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/*
 * Copyright 2014 the original author or authors.
 *
 * 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 net.kuujo.copycat.state;

import net.kuujo.copycat.cluster.Cluster;

/**
 * Copycat state context.
 *
 * @author Jordan Halterman
 */
public interface StateContext {

  /**
   * Returns the current state cluster.
   *
   * @return The current state cluster.
   */
  Cluster cluster();

  /**
   * Returns the current state.
   *
   * @return The current state.
   */
  T state();

  /**
   * Puts a value in the state context.
   *
   * @param key The state key.
   * @param value The state value.
   * @return The state context.
   */
  StateContext put(String key, Object value);

  /**
   * Gets a value from the state context.
   *
   * @param key The state key.
   * @param  The state value type.
   * @return The state value.
   */
   U get(String key);

  /**
   * Removes a value from the state context.
   *
   * @param key The state key.
   * @param  The state value type.
   * @return The removed state value.
   */
   U remove(String key);

  /**
   * Clears state from the state context.
   *
   * @return The state context.
   */
  StateContext clear();

  /**
   * Transitions the context to a new state.
   *
   * @param state The state to which to transition.
   * @return The state context.
   */
  StateContext transition(T state);

}