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The free Java library for Asterisk PBX integration.
There is a newer version: 3.41.0
package org.asteriskjava.util;

import java.util.HashSet;
import java.util.Locale;
import java.util.Set;

/**
 * Some static utility methods to imitate Asterisk specific logic. 

 * See Asterisk's util.c. 

 * Client code is not supposed to use this class.
 *
 * @author srt
 * @version $Id$
 */
public class AstUtil
{
    private static final Set TRUE_LITERALS;
    private static final Set NULL_LITERALS;

    static
    {
        TRUE_LITERALS = new HashSet<>(20);
        TRUE_LITERALS.add("yes");
        TRUE_LITERALS.add("true");
        TRUE_LITERALS.add("y");
        TRUE_LITERALS.add("t");
        TRUE_LITERALS.add("1");
        TRUE_LITERALS.add("on");
        TRUE_LITERALS.add("enabled");

        NULL_LITERALS = new HashSet<>(20);
        NULL_LITERALS.add("");
        NULL_LITERALS.add("unknown");
        NULL_LITERALS.add("none"); // VarSet event in pbx.c
        NULL_LITERALS.add("");
        NULL_LITERALS.add("-none-"); // IPaddress in PeerEntryEvent
        NULL_LITERALS.add("(none)");
        NULL_LITERALS.add("");
        NULL_LITERALS.add("(not set)");
        NULL_LITERALS.add("");
        NULL_LITERALS.add("n/a"); // channel in AgentsEvent
        NULL_LITERALS.add("");
        NULL_LITERALS.add("(null)"); // appData in ListDialplanEvent
    }

    private AstUtil()
    {
        // hide constructor
    }

    /**
     * Checks if a String represents true or false
     * according to Asterisk's logic. 

     * The original implementation is util.c is as follows: 

     * 
     *      *     int ast_true(const char *s)
     *     {
     *         if (!s || ast_strlen_zero(s))
     *             return 0;
     * 

     *         if (!strcasecmp(s, "yes") ||
     *             !strcasecmp(s, "true") ||
     *             !strcasecmp(s, "y") ||
     *             !strcasecmp(s, "t") ||
     *             !strcasecmp(s, "1") ||
     *             !strcasecmp(s, "on"))
     *             return -1;
     * 

     *         return 0;
     *     }
     * 
     * 
     * 

     * To support the dnd property of
     * {@link org.asteriskjava.manager.event.ZapShowChannelsEvent} this method
     * also consideres the string "Enabled" as true.
     *
     * @param o the Object (usually a String) to check for true.
     * @return true if s represents true,
     *         false otherwise.
     */
    public static boolean isTrue(Object o)
    {
        if (o == null)
        {
            return false;
        }

        if (o instanceof Boolean)
        {
            return (Boolean) o;
        }

        return TRUE_LITERALS.contains(o.toString().toLowerCase(Locale.US));
    }

    /**
     * @param a an object
     * @param b an object to be compared with {@code a} for equality
     * @return {@code true} if the arguments are equal to each other and
     *         {@code false} otherwise
     */
    public static boolean isEqual(Object a, Object b)
    {
        return a == b || a != null && a.equals(b);
    }

    /**
     * Parses a string for caller id information. 

     * The caller id string should be in the form
     * "Some Name" <1234>. 

     * This resembles ast_callerid_parse in callerid.c
     * but strips any whitespace.
     *
     * @param s the string to parse
     * @return a String[] with name (index 0) and number (index 1)
     */
    public static String[] parseCallerId(String s)
    {
        final String[] result = new String[2];
        final int lbPosition;
        final int rbPosition;
        String name;
        String number;

        if (s == null)
        {
            return result;
        }

        lbPosition = s.lastIndexOf('<');
        rbPosition = s.lastIndexOf('>');

        // no opening and closing brace? use value as CallerId name
        if (lbPosition < 0 || rbPosition < 0)
        {
            name = s.trim();
            if (name.length() == 0)
            {
                name = null;
            }
            result[0] = name;
            return result;
        }
        number = s.substring(lbPosition + 1, rbPosition).trim();
        if (number.length() == 0)
        {
            number = null;
        }

        name = s.substring(0, lbPosition).trim();
        if (name.startsWith("\"") && name.endsWith("\"") && name.length() > 1)
        {
            name = name.substring(1, name.length() - 1).trim();
        }
        if (name.length() == 0)
        {
            name = null;
        }

        result[0] = name;
        result[1] = number;
        return result;
    }

    /**
     * Checks if the value of s was null in Asterisk. 

     * This method is useful as Asterisk likes to replace null
     * values with different string values like "unknown", "<unknown>" or
     * "<null>". 

     * To find such replacements search for S_OR in Asterisk's
     * source code. You will find things like
     * 
     *      * S_OR(chan->cid.cid_num, "<unknown>")
     * fdprintf(fd, "agi_callerid: %s\n", S_OR(chan->cid.cid_num, "unknown"));
     * 
     * 
     * and more...
     *
     * @param s the string to test, may be null. If s is not a
     *            string the only test that is performed is a check for
     *            null.
     * @return true if the s was null in Asterisk;
     *         false otherwise.
     */
    public static boolean isNull(Object s)
    {
        if (s == null)
        {
            return true;
        }

        if (!(s instanceof String))
        {
            return false;
        }

        return NULL_LITERALS.contains(((String) s).toLowerCase(Locale.US));
    }
}