/*
 * 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.ArrayList;
import java.util.List;

import org.wamblee.xmlrouter.config.Transformation;

/**
 * Transformation path from a source document to a destination.
 * 
 * @author Erik Brakkee
 * 
 */
public class TransformationPath {

    private List<Transformation> transformations;

    /**
     * Constructs empty path.
     */
    public TransformationPath() {
        transformations = new ArrayList<Transformation>();
    }

    /**
     * Constructs path with single transformation.
     * 
     * @param aTransformation
     *            Single transformation.
     */
    public TransformationPath(Transformation aTransformation) {
        this();
        transformations.add(aTransformation);
    }

    /**
     * Constructs path with list of transformations.
     * 
     * @param aTransformations
     *            List of transformations.
     */
    public TransformationPath(List<Transformation> aTransformations) {
        this();
        transformations.addAll(aTransformations);
    }

    /**
     * Appends a transormation path to the current path.
     * 
     * @param aSequence
     *            Transformation sequence to append.
     * @return Appended transformations equence.
     * @throws Runtime
     *             exception if the appended transformation would not be valid.
     */
    public TransformationPath appendPath(TransformationPath aSequence) {
        if (transformations.isEmpty()) {
            return new TransformationPath(aSequence.transformations);
        }
        if (aSequence.transformations.isEmpty()) {
            // nothing to append
            return new TransformationPath(transformations);
        }
        // both are non-empty
        if (!getToType().equals(aSequence.getFromType())) {
            throw new RuntimeException(
                "error concatening sequence, destination of first differs from source of second");
        }
        List<Transformation> t = new ArrayList<Transformation>(transformations);
        t.addAll(aSequence.transformations);
        return new TransformationPath(t);
    }

    /**
     * @return Number of transformations.
     */
    public int size() {
        return transformations.size();
    }

    /**
     * @return From type of the path or null if the sequence is empty.
     */
    public String getFromType() {
        if (transformations.isEmpty()) {
            return null;
        }
        return transformations.get(0).getFromType();
    }

    /**
     * @return To type of the path or null if the sequence is empty.
     */
    public String getToType() {
        if (transformations.isEmpty()) {
            return null;
        }
        return transformations.get(transformations.size() - 1).getToType();
    }

    /**
     * @return The transformations.
     */
    public List<Transformation> getTransformations() {
        return transformations;
    }

    @Override
    public String toString() {
        StringBuffer buf = new StringBuffer();
        buf.append("TransformationPath(");
        for (int i = 0; i < transformations.size(); i++) {
            if (i > 0) {
                buf.append(", ");
            }
            buf.append(transformations.get(i).toString());
        }
        buf.append(")");
        return buf.toString();
    }
}