#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

/* Default values */
#define FPS 60.0
#define DUR 1.0
#define POS 0
#define WIDTH 1920
#define HEIGHT 1080
#define OPACITY 1.0

float kexpout(float i, float f, float t)
{
	if (i != f) {
		return i + (f - i) * (1 - pow(2, -10 * t));
	} else if (t == 1) {
		return i + (f - i);
	} else {
		return i;
	}
}

int main(int argc, char *argv[])
{
	float fps = FPS, dur = DUR;
	int x = POS, y = POS, w = WIDTH, h = HEIGHT;
	int X = POS, Y = POS, W = WIDTH, H = HEIGHT;
	double o = OPACITY, O = OPACITY;
	char method[9];
	int iX = 0, iY = 0, iW = 0, iH = 0, iO = 0;

	if (argc < 3) {
		fprintf(stderr,
"Usage: %s -m method [OPTIONS]\n\n\
Available options:\n\
 -m [expo-in|expo-out|sine-in|sine-out]\n\
 -x [Start X pos]   -X [End X pos]\n\
 -y [Start Y pos]   -Y [End Y pos]\n\
 -w [Start width]   -W [End width]\n\
 -h [Start height]  -H [End height]\n\
 -o [Start opacity] -O [End opacity]\n",
			argv[0]);
		return EXIT_FAILURE;
	}

	if (argc % 2 == 0) {
		fprintf(stderr, "Error: Wrong number of arguments.\n");
		return EXIT_FAILURE;
	}

	for (int i = 1; i < argc; i++) {
		if (strcmp(argv[i], "-m") == 0) {
			strcpy(method, argv[++i]);
		} else if (strcmp(argv[i], "-f") == 0) {
			fps = atof(argv[++i]);
		} else if (strcmp(argv[i], "-d") == 0) {
			dur = atof(argv[++i]);
		} else if (strcmp(argv[i], "-X") == 0) {
			X = atof(argv[++i]);
			iX = 1;
		} else if (strcmp(argv[i], "-Y") == 0) {
			Y = atof(argv[++i]);
			iY = 1;
		} else if (strcmp(argv[i], "-W") == 0) {
			W = atof(argv[++i]);
			iW = 1;
		} else if (strcmp(argv[i], "-H") == 0) {
			H = atof(argv[++i]);
			iH = 1;
		} else if (strcmp(argv[i], "-O") == 0) {
			O = atof(argv[++i]);
			iO = 1;
		} else if (strcmp(argv[i], "-x") == 0) {
			x = atof(argv[++i]);
			if (!iX)
				X = x;
		} else if (strcmp(argv[i], "-y") == 0) {
			y = atof(argv[++i]);
			if (!iY)
				Y = y;
		} else if (strcmp(argv[i], "-w") == 0) {
			w = atof(argv[++i]);
			if (!iW)
				W = w;
		} else if (strcmp(argv[i], "-h") == 0) {
			h = atof(argv[++i]);
			if (!iH)
				H = h;
		} else if (strcmp(argv[i], "-o") == 0) {
			o = atof(argv[++i]);
			if (!iO)
				O = o;
		} else {
			fprintf(stderr, "Unknown option: %s\n", argv[i]);
			return EXIT_FAILURE;
		}
	}

	printf("[{\"DisplayName\": \"Generated %s\", ", method);
	printf("\"in\": 0, ");
	printf("\"max\": 0, ");
	printf("\"min\": 0, ");
	printf("\"name\": \"rect\", ");
	printf("\"opacity\": true, ");
	printf("\"out\": %.2f, ", fps);
	printf("\"type\": 7, ");
	printf("\"value\": \"");

	int keyframes = (int)ceil(fps * dur);
	int xpos = x, ypos = y, width = w, height = h;
	float opacity = o;

	for (int i = 0; i < keyframes - 1; i++) {
		float t = (float)i / (keyframes - 1);

		if (strcmp(method, "expo-out") == 0) {
			xpos = kexpout(x, X, t);
			ypos = kexpout(y, Y, t);
			width = kexpout(w, W, t);
			height = kexpout(h, H, t);
			opacity = kexpout(o, O, t);
		}

		printf("%d=%d %d %d %d %.7f;", i, xpos, ypos, width, height,
		       opacity);
	}

	printf("\"}]\n");

	return EXIT_SUCCESS;
}