#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <OpenAL/al.h>
#include <OpenAL/alc.h>

#define CASE_RETURN(err) case (err): return "##err"
const char* al_err_str(ALenum err) {
	switch(err) {
		CASE_RETURN(AL_NO_ERROR);
		CASE_RETURN(AL_INVALID_NAME);
		CASE_RETURN(AL_INVALID_ENUM);
		CASE_RETURN(AL_INVALID_VALUE);
		CASE_RETURN(AL_INVALID_OPERATION);
		CASE_RETURN(AL_OUT_OF_MEMORY);
	}
	return "unknown";
}
#undef CASE_RETURN

#define __al_check_error(file,line) \
	do { \
		ALenum err = alGetError(); \
		for(; err!=AL_NO_ERROR; err=alGetError()) { \
			std::cerr << "AL Error " << al_err_str(err) << " at " << file << ":" << line << std::endl; \
		} \
	}while(0)

#define al_check_error() \
	__al_check_error(__FILE__, __LINE__)


void init_al() {
	ALCdevice *dev = NULL;
	ALCcontext *ctx = NULL;

	const char *defname = alcGetString(NULL, ALC_DEFAULT_DEVICE_SPECIFIER);
	std::cout << "Default device: " << defname << std::endl;

	dev = alcOpenDevice(defname);
	ctx = alcCreateContext(dev, NULL);
	alcMakeContextCurrent(ctx);
}

void exit_al() {
	ALCdevice *dev = NULL;
	ALCcontext *ctx = NULL;
	ctx = alcGetCurrentContext();
	dev = alcGetContextsDevice(ctx);

	alcMakeContextCurrent(NULL);
	alcDestroyContext(ctx);
	alcCloseDevice(dev);
}

int main(int argc, char* argv[]) {
	/* initialize OpenAL */
	init_al();

	/* Create buffer to store samples */
	ALuint buf;
	alGenBuffers(1, &buf);
	al_check_error();

	/* Fill buffer with Sine-Wave */
	float freq = 440.f;
	int seconds = 4;
	unsigned sample_rate = 22050;
	size_t buf_size = seconds * sample_rate;

	short *samples;
	samples = new short[buf_size];
	for(int i=0; i<buf_size; ++i) {
		samples[i] = 32760 * sin( (2.f*float(M_PI)*freq)/sample_rate * i );
	}

	/* Download buffer to OpenAL */
	alBufferData(buf, AL_FORMAT_MONO16, samples, buf_size, sample_rate);
	al_check_error();


	/* Set-up sound source and play buffer */
	ALuint src = 0;
	alGenSources(1, &src);
	alSourcei(src, AL_BUFFER, buf);
	alSourcePlay(src);

	/* While sound is playing, sleep */
	al_check_error();
	sleep(seconds);

	/* Dealloc OpenAL */
	exit_al();
	al_check_error();
	return 0;
}