WebPageQuickSearchProvider.java

/*
 * Created on 4. August 2008, 21:51
 */
package net.java.nboglpack.quicksearch;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.netbeans.spi.quicksearch.SearchProvider;
import org.netbeans.spi.quicksearch.SearchRequest;
import org.netbeans.spi.quicksearch.SearchResponse;
import org.openide.awt.HtmlBrowser.URLDisplayer;
import org.openide.util.RequestProcessor;


/**
 * Abstract Quicksearch provider. Just implement the filter method and register
 * in layer.xml and you are done.
 * @author Michael Bien
 */
public abstract class WebPageQuickSearchProvider implements SearchProvider {
    
    /**
     * Pattern to find hyperlinks and group them into attributes and name part.
     */
    private final static Pattern linkPattern = Pattern.compile("<a([^>]+)>([^<]+)</a>", Pattern.CASE_INSENSITIVE);

    /**
     * Pattern to find the value of the 'href' attribute.
     */
    private final static Pattern hrefPattern = Pattern.compile("href\\s*=\\s*\"([^\"]+)\"", Pattern.CASE_INSENSITIVE);

    private SearchItem[] items;
    
    private RequestProcessor.Task harvestTask;

    
    public WebPageQuickSearchProvider(final String url) {
        
        // async harvest task
        harvestTask = new RequestProcessor("GL Quicksearch Requestprocessor").create(new Runnable() {

            @Override
            public void run() {
                try {
                    harvest(new URL(url));
                } catch (MalformedURLException ex) {
                    Logger.getLogger(WebPageQuickSearchProvider.class.getName()).log(Level.SEVERE, null, ex);
                } catch (IOException ex) {
                    Logger.getLogger(WebPageQuickSearchProvider.class.getName()).log(Level.INFO, "unable to index page, retry after 5 minutes timeout", ex);
                    harvestTask.schedule((int)TimeUnit.MINUTES.toMillis(5));
                }
            }
            
        });
        
        harvestTask.schedule(0);
    }
    

    private void harvest(URL url) throws IOException {
        
        BufferedReader reader = null;
        ArrayList<SearchItem> itemList = new ArrayList<SearchItem>(128);
        
        try {
            // download content
            reader = new BufferedReader(new InputStreamReader(url.openStream()));
            char[] buffer = new char[512];
            StringBuilder sb = new StringBuilder();
            while(reader.read(buffer) != -1){
                sb.append(buffer);
            }
            
            // harvest everything usefull
            Matcher linkMatcher = linkPattern.matcher(sb);
            
            // find <a ></a>
            while(linkMatcher.find()) {
                
                String attributes = linkMatcher.group(1);
                Matcher hrefMatcher = hrefPattern.matcher(attributes);
                String name = linkMatcher.group(2);
                
                // find href and link name
                if(hrefMatcher.find()) {
                    
                    String href = hrefMatcher.group(1);
                    
                    href = filter(href, name);
                    if(href != null) {
                        itemList.add(new SearchItem(name, href));
                    }
                    
                }else{
                    Logger.getLogger(WebPageQuickSearchProvider.class.getName()).log(Level.WARNING, 
                            "no href found in attributes:\n"+attributes+"\nof hyplerlink: "+name);
                }
               
                // safepoint for beeing interrupted
                if (Thread.interrupted()) 
                    break;

            }
        }finally{
            if(reader != null)
                reader.close();
        }

        items = itemList.toArray(new SearchItem[itemList.size()]);
    }
    
    /**
     * Returns a valid link or null computed from the href attribute and the link name.
     */
    abstract String filter(String href, String name);
    
    
    /**
     * Method is called by infrastructure when search operation was requested.
     * Implementors should evaluate given request and fill response object with
     * apropriate results
     *
     * @param request Search request object that contains information what to search for
     * @param response Search response object that stores search results. 
     * Note that it's important to react to return value of SearchResponse.addResult(...) method
     * and stop computation if false value is returned.
     */
    @Override
    public void evaluate(SearchRequest request, SearchResponse response) {
        
        // make sure harvester is done
        if(harvestTask != null) {
            harvestTask.waitFinished();
            if(items != null)
                harvestTask = null;
        }
        
        if(items == null)
            return;
        
        // handle multi token search properly (everything case insensitive)
        String[] token = request.getText().toLowerCase().split("\\s+");
        
        for (SearchItem item : items) {
            
            boolean matches = true;
            for (int i = 0; i < token.length; i++) {
                if(!item.nameLC.contains(token[i])) {
                    matches = false;
                    break;
                }
            }
            
            if(matches) {
                boolean doContinue = response.addResult(item, item.name);
                if(!doContinue)
                    break;
            }
        }
        
    }
    
    /**
     * Item which may fit to the search string. Openes URL in browser when selected.
     */
    private static class SearchItem implements Runnable {
        
        private final URL url;
        private final String name;
        private final String nameLC;
        
        public SearchItem(String name, String url) throws MalformedURLException {
            this.name = name;
            this.nameLC = name.toLowerCase();
            this.url = new URL(url);
        }

        @Override
        public void run() {
            URLDisplayer.getDefault().showURL(url);
        }
        
    }
    
    
}