/*
    * $Id: WildcardHelper.java 829574 2009-10-25 14:15:31Z apetrelli $
    *
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *  http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.tiles.util;
  
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  /**
   * This class is an utility class that perform wilcard-patterns matching and
   * isolation taken from Apache Struts that is taken, in turn, from Apache
   * Struts.
   *
   * @version $Rev: 829574 $ $Date: 2009-10-26 01:15:31 +1100 (Mon, 26 Oct 2009) $
   * @since 2.1.0
   */
  public class WildcardHelper {
      /**
       * The int representing '*' in the pattern <code>int []</code>.
       *
       * @since 2.1.0
       */
      protected static final int MATCH_FILE = -1;
  
      /**
       * The int representing '**' in the pattern <code>int []</code>.
       *
       * @since 2.1.0
       */
      protected static final int MATCH_PATH = -2;
  
      /**
       * The int representing begin in the pattern <code>int []</code>.
       *
       * @since 2.1.0
       */
      protected static final int MATCH_BEGIN = -4;
  
      /**
       * The int representing end in pattern <code>int []</code>.
       *
       * @since 2.1.0
       */
      protected static final int MATCH_THEEND = -5;
  
      /**
       * The int value that terminates the pattern <code>int []</code>.
       *
       * @since 2.1.0
       */
      protected static final int MATCH_END = -3;
  
      /**
       * The length of the placeholder.
       *
       * @since 2.1.0
       */
      private static final int PLACEHOLDER_LENGTH = 3;
  
      /**
       * <p>
       * Translate the given <code>String</code> into a <code>int []</code>
       * representing the pattern matchable by this class. <br>
       * This function translates a <code>String</code> into an int array
       * converting the special '*' and '\' characters. <br>
       * Here is how the conversion algorithm works:
       * </p>
       *
       * <ul>
       *
       * <li>The '*' character is converted to MATCH_FILE, meaning that zero or
       * more characters (excluding the path separator '/') are to be matched.</li>
       *
       * <li>The '**' sequence is converted to MATCH_PATH, meaning that zero or
       * more characters (including the path separator '/') are to be matched.</li>
       *
       * <li>The '\' character is used as an escape sequence ('\*' is translated
       * in '*', not in MATCH_FILE). If an exact '\' character is to be matched
       * the source string must contain a '\\'. sequence.</li>
       *
      * </ul>
      *
      * <p>
      * When more than two '*' characters, not separated by another character,
      * are found their value is considered as '**' (MATCH_PATH). <br>
      * The array is always terminated by a special value (MATCH_END). <br>
      * All MATCH* values are less than zero, while normal characters are equal
      * or greater.
      * </p>
      *
      * @param data The string to translate.
      * @return The encoded string as an int array, terminated by the MATCH_END
      * value (don't consider the array length).
      * @throws NullPointerException If data is null.
      * @since 2.1.0
      */
     public int[] compilePattern(String data) {
         // Prepare the arrays
         int[] expr = new int[data.length() + 2];
         char[] buff = data.toCharArray();
 
         // Prepare variables for the translation loop
         int y = 0;
         boolean slash = false;
 
         // Must start from beginning
         expr[y++] = MATCH_BEGIN;
 
         if (buff.length > 0) {
             if (buff[0] == '\\') {
                 slash = true;
             } else if (buff[0] == '*') {
                 expr[y++] = MATCH_FILE;
             } else {
                 expr[y++] = buff[0];
             }
 
             // Main translation loop
             for (int x = 1; x < buff.length; x++) {
                 // If the previous char was '\' simply copy this char.
                 if (slash) {
                     expr[y++] = buff[x];
                     slash = false;
 
                     // If the previous char was not '\' we have to do a bunch of
                     // checks
                 } else {
                     // If this char is '\' declare that and continue
                     if (buff[x] == '\\') {
                         slash = true;
 
                         // If this char is '*' check the previous one
                     } else if (buff[x] == '*') {
                         // If the previous character als was '*' match a path
                         if (expr[y - 1] <= MATCH_FILE) {
                             expr[y - 1] = MATCH_PATH;
                         } else {
                             expr[y++] = MATCH_FILE;
                         }
                     } else {
                         expr[y++] = buff[x];
                     }
                 }
             }
         }
 
         // Must match end at the end
         expr[y] = MATCH_THEEND;
 
         return expr;
     }
 
     /**
      * Match a pattern agains a string and isolates wildcard replacement into a
      * <code>Stack</code>.
      *
      * @param data The string to match
      * @param expr The compiled wildcard expression
      * @return The list of matched variables, or <code>null</code> if it does not match.
      * @throws NullPointerException If any parameters are null
      * @since 2.2.0
      */
     public List<String> match(String data, int[] expr) {
         List<String> varsValues = null;
 
         if (data == null) {
             throw new NullPointerException("No data provided");
         }
 
         if (expr == null) {
             throw new NullPointerException("No pattern expression provided");
         }
 
         char[] buff = data.toCharArray();
 
