/*
 * Copyright 2005-2011 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.wamblee.xmlrouter.impl;

import java.util.logging.Level;
import java.util.logging.Logger;

import javax.xml.transform.dom.DOMSource;

import org.wamblee.xml.XMLDocument;
import org.wamblee.xmlrouter.common.Id;
import org.wamblee.xmlrouter.config.Transformation;

/**
 * This class provides robustness towards externally provided transformations.
 * 
 * @author Erik Brakkee
 * 
 */
public class RobustTransformation implements Transformation {

    private static final Logger LOGGER = Logger
        .getLogger(RobustTransformation.class.getName());

    private Id<Transformation> id;
    private Transformation transformation;

    /**
     * Constructs the wrapper.
     * 
     * @param aId
     *            Unique id.
     * @param aTransformation
     *            Wrapped transformation.
     */
    public RobustTransformation(Id<Transformation> aId,
        Transformation aTransformation) {
        id = aId;
        transformation = aTransformation;
    }

    @Override
    public String getName() {
        try {
            String name = transformation.getName();
            if (name == null) {
                logTypeReturnedNull("from");
                return Constants.UNKNOWN_DOCUMENT_TYPE.toString();
            }
            return name;
        } catch (Exception e) {
            logNameThrewException(e);
            return Constants.UNKNOWN_DOCUMENT_TYPE.toString();
        }
    }

    @Override
    public String getFromType() {
        try {
            String from = transformation.getFromType();
            if (from == null) {
                logTypeReturnedNull("from");
                return Constants.UNKNOWN_DOCUMENT_TYPE.toString();
            }
            return from;
        } catch (Exception e) {
            logTypeThrewException("from", e);
            return Constants.UNKNOWN_DOCUMENT_TYPE.toString();
        }
    }

    @Override
    public String getToType() {
        try {
            String to = transformation.getToType();
            if (to == null) {
                logTypeReturnedNull("to");
                return Constants.UNKNOWN_DOCUMENT_TYPE.toString();
            }
            return to;
        } catch (Exception e) {
            logTypeThrewException("to", e);
            return Constants.UNKNOWN_DOCUMENT_TYPE.toString();
        }
    }

    @Override
    public DOMSource transform(DOMSource aDocument) {
        try {
            DOMSource res = transformation.transform(aDocument);
            if (res == null) {
                logTransformationReturnedNull(aDocument);
                return null;
            }
            return res;
        } catch (Exception e) {
            logTranformationThrewException(aDocument, e);
            return null;
        }
    }

    private void logNameThrewException(Exception aE) {
        LOGGER.log(Level.WARNING, "getName" +
            " threw exception, returning default value " +
            Constants.UNKNOWN_NAME, aE);
    }

    private void logTypeThrewException(String aFromTo, Exception aE) {
        LOGGER.log(Level.WARNING, "get" + aFromTo +
            " threw exception, returning default value " +
            Constants.UNKNOWN_DOCUMENT_TYPE, aE);
    }

    private void logTypeReturnedNull(String aFromTo) {
        LOGGER.log(Level.WARNING, "get" + aFromTo +
            " returned null, returning default value " +
            Constants.UNKNOWN_DOCUMENT_TYPE);
    }

    private void logTranformationThrewException(DOMSource aEvent, Exception aE) {
        LOGGER.log(Level.WARNING,
            "transformation " + id + " threw exception for event " +
                new XMLDocument(aEvent).print(true), aE);
    }

    private void logTransformationReturnedNull(DOMSource aEvent) {
        LOGGER.log(Level.WARNING, "transformation " + id +
            " returned null for event " + new XMLDocument(aEvent).print(true));
    }

}