/*
 * @(#)Properties.java	1.73 03/01/23
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.util;

import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.BufferedWriter;
import java.util.Hashtable;

/**
 * The <code>Properties</code> class represents a persistent set of
 * properties. The <code>Properties</code> can be saved to a stream
 * or loaded from a stream. Each key and its corresponding value in
 * the property list is a string.
 * <p>
 * A property list can contain another property list as its
 * "defaults"; this second property list is searched if
 * the property key is not found in the original property list.
 * <p>
 * Because <code>Properties</code> inherits from <code>Hashtable</code>, the
 * <code>put</code> and <code>putAll</code> methods can be applied to a
 * <code>Properties</code> object.  Their use is strongly discouraged as they
 * allow the caller to insert entries whose keys or values are not
 * <code>Strings</code>.  The <code>setProperty</code> method should be used
 * instead.  If the <code>store</code> or <code>save</code> method is called
 * on a "compromised" <code>Properties</code> object that contains a
 * non-<code>String</code> key or value, the call will fail.
 * <p>
 * <a name="encoding"></a>
 * When saving properties to a stream or loading them from a stream, the
 * ISO 8859-1 character encoding is used. For characters that cannot be directly
 * represented in this encoding,
 * <a href="http://java.sun.com/docs/books/jls/html/3.doc.html#100850">Unicode escapes</a>
 * are used; however, only a single 'u' character is allowed in an escape sequence.
 * The native2ascii tool can be used to convert property files to and from
 * other character encodings.
 * 
 * @see <a href="../../../tooldocs/solaris/native2ascii.html">native2ascii tool for Solaris</a>
 * @see <a href="../../../tooldocs/windows/native2ascii.html">native2ascii tool for Windows</a>
 *
 * @author  Arthur van Hoff
 * @author  Michael McCloskey
 * @version 1.64, 06/26/00
 * @since   JDK1.0
 */
public
class Properties extends Hashtable {
    /**
     * use serialVersionUID from JDK 1.1.X for interoperability
     */
     private static final long serialVersionUID = 4112578634029874840L;

    /**
     * A property list that contains default values for any keys not
     * found in this property list.
     *
     * @serial
     */
    protected Properties defaults;

    /**
     * Creates an empty property list with no default values.
     */
    public Properties() {
	this(null);
    }

    /**
     * Creates an empty property list with the specified defaults.
     *
     * @param   defaults   the defaults.
     */
    public Properties(Properties defaults) {
	this.defaults = defaults;
    }

    /**
     * Calls the <tt>Hashtable</tt> method <code>put</code>. Provided for
     * parallelism with the <tt>getProperty</tt> method. Enforces use of
     * strings for property keys and values. The value returned is the
     * result of the <tt>Hashtable</tt> call to <code>put</code>.
     *
     * @param key the key to be placed into this property list.
     * @param value the value corresponding to <tt>key</tt>.
     * @return     the previous value of the specified key in this property
     *             list, or <code>null</code> if it did not have one.
     * @see #getProperty
     * @since    1.2
     */
    public synchronized Object setProperty(String key, String value) {
        return put(key, value);
    }

    private static final String keyValueSeparators = "=: \t\r\n\f";

    private static final String strictKeyValueSeparators = "=:";

    private static final String specialSaveChars = "=: \t\r\n\f#!";

    private static final String whiteSpaceChars = " \t\r\n\f";

