/***************************************
 *                                     *
 *  JBoss: The OpenSource J2EE WebOS   *
 *                                     *
 *  Distributable under LGPL license.  *
 *  See terms of license at gnu.org.   *
 *                                     *
 ***************************************/

package org.jboss.util;

import java.io.IOException;
import java.io.File;
import java.net.URL;
import java.net.MalformedURLException;
import java.util.Map;

/**
 * A collection of String utilities.
 *
 * @version <tt>$Revision: 1.4.2.4 $</tt>
 * @author  <a href="mailto:jason@planet57.com">Jason Dillon</a>
 * @author <a href="Scott.Stark@jboss.org">Scott Stark</a>
 */
public final class Strings
{
   /** An empty string constant */
   public static final String EMPTY = "";

   /** New line string constant */
   public static final String NEWLINE = org.jboss.util.platform.Constants.LINE_SEPARATOR;

   /**
    * List of valid Java keywords, see The Java Language Specification
    * Second Edition Section 3.9, 3.10.3 and 3.10.7
    */
   private static final String[] keywords =
   {
      "abstract",
      "boolean",
      "break",
      "byte",
      "case",
      "catch",
      "char",
      "class",
      "const",
      "continue",
      "default",
      "do",
      "double",
      "else",
      "extends",
      "final",
      "finally",
      "float",
      "for",
      "goto",
      "if",
      "implements",
      "import",
      "instanceof",
      "int",
      "interface",
      "long",
      "native",
      "new",
      "package",
      "private",
      "protected",
      "public",
      "return",
      "short",
      "static",
      "strictfp",
      "super",
      "switch",
      "synchronized",
      "this",
      "throw",
      "throws",
      "transient",
      "try",
      "void",
      "volatile",
      "while",

      "true",     // technically no keywords but we are not picky
      "false",
      "null"
   };

   /**
    * List of EJB-QL Identifiers as defined in the EJB 2.0 Specification
    * Section 11.2.6.1
    */
   private static final String[] ejbQlIdentifiers =
   {
      "AND",
      "AS",
      "BETWEEN",
      "DISTINCT",
      "EMPTY",
      "FALSE",
      "FROM",
      "IN",
      "IS",
      "LIKE",
      "MEMBER",
      "NOT",
      "NULL",
      "OBJECT",
      "OF",
      "OR",
      "SELECT",
      "UNKNOWN",
      "TRUE",
      "WHERE",
   };

   // States used in property parsing
   private static final int NORMAL = 0;
   private static final int SEEN_DOLLAR = 1;
   private static final int IN_BRACKET = 2;

   /////////////////////////////////////////////////////////////////////////
   //                         Substitution Methods                        //
   /////////////////////////////////////////////////////////////////////////

   /**
    * Substitute sub-strings in side of a string.
    *
    * @param buff    Stirng buffer to use for substitution (buffer is not reset)
    * @param from    String to substitute from
    * @param to      String to substitute to
    * @param string  String to look for from in
    * @return        Substituted string
    */
   public static String subst(final StringBuffer buff, final String from,
                              final String to, final String string)
   {
      int begin = 0, end = 0;

      while ((end = string.indexOf(from, end)) != -1) {
         // append the first part of the string
         buff.append(string.substring(begin, end));

         // append the replaced string
         buff.append(to);

         // update positions
         begin = end + from.length();
         end = begin;
      }

      // append the rest of the string
      buff.append(string.substring(begin, string.length()));

      return buff.toString();
   }

   /**
    * Substitute sub-strings in side of a string.
    *
    * @param from    String to substitute from
    * @param to      String to substitute to
    * @param string  String to look for from in
    * @return        Substituted string
    */
   public static String subst(final String from, final String to, 
                              final String string)
   {
      return subst(new StringBuffer(), from, to, string);
   }

