CronViewColumn.java

package hudson.plugins;

import java.util.Map;

import net.sf.json.JSONObject;

import org.kohsuke.stapler.StaplerRequest;

import hudson.Extension;
import hudson.model.AbstractProject;
import hudson.model.Descriptor;
import hudson.model.Job;
import hudson.scm.NullSCM;
import hudson.scm.SCM;
import hudson.triggers.SCMTrigger;
import hudson.triggers.TimerTrigger;
import hudson.triggers.Trigger;
import hudson.triggers.TriggerDescriptor;
import hudson.views.ListViewColumn;


/**
 * CronViewColumn
 * 
 * Column plugin that adds a column to a jobs overview page.
 * 
 * The column displays the cron expression of each Trigger on the Job.
 * 
 * 03/03/2010
 * @author Eelco de Vlieger
 */
public class CronViewColumn extends ListViewColumn{

	private static final String CRON_EXPRESSION_COMMENT_START = "#";
	private static final String CRON_EXPRESSION_COMMENT_COLOR = "#4a7b4a";

	
	/**
	 * @return HTML String containing the cron expression of each Trigger on the Job (when available). 
	 */
    public String getCronTrigger(Job job){
    	if( !(job instanceof AbstractProject<?, ?>) )
    		return "";
    	
    	StringBuilder expression = new StringBuilder();
    	
    	AbstractProject<?, ?> project = (AbstractProject<?, ?>)job;
    	
    	// Check if source code management is enabled.
    	SCM sourceCodeManagement = project.getScm();
		boolean hasSourceCodeManagement = sourceCodeManagement != null && !(sourceCodeManagement instanceof NullSCM);
    	
    	Map<TriggerDescriptor, Trigger> triggers = project.getTriggers();
    	for(Trigger trigger : triggers.values()){
    		if(trigger == null)
    			continue;
    		
    		String cronExpression = trigger.getSpec();
			if( cronExpression == null || cronExpression.trim().length() == 0 )
				continue;
    		
			cronExpression = formatComments(cronExpression);
			
			// Display each entry on a separate line. 
			if(expression.length() > 0)
				expression.append("\n<br/>\n");
			
			// Cron expression can still be set when Source Code Management has been disabled.
			if(!hasSourceCodeManagement && trigger instanceof SCMTrigger)
				expression.append("<i>(Disabled) </i>");
			
			// Add trigger name and cron expression.
			expression.append( getTriggerName(trigger) ).append(": ").append( cronExpression );
    	}
    	
    	return expression.toString();
    }

    /**
     * Change the font color on the comment text within a cron expression.
     */
    private String formatComments(String cronExpression){
    	if( !cronExpression.contains(CRON_EXPRESSION_COMMENT_START) )
    		return cronExpression; // No comment found.

    	StringBuilder formattedExpression = new StringBuilder();
    	
    	String[] expressionLines = cronExpression.split("\n");
    	for(String expressionLine : expressionLines){
    		int commentStartIndex = expressionLine.indexOf(CRON_EXPRESSION_COMMENT_START);
			if(commentStartIndex < 0){
				// No comment, so just add the original expression line.
				formattedExpression.append(expressionLine);
			}else{
				// Comment found, wrapping comment in font tags (setting the color).
	    		formattedExpression.append( expressionLine.substring(0, commentStartIndex) );
	    		formattedExpression.append("<b><i><font color=\"" + CRON_EXPRESSION_COMMENT_COLOR + "\">");
	    		formattedExpression.append( expressionLine.substring(commentStartIndex) );
	    		formattedExpression.append("</font></i></b>");
			}
    		formattedExpression.append(" ");
    	}
    	
    	return formattedExpression.toString().trim();
	}

	/**
     * Determines the trigger name.
     * 
     * @return Name of the trigger.
     */
	private String getTriggerName(Trigger<?> trigger){
		String type = trigger.getDescriptor().getDisplayName();
		if(type == null || type.trim().length() == 0){
			if(trigger instanceof SCMTrigger)
				type = "SCM polling";
			else if(trigger instanceof TimerTrigger)
				type = "Build Trigger";
			else
				type = "Unknown Type";
		}
		return type;
	}
	
	
    @Extension
    public static final Descriptor<ListViewColumn> DESCRIPTOR = new Descriptor<ListViewColumn>(){
        @Override
        public ListViewColumn newInstance(StaplerRequest req, JSONObject formData){
        	return new CronViewColumn();
        }
        
		@Override
		public String getDisplayName(){
			return "CronTrigger";
		}
    };

    public Descriptor<ListViewColumn> getDescriptor(){
        return DESCRIPTOR;
    }
}