com.meltmedia.cadmium.core.meta.AlternateContentConfigProcessor.java Source code

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Here is the source code for com.meltmedia.cadmium.core.meta.AlternateContentConfigProcessor.java

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/**
 *    Copyright 2012 meltmedia
 *
 *    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.meltmedia.cadmium.core.meta;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import com.meltmedia.cadmium.core.FileSystemManager;
import org.apache.commons.io.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.inject.Singleton;
import java.io.File;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.regex.Pattern;

/**
 * Parses the <em>alternate-content.json</em> file.
 *
 * @author John McEntire
 */
@Singleton
public class AlternateContentConfigProcessor implements ConfigProcessor {
    public static final String CONFIG_FILE_NAME = "alternate-content.json";
    private final Logger logger = LoggerFactory.getLogger(getClass());
    protected Configuration stagedConfig;
    protected Configuration liveConfig;

    @Override
    public void processFromDirectory(String metaDir) throws Exception {
        Configuration newStagedConfig = new Configuration();
        if (metaDir != null) {
            String configFile = FileSystemManager.getFileIfCanRead(metaDir, CONFIG_FILE_NAME);
            if (configFile != null) {
                newStagedConfig.metaDir = new File(metaDir);
                String contents = FileUtils.readFileToString(new File(configFile));
                logger.debug("Parsing {}/{}", new Object[] { newStagedConfig.metaDir, CONFIG_FILE_NAME });
                Collection<AlternateContent> parsedConfigs = new Gson().fromJson(contents,
                        new TypeToken<Collection<AlternateContent>>() {
                        }.getType());
                for (AlternateContent config : parsedConfigs) {
                    config.compiledPattern = Pattern.compile(config.getPattern());
                    newStagedConfig.configs.add(config);
                }
            }
        }
        stagedConfig = newStagedConfig;
    }

    @Override
    public void makeLive() {
        logger.trace("Promoting {} staged alternate content configurations.", stagedConfig.configs.size());
        liveConfig = stagedConfig;
    }

    /**
     * Iterates through AlternateContent objects trying to match against their pre compiled pattern.
     *
     * @param userAgent The userAgent request header.
     * @return the ContentDirectory of the matched AlternateContent instance or null if none are found.
     */
    public File getAlternateContentDirectory(String userAgent) {
        Configuration config = liveConfig;
        for (AlternateContent configuration : config.configs) {
            try {
                if (configuration.compiledPattern.matcher(userAgent).matches()) {
                    return new File(config.metaDir, configuration.getContentDirectory());
                }
            } catch (Exception e) {
                logger.warn("Failed to process config: " + configuration.getPattern() + "->"
                        + configuration.getContentDirectory(), e);
            }
        }
        return null;
    }

    public boolean hasConfig() {
        return liveConfig != null && liveConfig.configs.size() > 0;
    }

    private class Configuration {
        List<AlternateContent> configs = new ArrayList<AlternateContent>();
        File metaDir;
    }
}