         // Allocate the result buffer
         char[] rslt = new char[expr.length + buff.length];
 
         // The previous and current position of the expression character
         // (MATCH_*)
         int charpos = 0;
 
         // The position in the expression, input, translation and result arrays
         int exprpos = 0;
         int buffpos = 0;
         int rsltpos = 0;
         int offset = -1;
 
         // First check for MATCH_BEGIN
         boolean matchBegin = false;
 
         if (expr[charpos] == MATCH_BEGIN) {
             matchBegin = true;
             exprpos = ++charpos;
         }
 
         // Search the fist expression character (except MATCH_BEGIN - already
         // skipped)
         while (expr[charpos] >= 0) {
             charpos++;
         }
 
         // The expression charater (MATCH_*)
         int exprchr = expr[charpos];
 
         while (true) {
             // Check if the data in the expression array before the current
             // expression character matches the data in the input buffer
             if (matchBegin) {
                 if (!matchArray(expr, exprpos, charpos, buff, buffpos)) {
                     return null;
                 }
 
                 matchBegin = false;
             } else {
                 offset = indexOfArray(expr, exprpos, charpos, buff, buffpos);
 
                 if (offset < 0) {
                     return null;
                 }
             }
 
             // Check for MATCH_BEGIN
             if (matchBegin) {
                 if (offset != 0) {
                     return null;
                 }
 
                 matchBegin = false;
             }
 
             // Advance buffpos
             buffpos += (charpos - exprpos);
 
             // Check for END's
             if (exprchr == MATCH_END) {
                 if (rsltpos > 0) {
                     varsValues = addAndCreateList(varsValues, new String(rslt,
                             0, rsltpos));
                 }
 
                 // Don't care about rest of input buffer
                 varsValues = addElementOnTop(varsValues, data);
                 return varsValues;
             } else if (exprchr == MATCH_THEEND) {
                 if (rsltpos > 0) {
                     varsValues = addAndCreateList(varsValues, new String(rslt,
                             0, rsltpos));
                 }
 
                 // Check that we reach buffer's end
                 if (buffpos == buff.length) {
                     addElementOnTop(varsValues, data);
                     return varsValues;
                 }
                 return null;
             }
 
             // Search the next expression character
             exprpos = ++charpos;
 
             while (expr[charpos] >= 0) {
                 charpos++;
             }
 
             int prevchr = exprchr;
 
             exprchr = expr[charpos];
 
             // We have here prevchr == * or **.
             offset = (prevchr == MATCH_FILE) ? indexOfArray(expr, exprpos,
                     charpos, buff, buffpos) : lastIndexOfArray(expr, exprpos,
                     charpos, buff, buffpos);
 
             if (offset < 0) {
                 return null;
             }
 
             // Copy the data from the source buffer into the result buffer
             // to substitute the expression character
             if (prevchr == MATCH_PATH) {
                 while (buffpos < offset) {
                     rslt[rsltpos++] = buff[buffpos++];
                 }
             } else {
                 // Matching file, don't copy '/'
                 while (buffpos < offset) {
                     if (buff[buffpos] == '/') {
                         return null;
                     }
 
                     rslt[rsltpos++] = buff[buffpos++];
                 }
             }
 
             varsValues = addAndCreateList(varsValues, new String(rslt, 0,
                     rsltpos));
             rsltpos = 0;
         }
     }
 
     /**
      * Get the offset of a part of an int array within a char array. <br>
      * This method return the index in d of the first occurrence after dpos of
      * that part of array specified by r, starting at rpos and terminating at
      * rend.
      *
      * @param r The array containing the data that need to be matched in d.
      * @param rpos The index of the first character in r to look for.
      * @param rend The index of the last character in r to look for plus 1.
      * @param d The array of char that should contain a part of r.
      * @param dpos The starting offset in d for the matching.
      * @return The offset in d of the part of r matched in d or -1 if that was
      * not found.
      * @since 2.1.0
      */
     protected int indexOfArray(int[] r, int rpos, int rend, char[] d, int dpos) {
         // Check if pos and len are legal
         if (rend < rpos) {
             throw new IllegalArgumentException("rend < rpos");
         }
 
         // If we need to match a zero length string return current dpos
         if (rend == rpos) {
             return (d.length); // ?? dpos?
         }
 
         // If we need to match a 1 char length string do it simply
         if ((rend - rpos) == 1) {
             // Search for the specified character
             for (int x = dpos; x < d.length; x++) {
                 if (r[rpos] == d[x]) {
                     return (x);
                 }
             }
         }
 
         // Main string matching loop. It gets executed if the characters to
         // match are less then the characters left in the d buffer
         while (((dpos + rend) - rpos) <= d.length) {
             // Set current startpoint in d
             int y = dpos;
 
             // Check every character in d for equity. If the string is matched
             // return dpos
             for (int x = rpos; x <= rend; x++) {
                 if (x == rend) {
                     return (dpos);
                 }
 
                 if (r[x] != d[y++]) {
                     break;
                 }
             }
 
