/*
 * Copyright 2008 Google Inc.
 *
 * Licensed 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 com.google.gwt.uibinder.rebind;

import java.util.HashMap;
import java.util.Map;

/**
 * Methods to dispense unique text tokens to be stitched into text, and
 * to help replace the tokens with arbitrary content. Multiple tokenators
 * can be used across the same body of text without fear of the tokens they
 * vend colliding with each other.
 */
public class Tokenator {
  /**
   * Resolves a token to its literal value.
   */
  public interface Resolver {
    String resolveToken(String token);
  }

  private static final String TOKEN = "--token--";
  private static final String TOKEN_REGEXP = "\\-\\-token\\-\\-";
  private static int curId = 0;

  public static String detokenate(String betokened, Resolver resolver) {
    StringBuilder detokenated = new StringBuilder();

    int index = 0, nextToken = 0;
    while ((nextToken = betokened.indexOf(TOKEN, index)) > -1) {
      detokenated.append(betokened.substring(index, nextToken));

      int endToken = betokened.indexOf(TOKEN, nextToken + TOKEN.length());
      String token = betokened.substring(nextToken, endToken + TOKEN.length());
      detokenated.append(resolver.resolveToken(token));

      index = endToken + TOKEN.length();
    }

    detokenated.append(betokened.substring(index));
    return detokenated.toString();
  }

  public static boolean hasToken(String s) {
    return s.matches(".*" + TOKEN_REGEXP + "\\d+" + TOKEN_REGEXP + ".*");
  }

  private static String nextToken() {
    return TOKEN + (curId++) + TOKEN;
  }

  private Map<String, String> tokenToResolved =
    new HashMap<String, String>();

  public String detokenate(String betokened) {
    return detokenate(betokened, new Resolver() {
      public String resolveToken(String token) {
        return tokenToResolved.get(token);
      }
    });
  }

  public String nextToken(final String resolved) {
    String token = nextToken();
    tokenToResolved.put(token, resolved);
    return token;
  }
}