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/*
	Milyn - Copyright (C) 2006 - 2010

	This library is free software; you can redistribute it and/or
	modify it under the terms of the GNU Lesser General Public
	License (version 2.1) as published by the Free Software
	Foundation.

	This library is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

	See the GNU Lesser General Public License for more details:
	http://www.gnu.org/licenses/lgpl.txt
*/
package org.milyn.util;

import freemarker.cache.ClassTemplateLoader;
import freemarker.cache.FileTemplateLoader;
import freemarker.cache.MultiTemplateLoader;
import freemarker.cache.TemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import org.milyn.SmooksException;
import org.milyn.assertion.AssertArgument;

import java.io.*;

/**
 *  FreeMarker template.
 *
 * @author [email protected]
*/
public class FreeMarkerTemplate {

    public static final String DEFAULT_MACHINE_READABLE_NUMBER_FORMAT = "#.##########";
    
    private String templateText;
    private Template template;

    public FreeMarkerTemplate(String templateText) {
        this(templateText, createDefaultConfiguration());
    }

    public FreeMarkerTemplate(String templateText, Configuration config) {
        AssertArgument.isNotNullAndNotEmpty(templateText, "templateText");
        this.templateText = templateText;
        Reader templateReader = new StringReader(templateText);

        try {
            try {
                template = new Template("free-marker-template", templateReader, config);
            } finally {
                templateReader.close();
            }
        } catch (IOException e) {
            throw new IllegalStateException("Exception creating FreeMarker Template instance for template:\n\n[" + templateText + "]\n\n", e);
        }
    }

    public FreeMarkerTemplate(String templatePath, Class basePath) {
        this(templatePath, basePath, createDefaultConfiguration());        
    }

    public FreeMarkerTemplate(String templatePath, Class basePath, Configuration config) {
        AssertArgument.isNotNullAndNotEmpty(templatePath, "templatePath");
        this.templateText = templatePath;

        try {
            if(basePath != null) {
                config.setClassForTemplateLoading(basePath, "");
            }
            template = config.getTemplate(templatePath);
        } catch (IOException e) {
            throw new IllegalStateException("Unexpected IOException.", e);
        }
    }

    public String getTemplateText() {
        return templateText;
    }

    public String apply(Object contextObject) {
        StringWriter outputWriter = new StringWriter();
        apply(contextObject, outputWriter);
        return outputWriter.toString();
    }

    public void apply(Object contextObject, Writer outputWriter) {
        try {
            template.process(contextObject, outputWriter);
        } catch (TemplateException e) {
            throw new SmooksException("Failed to apply template.", e);
        } catch (IOException e) {
            throw new IllegalStateException("Unexpected IOException.", e);
        }
    }

    private static Configuration createDefaultConfiguration() {
        Configuration config = new Configuration();
        config.setNumberFormat(DEFAULT_MACHINE_READABLE_NUMBER_FORMAT);
        return config;
    }
}