    /**
     * Reads a property list (key and element pairs) from the input
     * stream.  The stream is assumed to be using the ISO 8859-1
     * character encoding; that is each byte is one Latin1 character.
     * Characters not in Latin1, and certain special characters, can
     * be represented in keys and elements using escape sequences
     * similar to those used for character and string literals (see <a
     * href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#100850">§3.3</a>
     * and <a
     * href="http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#101089">§3.10.6</a>
     * of the <i>Java Language Specification</i>).
     *
     * The differences from the character escape sequences used for
     * characters and strings are:
     *
     * <ul>
     * <li> Octal escapes are not recognized.
     *
     * <li> The character sequence <code>\b</code> does <i>not</i>
     * represent a backspace character.
     *
     * <li> The method does not treat a backslash character,
     * <code>\</code>, before a non-valid escape character as an
     * error; the backslash is silently dropped.  For example, in a
     * Java string the sequence <code>"\z"</code> would cause a
     * compile time error.  In contrast, this method silently drops
     * the backslash.  Therefore, this method treats the two character
     * sequence <code>"\b"</code> as equivalent to the single
     * character <code>'b'</code>.
     *
     * <li> Escapes are not necessary for single and double quotes;
     * however, by the rule above, single and double quote characters
     * preceded by a backslash still yield single and double quote
     * characters, respectively.
     *
     * </ul>
     *
     * An <code>IllegalArgumentException</code> is thrown if a
     * malformed Unicode escape appears in the input.
     *
     * <p>
     * This method processes input in terms of lines.  A natural line
     * of input is terminated either by a set of line terminator
     * characters (<code>\n</code> or <code>\r</code> or
     * <code>\r\n</code>) or by the end of the file.  A natural line
     * may be either a blank line, a comment line, or hold some part
     * of a key-element pair.  The logical line holding all the data
     * for a key-element pair may be spread out across several adjacent
     * natural lines by escaping the line terminator sequence with a
     * backslash character, <code>\</code>.  Note that a comment line
     * cannot be extended in this manner; every natural line that is a
     * comment must have its own comment indicator, as described
     * below.  If a logical line is continued over several natural
     * lines, the continuation lines receive further processing, also
     * described below.  Lines are read from the input stream until
     * end of file is reached.
     *
     * <p>
     * A natural line that contains only white space characters is
     * considered blank and is ignored.  A comment line has an ASCII
     * <code>'#'</code> or <code>'!'</code> as its first non-white
     * space character; comment lines are also ignored and do not
     * encode key-element information.  In addition to line
     * terminators, this method considers the characters space
     * (<code>' '</code>, <code>'\u0020'</code>), tab
     * (<code>'\t'</code>, <code>'\u0009'</code>), and form feed
     * (<code>'\f'</code>, <code>'\u000C'</code>) to be white
     * space.
     *
     * <p>
     * If a logical line is spread across several natural lines, the
     * backslash escaping the line terminator sequence, the line
     * terminator sequence, and any white space at the start the
     * following line have no affect on the key or element values.
     * The remainder of the discussion of key and element parsing will
     * assume all the characters constituting the key and element
     * appear on a single natural line after line continuation
     * characters have been removed.  Note that it is <i>not</i>
     * sufficient to only examine the character preceding a line
     * terminator sequence to to see if the line terminator is
     * escaped; there must be an odd number of contiguous backslashes
     * for the line terminator to be escaped.  Since the input is
     * processed from left to right, a non-zero even number of
     * 2<i>n</i> contiguous backslashes before a line terminator (or
     * elsewhere) encodes <i>n</i> backslashes after escape
     * processing.
     *
     * <p>
     * The key contains all of the characters in the line starting
     * with the first non-white space character and up to, but not
     * including, the first unescaped <code>'='</code>,
     * <code>':'</code>, or white space character other than a line
     * terminator. All of these key termination characters may be
     * included in the key by escaping them with a preceding backslash
     * character; for example,<p>
     *
     * <code>\:\=</code><p>
     *
     * would be the two-character key <code>":="</code>.  Line
     * terminator characters can be included using <code>\r</code> and
     * <code>\n</code> escape sequences.  Any white space after the
     * key is skipped; if the first non-white space character after
     * the key is <code>'='</code> or <code>':'</code>, then it is
     * ignored and any white space characters after it are also
     * skipped.  All remaining characters on the line become part of
     * the associated element string; if there are no remaining
     * characters, the element is the empty string
     * <code>""</code>.  Once the raw character sequences
     * constituting the key and element are identified, escape
     * processing is performed as described above.
     *
     * <p>
     * As an example, each of the following three lines specifies the key
     * <code>"Truth"</code> and the associated element value
     * <code>"Beauty"</code>:
     * <p>
     * <pre>
     * Truth = Beauty
     *	Truth:Beauty
     * Truth			:Beauty
     * </pre>
     * As another example, the following three lines specify a single
     * property:
     * <p>
     * <pre>
     * fruits                           apple, banana, pear, \
     *                                  cantaloupe, watermelon, \
     *                                  kiwi, mango
     * </pre>
     * The key is <code>"fruits"</code> and the associated element is:
     * <p>
     * <pre>"apple, banana, pear, cantaloupe, watermelon, kiwi, mango"</pre>
     * Note that a space appears before each <code>\</code> so that a space
     * will appear after each comma in the final result; the <code>\</code>,
     * line terminator, and leading white space on the continuation line are
     * merely discarded and are <i>not</i> replaced by one or more other
     * characters.
     * <p>
     * As a third example, the line:
     * <p>
     * <pre>cheeses
     * </pre>
     * specifies that the key is <code>"cheeses"</code> and the associated
     * element is the empty string <code>""</code>.<p>
     *
     * @param      inStream   the input stream.
     * @exception  IOException  if an error occurred when reading from the
     *               input stream.
     * @throws	   IllegalArgumentException if the input stream contains a
     * 		   malformed Unicode escape sequence.
     */
    public synchronized void load(InputStream inStream) throws IOException {

