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

#define WIDTH 1600
#define HEIGHT 700
#define PRINT 1

void printargs(int argc, char * argv[]);
void inputppm(char * filename, char *** red, char *** green, char *** blue);
void findedges(char ** red, char ** green, char ** blue);

void main(int argc, char * argv[])
{
	char * infilename;
	FILE * infile;

	char ** red;
	char ** green;
	char ** blue;

	int i,j;

	if (PRINT)
		printargs(argc, argv);

	if (argc < 2)
	{
		printf("Usage: gigo filename\n");
		exit(0);
	}
	
	infilename = argv[1];	

	if ((infile = fopen(infilename, "rb")) == NULL)
	{
		printf("Couldn't find %s\n", infilename);
		exit(0);
	}

	printf("Mallocing red[].\n");
	red = (char **) malloc (WIDTH * sizeof (char *));
	for (i=0; i<WIDTH; i++)
	{
		if (PRINT && !(i %100)) 
			printf("Mallocing red[%d].\n", i);
		red[i] = (char *) malloc (HEIGHT * sizeof (char));
	}	

	printf("Mallocing green[].\n");
	green = (char **) malloc (WIDTH * sizeof (char *));
	for (i=0; i<WIDTH; i++)
	{
		if (PRINT && !(i %100)) 
			printf("Mallocing green[%d].\n", i);
		green[i] = (char *) malloc (HEIGHT * sizeof (char));
	}	

	printf("Mallocing blue[].\n");
	blue = (char **) malloc (WIDTH * sizeof (char *));
	for (i=0; i<WIDTH; i++)
	{
		if (PRINT && !(i %100)) 
			printf("Mallocing blue[%d].\n", i);
		blue[i] = (char *) malloc (HEIGHT * sizeof (char));
	}	

	inputppm(infilename, &red, &green, &blue);

	findedges(red, green, blue);
}

void inputppm(char * filename, char *** red, char *** green, char *** blue)
{
	FILE * infile;
	int w, h, i, j;

	infile = fopen(filename, "rb");

	fscanf(infile, "P6\n%d %d\n255\n", &w, &h);  

	if (w != WIDTH || h != HEIGHT)
	{
		printf("Oops! w and h are %d, %d\n", w, h);
		exit(0);
	}

        for (j=0; j<HEIGHT; j++) 
        {
	    if (PRINT && !(i %100)) 
                printf("Reading line %d\n", j); 
            for (i=0; i<WIDTH; i++) 
            {
                fscanf(infile, "%c", &((*red)[i][j])); 
                fscanf(infile, "%c", &((*green)[i][j])); 
                fscanf(infile, "%c", &((*blue)[i][j])); 
            }
        }

	fclose(infile);
}

void findedges(char **red, char **green, char **blue)
{
	int i, j;
	int allblack = 1;
	
	if (PRINT) 
		printf("Checking lines from top...\n");
	
	j = 0;
	while (allblack && j < HEIGHT)
	{
	    i = 0;
	    while (allblack && i < WIDTH)
	    {
		if (red[i][j] > 0 || green[i][j] > 0 || blue[i][j] > 0)
		{		
		    allblack = 0;
		}
		else i++;		
	    }
	    if (!allblack)
		if (PRINT)
		    printf("First nonblack horiz line found at j = %d\n", j);
	    else j++;
	}

	if (allblack)
	{
	    if (PRINT)
		printf("No nonblack horiz lines found!\n");	
	    return;
	}
}

void printargs(int argc, char * argv[])
{
	int i;

	for (i=0; i<argc; i++)
	{
		printf("%d: %s\n", i, argv[i]);
	}
}