/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.felix.hc.generalchecks;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;

import org.apache.felix.hc.annotation.HealthCheckService;
import org.apache.felix.hc.api.FormattingResultLog;
import org.apache.felix.hc.api.HealthCheck;
import org.apache.felix.hc.api.Result;
import org.apache.felix.hc.api.ResultLog.Entry;
import org.apache.felix.hc.generalchecks.scrutil.DsRootCauseAnalyzer;
import org.osgi.framework.BundleContext;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.ConfigurationPolicy;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.component.annotations.ReferencePolicyOption;
import org.osgi.service.component.runtime.ServiceComponentRuntime;
import org.osgi.service.component.runtime.dto.ComponentConfigurationDTO;
import org.osgi.service.component.runtime.dto.ComponentDescriptionDTO;
import org.osgi.service.metatype.annotations.AttributeDefinition;
import org.osgi.service.metatype.annotations.Designate;
import org.osgi.service.metatype.annotations.ObjectClassDefinition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component(configurationPolicy = ConfigurationPolicy.REQUIRE)
@HealthCheckService(name = DsComponentsCheck.HC_NAME, tags = { DsComponentsCheck.HC_DEFAULT_TAG })
@Designate(ocd = DsComponentsCheck.Config.class, factory = true)
public class DsComponentsCheck implements HealthCheck {

    private static final Logger LOG = LoggerFactory.getLogger(DsComponentsCheck.class);

    public static final String HC_NAME = "DS Components Ready Check";
    public static final String HC_DEFAULT_TAG = "systemalive";

    @ObjectClassDefinition(name = "Health Check: "
            + HC_NAME, description = "System ready check that checks a list of DS components and provides root cause analysis in case of errors")
    public @interface Config {

        @AttributeDefinition(name = "Name", description = "Name of this health check")
        String hc_name() default HC_NAME;

        @AttributeDefinition(name = "Tags", description = "List of tags for this health check, used to select subsets of health checks for execution e.g. by a composite health check.")
        String[] hc_tags() default { HC_DEFAULT_TAG };

        @AttributeDefinition(name = "Required Component Names", description = "The components that are required to be enabled")
        String[] components_list();

        @AttributeDefinition(name = "Status for missing component", description = "Status in case components are missing enabled components")
        Result.Status statusForMissing() default Result.Status.TEMPORARILY_UNAVAILABLE;

        @AttributeDefinition
        String webconsole_configurationFactory_nameHint() default "{hc.name}: {components.list} / missing -> {statusForMissing}";
    }

    private List<String> componentsList;
    private Result.Status statusForMissing;

    @Reference(policyOption = ReferencePolicyOption.GREEDY)
    private DsRootCauseAnalyzer analyzer;

    @Reference(policyOption = ReferencePolicyOption.GREEDY)
    ServiceComponentRuntime scr;

    @Activate
    public void activate(final BundleContext ctx, final Config config) throws InterruptedException {
        componentsList = Arrays.asList(config.components_list());
        statusForMissing = config.statusForMissing();
        LOG.debug("Activated DS Components HC for componentsList={}", componentsList);
    }

    @Override
    public Result execute() {
        FormattingResultLog log = new FormattingResultLog();

        Collection<ComponentDescriptionDTO> componentDescriptionDTOs = scr.getComponentDescriptionDTOs();
        List<ComponentDescriptionDTO> watchedComps = new LinkedList<ComponentDescriptionDTO>();
        List<String> missingComponents = new LinkedList<String>(componentsList);
        for (ComponentDescriptionDTO desc : componentDescriptionDTOs) {
            if (componentsList.contains(desc.name)) {
                watchedComps.add(desc);
                missingComponents.remove(desc.name);
            }
        }
        for (String missingComp : missingComponents) {
            log.info("No component with name {} is registered in SCR runtime", missingComp);
        }

        int countEnabled = 0;
        int countDisabled = 0;
        for (ComponentDescriptionDTO dsComp : watchedComps) {

            boolean isActive;

            boolean componentEnabled = scr.isComponentEnabled(dsComp);
            if (componentEnabled) {

                Collection<ComponentConfigurationDTO> componentConfigurationDTOs = scr.getComponentConfigurationDTOs(dsComp);
                List<String> idStateTuples = new ArrayList<>();
                boolean foundActiveOrSatisfiedConfig = false;
                for (ComponentConfigurationDTO configDto : componentConfigurationDTOs) {
                    idStateTuples.add("id " + configDto.id + ":" + toStateString(configDto.state));
                    if (configDto.state == ComponentConfigurationDTO.ACTIVE || configDto.state == ComponentConfigurationDTO.SATISFIED) {
                        foundActiveOrSatisfiedConfig = true;
                    }
                }
                log.debug(dsComp.name + " (" + String.join(",", idStateTuples) + ")");

                if (componentConfigurationDTOs.isEmpty() || foundActiveOrSatisfiedConfig) {
                    countEnabled++;
                    isActive = true;
                } else {
                    countDisabled++;
                    isActive = false;
                }

            } else {
                countDisabled++;
                isActive = false;
            }

            if (!isActive) {
                analyzer.logNotEnabledComponent(log, dsComp);
            }
        }

        if (!missingComponents.isEmpty()) {
            log.add(new Entry(statusForMissing, missingComponents.size() + " required components are missing in SCR runtime"));
        }
        if (countDisabled > 0) {
            log.add(new Entry(statusForMissing, countDisabled + " required components are not active"));
        }
        log.info("{} required components are active", countEnabled);

        return new Result(log);
    }

    static final String toStateString(int state) {

        final int FAILED_ACTIVATION = 16; // not yet available in r6, but dependency should be left on r6 for max compatibility

        switch (state) {
        case ComponentConfigurationDTO.ACTIVE:
            return "active";
        case ComponentConfigurationDTO.SATISFIED:
            return "satisfied";
        case ComponentConfigurationDTO.UNSATISFIED_CONFIGURATION:
            return "unsatisfied (configuration)";
        case ComponentConfigurationDTO.UNSATISFIED_REFERENCE:
            return "unsatisfied (reference)";
        case FAILED_ACTIVATION:
            return "failed activation";
        default:
            return String.valueOf(state);
        }
    }

}