   /**
    * Substitute sub-strings in side of a string.
    *
    * @param buff       String buffer to use for substitution (buffer is not reset)
    * @param string     String to subst mappings in
    * @param map        Map of from->to strings
    * @param beginToken Beginning token
    * @param endToken   Ending token
    * @return           Substituted string
    */
   public static String subst(final StringBuffer buff, final String string,
                              final Map map, final String beginToken,
                              final String endToken)
   {
      int begin = 0, rangeEnd = 0;
      Range range;

      while ((range = rangeOf(beginToken, endToken, string, rangeEnd)) != null) {
         // append the first part of the string
         buff.append(string.substring(begin, range.begin));

         // Get the string to replace from the map
         String key = string.substring(range.begin + beginToken.length(),
                                       range.end);
         Object value = map.get(key);
         // if mapping does not exist then use empty;
         if (value == null) value = EMPTY;

         // append the replaced string
         buff.append(value);

         // update positions
         begin = range.end + endToken.length();
         rangeEnd = begin;
      }

      // append the rest of the string
      buff.append(string.substring(begin, string.length()));

      return buff.toString();
   }

   /**
    * Substitute sub-strings in side of a string.
    *
    * @param string     String to subst mappings in
    * @param map        Map of from->to strings
    * @param beginToken Beginning token
    * @param endToken   Ending token
    * @return           Substituted string
    */
   public static String subst(final String string, final Map map,
                              final String beginToken, final String endToken)
   {
      return subst(new StringBuffer(), string, map, beginToken, endToken);
   }

   /**
    * Substitute index identifiers with the replacement value from the
    * given array for the corresponding index.
    *
    * @param buff       The string buffer used for the substitution
    *                   (buffer is not reset).
    * @param string     String substitution format.
    * @param replace    Array of strings whose values will be used as 
    *                   replacements in the given string when a token with
    *                   their index is found.
    * @param token      The character token to specify the start of an index
    *                   reference.
    * @return           Substituted string.
    */
   public static String subst(final StringBuffer buff, final String string, 
                              final String replace[], final char token)
   {
      int i = string.length();
      for (int j = 0; j >= 0 && j < i; j++) {
         char c = string.charAt(j);

         // if the char is the token, then get the index
         if (c == token) {

            // if we aren't at the end of the string, get the index
            if (j != i) {
               int k = Character.digit(string.charAt(j + 1), 10);

               if (k == -1) {
                  buff.append(string.charAt(j + 1));
               }
               else if (k < replace.length) {
                  buff.append(replace[k]);
               }

               j++;
            }  
         }
         else {
            buff.append(c);
         }
      }

      return buff.toString();
   }

   /**
    * Substitute index identifiers with the replacement value from the
    * given array for the corresponding index.
    *
    * @param string     String substitution format.
    * @param replace    Array of strings whose values will be used as 
    *                   replacements in the given string when a token with
    *                   their index is found.
    * @param token      The character token to specify the start of an index
    *                   reference.
    * @return           Substituted string.
    */
   public static String subst(final String string, final String replace[], 
                              final char token)
   {
      return subst(new StringBuffer(), string, replace, token);
   }

   /**
    * Substitute index identifiers (with <code>%</code> for the index token)
    * with the replacement value from the given array for the corresponding
    * index.
    *
    * @param string     String substitution format.
    * @param replace    Array of strings whose values will be used as 
    *                   replacements in the given string when a token with
    *                   their index is found.
    * @return           Substituted string.
    */
   public static String subst(final String string, final String replace[]) {
      return subst(new StringBuffer(), string, replace, '%');
   }

   /////////////////////////////////////////////////////////////////////////
   //                             Regex Methods                           //
   /////////////////////////////////////////////////////////////////////////

