AbstractVelocityStatus.java

/**
 * AbstractVelocityStatus.java
 * 
 * @author Philip Crotwell
 */
package edu.sc.seis.sod.status;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StringWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.sql.SQLException;

import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.context.Context;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import edu.sc.seis.fissuresUtil.exceptionHandler.GlobalExceptionHandler;
import edu.sc.seis.sod.SodUtil;
import edu.sc.seis.sod.process.waveform.LocalSeismogramTemplateGenerator;
import edu.sc.seis.sod.status.networkArm.NetworkMonitor;
import edu.sc.seis.sod.status.waveformArm.WaveformMonitor;

public abstract class AbstractVelocityStatus implements WaveformMonitor,
        NetworkMonitor {

    public AbstractVelocityStatus(Element config) throws SQLException,
            MalformedURLException, IOException {
        this(FileWritingTemplate.getBaseDirectoryName(),
             getTemplateName(config));
    }

    public AbstractVelocityStatus(String fileDir, String templateName)
            throws SQLException, IOException {
        this.fileDir = fileDir;
        this.templateName = templateName;
        template = loadTemplate(templateName);
        try {
            Element menuEl = TemplateFileLoader.getTemplate(getClass().getClassLoader(),
                                                            MenuTemplate.TEMPLATE_LOC);
            MenuTemplate menu = new MenuTemplate(menuEl,
                                                 createExamplePath(),
                                                 fileDir);
            renderedMenu = menu.getResult();
        } catch(Exception e) {
            GlobalExceptionHandler.handle("Trouble creating menuTemplate for Velocity based status",
                                          e);
        }
    }

    public static String getTemplateName(Element config)
            throws MalformedURLException {
        String templateName = getNestedTextForElement("template", config);
        if(templateName != null) { return templateName; }
        throw new MalformedURLException("template config param is null");
    }

    public static String getNestedTextForElement(String elementName,
                                                 Element config) {
        NodeList nl = config.getChildNodes();
        for(int i = 0; i < nl.getLength(); i++) {
            Node n = nl.item(i);
            if(n instanceof Element) {
                Element element = (Element)n;
                if(element.getTagName().equals(elementName)) { return SodUtil.getNestedText(element); }
            }
        }
        return null;
    }

    //creates a path with the same number of directories as the actual location
    //will for use in menu creationw
    private String createExamplePath() {
        String path = fileDir + '/';
        for(int i = 0; i < getNumDirDeep(); i++) {
            path += "dir/";
        }
        return path + "file.html";
    }

    /**
     * Method getNumDirDeep returns how many directories below the base status
     * directory this template will write
     */
    public abstract int getNumDirDeep();

    /** loads the default template, given by the <template> tag in the config. */
    protected String loadTemplate() throws IOException {
        return loadTemplate(templateName);
    }

    /**
     * loads the named template. This method is in case a velocity processor has
     * more than one template generated by the same java class.
     */
    protected String loadTemplate(String templateName) throws IOException {
        URL templateURL = TemplateFileLoader.getUrl(this.getClass()
                .getClassLoader(), templateName);
        BufferedReader read = new BufferedReader(new InputStreamReader(templateURL.openStream()));
        String line, outTemplate = "";
        while((line = read.readLine()) != null) {
            outTemplate += line + System.getProperty("line.separator");
        }
        read.close();
        return outTemplate;
    }

    /**
     * Schedules the default template, from the <template> element in the config,
     * for output.
     */
    public void scheduleOutput(final String filename, final Context context) {
        scheduleOutput(filename, context, template);
    }

    /** Schedules the given template for output. */
    public void scheduleOutput(String filename, Context context, String template) {
        OutputScheduler.getDefault().schedule(new VelocityRenderer(filename,
                                                                   context,
                                                                   template));
    }

    private final class VelocityRenderer implements Runnable {

        private final String filename;

        private final Context context;

        private final String template;

        private VelocityRenderer(String filename, Context context,
                String template) {
            this.filename = filename;
            this.context = context;
            this.template = template;
        }

        public void run() {
            StringWriter out = new StringWriter();
            try {
                VelocityEngine engine = LocalSeismogramTemplateGenerator.getVelocity();
                synchronized(engine) {
                    // the new VeocityContext "wrapper" is to help with a
                    // possible memory leak
                    // due to velocity gathering introspection information,
                    // see
                    // http://jakarta.apache.org/velocity/developer-guide.html#Other%20Context%20Issues
                    Context tempContext = new VelocityContext(context);
                    tempContext.put("menu", renderedMenu);
                    engine.evaluate(tempContext, out, filename, template);
                }
                FileWritingTemplate.write(fileDir + "/" + filename,
                                          out.getBuffer().toString());
            } catch(Exception e) {
                GlobalExceptionHandler.handle(e);
            }
        }

        public boolean equals(Object o) {
            if(o instanceof VelocityRenderer) { return ((VelocityRenderer)o).filename.equals(this.filename); }
            return false;
        }

        public int hashCode() {
            return filename.hashCode();
        }
    }

    private String renderedMenu, fileDir, templateName, template = "";
}