#define _XOPEN_SOURCE 700
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <inttypes.h>

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

int
pgm_read(char *filename, unsigned char **buf, int *xsize, int *ysize)
{
	FILE *f = NULL;
	unsigned char *b = NULL;
	int width, height;
	ssize_t n;

	f = fopen(filename, "r");
	if (f == NULL)
		return -1;

	if (fscanf(f, "P5\n%d %d\n255\n", &width, &height) == 0)
		goto fail;

	if (width * height <= 0)
		goto fail;

	if ((b = malloc(width * height)) == NULL)
		goto fail;
	if ((n = fread(b, 1, width * height, f)) == 0 || n != width * height)
		goto fail;

	fclose(f);

	*buf = b;
	*xsize = width;
	*ysize = height;

	return 0;

fail:
	if (f) fclose(f);
	if (b) free(b);
	return -1;
}

int
pgm_save(unsigned char *buf, int wrap, int xsize, int ysize, char *filename)
{
	FILE *f;
	int i;

	f = fopen(filename, "w");
	if (f == NULL)
		return -1;
	fprintf(f, "P5\n%d %d\n%d\n", xsize, ysize, 255);
	for(i = 0; i < ysize; i++)
		fwrite(buf + i * wrap, 1, xsize, f);
	fclose(f);

	return 0;
}

void
frame_mix(struct video_frame *frame_a, struct video_frame *frame_b)
{
        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) {
			if (x > frame_a->width / 2)
	                        *col_a = *col_b;
                        col_a++;
                        col_b++;
                }
                row_a += frame_a->stride;
                row_b += frame_b->stride;
        }
}

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);
}

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);
}


/* print time in format: "hh:mm:ss.xxx" */
void
print_time(int64_t msec) {

	int hh = msec / 1000 / 60 / 60;
	msec -= hh * 1000 * 60 * 60;
	int mm = msec / 1000 / 60;
	msec -= mm * 1000 * 60;
	int ss = msec / 1000;
	msec -= ss * 1000;

	printf("%02d:%02d:%02d.%03" PRId64, hh, mm, ss, msec);
}

int
sobel(struct video_frame *frame, unsigned char **d)
{
	unsigned char *data;
	unsigned char *p = frame->data;
	int x,y;
	int Yx, Yy, Y;

	data = malloc(frame->width * frame->height);
	if (data == NULL)
		return -1;

	for (y = 1; y < frame->height-1; ++y) {
		for (x = 1; x < frame->width-1; ++x) {
			Yx = (+1 * p[(y-1) * frame->stride + (x-1)]
			      -1 * p[(y-1) * frame->stride + (x+1)]
			      +2 * p[(y  ) * frame->stride + (x-1)]
			      -2 * p[(y  ) * frame->stride + (x+1)]
			      +1 * p[(y+1) * frame->stride + (x-1)]
			      -1 * p[(y+1) * frame->stride + (x+1)]);
			Yx = abs(Yx);

			Yy = (+1 * p[(y-1) * frame->stride + (x-1)]
			      +2 * p[(y-1) * frame->stride + (x  )]
			      +1 * p[(y-1) * frame->stride + (x+1)]
			      -1 * p[(y+1) * frame->stride + (x-1)]
			      -2 * p[(y+1) * frame->stride + (x  )]
			      -1 * p[(y+1) * frame->stride + (x+1)]);
			Yy = abs(Yy);

			Y = (Yx > Yy ? Yx : Yy) / 4;
			if (Y > 255) Y = 255;
			
			data[y * frame->width + x] = Y;
		}
	}

	*d = data;

	return 0;
}