   /** Go through the input string and replace any occurance of ${p} with
    *the System.getProperty(p) value. If there is no such property p defined, then
    * the ${p} reference will remain unchanged.
    *@return the input string with all property references replaced
    */
   public static String replaceProperties(final String string)
   {
      final char[] chars = string.toCharArray();
      StringBuffer buffer = new StringBuffer();
      boolean properties = false;
      int state = NORMAL;
      int start = 0;
      for (int i = 0; i < chars.length; ++i)
      {
         char c = chars[i];

         // Dollar sign outside brackets
         if (c == '$' && state != IN_BRACKET)
            state = SEEN_DOLLAR;

         // Open bracket immediatley after dollar
         else if (c == '{' && state == SEEN_DOLLAR)
         {
            buffer.append(string.substring(start, i-1));
            state = IN_BRACKET;
            start = i-1;
         }

         // No open bracket after dollar
         else if (state == SEEN_DOLLAR)
            state = NORMAL;

         // Closed bracket after open bracket
         else if (c == '}' && state == IN_BRACKET)
         {
            // No content
            if (start+2 == i)
               buffer.append("${}"); // REVIEW: Correct?

            // Collect the system property
            else
            {
               String value = System.getProperty(string.substring(start+2, i));
               if( value != null )
               {
                  properties = true;
                  buffer.append(value);
               }
            }
            start = i+1;
            state = NORMAL;
         }
      }

      // No properties
      if (properties == false)
         return string;

      // Collect the trailing characters
      if (start != chars.length)
         buffer.append(string.substring(start, chars.length));

      // Done
      return buffer.toString();
   }

   /////////////////////////////////////////////////////////////////////////
   //                             Range Methods                           //
   /////////////////////////////////////////////////////////////////////////

   /**
    * Represents a range between two integers.
    */
   public static class Range
   {
      /** The beginning of the range. */
      public int begin;
      
      /** The end of the range. */
      public int end;
   
      /**
       * Construct a new range.
       *
       * @param begin   The beginning of the range.
       * @param end     The end of the range.
       */
      public Range(int begin, int end) {
         this.begin = begin;
         this.end = end;
      }
   
      /**
       * Default constructor.
       */
      public Range() {}
   }
      
   /**
    * Return the range from a begining token to an ending token.
    *
    * @param beginToken String to indicate begining of range.
    * @param endToken   String to indicate ending of range.
    * @param string     String to look for range in.
    * @param fromIndex  Beginning index.
    * @return           (begin index, end index) or <i>null</i>.
    */
   public static Range rangeOf(final String beginToken, final String endToken,
                               final String string, final int fromIndex)
   {
      int begin = string.indexOf(beginToken, fromIndex);

      if (begin != -1) {
         int end = string.indexOf(endToken, begin + 1);
         if (end != -1) {
            return new Range(begin, end);
         }
      }

      return null;
   }

   /**
    * Return the range from a begining token to an ending token.
    *
    * @param beginToken String to indicate begining of range.
    * @param endToken   String to indicate ending of range.
    * @param string     String to look for range in.
    * @return           (begin index, end index) or <i>null</i>.
    */
   public static Range rangeOf(final String beginToken, final String endToken,
                               final String string)
   {
      return rangeOf(beginToken, endToken, string, 0);
   }


   /////////////////////////////////////////////////////////////////////////
   //                           Spliting Methods                          //
   /////////////////////////////////////////////////////////////////////////

   /**
    * Split up a string into multiple strings based on a delimiter.
    *
    * @param string  String to split up.
    * @param delim   Delimiter.
    * @param limit   Limit the number of strings to split into
    *                (-1 for no limit).
    * @return        Array of strings.
    */
   public static String[] split(final String string, final String delim,
                                final int limit)
   {
      // get the count of delim in string, if count is > limit 
      // then use limit for count.  The number of delimiters is less by one
      // than the number of elements, so add one to count.
      int count = count(string, delim) + 1;
      if (limit > 0 && count > limit) {
         count = limit;
      }

      String strings[] = new String[count];
      int begin = 0;

      for (int i=0; i<count; i++) {
         // get the next index of delim
         int end = string.indexOf(delim, begin);
         
