/*-
 * ============LICENSE_START=======================================================
 * SDC
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. 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.openecomp.sdc.common.impl;

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;
import org.openecomp.sdc.common.api.BasicConfiguration;
import org.openecomp.sdc.common.api.ConfigurationListener;
import org.openecomp.sdc.common.log.enums.EcompLoggerErrorCode;
import org.openecomp.sdc.common.log.wrappers.Logger;
import org.openecomp.sdc.common.util.YamlToObjectConverter;
import org.openecomp.sdc.exception.YamlConversionException;


public class ConfigFileChangeListener extends FileAlterationListenerAdaptor {

    private static final Logger LOGGER = Logger.getLogger(ConfigFileChangeListener.class.getName());
    private Map<String, List<ConfigurationListener>> fileChangeToCallBack = new HashMap<>();
    private Object lock = new Object();
    private YamlToObjectConverter yamlToObjectConverter = new YamlToObjectConverter();

    @Override
    public void onFileChange(File pFile) {
        if (pFile == null) {
            LOGGER.debug("Invalid file '{}'.", pFile);
            return;
        }
        if (fileChangeToCallBack == null) {
            LOGGER.debug("File '{}' callback is null.", pFile);
            return;
        }
        final String id = findIdFromFileName(pFile.getName());
        if (id == null) {
            LOGGER.warn(EcompLoggerErrorCode.UNKNOWN_ERROR, "", "", "Cannot calculate id from file {}", pFile.getName());
            return;
        }
        final List<ConfigurationListener> listeners = fileChangeToCallBack.get(id);
        if (CollectionUtils.isEmpty(listeners)) {
            LOGGER.debug("No file listeners for file '{}', id '{}'.", pFile, id);
            return;
        }
        for (final ConfigurationListener configurationListener : listeners) {
            final Class<? extends BasicConfiguration> configClass = configurationListener.getType();
            final BasicConfiguration basicConfiguration;
            try {
                basicConfiguration = yamlToObjectConverter.convert(pFile.getAbsolutePath(), configClass);
            } catch (final YamlConversionException e) {
                LOGGER.warn(EcompLoggerErrorCode.SCHEMA_ERROR, "Configuration", "Configuration",
                        "Cannot update the listeners for file Change since the file content is invalid: {}", e.getLocalizedMessage());
                continue;
            }
            LOGGER.debug("Loaded configuration after converting is {}", basicConfiguration);
            configurationListener.getCallBack().reconfigure(basicConfiguration);
        }
        LOGGER.debug("File {} was changed.", pFile);
    }

    private String findIdFromFileName(String name) {
        String result = null;
        if (name != null) {
            int startIndex = 0;
            int endIndex = name.length();
            if (name.contains(File.separator)) {
                startIndex = name.lastIndexOf(File.separator);
            }
            result = name.substring(startIndex, endIndex);
        }
        return result;
    }

    public void register(String id, ConfigurationListener configurationListener) {
        if (configurationListener != null) {
            synchronized (lock) {
                List<ConfigurationListener> callbacks = fileChangeToCallBack.get(id);
                if (callbacks == null) {
                    callbacks = new ArrayList<>();
                    fileChangeToCallBack.put(id, callbacks);
                }
                callbacks.add(configurationListener);
            }
        }
    }
}