr, "-- Failed to initialize portaudio --\n");
    fprintf(stderr, "PortAudio error (%d): %s\n", err, Pa_GetErrorText(err));
    initialized = false;
    delete[] data;
    return false;
}

/**
 * Close the running audio stream, and deinitialize portaudio.
 * Should be called at the end of program execution.
 * @return Returns true if the initialization was successful, or false if an error occured.
 The error code may be retrieved by Audio::getError().
 */
bool Audio::terminate ()
{
    if (!initialized) {
        return true;
    } else {
        initialized = false;
        
        err = Pa_CloseStream(stream);
        if (err != paNoError) goto error;
        
        delete data;
        
        err = Pa_Terminate();
        if (err != paNoError) goto error;
        
        return true;
    }
    
error:
    fprintf(stderr, "-- portaudio termination error --\n");
    fprintf(stderr, "PortAudio error (%d): %s\n", err, Pa_GetErrorText(err));
    return false;
}