net.leanix.mtm.api.dropwizard.TemplateFactory Maven / Gradle / Ivy

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package net.leanix.mtm.api.dropwizard;

import com.google.common.base.Charsets;
import com.google.common.io.Resources;
import com.google.inject.Singleton;
import java.io.IOException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import net.leanix.mtm.api.models.NotificationTemplate;

/**
 * Notification template factory.
 * 
 * Works only in jars and in Unix file systems. Expects a subfolder for each channel.
 * 
 */
@Singleton
public class TemplateFactory
{
    private final Map loadedTemplates = new HashMap();
    
    private String basePath = "views/notifications/";

    /**
     * Sets the relative base path of the mustache templates.
     * 
     * Defaults to "views/notifications/"
     * 
     * @param basePath 
     */
    public void setBasePath(String basePath)
    {
        this.basePath = basePath;
    }
    
    /**
     * Returns a notification template for an event and recipient.
     * 
     * @param channel
     * @param eventType
     * @param recipientType
     * @return 
     */
    public NotificationTemplate getTemplate(String channel, String eventType, String recipientType)
    {
        return getTemplate(channel, eventType.toLowerCase() + "." + recipientType.toLowerCase());
    }
    
    /**
     * Returns a notification template with a name.
     * 
     * @param channel
     * @param name
     * @return 
     */
    public NotificationTemplate getTemplate(String channel, String name)
    {
        String path = basePath + channel + "/"
                + name.toLowerCase()
                + ".mustache";
        
        return createTemplate(channel, path);
    }
    
    private NotificationTemplate createTemplate(String channel, String path)
    {
        try
        {
            NotificationTemplate template = new NotificationTemplate();
            template.setChannel(channel);
            template.setContent(getTemplateString(path));
            return template;
        } catch (IOException ex)
        {
            Logger.getLogger(TemplateFactory.class.getName()).log(Level.SEVERE, null, ex);
            return null;
        }
    }
    
    /**
     * Loads relative file locate in a jar.
     * 
     * Works only with jars: http://stackoverflow.com/questions/574809/load-a-resource-contained-in-a-jar
     * 
     * @param path
     * @return 
     */
    private String getTemplateString(String path) throws IOException
    {
        if (loadedTemplates.containsKey(path))
            return loadedTemplates.get(path);
        
        URL url = ClassLoader.getSystemResource(path);
        if (url == null)
        {
            throw new IllegalArgumentException("Cannot load template from " + path);
        }
        
        String template = Resources.toString(url, Charsets.UTF_8);
        loadedTemplates.put(path, template);
        return template;
    }
}