/* Copyright (c) 1993 Association of Universities for Research
 * in Astronomy. All rights reserved. Produced under National
 * Aeronautics and Space Administration Contract No. NAS5-26555.
 */
/*       LISTXY
 *
 * PURPOSE:
 *       List subimages required to extract a NX,NY section at position XC,YC
 *       from a plate.  This may be used to find out which images GETXY is
 *       going to require so they can be moved from CD to disk in case the
 *       CD cannot be read directly from the program.
 *
 * CALLING SEQUENCE:
 *       listxy(h,xc,yc,nx,ny)
 *
 * INPUTS:
 *       h          (* Header) header structure
 *       xc,yc      (float) center of image on plate
 *       nx,ny      (int) size of image
 *
 * OUTPUTS:
 *       list of required images is printed on stdout
 *
 * PROCEDURE:
 *       The plate is assumed to be stored in compressed 500x500 blocks
 *       (or 500x499 for the last row).
 *       A warning is printed if the entire image is off the plate.
 *
 * MODIFICATION HISTORY
 *       Created by R. White, 5 August 1991
 */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include "header.h"

static char translate[37] = "0123456789abcdefghijklmnopqr";

extern char *makepname();

extern void
listxy(h,xc,yc,nx,ny)
Header *h;
double xc,yc;
int nx,ny;
{
int i, j, i1, i2, j1, j2, x0, y0, x1, x2, y1, y2;
char *filename;
int nf;

    /*
     * calculate corner position
     */
    x0=xc-(nx/2);
    y0=yc-(ny/2);
    /*
     * get plate file template
     */
    filename = makepname(h);
    nf = strlen(filename)+1;
    /*
     * get range of image pixels which we will extract if we're not off edge
     */
    x1 = x0;
    x2 = x0+nx-1;
    y1 = y0;
    y2 = y0+ny-1;
    /*
     * now get actual range of sections (limited to 0 -- 27)
     */
    i1=x1/500; if (i1< 0) i1 = 0;
    i2=x2/500; if (i2>27) i1 = 27;
    j1=y1/500; if (j1< 0) j1 = 0;
    j2=y2/500; if (j2>27) j2 = 27;
    if ((i2 < i1) || (j2 < j1)) {
        fprintf(stderr,
            "warning: image section lies entirely off edge of plate\n");
        return;
    }
    /*
     * get filename for each section
     */
    fprintf(stdout,"%1d files required:\n",(i2-i1+1)*(j2-j1+1));
    for (i = i1; i <= i2; i++) {
        for (j = j1; j <= j2; j++) {
            filename[nf-3] = translate[j];
            filename[nf-2] = translate[i];
            fprintf(stdout,"%s\n", filename);
        }
    }
}