com.opsmatters.newrelic.batch.renderers.OutputFileRenderer Maven / Gradle / Ivy

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/*
 * Copyright 2018 Gerald Curley
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.opsmatters.newrelic.batch.renderers;

import java.io.IOException;
import java.util.List;
import java.util.ArrayList;
import java.util.logging.Logger;
import com.opsmatters.core.documents.OutputFileWriter;
import com.opsmatters.newrelic.api.model.NamedResource;
import com.opsmatters.newrelic.batch.templates.FileTemplate;
import com.opsmatters.newrelic.batch.templates.TemplateFactory;

/**
 * The base class for all output file renderers.
 * 
 * @author Gerald Curley (opsmatters)
 */
public abstract class OutputFileRenderer
{
    private static final Logger logger = Logger.getLogger(OutputFileRenderer.class.getName());

    /**
     * Writes the given items to a writer.
     * @param items The items to be serialized
     * @param writer The writer to use to serialize the items
     * @throws IOException if there was an error writing the items
     */
    public void render(List items, OutputFileWriter writer) throws IOException
    {
        List lines = new ArrayList();
        FileTemplate template = TemplateFactory.getTemplate(getClass());
        String[] headers = template.getOutputHeaders();
        lines.add(headers);
        for(T item : items)
            lines.add(serialize(template, item));

        logger.fine("Rendering "+template.getType()+" file: headers="+headers.length+" lines="+lines.size());
        writer.write(lines);
    }

    /**
     * Serializes the item to a line.
     * 
     * Implemented by super-class.
     * 
     * @param template The template with the columns
     * @param item The item to be serialized
     * @return The line representing the item
     */
    protected String[] serialize(FileTemplate template, T item)
    {
        return null;
    }

    /**
     * Converts the given list of items to a comma-separated list of names.
     * @param items The list of items to be serialized
     * @return The comma-separated string representing the names of the items
     */
    protected String fromItemList(List items)
    {
        StringBuilder sb = new StringBuilder();
        for(NamedResource item : items)
        {
            if(sb.length() > 0)
                sb.append(",");
            sb.append(item.getName());
        }
        return sb.toString();
    }
}