/*
 * 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.
 */
package org.apache.commons.scxml2.model;

import java.io.Serializable;

import org.apache.commons.scxml2.ActionExecutionContext;
import org.apache.commons.scxml2.SCXMLExpressionException;

/**
 * An abstract base class for executable elements in SCXML,
 * such as &lt;assign&gt;, &lt;log&gt; etc.
 *
 */
public abstract class Action implements Serializable {

    /**
     * Link to its parent or container.
     */
    private Executable parent;

    /**
     * Constructor.
     */
    public Action() {
        this.parent = null;
    }

    /**
     * Get the Executable parent.
     *
     * @return Returns the parent.
     */
    public Executable getParent() {
        return parent;
    }

    /**
     * Set the Executable parent.
     *
     * @param parent The parent to set.
     */
    public void setParent(final Executable parent) {
        this.parent = parent;
    }

    /**
     * Return the {@link EnterableState} whose {@link org.apache.commons.scxml2.Context} this action
     * executes in.
     *
     * @return The parent {@link EnterableState}
     * @throws ModelException For an unknown EnterableState subclass
     *
     * @since 0.9
     */
    public EnterableState getParentEnterableState()
    throws ModelException {
        if (parent == null && this instanceof Script && ((Script)this).isGlobalScript()) {
            // global script doesn't have a EnterableState
            return null;
        }
        else if (parent == null) {
            throw new ModelException("Action "
                    + this.getClass().getName() + " instance missing required parent TransitionTarget");
        }
        return parent.getParent();
    }

    /**
     * Execute this action instance.
     *
     * @param exctx The ActionExecutionContext for this execution instance
     *
     * @throws ModelException If the execution causes the model to enter
     *                        a non-deterministic state.
     * @throws SCXMLExpressionException If the execution involves trying
     *                        to evaluate an expression which is malformed.
     * @throws ActionExecutionError to be thrown if the execution caused an error (event) to be raised,
     * which then shall stop execution of (possible) following actions within the same executable content block
     */
    public abstract void execute(ActionExecutionContext exctx) throws ModelException, SCXMLExpressionException, ActionExecutionError;
}