         // if the end index is -1 or if this is the last element
         // then use the string's length for the end index
         if (end == -1 || i + 1 == count)
            end = string.length();

         // if end is 0, then the first element is empty
         if (end == 0)
            strings[i] = EMPTY;
         else
            strings[i] = string.substring(begin, end);

         // update the begining index
         begin = end + 1;
      }

      return strings;
   }

   /**
    * Split up a string into multiple strings based on a delimiter.
    *
    * @param string  String to split up.
    * @param delim   Delimiter.
    * @return        Array of strings.
    */
   public static String[] split(final String string, final String delim) {
      return split(string, delim, -1);
   }


   /////////////////////////////////////////////////////////////////////////
   //                    Joining/Concatenation Methods                    //
   /////////////////////////////////////////////////////////////////////////

   /**
    * Join an array of strings into one delimited string.
    *
    * @param buff    String buffered used for join (buffer is not reset).
    * @param array   Array of objects to join as strings.
    * @param delim   Delimiter to join strings with or <i>null</i>.
    * @return        Joined string.
    */
   public static String join(final StringBuffer buff, final Object array[],
                             final String delim)
   {
      boolean haveDelim = (delim != null);
   
      for (int i=0; i<array.length; i++) {
         buff.append(array[i]);

         // if this is the last element then don't append delim
         if (haveDelim && (i + 1) < array.length) {
            buff.append(delim);
         }
      } 

      return buff.toString();
   }

   /**
    * Join an array of strings into one delimited string.
    *
    * @param array   Array of objects to join as strings.
    * @param delim   Delimiter to join strings with or <i>null</i>.
    * @return        Joined string.
    */
   public static String join(final Object array[], final String delim) {
      return join(new StringBuffer(), array, delim);
   }

   /**
    * Convert and join an array of objects into one string.
    *
    * @param array   Array of objects to join as strings.
    * @return        Converted and joined objects.
    */
   public static String join(final Object array[]) {
      return join(array, null);
   }

   /**
    * Convert and join an array of bytes into one string.
    *
    * @param array   Array of objects to join as strings.
    * @return        Converted and joined objects.
    */
   public static String join(final byte array[]) {
      Byte bytes[] = new Byte[array.length];
      for (int i=0; i<bytes.length; i++) {
         bytes[i] = new Byte(array[i]);
      }

      return join(bytes, null);
   }

   /**
    * Return a string composed of the given array.
    *
    * @param buff       Buffer used to construct string value (not reset).
    * @param array      Array of objects.
    * @param prefix     String prefix.
    * @param separator  Element sepearator.
    * @param suffix     String suffix.
    * @return           String in the format of:
    *                   prefix + n ( + separator + n+i)* + suffix.
    */
   public static String join(final StringBuffer buff, final Object[] array, 
                             final String prefix, final String separator,
                             final String suffix)
   {
      buff.append(prefix);
      join(buff, array, separator);
      buff.append(suffix);

      return buff.toString();
   }

   /**
    * Return a string composed of the given array.
    *
    * @param array      Array of objects.
    * @param prefix     String prefix.
    * @param separator  Element sepearator.
    * @param suffix     String suffix.
    * @return           String in the format of:
    *                   prefix + n ( + separator + n+i)* + suffix.
    */
   public static String join(final Object[] array, final String prefix, 
                             final String separator, final String suffix)
   {
      return join(new StringBuffer(), array, prefix, separator, suffix);
   }


   /////////////////////////////////////////////////////////////////////////
   //                          Counting Methods                           //
   /////////////////////////////////////////////////////////////////////////