             // Increase dpos to search for the same string at next offset
             dpos++;
         }
 
         // The remaining chars in d buffer were not enough or the string
         // wasn't matched
         return (-1);
     }
 
     /**
      * Get the offset of a last occurance of an int array within a char array.
      * <br>
      * This method return the index in d of the last occurrence after dpos of
      * that part of array specified by r, starting at rpos and terminating at
      * rend.
      *
      * @param r The array containing the data that need to be matched in d.
      * @param rpos The index of the first character in r to look for.
      * @param rend The index of the last character in r to look for plus 1.
      * @param d The array of char that should contain a part of r.
      * @param dpos The starting offset in d for the matching.
      * @return The offset in d of the last part of r matched in d or -1 if that
      * was not found.
      * @since 2.1.0
      */
     protected int lastIndexOfArray(int[] r, int rpos, int rend, char[] d,
             int dpos) {
         // Check if pos and len are legal
         if (rend < rpos) {
             throw new IllegalArgumentException("rend < rpos");
         }
 
         // If we need to match a zero length string return current dpos
         if (rend == rpos) {
             return (d.length); // ?? dpos?
         }
 
         // If we need to match a 1 char length string do it simply
         if ((rend - rpos) == 1) {
             // Search for the specified character
             for (int x = d.length - 1; x > dpos; x--) {
                 if (r[rpos] == d[x]) {
                     return (x);
                 }
             }
         }
 
         // Main string matching loop. It gets executed if the characters to
         // match are less then the characters left in the d buffer
         int l = d.length - (rend - rpos);
 
         while (l >= dpos) {
             // Set current startpoint in d
             int y = l;
 
             // Check every character in d for equity. If the string is matched
             // return dpos
             for (int x = rpos; x <= rend; x++) {
                 if (x == rend) {
                     return (l);
                 }
 
                 if (r[x] != d[y++]) {
                     break;
                 }
             }
 
             // Decrease l to search for the same string at next offset
             l--;
         }
 
         // The remaining chars in d buffer were not enough or the string
         // wasn't matched
         return (-1);
     }
 
     /**
      * Matches elements of array r from rpos to rend with array d, starting from
      * dpos. <br>
      * This method return true if elements of array r from rpos to rend equals
      * elements of array d starting from dpos to dpos+(rend-rpos).
      *
      * @param r The array containing the data that need to be matched in d.
      * @param rpos The index of the first character in r to look for.
      * @param rend The index of the last character in r to look for.
      * @param d The array of char that should start from a part of r.
      * @param dpos The starting offset in d for the matching.
      * @return true if array d starts from portion of array r.
      * @since 2.1.0
      */
     protected boolean matchArray(int[] r, int rpos, int rend, char[] d, int dpos) {
         if ((d.length - dpos) < (rend - rpos)) {
             return (false);
         }
 
         for (int i = rpos; i < rend; i++) {
             if (r[i] != d[dpos++]) {
                 return (false);
             }
         }
 
         return (true);
     }
 
     /**
      * <p>
      * Inserts into a value wildcard-matched strings where specified.
      * </p>
      *
      * @param val The value to convert
      * @param vars A Map of wildcard-matched strings
      * @return The new value
      * @since 2.1.0
      */
     public static String convertParam(String val, Map<Integer, String> vars) {
         if (val == null) {
             return null;
         } else if (val.indexOf("{") == -1) {
             return val;
         }
 
         Map.Entry<Integer, String> entry;
         StringBuffer key = new StringBuffer("{0}");
         StringBuffer ret = new StringBuffer(val);
         String keyTmp;
         int x;
 
         for (Iterator<Map.Entry<Integer, String>> i = vars.entrySet()
                 .iterator(); i.hasNext();) {
             entry = i.next();
             key.setCharAt(1, entry.getKey().toString().charAt(0));
             keyTmp = key.toString();
 
             // Replace all instances of the placeholder
             while ((x = ret.toString().indexOf(keyTmp)) > -1) {
                 ret.replace(x, x + PLACEHOLDER_LENGTH, entry.getValue());
             }
         }
 
         return ret.toString();
     }
 
     /**
      * Adds and object to a list. If the list is null, it creates it.
      *
      * @param <T> The type of the element.
      * @param list The list.
      * @param data The data to add.
      * @return The list itself, or a new one if it is <code>null</code>.
      */
     private <T> List<T> addAndCreateList(List<T> list, T data) {
         if (list == null) {
             list = new ArrayList<T>();
         }
         list.add(data);
         return list;
     }
 
     /**
      * Adds and object on top of a list. If the list is null, it creates it.
      *
      * @param <T> The type of the element.
      * @param list The list.
      * @param data The data to add.
      * @return The list itself, or a new one if it is <code>null</code>.
      */
     private <T> List<T> addElementOnTop(List<T> list, T data) {
         if (list == null) {
             list = new ArrayList<T>();
         }
         list.add(0, data);
         return list;
     }
 }