        BufferedReader in = new BufferedReader(new InputStreamReader(inStream, "8859_1"));
	while (true) {
            // Get next line
            String line = in.readLine();
            if (line == null)
                return;

            if (line.length() > 0) {
                
                // Find start of key
                int len = line.length();
                int keyStart;
                for (keyStart=0; keyStart<len; keyStart++)
                    if (whiteSpaceChars.indexOf(line.charAt(keyStart)) == -1)
                        break;

                // Blank lines are ignored
                if (keyStart == len)
                    continue;

                // Continue lines that end in slashes if they are not comments
                char firstChar = line.charAt(keyStart);
                if ((firstChar != '#') && (firstChar != '!')) {
                    while (continueLine(line)) {
                        String nextLine = in.readLine();
                        if (nextLine == null)
                            nextLine = "";
                        String loppedLine = line.substring(0, len-1);
                        // Advance beyond whitespace on new line
                        int startIndex;
                        for (startIndex=0; startIndex<nextLine.length(); startIndex++)
                            if (whiteSpaceChars.indexOf(nextLine.charAt(startIndex)) == -1)
                                break;
                        nextLine = nextLine.substring(startIndex,nextLine.length());
                        line = new String(loppedLine+nextLine);
                        len = line.length();
                    }

                    // Find separation between key and value
                    int separatorIndex;
                    for (separatorIndex=keyStart; separatorIndex<len; separatorIndex++) {
                        char currentChar = line.charAt(separatorIndex);
                        if (currentChar == '\\')
                            separatorIndex++;
                        else if (keyValueSeparators.indexOf(currentChar) != -1)
                            break;
                    }

                    // Skip over whitespace after key if any
                    int valueIndex;
                    for (valueIndex=separatorIndex; valueIndex<len; valueIndex++)
                        if (whiteSpaceChars.indexOf(line.charAt(valueIndex)) == -1)
                            break;

                    // Skip over one non whitespace key value separators if any
                    if (valueIndex < len)
                        if (strictKeyValueSeparators.indexOf(line.charAt(valueIndex)) != -1)
                            valueIndex++;

                    // Skip over white space after other separators if any
                    while (valueIndex < len) {
                        if (whiteSpaceChars.indexOf(line.charAt(valueIndex)) == -1)
                            break;
                        valueIndex++;
                    }
                    String key = line.substring(keyStart, separatorIndex);
                    String value = (separatorIndex < len) ? line.substring(valueIndex, len) : "";

                    // Convert then store key and value
                    key = loadConvert(key);
                    value = loadConvert(value);
                    put(key, value);
                }
            }
	}
    }

    /*
     * Returns true if the given line is a line that must
     * be appended to the next line
     */
    private boolean continueLine(String line) {
        int slashCount = 0;
        int index = line.length() - 1;
        while ((index >= 0) && (line.charAt(index--) == '\\'))
            slashCount++;
        return (slashCount % 2 == 1);
    }

    /*
     * Converts encoded \uxxxx to unicode chars
     * and changes special saved chars to their original forms
     */
    private String loadConvert(String theString) {
        char aChar;
        int len = theString.length();
        StringBuffer outBuffer = new StringBuffer(len);

        for (int x=0; x<len; ) {
            aChar = theString.charAt(x++);
            if (aChar == '\\') {
                aChar = theString.charAt(x++);
                if (aChar == 'u') {
                    // Read the xxxx
                    int value=0;
		    for (int i=0; i<4; i++) {
		        aChar = theString.charAt(x++);
		        switch (aChar) {
		          case '0': case '1': case '2': case '3': case '4':
		          case '5': case '6': case '7': case '8': case '9':
		             value = (value << 4) + aChar - '0';
			     break;
			  case 'a': case 'b': case 'c':
                          case 'd': case 'e': case 'f':
			     value = (value << 4) + 10 + aChar - 'a';
			     break;
			  case 'A': case 'B': case 'C':
                          case 'D': case 'E': case 'F':
			     value = (value << 4) + 10 + aChar - 'A';
			     break;
			  default:
                              throw new IllegalArgumentException(
                                           "Malformed \\uxxxx encoding.");
                        }
                    }
                    outBuffer.append((char)value);
                } else {
                    if (aChar == 't') aChar = '\t';
                    else if (aChar == 'r') aChar = '\r';
                    else if (aChar == 'n') aChar = '\n';
                    else if (aChar == 'f') aChar = '\f';
                    outBuffer.append(aChar);
                }
            } else
                outBuffer.append(aChar);
        }
        return outBuffer.toString();
    }

