/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.test.ports;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

/**
 * A source for free ports on this machine
 */
public class PortAuthority {
    // this is quite an arbitrary choice and not currently configurable - but it works.
    private static final int PORT_RANGE_MINIMUM = 20000;

    private static final PortProvider portProvider;

    static {
        String portAuthorityDirectory = System.getProperty("port.authority.directory");

        if (portAuthorityDirectory == null) {
            portProvider = new SimplePortProvider(new DefaultPortProbe(), PORT_RANGE_MINIMUM);
        } else {
            try {
                Path directory = Paths.get(portAuthorityDirectory);
                Files.createDirectories(directory);
                PortRepository portRepository = new PortRepository(directory, PORT_RANGE_MINIMUM);
                PortProbe portProbe = new DefaultPortProbe();
                portProvider = new CoordinatingPortProvider(portRepository, portProbe);
            } catch (IOException e) {
                throw new ExceptionInInitializerError(e);
            }
        }
    }

    public static int allocatePort() {
        String trace = buildTrace();

        return portProvider.getNextFreePort(trace);
    }

    private static String buildTrace() {
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

        try (PrintWriter printWriter = new PrintWriter(outputStream)) {
            new Exception().printStackTrace(printWriter);
        }

        return outputStream.toString();
    }
}
