/**
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2017-2018 AT&T Intellectual Property.
 * Copyright © 2017-2018 Amdocs
 * All rights reserved.
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.aaiutils.oxm;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.xml.bind.JAXBException;

import org.eclipse.persistence.jaxb.JAXBContextProperties;
import org.eclipse.persistence.jaxb.dynamic.DynamicJAXBContext;
import org.eclipse.persistence.jaxb.dynamic.DynamicJAXBContextFactory;
import org.onap.aai.cl.api.Logger;
import org.onap.aai.cl.eelf.LoggerFactory;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;

public class OxmModelLoader {

    private static final Pattern AAI_OXM_FILE_PATTERN = Pattern.compile("aai_oxm_(.*).xml");
    private static Map<String, DynamicJAXBContext> versionContextMap = new ConcurrentHashMap<>();
    private static final Logger LOGGER = LoggerFactory.getInstance().getLogger(OxmModelLoader.class.getName());

    public synchronized static void loadModels() throws Exception {
        OxmModelLoader.loadModels("classpath*:/oxm/aai_oxm*.xml", AAI_OXM_FILE_PATTERN);
    }

    synchronized static void loadModels(String oxmResourcesPattern, Pattern aai_oxm_file_pattern) throws Exception {
        Resource[] resources = getResources(oxmResourcesPattern);

        for (Resource resource : resources) {
            Matcher matcher = aai_oxm_file_pattern.matcher(resource.getFilename());

            if (matcher.matches()) {
                try {
                    OxmModelLoader.loadModel(matcher.group(1), resource);
                } catch (Exception e) {
                    LOGGER.error(OxmModelLoaderMsgs.OXM_LOAD_ERROR,
                            "Failed to load " + resource.getFilename() + ": " + e.getMessage());
                    throw new Exception("Failed to load schema");
                }
            }
        }
    }

    private static Resource[] getResources(String oxmResourcesPattern) throws Exception {
        ClassLoader cl = OxmModelLoader.class.getClassLoader();
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver(cl);

        Resource[] resources = resolver.getResources(oxmResourcesPattern);
        if (resources.length == 0) {
            LOGGER.error(OxmModelLoaderMsgs.OXM_LOAD_ERROR, "No OXM schema files found on classpath");
            throw new Exception("Failed to load schema");
        }
        return resources;

    }

    public static DynamicJAXBContext getContextForVersion(String version) throws Exception {
        if (versionContextMap == null || versionContextMap.isEmpty()) {
            loadModels();
        } else if (!versionContextMap.containsKey(version)) {
            String filename = OxmModelLoaderConstants.AaiUtils_HOME_MODEL + "aai_oxm_" + version + ".xml";
            try {
                loadModel(version, new File(filename));
            } catch (Exception e) {
                throw new FileNotFoundException(filename);
            }
        }

        return versionContextMap.get(version);
    }

    public static Map<String, DynamicJAXBContext> getVersionContextMap() {
        return Collections.unmodifiableMap(versionContextMap);
    }

    public static void setVersionContextMap(Map<String, DynamicJAXBContext> versionContextMap) {
        OxmModelLoader.versionContextMap = versionContextMap;
    }

    private synchronized static void loadModel(String version, File file) throws JAXBException, IOException {
        InputStream inputStream = new FileInputStream(file);
        loadModel(version, file.getName(), inputStream);
    }

    private synchronized static void loadModel(String version, Resource resource) throws JAXBException, IOException {
        InputStream inputStream = resource.getInputStream();
        loadModel(version, resource.getFilename(), inputStream);
    }

    private synchronized static void loadModel(String version, String resourceName, InputStream inputStream)
            throws JAXBException, IOException {

        Map<String, Object> properties = new HashMap<>();
        properties.put(JAXBContextProperties.OXM_METADATA_SOURCE, inputStream);

        final DynamicJAXBContext jaxbContext = DynamicJAXBContextFactory
                .createContextFromOXM(Thread.currentThread().getContextClassLoader(), properties);

        versionContextMap.put(version, jaxbContext);

        LOGGER.info(OxmModelLoaderMsgs.LOADED_OXM_FILE, resourceName);
    }

}