    /*
     * Converts unicodes to encoded \uxxxx
     * and writes out any of the characters in specialSaveChars
     * with a preceding slash
     */
    private String saveConvert(String theString, boolean escapeSpace) {
        int len = theString.length();
        StringBuffer outBuffer = new StringBuffer(len*2);

        for(int x=0; x<len; x++) {
            char aChar = theString.charAt(x);
            switch(aChar) {
		case ' ':
		    if (x == 0 || escapeSpace) 
			outBuffer.append('\\');

		    outBuffer.append(' ');
		    break;
                case '\\':outBuffer.append('\\'); outBuffer.append('\\');
                          break;
                case '\t':outBuffer.append('\\'); outBuffer.append('t');
                          break;
                case '\n':outBuffer.append('\\'); outBuffer.append('n');
                          break;
                case '\r':outBuffer.append('\\'); outBuffer.append('r');
                          break;
                case '\f':outBuffer.append('\\'); outBuffer.append('f');
                          break;
                default:
                    if ((aChar < 0x0020) || (aChar > 0x007e)) {
                        outBuffer.append('\\');
                        outBuffer.append('u');
                        outBuffer.append(toHex((aChar >> 12) & 0xF));
                        outBuffer.append(toHex((aChar >>  8) & 0xF));
                        outBuffer.append(toHex((aChar >>  4) & 0xF));
                        outBuffer.append(toHex( aChar        & 0xF));
                    } else {
                        if (specialSaveChars.indexOf(aChar) != -1)
                            outBuffer.append('\\');
                        outBuffer.append(aChar);
                    }
            }
        }
        return outBuffer.toString();
    }

    /**
     * Calls the <code>store(OutputStream out, String header)</code> method
     * and suppresses IOExceptions that were thrown.
     *
     * @deprecated This method does not throw an IOException if an I/O error
     * occurs while saving the property list.  As of the Java 2 platform v1.2, the preferred
     * way to save a properties list is via the <code>store(OutputStream out,
     * String header)</code> method.
     *
     * @param   out      an output stream.
     * @param   header   a description of the property list.
     * @exception  ClassCastException  if this <code>Properties</code> object
     *             contains any keys or values that are not <code>Strings</code>.
     */
    public synchronized void save(OutputStream out, String header)  {
        try {
            store(out, header);
        } catch (IOException e) {
        }
    }

    /**
     * Writes this property list (key and element pairs) in this
     * <code>Properties</code> table to the output stream in a format suitable
     * for loading into a <code>Properties</code> table using the
     * {@link #load(InputStream) load} method.
     * The stream is written using the ISO 8859-1 character encoding.
     * <p>
     * Properties from the defaults table of this <code>Properties</code>
     * table (if any) are <i>not</i> written out by this method.
     * <p>
     * If the header argument is not null, then an ASCII <code>#</code>
     * character, the header string, and a line separator are first written
     * to the output stream. Thus, the <code>header</code> can serve as an
     * identifying comment.
     * <p>
     * Next, a comment line is always written, consisting of an ASCII
     * <code>#</code> character, the current date and time (as if produced
     * by the <code>toString</code> method of <code>Date</code> for the
     * current time), and a line separator as generated by the Writer.
     * <p>
     * Then every entry in this <code>Properties</code> table is
     * written out, one per line. For each entry the key string is
     * written, then an ASCII <code>=</code>, then the associated
     * element string. Each character of the key and element strings
     * is examined to see whether it should be rendered as an escape
     * sequence. The ASCII characters <code>\</code>, tab, form feed,
     * newline, and carriage return are written as <code>\\</code>,
     * <code>\t</code>, <code>\f</code> <code>\n</code>, and
     * <code>\r</code>, respectively. Characters less than
     * <code>\u0020</code> and characters greater than
     * <code>\u007E</code> are written as
     * <code>\u</code><i>xxxx</i> for the appropriate hexadecimal
     * value <i>xxxx</i>.  For the key, all space characters are
     * written with a preceding <code>\</code> character.  For the
     * element, leading space characters, but not embedded or trailing
     * space characters, are written with a preceding <code>\</code>
     * character. The key and element characters <code>#</code>,
     * <code>!</code>, <code>=</code>, and <code>:</code> are written
     * with a preceding backslash to ensure that they are properly loaded.
     * <p>
     * After the entries have been written, the output stream is flushed.  The
     * output stream remains open after this method returns.
     *
     * @param   out      an output stream.
     * @param   header   a description of the property list.
     * @exception  IOException if writing this property list to the specified
     *             output stream throws an <tt>IOException</tt>.
     * @exception  ClassCastException  if this <code>Properties</code> object
     *             contains any keys or values that are not <code>Strings</code>.
     * @exception  NullPointerException  if <code>out</code> is null.
     * @since 1.2
     */
    public synchronized void store(OutputStream out, String header)
    throws IOException
    {
        BufferedWriter awriter;
        awriter = new BufferedWriter(new OutputStreamWriter(out, "8859_1"));
        if (header != null)
            writeln(awriter, "#" + header);
        writeln(awriter, "#" + new Date().toString());
        for (Enumeration e = keys(); e.hasMoreElements();) {
            String key = (String)e.nextElement();
            String val = (String)get(key);
            key = saveConvert(key, true);

