/**
 *  Copyright 2005-2016 Red Hat, Inc.
 *
 *  Red Hat 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 io.fabric8.jaxb.dynamic.profile;

import java.io.File;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedSet;
import java.util.Timer;
import java.util.TimerTask;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicBoolean;

import com.google.common.base.Throwables;

import io.hawt.util.introspect.ClassLoaderProvider;
import io.hawt.introspect.Introspector;

import org.apache.aries.util.AriesFrameworkUtil;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.ConfigurationPolicy;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
import org.apache.felix.scr.annotations.Service;
import org.eclipse.jgit.api.Git;

import io.fabric8.common.util.Maps;
import io.fabric8.common.util.Strings;
import io.fabric8.api.Container;
import io.fabric8.api.Containers;
import io.fabric8.api.DataStore;
import io.fabric8.api.FabricService;
import io.fabric8.api.Profile;
import io.fabric8.api.ProfileRegistry;
import io.fabric8.api.Profiles;
import io.fabric8.api.scr.AbstractComponent;
import io.fabric8.git.GitService;
import io.fabric8.git.internal.GitHelpers;
import io.fabric8.jaxb.dynamic.CompileResults;
import io.fabric8.jaxb.dynamic.CompileResultsHandler;
import io.fabric8.jaxb.dynamic.DynamicCompiler;
import io.fabric8.jaxb.dynamic.DynamicXJC;

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

/**
 * Watches the {@link DataStore} for XSD files to recompile
 */
@Component(name = "io.fabric8.profile.jaxb.compiler", label = "Fabric8 Profile JAXB Compiler", policy = ConfigurationPolicy.OPTIONAL, immediate = true, metatype = true)
@Service({DynamicCompiler.class})
public class ProfileDynamicJaxbCompiler extends AbstractComponent implements DynamicCompiler {
    public static final String PROPERTY_SCHEMA_PATH = "schemaPath";

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

    private BundleContext bundleContext;

    @Reference(referenceInterface = FabricService.class)
    private FabricService fabricService;
    @Reference(referenceInterface = Introspector.class, cardinality = ReferenceCardinality.OPTIONAL_UNARY)
    private Introspector introspector;
    @Reference(referenceInterface = GitService.class)
    private GitService gitService;

    private String schemaPath;
    private Timer timer = new Timer();
    private AtomicBoolean startedFlag = new AtomicBoolean(false);

    private ExecutorService executorService = Executors.newFixedThreadPool(2);
    private final ConcurrentMap<String, PathChildrenCache> pathCacheMap = new ConcurrentHashMap<String, PathChildrenCache>();
    private long timerDelay = 1000;
    private CompileResults compileResults;
    private CompileResultsHandler handler;
    private Runnable changeRunnable = new Runnable() {
        @Override
        public void run() {
            asyncRecompile();
        }
    };
    private Introspector localIntrospector;

    public ProfileDynamicJaxbCompiler() {
    }

    @Activate
    void activate(BundleContext bundleContext, Map<String,String> configuration) {
        try {
            this.bundleContext = bundleContext;
            this.schemaPath = Maps.stringValue(configuration, PROPERTY_SCHEMA_PATH, "schemas");
            getDataStore().trackConfiguration(changeRunnable);

            if (introspector == null) {
                localIntrospector = new Introspector();
                localIntrospector.init();
                introspector = localIntrospector;
            }
            asyncRecompile();
        } catch (Exception e) {
            throw Throwables.propagate(e);
        }
        activateComponent();
    }

    @Deactivate
    void deactivate() throws Exception {
        getDataStore().untrackConfiguration(changeRunnable);
        executorService.shutdown();
        timer.cancel();
        if (localIntrospector != null) {
            localIntrospector.destroy();
        }
        deactivateComponent();
    }

    public void setHandler(CompileResultsHandler handler) throws Exception {
        this.handler = handler;
        // lets pass in the first set of results if we've compiled before the
        // handler is registered
        if (handler != null && compileResults != null) {
            handler.onCompileResults(compileResults);
        }
    }

    // Properties
    //-------------------------------------------------------------------------

    /**
     * Returns the latest XJC compiler results
     */
    public CompileResults getCompileResults() {
        return compileResults;
    }

    public FabricService getFabricService() {
        return fabricService;
    }

    public DataStore getDataStore() {
        return getFabricService().adapt(DataStore.class);
    }

    public BundleContext getBundleContext() {
        return bundleContext;
    }

    public void setBundleContext(BundleContext bundleContext) {
        this.bundleContext = bundleContext;
    }

    public String getSchemaPath() {
        return schemaPath;
    }

    public void setSchemaPath(String schemaPath) {
        this.schemaPath = schemaPath;
    }

    public Timer getTimer() {
        return timer;
    }

    public void setTimer(Timer timer) {
        this.timer = timer;
    }

    public long getTimerDelay() {
        return timerDelay;
    }

    public void setTimerDelay(long timerDelay) {
        this.timerDelay = timerDelay;
    }

    // Implementation
    //-------------------------------------------------------------------------

    protected void asyncRecompile() {
        if (startedFlag.compareAndSet(false, true)) {
            timer.schedule(new RecompileTask(), timerDelay);
        }
    }


    private class RecompileTask extends TimerTask {
        @Override
        public void run() {
            recompile();
        }
    }

    protected void recompile() {
        LOG.debug("Looking for XSDs to recompile");

        Set<String> urls = new TreeSet<String>();
        FabricService fabric = getFabricService();
        Container container = fabric.getCurrentContainer();
        String versionId = container.getVersion().getId();
        List<String> profileIds = Containers.overlayProfiles(container);
        Collection<String> names = listFiles(versionId, profileIds, schemaPath);
        for (String name : names) {
            if (name.endsWith(".xsd")) {
                String prefix = schemaPath;
                if (Strings.isNotBlank(prefix)) {
                    prefix += "/";
                }
                urls.add("profile:" + prefix + name);
            }
        }

        LOG.info("Recompiling XSDs at URLs: " + urls);
        startedFlag.set(false);

        ClassLoader classLoader = AriesFrameworkUtil.getClassLoader(bundleContext.getBundle());
        if (classLoader == null) {
            classLoader = getClass().getClassLoader();
        }
        DynamicXJC xjc = new DynamicXJC(classLoader);
        xjc.setSchemaUrls(new ArrayList<String>(urls));
        compileResults = xjc.compileSchemas();
        if (handler != null) {
            handler.onCompileResults(compileResults);
        }
        if (introspector != null) {
            introspector.setClassLoaderProvider("dynamic.jaxb", new ClassLoaderProvider() {
                @Override
                public ClassLoader getClassLoader() {
                    return compileResults.getClassLoader();
                }
            });
        }
    }

    private Collection<String> listFiles(final String versionId, final Iterable<String> profileIds, final String path) {
        assertValid();
        Git git = gitService.getGit();
        ProfileRegistry profileRegistry = getFabricService().adapt(ProfileRegistry.class);
        SortedSet<String> answer = new TreeSet<String>();
        for (String profileId : profileIds) {
            profileRegistry.getRequiredProfile(versionId, profileId);
            File profileDirectory = GitHelpers.getProfileDirectory(git, profileId);
            File file = Strings.isNotBlank(path) ? new File(profileDirectory, path) : profileDirectory;
            if (file.exists()) {
                String[] values = file.list();
                if (values != null) {
                    for (String value : values) {
                        answer.add(value);
                    }
                }
            }
        }
        return Collections.unmodifiableSet(answer);
    }
}
