TransformerManager.java

/**
 * Copyright (c) Codice Foundation
 * <p>
 * This is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser
 * General Public License as published by the Free Software Foundation, either version 3 of the
 * License, or any later version.
 * <p>
 * This program 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. A copy of the GNU Lesser General Public License
 * is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 */
package org.codice.ddf.spatial.ogc.csw.catalog.common.transformer;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.osgi.framework.BundleContext;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.ServiceReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Maintains a list of available Transformers and their properties.
 */
public class TransformerManager {

    private static final Logger LOGGER = LoggerFactory.getLogger(TransformerManager.class);

    public static final String MIME_TYPE = "mime-type";

    public static final String SCHEMA = "schema";

    public static final String ID = "id";

    private final List<ServiceReference> serviceRefs;

    public TransformerManager(List<ServiceReference> serviceReferences) {
        this.serviceRefs = serviceReferences;
    }

    public List<String> getAvailableMimeTypes() {
        return getAvailableProperty(MIME_TYPE);
    }

    public List<String> getAvailableSchemas() {
        return getAvailableProperty(SCHEMA);
    }

    public List<String> getAvailableIds() {
        return getAvailableProperty(ID);
    }

    public String getTransformerIdForSchema(String schema) {

        List<Map<String, Object>> properties = getRelatedTransformerProperties(SCHEMA, schema);
        if (properties.size() > 0) {
            return (String) properties.get(0)
                    .get(ID);
        }
        return "";
    }

    public String getTransformerSchemaForId(String id) {
        List<Map<String, Object>> properties = getRelatedTransformerProperties(ID, id);
        if (properties.size() > 0) {
            return (String) properties.get(0)
                    .get(SCHEMA);
        }
        return "";
    }

    public List<String> getAvailableProperty(String propertyName) {
        List<String> properties = new ArrayList<String>();

        for (ServiceReference serviceRef : serviceRefs) {
            Object mimeObject = serviceRef.getProperty(propertyName);
            if (mimeObject != null && mimeObject instanceof String) {
                properties.add((String) mimeObject);
            }
        }
        return properties;
    }

    public <T> T getTransformerBySchema(String schema) {
        return getTransformerByProperty(SCHEMA, schema);
    }

    public <T> T getTransformerByMimeType(String mimeType) {
        return getTransformerByProperty(MIME_TYPE, mimeType);
    }

    public <T> T getTransformerById(String id) {
        return getTransformerByProperty(ID, id);
    }

    public <T> T getTransformerByProperty(String property, String value) {
        if (value == null) {
            return null;
        }
        LOGGER.trace("Looking up transformer for property: {} == value: {}", property, value);
        for (ServiceReference serviceRef : serviceRefs) {
            Object propertyObject = serviceRef.getProperty(property);
            if (propertyObject != null && propertyObject instanceof String) {
                if (value.equals((String) propertyObject)) {
                    LOGGER.trace("Found transformer for property: {} == value: {}",
                            property,
                            value);
                    T serviceObject = (T) getBundleContext().getService(serviceRef);
                    LOGGER.trace("Transformer is {}", serviceObject);
                    return serviceObject;
                }
            }
        }
        LOGGER.debug("Did not find transformer for property: {} == value: {}", property, value);
        return null;
    }

    /**
     * Returns a list of property maps for transformers that match the given property and value
     *
     * @param property The transformer property name
     * @param value    The value of the transformer property to match
     * @return List of property maps for the matching transformers
     */
    public List<Map<String, Object>> getRelatedTransformerProperties(String property,
            String value) {
        List<Map<String, Object>> properties = new ArrayList<>();
        for (ServiceReference serviceRef : serviceRefs) {
            Object propertyObject = serviceRef.getProperty(property);
            if (value.equals(propertyObject)) {
                Map<String, Object> map = new HashMap<>();
                for (String key : serviceRef.getPropertyKeys()) {
                    map.put(key, serviceRef.getProperty(key));
                }
                properties.add(map);
            }

        }
        return properties;
    }

    protected BundleContext getBundleContext() {
        return FrameworkUtil.getBundle(this.getClass())
                .getBundleContext();
    }
}