/*
	BASS simple synth
	Copyright (c) 2001-2017 Un4seen Developments Ltd.
*/

#include <gtk/gtk.h>
#include <gdk/gdkkeysyms.h>
#include <glade/glade.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "bass.h"

// path to glade file
#ifndef GLADE_PATH
#define GLADE_PATH ""
#endif

GladeXML *glade;
GtkWidget *win = 0;

BASS_INFO info;
HSTREAM stream;		// the stream

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

#define KEYS 20
const guint keys[KEYS] = {
	'Q','2','W','3','E','R','5','T','6','Y','7','U',
	'I','9','O','0','P', GDK_bracketleft, GDK_equal, GDK_bracketright
};
#define MAXVOL 0.22
#define DECAY (MAXVOL/4000)
float vol[KEYS] = { 0 }, pos[KEYS]; // keys' volume and pos

const DWORD fxtype[5] = { BASS_FX_DX8_CHORUS,BASS_FX_DX8_DISTORTION,BASS_FX_DX8_ECHO,BASS_FX_DX8_FLANGER,BASS_FX_DX8_REVERB };
HFX fx[5] = { 0 }; // effect handles

// display error messages
void Error(const char *es)
{
	GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(win), GTK_DIALOG_DESTROY_WITH_PARENT,
		GTK_MESSAGE_ERROR, GTK_BUTTONS_OK, "%s\n(error code: %d)", es, BASS_ErrorGetCode());
	gtk_dialog_run(GTK_DIALOG(dialog));
	gtk_widget_destroy(dialog);
}

#define GetWidget(id) glade_xml_get_widget(glade,id)

void WindowDestroy(GtkObject *obj, gpointer data)
{
	gtk_main_quit();
}

DWORD CALLBACK WriteStream(HSTREAM handle, float *buffer, DWORD length, void *user)
{
	int k, c;
	float omega, s;
	memset(buffer, 0, length);
	for (k = 0; k < KEYS; k++) {
		if (!vol[k]) continue;
		omega = 2 * M_PI * pow(2.0, (k + 3) / 12.0) * 440.0 / info.freq;
		for (c = 0; c < length / sizeof(float); c += 2) {
			buffer[c] += sin(pos[k]) * vol[k];
			buffer[c + 1] = buffer[c]; // left and right channels are the same
			pos[k] += omega;
			if (vol[k] < MAXVOL) {
				vol[k] -= DECAY;
				if (vol[k] <= 0) { // faded-out
					vol[k] = 0;
					break;
				}
			}
		}
		pos[k] = fmod(pos[k], 2 * M_PI);
	}
	return length;
}

void FXToggled(GtkToggleButton *obj, gpointer data)
{ // toggle effects
	const gchar *objname = gtk_widget_get_name(GTK_WIDGET(obj));
	int n = atoi(objname + 2);
	if (fx[n]) {
		BASS_ChannelRemoveFX(stream, fx[n]);
		fx[n] = 0;
	} else
		fx[n] = BASS_ChannelSetFX(stream, fxtype[n], 0);
}

gboolean KeyHandler(GtkWidget *grab_widget, GdkEventKey *event, gpointer data)
{
	int key, kv = event->keyval;
	if (kv >= 'a' && kv <= 'z') kv -= 0x20;
	for (key = 0; key < KEYS; key++) {
		if (kv == keys[key]) {
			if (event->type == GDK_KEY_PRESS && vol[key] < MAXVOL) {
				pos[key] = 0;
				vol[key] = MAXVOL + DECAY / 2; // start key (setting "vol" slightly higher than MAXVOL to cover any rounding-down)
			} else if (event->type == GDK_KEY_RELEASE && vol[key])
				vol[key] -= DECAY; // trigger key fadeout
			break;
		}
	}
	return FALSE;
}

int main(int argc, char* argv[])
{
	gtk_init(&argc, &argv);

	// check the correct BASS was loaded
	if (HIWORD(BASS_GetVersion()) != BASSVERSION) {
		Error("An incorrect version of BASS was loaded");
		return 0;
	}

	// initialize default output device
	if (!BASS_Init(-1, 44100, 0, NULL, NULL)) {
		Error("Can't initialize device");
		return 0;
	}

	// initialize GUI
	glade = glade_xml_new(GLADE_PATH"synth.glade", NULL, NULL);
	if (!glade) return 0;
	win = GetWidget("window1");
	if (!win) return 0;
	glade_xml_signal_autoconnect(glade);

	BASS_GetInfo(&info);
	stream = BASS_StreamCreate(info.freq, 2, BASS_SAMPLE_FLOAT, (STREAMPROC*)WriteStream, 0); // create a stream (stereo for effects)
	BASS_ChannelSetAttribute(stream, BASS_ATTRIB_BUFFER, 0); // no buffering for minimum latency
	BASS_ChannelPlay(stream, FALSE); // start it

	g_signal_connect(win, "key-press-event", G_CALLBACK(KeyHandler), NULL);
	g_signal_connect(win, "key-release-event", G_CALLBACK(KeyHandler), NULL);

	gtk_main();

	BASS_Free();

	return 0;
}