/**
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2019 AT&T Intellectual Property. All rights reserved.
 * Copyright © 2019 Amdocs
 * ================================================================================
 * 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.aai.schemaif.oxm;

import com.google.common.collect.Multimap;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Arrays;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

import org.apache.commons.io.IOUtils;
import org.onap.aai.cl.api.Logger;
import org.onap.aai.cl.eelf.LoggerFactory;
import org.onap.aai.edges.EdgeIngestor;
import org.onap.aai.edges.EdgeRule;
import org.onap.aai.edges.exceptions.EdgeRuleNotFoundException;
import org.onap.aai.schemaif.SchemaProviderException;
import org.onap.aai.schemaif.SchemaProviderMsgs;
import org.onap.aai.setup.SchemaVersion;
import org.onap.aai.setup.Translator;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class OxmEdgeRulesLoader {

    private static Translator translator;
    private static EdgeIngestor edgeIngestor;

    private static EdgePropsConfiguration edgePropsConfiguration;

    private static Map<String, RelationshipSchema> versionContextMap = new ConcurrentHashMap<>();

    static final Pattern versionPattern = Pattern.compile("(?i)v(\\d*)");
    static final String propsPrefix = "edge_properties_";
    static final String propsSuffix = ".json";
    final static Pattern propsFilePattern = Pattern.compile(propsPrefix + "(.*)" + propsSuffix);
    final static Pattern propsVersionPattern = Pattern.compile("(?i)v\\d*");

    private static Logger logger = LoggerFactory.getInstance().getLogger(OxmEdgeRulesLoader.class.getName());

    private OxmEdgeRulesLoader() {
    }

    /**
     * This constructor presents an awkward marrying of Spring bean creation and static method use. This
     * is technical debt that will need fixing.
     *
     * @param translator contains schema versions configuration
     * @param edgeIngestor provides edge rules
     * @param edgePropsConfiguration edge property validation configuration
     */
    @Autowired
    public OxmEdgeRulesLoader(Translator translator, EdgeIngestor edgeIngestor,
            EdgePropsConfiguration edgePropsConfiguration) {
        OxmEdgeRulesLoader.translator = translator;
        OxmEdgeRulesLoader.edgeIngestor = edgeIngestor;
        OxmEdgeRulesLoader.edgePropsConfiguration = edgePropsConfiguration;
    }

    /**
     * Finds all DB Edge Rules and Edge Properties files for all OXM models.
     *
     * @throws SchemaProviderException
     * @throws SchemaProviderException
     */
    public static synchronized void loadModels() throws SchemaProviderException {
        Map<String, File> propFiles = edgePropertyFiles(edgePropsConfiguration);

        if (logger.isDebugEnabled()) {
            logger.debug("Loading DB Edge Rules");
        }

        for (String version : OxmSchemaLoader.getLoadedOXMVersions()) {
            try {
                SchemaVersion schemaVersion = translator.getSchemaVersions().getVersions().stream()
                        .filter(s -> s.toString().equalsIgnoreCase(version)).findAny().orElse(null);
                loadModel(schemaVersion, edgeIngestor, propFiles);
            } catch (IOException | EdgeRuleNotFoundException e) {
                throw new SchemaProviderException(e.getMessage(), e);
            }
        }
    }

    /**
     * Loads DB Edge Rules and Edge Properties for a given version.
     *
     * @throws SchemaProviderException
     */

    public static synchronized void loadModels(String v) throws SchemaProviderException {
        Map<String, File> propFiles = edgePropertyFiles(edgePropsConfiguration);

        if (logger.isDebugEnabled()) {
            logger.debug("Loading DB Edge Rules ");
        }

        try {
            SchemaVersion schemaVersion = translator.getSchemaVersions().getVersions().stream()
                    .filter(s -> s.toString().equalsIgnoreCase(v)).findAny().orElse(null);

            loadModel(schemaVersion, edgeIngestor, propFiles);
        } catch (IOException | EdgeRuleNotFoundException e) {
            throw new SchemaProviderException(e.getMessage());
        }
    }

    /**
     * Retrieves the DB Edge Rule relationship schema for a given version.
     *
     * @param version - The OXM version that we want the DB Edge Rule for.
     * @return - A RelationshipSchema of the DB Edge Rule for the OXM version.
     * @throws SchemaProviderException
     */
    public static RelationshipSchema getSchemaForVersion(String version) throws SchemaProviderException {

