#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>

#include "video_decode.h"
#include "util.h"

static double
frame_diff(struct video_frame *frame_a, struct video_frame *frame_b)
{
	double average = 0;
	uint8_t *row_a = frame_a->data, *col_a = NULL;
	uint8_t *row_b = frame_b->data, *col_b = NULL;

	for (int y = 0; y < frame_a->height; ++y) {
		col_a = row_a;
		col_b = row_b;
		for (int x = 0; x < frame_a->width; ++x) {
			average += abs(*col_a - *col_b);
			col_a++;
			col_b++;
		}
		row_a += frame_a->stride;
		row_b += frame_b->stride;
	}

	return average / (frame_a->width * frame_a->height);
}

static double
frame_average(struct video_frame *frame)
{
	double average = 0;
	uint8_t *row = frame->data;
	uint8_t *col = NULL;

	for (int y = 0; y < frame->height; ++y) {
		col = row;
		for (int x = 0; x < frame->width; ++x) {
			average += *col;
			col++;
		}
		row += frame->stride;
	}

	return average / (frame->width * frame->height);
}

static void
usage(void)
{
	fprintf(stderr, "advtime [-a] [-d] FILE\n");
	exit(EXIT_FAILURE);
}

int
main(int argc, char **argv)
{
	struct video_decode *vd;
	struct video_frame *frame_a;
	struct video_frame *frame_b;
	int ret, ch;
	int diff_flag = 0, average_flag = 0;
	int64_t timestamp = 0;
	double diff = 0.0;
	char filename[BUFSIZ];

	while ((ch = getopt(argc, argv, "ad")) != -1) {
		switch (ch) {
		case 'a':
			average_flag = 1;
			break;
		case 'd':
			diff_flag = 1;
			break;
		default:
			usage();
			/* NOTREACHED */
		}
	}
	argc -= optind;
	argv += optind;

	if (argc < 1)
		usage();

	if (argc == 2 && strtol(argv[1], NULL, 10) > 0)
		timestamp = strtol(argv[1], NULL, 10);

	ret = video_decode_init(&vd, argv[0], timestamp);
	if (ret < 0)
		return -ret;

	ret = video_decode_get_frame(vd, &frame_a);
	if (ret < 0)
		return -ret;

	for (int i = 0; video_decode_get_frame(vd, &frame_b) == 0; ++i) {

		printf("%d\t", i);

		if (average_flag == 1)
			printf("%f", frame_average(frame_a));

		if (average_flag == 1 && diff_flag == 1)
			printf("\t");

		if (diff_flag == 1)
			printf("%f", diff = frame_diff(frame_a, frame_b));

		if (diff > 40.0) {
			snprintf(filename, BUFSIZ, "img/%04i.pgm", i);
			frame_mix(frame_a, frame_b);
			if (pgm_save(frame_a->data, frame_a->stride,
				     frame_a->width, frame_a->height,
				     filename) < 0)
				exit(EXIT_FAILURE);
		}

		printf("\n");
		video_decode_free_frame(&frame_a);
		frame_a = frame_b;
	}

	video_decode_free_frame(&frame_b);
	video_decode_uninit(&vd);
	return EXIT_SUCCESS;
}