   /**
    * Count the number of instances of substring within a string.
    *
    * @param string     String to look for substring in.
    * @param substring  Sub-string to look for.
    * @return           Count of substrings in string.
    */
   public static int count(final String string, final String substring) {
      int count = 0;
      int idx = 0;

      while ((idx = string.indexOf(substring, idx)) != -1) {
         idx++;
         count++;
      }

      return count;
   }

   /**
    * Count the number of instances of character within a string.
    *
    * @param string     String to look for substring in.
    * @param c          Character to look for.
    * @return           Count of substrings in string.
    */
   public static int count(final String string, final char c) {
      return count(string, String.valueOf(c));
   }


   /////////////////////////////////////////////////////////////////////////
   //                            Padding Methods                          //
   /////////////////////////////////////////////////////////////////////////

   /**
    * Return a string padded with the given string for the given count.
    *
    * @param buff       String buffer used for padding (buffer is not reset).
    * @param string     Pad element.
    * @param count      Pad count.
    * @return           Padded string.
    */
   public static String pad(final StringBuffer buff, final String string,
                            final int count)
   {
      for (int i=0; i<count; i++) {
         buff.append(string);
      }

      return buff.toString();
   }

   /**
    * Return a string padded with the given string for the given count.
    *
    * @param string     Pad element.
    * @param count      Pad count.
    * @return           Padded string.
    */
   public static String pad(final String string, final int count) {
      return pad(new StringBuffer(), string, count);
   }

   /**
    * Return a string padded with the given string value of an object
    * for the given count.
    *
    * @param obj     Object to convert to a string.
    * @param count   Pad count.
    * @return        Padded string.
    */
   public static String pad(final Object obj, final int count) {
      return pad(new StringBuffer(), String.valueOf(obj), count);
   }


   /////////////////////////////////////////////////////////////////////////
   //                              Misc Methods                           //
   /////////////////////////////////////////////////////////////////////////

   /**
    * <p>Compare two strings.
    *
    * <p>Both or one of them may be null.
    *
    * @return true if object equals or intern ==, else false. 
    */
   public static boolean compare(final String me, final String you) {
      // If both null or intern equals
      if (me == you)
         return true;
      
      // if me null and you are not
      if (me == null && you != null)
         return false;
      
      // me will not be null, test for equality
      return me.equals(you);
   }
      
   /**
    * Check if the given string is empty.
    *
    * @param string     String to check
    * @return           True if string is empty
    */
   public static boolean isEmpty(final String string) {
      return string.equals(EMPTY);
   }

   /**
    * Return the <i>nth</i> index of the given token occurring in the given string.
    *
    * @param string     String to search.
    * @param token      Token to match.
    * @param index      <i>Nth</i> index.
    * @return           Index of <i>nth</i> item or -1.
    */
   public static int nthIndexOf(final String string, final String token,
                                final int index)
   {
      int j = 0;

      for (int i = 0; i < index; i++) {
         j = string.indexOf(token, j + 1);
         if (j == -1) break;
      }

      return j;
   }

   /**
    * Capitalize the first character of the given string.
    *
    * @param string     String to capitalize.
    * @return           Capitalized string.
    *
    * @throws IllegalArgumentException    String is <kk>null</kk> or empty.
    */
   public static String capitalize(final String string) {
      if (string == null)
         throw new NullArgumentException("string");
      if (string.equals(""))
         throw new EmptyStringException("string");

      return Character.toUpperCase(string.charAt(0)) + string.substring(1);
   }

   /**
    * Trim each string in the given string array.
    *
    * <p>This modifies the string array.
    *
    * @param strings    String array to trim.
    * @return           String array with each element trimmed.
    */
   public static String[] trim(final String[] strings) {
      for (int i=0; i<strings.length; i++) {
         strings[i] = strings[i].trim();
      }

      return strings;
   }

   /**
    * Make a URL from the given string.
    *
    * <p>
    * If the string is a properly formatted file URL, then the file
    * portion will be made canonical.
    *
    * <p>
    * If the string is an invalid URL then it will be converted into a
    * file URL.
    *
    * @param urlspec           The string to construct a URL for.
    * @param relativePrefix    The string to prepend to relative file
    *                          paths, or null to disable prepending.
    * @return                  A URL for the given string.
    *
    * @throws MalformedURLException  Could not make a URL for the given string.
    */
   public static URL toURL(String urlspec, final String relativePrefix) throws MalformedURLException
   {
      urlspec = urlspec.trim();
      