	    /* No need to escape embedded and trailing spaces for value, hence
	     * pass false to flag.
	     */
            val = saveConvert(val, false);
            writeln(awriter, key + "=" + val);
        }
        awriter.flush();
    }

    private static void writeln(BufferedWriter bw, String s) throws IOException {
        bw.write(s);
        bw.newLine();
    }

    /**
     * Searches for the property with the specified key in this property list.
     * If the key is not found in this property list, the default property list,
     * and its defaults, recursively, are then checked. The method returns
     * <code>null</code> if the property is not found.
     *
     * @param   key   the property key.
     * @return  the value in this property list with the specified key value.
     * @see     #setProperty
     * @see     #defaults
     */
    public String getProperty(String key) {
	Object oval = super.get(key);
	String sval = (oval instanceof String) ? (String)oval : null;
	return ((sval == null) && (defaults != null)) ? defaults.getProperty(key) : sval;
    }

    /**
     * Searches for the property with the specified key in this property list.
     * If the key is not found in this property list, the default property list,
     * and its defaults, recursively, are then checked. The method returns the
     * default value argument if the property is not found.
     *
     * @param   key            the hashtable key.
     * @param   defaultValue   a default value.
     *
     * @return  the value in this property list with the specified key value.
     * @see     #setProperty
     * @see     #defaults
     */
    public String getProperty(String key, String defaultValue) {
	String val = getProperty(key);
	return (val == null) ? defaultValue : val;
    }

    /**
     * Returns an enumeration of all the keys in this property list,
     * including distinct keys in the default property list if a key
     * of the same name has not already been found from the main
     * properties list.
     *
     * @return  an enumeration of all the keys in this property list, including
     *          the keys in the default property list.
     * @see     java.util.Enumeration
     * @see     java.util.Properties#defaults
     */
    public Enumeration propertyNames() {
	Hashtable h = new Hashtable();
	enumerate(h);
	return h.keys();
    }

    /**
     * Prints this property list out to the specified output stream.
     * This method is useful for debugging.
     *
     * @param   out   an output stream.
     */
    public void list(PrintStream out) {
	out.println("-- listing properties --");
	Hashtable h = new Hashtable();
	enumerate(h);
	for (Enumeration e = h.keys() ; e.hasMoreElements() ;) {
	    String key = (String)e.nextElement();
	    String val = (String)h.get(key);
	    if (val.length() > 40) {
                val = val.substring(0, 37) + "...";
	    }
	    out.println(key + "=" + val);
	}
    }

    /**
     * Prints this property list out to the specified output stream.
     * This method is useful for debugging.
     *
     * @param   out   an output stream.
     * @since   JDK1.1
     */
    /*
     * Rather than use an anonymous inner class to share common code, this
     * method is duplicated in order to ensure that a non-1.1 compiler can
     * compile this file.
     */
    public void list(PrintWriter out) {
	out.println("-- listing properties --");
	Hashtable h = new Hashtable();
	enumerate(h);
	for (Enumeration e = h.keys() ; e.hasMoreElements() ;) {
	    String key = (String)e.nextElement();
	    String val = (String)h.get(key);
	    if (val.length() > 40) {
		val = val.substring(0, 37) + "...";
	    }
	    out.println(key + "=" + val);
	}
    }

    /**
     * Enumerates all key/value pairs in the specified hastable.
     * @param h the hashtable
     */
    private synchronized void enumerate(Hashtable h) {
	if (defaults != null) {
	    defaults.enumerate(h);
	}
	for (Enumeration e = keys() ; e.hasMoreElements() ;) {
	    String key = (String)e.nextElement();
	    h.put(key, get(key));
	}
    }

    /**
     * Convert a nibble to a hex character
     * @param	nibble	the nibble to convert.
     */
    private static char toHex(int nibble) {
	return hexDigit[(nibble & 0xF)];
    }

    /** A table of hex digits */
    private static final char[] hexDigit = {
	'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'
    };
}