// Copyright 2001, FreeHEP.
package org.freehep.util.io;

import java.io.*;

/**
 * The ASCII85InputStream encodes binary data as ASCII base-85 encoding.
 * The exact definition of ASCII base-85 encoding can be found
 * in the PostScript Language Reference (3rd ed.) chapter 3.13.3.
 *
 * @author Mark Donszelmann
 * @version $Id: ASCII85OutputStream.java,v 1.4 2003/04/13 05:34:45 duns Exp $
 */
public class ASCII85OutputStream extends FilterOutputStream implements ASCII85, FinishableOutputStream {

    private boolean end;
    private int characters;
    private int b[] = new int[4];
    private int bIndex;
    private int c[] = new int[5];

    public ASCII85OutputStream(OutputStream out) {
        super(out);
        characters = MAX_CHARS_PER_LINE;
        end = false;
        bIndex = 0;
    }

    public void write(int a) throws IOException {
        b[bIndex] = a & 0x00FF;
        bIndex++;
        if (bIndex >= b.length) {
            writeTuple();
            bIndex = 0;
        }
    }

    public void finish() throws IOException {
        if (!end) {
            end = true;
            if (bIndex > 0) {
                writeTuple();
            }
            writeChar('~');
            writeChar('>');
            flush();
            if (out instanceof FinishableOutputStream) {
                ((FinishableOutputStream)out).finish();
            }
        }
    }

    public void close() throws IOException {
        finish();
        super.close();
    }

    private void writeTuple() throws IOException {
        // fill the rest
        for (int i=bIndex; i<b.length; i++) {
            b[i] = 0;
        }

        // convert
        long d = ((b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3]) & 0x00000000FFFFFFFFL;

        c[0] = (int)(d / a85p4 + '!');
        d = d % a85p4;
        c[1] = (int)(d / a85p3 + '!');
        d = d % a85p3;
        c[2] = (int)(d / a85p2 + '!');
        d = d % a85p2;
        c[3] = (int)(d / a85p1 + '!');
        c[4] = (int)(d % a85p1 + '!');

        // convert !!!!! to z
        if ((bIndex >= b.length) &&
            (c[0] == '!') && (c[1] == '!') &&
            (c[2] == '!') && (c[3] == '!') && (c[4] == '!')) {
            writeChar('z');
        } else {
            for (int i=0; i<bIndex+1; i++) {
                writeChar(c[i]);
            }
        }
    }

    private void writeChar(int b) throws IOException {
        if (characters == 0) {
            characters = MAX_CHARS_PER_LINE;
            super.write('\n');
        }
        characters--;
        super.write(b);
    }
}