/* ppmtoTbmp.c - read a portable pixmap and write a pilot Tbmp file
 *
 * Program by Ian Goldberg <iang@cs.berkeley.edu>
 *
 * Based on ppmtopuzz.c by Jef Paskanzer, from the netpbm-1mar1994 package.
 */

#include "ppm.h"

static int colcompare(const void *a, const void *b)
{
    colorhist_vector ch1 = (colorhist_vector)a;
    colorhist_vector ch2 = (colorhist_vector)b;
    return
	(int) PPM_GETR(ch1->color) - (int) PPM_GETR(ch2->color) +
	(int) PPM_GETG(ch1->color) - (int) PPM_GETG(ch2->color) +
	(int) PPM_GETB(ch1->color) - (int) PPM_GETB(ch2->color);
}

int
main( int argc, char **argv )
{
    FILE* ifp;
    pixel** pixels;
    register pixel* pP;
    colorhist_vector chv;
    colorhash_table cht;
    int rows, cols, row, colors;
    register int col;
    pixval maxval;
    unsigned char outbyte, outbit;
    int twobit = 0;

    /* Parse default params */
    ppm_init( &argc, argv );

    if (argc > 1 && !strcmp(argv[1], "-2bit")) {
	twobit = 1;
	--argc; ++argv;
    }
    if ( argc > 2 || (argc == 2 && argv[1][0] == '-')) {
	pm_usage( "[-2bit] [ppmfile]" );
    }

    if ( argc == 2 )
	ifp = pm_openr( argv[1] );
    else
	ifp = stdin;

    pixels = ppm_readppm( ifp, &cols, &rows, &maxval );
    pm_close( ifp );

    pm_message( "computing colormap..." );
    chv = ppm_computecolorhist( pixels, cols, rows, twobit ? 4 : 2, &colors );
    if ( chv == (colorhist_vector) 0 )
	{
	pm_message(
	    "too many colors - try doing a 'ppmquant %d'", twobit ? 4 : 2 );
	exit( 1 );
	}
    qsort((char *)chv, colors, sizeof(struct colorhist_item), colcompare);
    pm_message( "%d colors found", colors );

    /* Write Tbmp header. */
    (void) pm_writebigshort( stdout, cols*(twobit ? 2 : 1) );   /* width */
    (void) pm_writebigshort( stdout, rows );                    /* height */
    if (twobit) {
	(void) pm_writebigshort( stdout, ((cols+7)/8)*2 );      /* chars/row */
    } else {
	(void) pm_writebigshort( stdout, ((cols+15)/16)*2 );    /* chars/row */
    }
    (void) pm_writebigshort( stdout, 0 );                       /* flags */
    (void) pm_writebiglong( stdout, 0 );                        /* pad */
    (void) pm_writebiglong( stdout, 0 );                        /* pad */

    /* Convert color vector to color hash table, for fast lookup. */
    cht = ppm_colorhisttocolorhash( chv, colors );
    ppm_freecolorhist( chv );

    /* And write out the data. */
    for ( row = 0; row < rows; ++row ) {
	outbyte = 0x00;
	outbit = twobit ? 6 : 7;
	for ( col = 0, pP = pixels[row]; col < cols; ++col, ++pP ) {
	    register int color;

	    color = ppm_lookupcolor( cht, pP );
	    if ( color == -1 )
		pm_error(
		    "color not found?!?  row=%d col=%d  r=%d g=%d b=%d",
		    row, col, PPM_GETR(*pP), PPM_GETG(*pP), PPM_GETB(*pP) );
	    if (twobit) {
		if (color == 0) {
		    outbyte |= (3 << outbit);
		} else if (color == 1) {
		    outbyte |= (2 << outbit);
		} else if (color == 2) {
		    outbyte |= (1 << outbit);
		}
	    } else {
		if (color == 0) {
		    outbyte |= (1 << outbit);
		}
	    }
	    if (!outbit) {
		(void) putchar(outbyte);
		outbyte = 0x00;
		outbit = (twobit ? 6 : 7);
	    } else {
		outbit -= (twobit ? 2 : 1);
	    }
	}
	if (twobit) {
	    /* Output any partial byte remaining */
	    if (cols & 0x03) {
		(void) putchar(outbyte);
	    }
	    if (!((cols+7) & 0x04)) {
		(void) putchar(0x00);
	    }
	} else {
	    /* Output any partial byte remaining */
	    if (cols & 0x07) {
		(void) putchar(outbyte);
	    }
	    if (!((cols+15) & 0x08)) {
		(void) putchar(0x00);
	    }
	}
    }

    exit( 0 );
}