        // If we haven't already loaded in the available OXM models, then do so now.
        if (versionContextMap == null || versionContextMap.isEmpty()) {
            loadModels();
        } else if (!versionContextMap.containsKey(version)) {
            logger.error(SchemaProviderMsgs.SCHEMA_LOAD_ERROR, "Error loading DB Edge Rules for: " + version);
            throw new SchemaProviderException("Error loading DB Edge Rules for: " + version);
        }

        return versionContextMap.get(version);
    }

    /**
     * Retrieves the DB Edge Rule relationship schema for all loaded OXM versions.
     *
     * @return - A Map of the OXM version and it's corresponding RelationshipSchema of the DB Edge Rule.
     * @throws SchemaProviderException
     */
    public static Map<String, RelationshipSchema> getSchemas() throws SchemaProviderException {

        // If we haven't already loaded in the available OXM models, then do so now.
        if (versionContextMap == null || versionContextMap.isEmpty()) {
            loadModels();
        }
        return versionContextMap;
    }

    /**
     * Returns the latest available DB Edge Rule version.
     *
     * @return - A Map of the OXM version and it's corresponding RelationshipSchema of the DB Edge Rule.
     * @throws SchemaProviderException
     */
    public static String getLatestSchemaVersion() throws SchemaProviderException {

        // If we haven't already loaded in the available OXM models, then do so now.
        if (versionContextMap == null || versionContextMap.isEmpty()) {
            loadModels();
        }

        // If there are still no models available, then there's not much we can do...
        if (versionContextMap.isEmpty()) {
            logger.error(SchemaProviderMsgs.SCHEMA_LOAD_ERROR, "No available DB Edge Rules to get latest version for.");
            throw new SchemaProviderException("No available DB Edge Rules to get latest version for.");
        }

        // Iterate over the available model versions to determine which is the most
        // recent.
        Integer latestVersion = null;
        String latestVersionStr = null;
        for (String versionKey : versionContextMap.keySet()) {

            Matcher matcher = versionPattern.matcher(versionKey);
            if (matcher.find()) {

                int currentVersion = Integer.parseInt(matcher.group(1));

                if ((latestVersion == null) || (currentVersion > latestVersion)) {
                    latestVersion = currentVersion;
                    latestVersionStr = versionKey;
                }
            }
        }

        return latestVersionStr;
    }

    /**
     * Reset the loaded DB Edge Rule schemas
     *
     */
    public static void resetSchemaVersionContext() {
        versionContextMap = new ConcurrentHashMap<>();
    }

    private static synchronized void loadModel(SchemaVersion version, EdgeIngestor edgeIngestor,
            Map<String, File> props) throws IOException, SchemaProviderException, EdgeRuleNotFoundException {

        Multimap<String, EdgeRule> edges = edgeIngestor.getAllRules(version);
        String edgeProps;
        if (props.get(version.toString().toLowerCase()) != null) {
            edgeProps = IOUtils.toString(new FileInputStream(props.get(version.toString().toLowerCase())), "UTF-8");
        } else {
            throw new FileNotFoundException("The Edge Properties file for OXM version " + version + "was not found.");
        }
        if (edges != null) {
            RelationshipSchema rs = new RelationshipSchema(edges, edgeProps);
            versionContextMap.put(version.toString().toLowerCase(), rs);
            logger.info(SchemaProviderMsgs.LOADED_DB_RULE_FILE, version.toString());
        }
    }

    private static Map<String, File> edgePropertyFiles(EdgePropsConfiguration edgePropsConfiguration)
            throws SchemaProviderException {
        Map<String, File> propsFiles = Arrays
                .stream(new File(edgePropsConfiguration.getEdgePropsDir())
                        .listFiles((d, name) -> propsFilePattern.matcher(name).matches()))
                .collect(Collectors.toMap(new Function<File, String>() {
                    @Override
                    public String apply(File f) {
                        Matcher m1 = propsVersionPattern.matcher(f.getName());
                        m1.find();
                        return m1.group(0);
                    }
                }, f -> f));
        return propsFiles;
    }
}