<?php
/**
 * 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.
 */

/**
 *  Handles generation of signing tokens for various request types.
 *  Implementations are free to define their own signing parameters in any
 *  way that is suitable for their site.
 */
abstract class GadgetSigner {

  /**
   * Generates a token for the given gadget.
   * Implementations should also add their own user-related context data
   * to the token.
   * 
   * Or generates a token from an input string. This call must produce a token that
   * will validate against a token produced directly from a gadget so that the
   * following function will always returns a valid SecurityToken:
   *
   * <code>
   * SecurityToken testToken(Gadget gadget, GadgetSigner signer) {
   *   SecurityToken token = signer.createToken(gadget);
   *   return signer.createToken(token.toSerialForm());
   * }
   * </code>
   *
   * @param tokenString String representation of the token to be created.
   * @return The token representation of the input data.
   * @throws GadgetException If tokenString is not a valid token
   */
  abstract public function createToken($gadget);
}
