#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//#include <png.h>

#define HEADER_FORMAT "#N canvas 0 0 %d %d 10;\n"
#define OUT_HEADER(w, h) fprintf(stdout, HEADER_FORMAT, w, h)
#define CNV_FORMAT "#X obj %d %d cnv 1 %d %d empty empty empty 20 12 0 14 %d -1 0;\n"
#define OUT_PIXEL(x, y, w, h, col) fprintf(stdout, CNV_FORMAT, x, y, w, h, col)
#define OUT_PIXEL_pix(p) OUT_PIXEL(p->x, p->y, p->w, p->h, p->color)
#define C6bit(b) ((b>>2)&0x3F)
#define RGB(r, g, b) ((-1)-(C6bit(r)<<12)-(C6bit(g)<<6)-(C6bit(b)))
#define TRANSPARENT_COLOR (-262144) // WHITE

typedef struct _pix {
	int x;
	int y;
	int w;
	int h;
	int color;
	struct _pix* next;
} pix;

typedef struct _line {
	pix* head;
	struct _line* next;
} line;

line image;

void optimize(pix* pix_head);

int main(int argc, char **argv)
{
	if(argc < 2) {
		fprintf(stderr, "Please specify a PPM image!\n");
		return 1;
	}
	
	FILE *fp = fopen(argv[1], "rb");
	
	if(!fp) {
		fprintf(stderr, "Cannot open file: %s!\n", argv[1]);
		return 1;
	}
	
	char magic;
	int x,y,w,h,r,g,b,maxval,magicn;
	fscanf(fp, "%c%d\n%d %d\n%d\n", &magic, &magicn, &w, &h, &maxval);
	// WARNING: ppm must be stripped from commnets!
	//          expect program (or system) crash otherwise!
	fprintf(stderr, "Found %c%d image %dx%d (%d values)\n", magic, magicn, w, h, maxval);
	
	OUT_HEADER(w, h);

	line* pline = &image;
	pix*  ppix  = 0L;

	for(y=0; y<h; y++) {
		pline->next = (line*)malloc(sizeof(line));
		pline = pline->next;
		ppix = pline->head = (pix*)malloc(sizeof(pix));

		for(x=0; x<w; x++) {
			r = fgetc(fp);
			g = fgetc(fp);
			b = fgetc(fp);
			if(r==EOF || g==EOF || b==EOF) continue;

			ppix->next = (pix*)malloc(sizeof(pix));
			ppix = ppix->next;
			ppix->w = 1;
			ppix->h = 1;

			ppix->color = RGB(r*255/maxval,g*255/maxval,b*255/maxval);
			ppix->x = x*2;
			ppix->y = y*2;
		}
	}

	for(pline = &image; pline->next != 0L; ) { pline = pline->next;
		// stupid one-axis optimization made by me 8]
		// I should research for a better 2d-shape optimization algo
		optimize(pline->head);

		for(ppix = pline->head; ppix->next != 0L; ) { ppix = ppix->next;
			if(ppix->color != TRANSPARENT_COLOR)
				OUT_PIXEL_pix(ppix);
		}
	}
	return 0;
}

void optimize(pix* pix_head) {
	pix* ppix = pix_head->next;
	pix* temp1 = 0L;

	while(ppix && ppix->next) {
		if(ppix->color == ppix->next->color) {
			temp1 = ppix->next->next;
			free(ppix->next);
			ppix->next = temp1;
			temp1 = 0L;
			ppix->w += 2;
		} else {
			ppix = ppix->next;
		}
	}
}