import java.io.*;
import java.util.*;
import java.util.zip.*;

/**
 * Minimal zipalign: copies a zip, padding STORED entries so their data is 4-byte aligned,
 * and appends any extra files given after the output path (compressed, at the zip root).
 */
public class ZipAlign {
    public static void main(String[] a) throws IOException {
        try (ZipFile in = new ZipFile(a[0]);
             CountingOut cnt = new CountingOut(new BufferedOutputStream(new FileOutputStream(a[1])));
             ZipOutputStream out = new ZipOutputStream(cnt)) {
            for (ZipEntry e : Collections.list(in.entries())) {
                ZipEntry n = new ZipEntry(e.getName());
                n.setMethod(e.getMethod());
                n.setTime(946684800000L); // 2000-01-01, inside the DOS date range (no extra timestamp field)
                if (e.getMethod() == ZipEntry.STORED) {
                    n.setSize(e.getSize());
                    n.setCompressedSize(e.getSize());
                    n.setCrc(e.getCrc());
                    out.flush();
                    long dataStart = cnt.count + 30 + n.getName().getBytes("UTF-8").length;
                    int pad = (int) ((4 - dataStart % 4) % 4);
                    if (pad > 0) n.setExtra(padExtra(pad));
                }
                out.putNextEntry(n);
                in.getInputStream(e).transferTo(out);
                out.closeEntry();
            }
            for (int i = 2; i < a.length; i++) {
                File f = new File(a[i]);
                ZipEntry n = new ZipEntry(f.getName());
                n.setTime(946684800000L);
                out.putNextEntry(n);
                try (InputStream fin = new FileInputStream(f)) { fin.transferTo(out); }
                out.closeEntry();
            }
        }
    }

    // An extra field needs a 4-byte header, so use one field of pad+4 bytes (Android's 0xD935 alignment tag).
    static byte[] padExtra(int pad) {
        byte[] x = new byte[pad + 4];
        x[0] = 0x35; x[1] = (byte) 0xD9; x[2] = (byte) pad;
        return x;
    }

    static class CountingOut extends FilterOutputStream {
        long count;
        CountingOut(OutputStream o) { super(o); }
        @Override public void write(int b) throws IOException { out.write(b); count++; }
        @Override public void write(byte[] b, int off, int len) throws IOException { out.write(b, off, len); count += len; }
    }
}