      URL url;
      
      try {
         url = new URL(urlspec);
         if (url.getProtocol().equals("file")) {
            url = makeURLFromFilespec(url.getFile(), relativePrefix);
         }
      }
      catch (Exception e) {
         // make sure we have a absolute & canonical file url
         try {
            url = makeURLFromFilespec(urlspec, relativePrefix);
         }
         catch (IOException n) {
            //
            // jason: or should we rethrow e?
            //
            throw new MalformedURLException(n.toString());
         }
      }
      
      return url;
   }

   /** A helper to make a URL from a filespec. */
   private static URL makeURLFromFilespec(final String filespec, final String relativePrefix)
      throws IOException
   {
      // make sure the file is absolute & canonical file url
      File file = new File(filespec);
      
      // if we have a prefix and the file is not abs then prepend
      if (relativePrefix != null && !file.isAbsolute()) {
         file = new File(relativePrefix, filespec);
      }
      
      // make sure it is canonical (no ../ and such)
      file = file.getCanonicalFile();
      
      return file.toURL();
   }
   
   /**
    * Make a URL from the given string.
    *
    * @see #toURL(String,String)
    *
    * @param urlspec    The string to construct a URL for.
    * @return           A URL for the given string.
    *
    * @throws MalformedURLException  Could not make a URL for the given string.
    */
   public static URL toURL(final String urlspec) throws MalformedURLException
   {
      return toURL(urlspec, null);
   }

   /**
    * Check whether the given String is a reserved Java Keyword
    * according to the Java Language Specifications.
    *
    * @param s String to check
    *
    * @return <code>true</code> if the given String is a reserved Java
    *         keyword, <code>false</code> otherwise.
    */
   public final static boolean isJavaKeyword( String s )
   {
      if( s == null || s.length() == 0 )
      {
         return false;
      }

      for( int i = 0; i < keywords.length; i++ )
      {
         if( keywords[i].equals(s) )
         {
            return true;
         }
      }

      return false;
   }

   /**
    * Check whether the given String is an identifier according to the
    * EJB-QL definition. See The EJB 2.0 Documentation Section 11.2.6.1.
    *
    * @param s String to check
    *
    * @return <code>true</code> if the given String is a reserved
    *         identifier in EJB-QL, <code>false</code> otherwise.
    */
   public final static boolean isEjbQlIdentifier( String s )
   {
      if( s == null || s.length() == 0 )
      {
         return false;
      }

      for( int i = 0; i < ejbQlIdentifiers.length; i++ )
      {
         if( ejbQlIdentifiers[i].equalsIgnoreCase(s) )
         {
            return true;
         }
      }

      return false;
   }

   /**
    * Check whether the given String is a valid identifier according
    * to the Java Language specifications.
    *
    * See The Java Language Specification Second Edition, Section 3.8
    * for the definition of what is a valid identifier.
    *
    * @param s String to check
    *
    * @return <code>true</code> if the given String is a valid Java
    *         identifier, <code>false</code> otherwise.
    */
   public final static boolean isValidJavaIdentifier( String s )
   {
      // an empty or null string cannot be a valid identifier
      if( s == null || s.length() == 0 )
      {
         return false;
      }

      char[] c = s.toCharArray();
      if( !Character.isJavaIdentifierStart(c[0]) )
      {
         return false;
      }

      for( int i = 1; i < c.length; i++ )
      {
         if( !Character.isJavaIdentifierPart(c[i]) )
         {
            return false;
         }
      }

      return true;
   }

}
/*
vim:ts=3:sw=3:et
*/