/*
 * Copyright 2004-2012 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 org.springframework.webflow.engine;

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import org.springframework.core.style.StylerUtils;
import org.springframework.webflow.core.collection.CollectionUtils;
import org.springframework.webflow.execution.RequestContext;

/**
 * A typed set of transitions for use internally by artifacts that can apply transition execution logic.
 * 
 * @see TransitionableState#getTransitionSet()
 * @see Flow#getGlobalTransitionSet()
 * 
 * @author Keith Donald
 */
public class TransitionSet implements Iterable<Transition> {

	/**
	 * The set of transitions.
	 */
	private List<Transition> transitions = new LinkedList<Transition>();

	/**
	 * Add a transition to this set.
	 * @param transition the transition to add
	 * @return true if this set's contents changed as a result of the add operation
	 */
	public boolean add(Transition transition) {
		if (contains(transition)) {
			return false;
		}
		return transitions.add(transition);
	}

	/**
	 * Add a collection of transition instances to this set.
	 * @param transitions the transitions to add
	 * @return true if this set's contents changed as a result of the add operation
	 */
	public boolean addAll(Transition... transitions) {
		return CollectionUtils.addAllNoDuplicates(this.transitions, transitions);
	}

	/**
	 * Tests if this transition is in this set.
	 * @param transition the transition
	 * @return true if the transition is contained in this set, false otherwise
	 */
	public boolean contains(Transition transition) {
		return transitions.contains(transition);
	}

	/**
	 * Remove the transition instance from this set.
	 * @param transition the transition to remove
	 * @return true if this list's contents changed as a result of the remove operation
	 */
	public boolean remove(Transition transition) {
		return transitions.remove(transition);
	}

	/**
	 * Returns the size of this transition set.
	 * @return the exception handler set size
	 */
	public int size() {
		return transitions.size();
	}

	/**
	 * Returns an iterator over this transition set.
	 * @return an iterator
	 */
	public Iterator<Transition> iterator() {
		return transitions.iterator();
	}

	/**
	 * Convert this set to a typed transition array.
	 * @return the transition set as a typed array
	 */
	public Transition[] toArray() {
		return transitions.toArray(new Transition[transitions.size()]);
	}

	/**
	 * Returns a list of the supported transitional criteria used to match transitions in this state.
	 * @return the list of transitional criteria
	 */
	public TransitionCriteria[] getTransitionCriterias() {
		TransitionCriteria[] criterias = new TransitionCriteria[transitions.size()];
		int i = 0;
		for (Transition transition : transitions) {
			criterias[i++] = transition.getMatchingCriteria();
		}
		return criterias;
	}

	/**
	 * Gets a transition for given flow execution request context. The first matching transition will be returned.
	 * @param context a flow execution context
	 * @return the transition, or null if no transition matches
	 */
	public Transition getTransition(RequestContext context) {
		for (Transition transition : transitions) {
			if (transition.matches(context)) {
				return transition;
			}
		}
		return null;
	}

	/**
	 * Returns whether or not this list has a transition that will fire for given flow execution request context.
	 * @param context a flow execution context
	 */
	public boolean hasMatchingTransition(RequestContext context) {
		return getTransition(context) != null;
	}

	public String toString() {
		return StylerUtils.style(transitions);
	}
}