/*
 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

import java.io.File;
import java.util.HashMap;
import java.util.Map;

/**
 * Utility class for finding the command on the current system
 */
public class UnixCommands {

    private static final String[] paths = {"/bin", "/usr/bin",
            "/usr/local/bin", "/system/bin", "/sbin", "/usr/bin/sbin",
            "/usr/local/sbin", "/system/sbin"};

    private static Map<String,String> nameToCommand = new HashMap<>(16);

    /**
     * If can find the path to the command, returns the command with the full path.
     * Otherwise, returns the name of the command.
     */
    public static String cat() { return findCommand("cat"); }
    public static String sh() { return findCommand("sh"); }
    public static String kill() { return findCommand("kill"); }
    public static String sleep() { return findCommand("sleep"); }
    public static String tee() { return findCommand("tee"); }
    public static String echo() { return findCommand("echo"); }
    public static String true_() { return findCommand("true"); }
    public static String false_() { return findCommand("false"); }

    public static String findCommand(String name) {
        if (nameToCommand.containsKey(name)) {
            return nameToCommand.get(name);
        }
        String command = findCommand0(name);
        nameToCommand.put(name, command);
        return command;
    }

    private static String findCommand0(String name) {
        for (String path : paths) {
            String command = path + '/' + name;
            if (new File(command).canExecute()) {
                return command;
            }
        }
        return name;
    }
}