/*
 * Copyright 2015 Robert von Burg <eitch@eitchnet.ch>
 *
 * 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 li.strolch.policy;

import static li.strolch.model.StrolchModelConstants.PolicyConstants.PARAM_ORDER;

import li.strolch.agent.api.ComponentContainer;
import li.strolch.agent.api.StrolchComponent;
import li.strolch.model.Order;
import li.strolch.model.activity.IActivityElement;
import li.strolch.persistence.api.StrolchTransaction;
import li.strolch.service.api.Command;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Interface for all Strolch policies, which are instantiated by the {@link PolicyHandler}
 *
 * @author Robert von Burg <eitch@eitchnet.ch>
 */
public abstract class StrolchPolicy {

    protected static final Logger logger = LoggerFactory.getLogger(StrolchPolicy.class);

    private final ComponentContainer container;
    private final StrolchTransaction tx;

    /**
     * Instantiate a new {@link StrolchPolicy}
     *
     * @param tx the transaction for this policy
     */
    public StrolchPolicy(StrolchTransaction tx) {
        this.container = tx.getContainer();
        this.tx = tx;
    }


    /**
     * Returns true if the given component is registered on th container
     *
     * @param clazz the type of component to check for
     * @return true if the component is available
     */
    public boolean hasComponent(Class<?> clazz) {
        return this.container.hasComponent(clazz);
    }

    /**
     * Allows the concrete {@link Command} implementation access to {@link StrolchComponent StrolchComponents} at
     * runtime
     *
     * @param clazz the type of component to be returned
     * @return the component with the given {@link Class} which is registered on the {@link ComponentContainer}
     * @throws IllegalArgumentException if the component with the given class does not exist
     */
    protected <V> V getComponent(Class<V> clazz) throws IllegalArgumentException {
        return this.container.getComponent(clazz);
    }

    /**
     * @return the container
     */
    protected ComponentContainer getContainer() {
        return this.container;
    }

    /**
     * Returns the {@link StrolchTransaction} bound to this {@link Command}'s runtime
     *
     * @return the {@link StrolchTransaction} bound to this {@link Command}'s runtime
     */
    protected StrolchTransaction tx() {
        return this.tx;
    }

    protected Order getOrder(IActivityElement element) {
        return tx().getOrderByRelation(element.getRootElement(), PARAM_ORDER, true);
    }

    /**
     * @see Command#undo()
     */
    public void undo() {
        // empty implementation
    }
}