Master Link Transformer

ReferenceLinkTransformer.java

package com.aemks.core.transformers;

import com.day.cq.wcm.api.Page;
import com.day.cq.wcm.api.PageManager;
import com.day.cq.wcm.api.WCMException;
import com.day.cq.wcm.msm.api.LiveRelationship;
import com.day.cq.wcm.msm.api.LiveRelationshipManager;
import org.apache.cocoon.xml.sax.AbstractSAXPipe;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.rewriter.ProcessingComponentConfiguration;
import org.apache.sling.rewriter.ProcessingContext;
import org.apache.sling.rewriter.Transformer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;

import java.io.IOException;

public class ReferenceLinkTransformer extends AbstractSAXPipe implements Transformer {

    private static final String ANCHOR_TAG = "a";

    private static final String HREF_ATTRIBUTE = "href";

    private Page currentPage;

    private String blueprintPath;

    private String liveCopyPath;

    private boolean isLiveCopy;

    private static final Logger LOGGER = LoggerFactory.getLogger(ReferenceLinkTransformer.class);

    @Override
    public void init(ProcessingContext processingContext,
            ProcessingComponentConfiguration processingComponentConfiguration) throws IOException {
        Resource resource = processingContext.getRequest().getResource();
        setBlueprintAndLiveCopyPaths(resource);
    }

    /**
     * @param resource
     * This method checks whether the current page is a live copy.
     * If the page or root is live copy, the blueprint path and live copy path are retrieved
     * and set.
     */
    private void setBlueprintAndLiveCopyPaths(Resource resource) {
        LiveRelationshipManager liveRelationshipManager =resource.getResourceResolver().adaptTo(LiveRelationshipManager.class);
        LiveRelationship liveRelationship = null;
        PageManager pageManager = resource.getResourceResolver().adaptTo(PageManager.class);
        if(pageManager==null){
            return;
        }
        currentPage = pageManager.getContainingPage(resource);
        if(currentPage==null){
            return;
        }
        Resource pageResource = currentPage.adaptTo(Resource.class);
        try {
            isLiveCopy = liveRelationshipManager.getLiveRelationship(pageResource,false)!=null ? true : false;
            if(isLiveCopy){
                liveRelationship = liveRelationshipManager.getLiveRelationship(pageResource,false);
                if(liveRelationship.getLiveCopy()==null){
                    return;
                }
                blueprintPath = liveRelationship.getLiveCopy().getBlueprintPath();
                liveCopyPath = liveRelationship.getLiveCopy().getPath();
                return;
            }
        } catch (WCMException e) {
            LOGGER.error("An error ocurred while getting live copy",e);
        }
    }

    /**
     * @param uri
     * @param localName
     * @param qName
     * @param atts
     * @throws SAXException
     * This method checks for anchor tags and replaces master link with live copy link.
     */
    @Override public void startElement(String uri, String localName, String qName, Attributes atts)
            throws SAXException {
        final AttributesImpl attributes = new AttributesImpl(atts);
        if(ANCHOR_TAG.equalsIgnoreCase(localName) && currentPage!=null && isLiveCopy){
            String href = attributes.getValue(HREF_ATTRIBUTE);
            if(href!=null && href.startsWith(blueprintPath)){
                replaceMasterLink(attributes,href);
            }
        }
        contentHandler.startElement(uri, localName, qName, attributes);
    }

    private void replaceMasterLink(AttributesImpl attributes, String href) {
        for (int attributeIndex = 0; attributeIndex < attributes.getLength(); attributeIndex++) {
            if (HREF_ATTRIBUTE.equalsIgnoreCase(attributes.getQName(attributeIndex))) {
                href= href.replace(blueprintPath, liveCopyPath);
                attributes.setValue(attributeIndex,href);
                break;
            }
        }
    }

    @Override public void dispose() {
        // No operation required.
    }

}