package com.it_jaros.networkScanner;

import java.util.BitSet;
import java.util.NoSuchElementException;

public class PortRange {

    public static final int MIN_PORT = 1;
    public static final int MAX_PORT = 65535;
    private final BitSet specifiedPorts = new BitSet(MAX_PORT);
    private final BitSet availablePorts = new BitSet(MAX_PORT);

    private int cursor;
    private int done = 0;

    public PortRange(String ports) {
        if (ports == null || "".equals(ports)) {
            // keep defaults
            specifiedPorts.set(1, 1024 + 1);
            return;
        }

        String[] splitComma = ports.split(",");
        for (String commaValue : splitComma) {
            if (commaValue.contains("-")) {
                String[] rangeValue = commaValue.split("-");
                if (rangeValue.length > 2) {
                    throw new IllegalArgumentException(String.format("Argument contains too many '-'' %s", commaValue));
                }

                int start = Integer.parseInt(rangeValue[0]);
                int end = Integer.parseInt(rangeValue[1]);
                checkValues(start, end);
                specifiedPorts.set(start, end + 1);
            } else {
                int port = Integer.parseInt(commaValue);
                checkValue(port);
                specifiedPorts.set(Integer.parseInt(commaValue));
            }
        }

        availablePorts.or(specifiedPorts);
        cursor = availablePorts.nextSetBit(MIN_PORT);
    }

    private void checkValues(int start, int end) {
        checkValue(start);
        checkValue(end);

        if (start >= end) {
            throw new IllegalArgumentException(
                    String.format("Start value cannot be equal or bigger than end value '%s >= %s'", start, end));
        }
    }

    private void checkValue(int port) {
        if (port < MIN_PORT) {
            throw new IllegalArgumentException(
                    String.format("Start value smaller than allowed range %s < %s", port, MIN_PORT));
        }

        if (port > MAX_PORT) {
            throw new IllegalArgumentException(
                    String.format("End value bigger than allowed range %s > %s", port, MAX_PORT));
        }
    }

    public synchronized int next() {
        int p = availablePorts.nextSetBit(cursor);
        if (p > 0) {
            availablePorts.clear(p);
            cursor = p + 1;
            done++;
            return p;
        }

        throw new NoSuchElementException("Reached end of port range");
    }

    public synchronized boolean hasNext() {
        return availablePorts.nextSetBit(cursor) > 0;
    }

    public int getTotal() {
        return specifiedPorts.cardinality();
    }

    public int getDone() {
        return done;
    }
}