/*
 * Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
 *
 *   Portions of this software were developed by the Unidata Program at the
 *   University Corporation for Atmospheric Research.
 *
 *   Access and use of this software shall impose the following obligations
 *   and understandings on the user. The user is granted the right, without
 *   any fee or cost, to use, copy, modify, alter, enhance and distribute
 *   this software, and any derivative works thereof, and its supporting
 *   documentation for any purpose whatsoever, provided that this entire
 *   notice appears in all copies of the software, derivative works and
 *   supporting documentation.  Further, UCAR requests that the user credit
 *   UCAR/Unidata in any publications that result from the use of this
 *   software or in any product that includes this software. The names UCAR
 *   and/or Unidata, however, may not be used in any advertising or publicity
 *   to endorse or promote any products or commercial entity unless specific
 *   written permission is obtained from UCAR/Unidata. The user also
 *   understands that UCAR/Unidata is not obligated to provide the user with
 *   any support, consulting, training or assistance of any kind with regard
 *   to the use, operation and performance of this software nor to provide
 *   the user with any updates, revisions, new versions or "bug fixes."
 *
 *   THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
 *   IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *   DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
 *   INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 *   FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 *   NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 *   WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
 */
package thredds.servlet;

import ucar.unidata.util.StringUtil2;

import java.util.*;

/**
 * A Collection of (String key, Object value) which is sorted on key.
 * match( String path) returns the Object whose key is the longest that matches path.
 * Match means that path.startsWith( key).
 *
 * Matching is thread-safe, as long as put() is no longer being called.
 */
public class PathMatcher<T> {
  static private final boolean debug = false;
  private final TreeMap<String, T> treeMap;

  public PathMatcher() {
    treeMap = new TreeMap<>( new PathComparator());
  }

  /**
   * Add an object to the collection to be searched by a String key.
   * @param key sort key
   * @param value add this object to the list to be searched.
   */
  public void put(String key, T value) {
    // treeMap.put( key, value == null ? key : value);  LOOK
    treeMap.put( key, value);
  }

  /**
   * See if this object already exists in the collection, using equals().
   * @param key find object that has this key
   * @return existing object, else null.
   */
  public T get(String  key) {
    return treeMap.get( key);
  }

  /**
   * Get an iterator over the values, in sorted order.
   * @return iterator
   */
  public Iterator<T> iterator() {
    return treeMap.values().iterator();
  }

  /**
   * Find the longest match.
   * @param path find object with longest match where path.startsWith( key)
   * @return the value whose key is the longest that matches path, or null if none
   */
  public T match( String path) {
    SortedMap<String, T> tail = treeMap.tailMap( path);
    if (tail.isEmpty()) return null;
    String after = tail.firstKey();
    //System.out.println("  "+path+"; after="+afterPath);
    if (path.startsWith( after)) // common case
      return treeMap.get( after);

    // have to check more, until no common starting chars
    for (String key : tail.keySet()) {
      if (path.startsWith(key))
        return treeMap.get(key);
      // terminate when there's no match at all.
      if (StringUtil2.match(path, key) == 0)
        break;
    }

    return null;
  }

  private static class PathComparator implements Comparator<String> {
    public int compare(String s1, String s2) {
      int compare = s2.compareTo( s1); // reverse sort
      if (debug) System.out.println(" compare "+s1+" to "+s2+" = "+compare);
      return compare;
    }
  }

}