import java.nio.CharBuffer;
import java.text.Collator;
import java.util.Comparator;
import static java.nio.CharBuffer.wrap;

public class UnidadeComparador implements Comparator<Unidade>{

    private final Collator collator;

    public UnidadeComparador() {
        collator = null;
    }

    public int compare(final Unidade s1, final Unidade s2) {
        final CharBuffer b1 = wrap(s1.getNome());
        final CharBuffer b2 = wrap(s2.getNome());

        while (b1.hasRemaining() && b2.hasRemaining()) {
            moverJanela(b1);
            moverJanela(b2);
            final int result = comparar(b1, b2);
            if (result != 0) {
                return result;
            }
            preparaParaProximaInteracao(b1);
            preparaParaProximaInteracao(b2);
        }
        return s1.getNome().length() - s2.getNome().length();
    }

    private void moverJanela(final CharBuffer buffer) {
        int start = buffer.position();
        int end = buffer.position();
        final boolean isNumerical = isDigito(buffer.get(start));
        while (end < buffer.limit() && isNumerical == isDigito(buffer.get(end))) {
            ++end;
            if (isNumerical && (start + 1 < buffer.limit())
                    && isZero(buffer.get(start)) && isDigito(buffer.get(end))) {
                ++start;
            }
        }
        buffer.position(start).limit(end);
    }

    private int comparar(final CharBuffer b1, final CharBuffer b2) {
        if (isNumero(b1) && isNumero(b2)) {
            return compararNumerico(b1, b2);
        }
        return compararStrings(b1, b2);
    }

    private boolean isNumero(final CharBuffer buffer) {
        return isDigito(buffer.charAt(0));
    }

    private boolean isDigito(final char c) {
        if (collator == null) {
            final int intValue = (int) c;
            return intValue >= 48 && intValue <= 57;
        }
        return Character.isDigit(c);
    }

    private int compararNumerico(final CharBuffer b1, final CharBuffer b2) {
        final int diff = b1.length() - b2.length();
        if (diff != 0) {
            return diff;
        }
        for (int i = 0; i < b1.remaining() && i < b2.remaining(); ++i) {
            //final int result = Character.comparar(b1.charAt(i), b2.charAt(i));
            final int result = Character.valueOf(b1.charAt(i))
                    .compareTo(Character.valueOf(b2.charAt(i)));
            if (result != 0) {
                return result;
            }
        }
        return 0;
    }

    private void preparaParaProximaInteracao(final CharBuffer buffer) {
        buffer.position(buffer.limit()).limit(buffer.capacity());
    }

    private int compararStrings(final CharBuffer b1, final CharBuffer b2) {
        if (collator != null) {
            return collator.compare(b1.toString(), b2.toString());
        }
        return b1.toString().compareTo(b2.toString());
    }

    private boolean isZero(final char c) {
        return c == '0';
    }
}