/*
 * dCache - http://www.dcache.org/
 *
 * Copyright (C) 2016 Deutsches Elektronen-Synchrotron
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.dcache.pool.repository.meta.db;

import com.sleepycat.collections.StoredMap;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.EnvironmentConfig;
import com.sleepycat.je.EnvironmentFailureException;
import com.sleepycat.je.Transaction;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Map;
import java.util.Properties;

import diskCacheV111.util.CacheException;
import diskCacheV111.util.PnfsId;
import diskCacheV111.vehicles.StorageInfo;

import dmg.cells.nucleus.EnvironmentAware;

import org.dcache.pool.movers.IoMode;
import org.dcache.pool.repository.ReplicaStore;
import org.dcache.pool.repository.RepositoryChannel;
import org.dcache.util.ConfigurationMapFactoryBean;

/**
 * Base class for BerkeleyDB backed ReplicaStore implementations.
 *
 * The database is stored in a subdirectory of the pool directory
 * called 'meta'.
 *
 * The cache repository entries generated by this store fetch storage
 * info from the database on demand.
 */
public abstract class AbstractBerkeleyDBReplicaStore implements ReplicaStore, EnvironmentAware
{
    protected static final Logger LOGGER =
        LoggerFactory.getLogger(AbstractBerkeleyDBReplicaStore.class);
    protected static final String DIRECTORY_NAME = "meta";

    protected final boolean readOnly;

    /**
     * Berkeley DB configuration properties.
     */
    private final Properties properties = new Properties();

    /**
     * Directory containing the database.
     */
    protected final Path dir;

    /**
     * The BerkeleyDB database to use.
     */
    private ReplicaStoreDatabase database;

    /**
     * The BerkeleyDB database to use.
     */
    protected ReplicaStoreView views;


    public AbstractBerkeleyDBReplicaStore(Path directory, boolean readOnly) throws IOException
    {
        this.readOnly = readOnly;
        dir = directory.resolve(DIRECTORY_NAME);

        if (!Files.exists(dir)) {
            Files.createDirectory(dir);
        } else if (!Files.isDirectory(dir)) {
            throw new FileNotFoundException("No such directory: " + dir);
        }
    }

    @Override
    public void setEnvironment(Map<String, Object> environment)
    {
        ConfigurationMapFactoryBean factory = new ConfigurationMapFactoryBean();
        factory.setEnvironment(environment);
        factory.setPrefix("pool.plugins.meta.db");
        factory.buildMap();
        properties.clear();
        properties.putAll(factory.getObject());
    }

    @Override
    public void init() throws CacheException
    {
        try {
            database = new ReplicaStoreDatabase(properties, dir.toFile(), readOnly);
            views = new ReplicaStoreView(database);
        } catch (EnvironmentFailureException e) {
            throw new CacheException(CacheException.PANIC, "Failed to open Berkeley DB database. When upgrading to " +
                                                           "dCache 2.6, it may be necessary to run the /usr/sbin/dcache-pool-meta-preupgrade utility " +
                                                           "before starting the pool. If that does not resolve the problem, you should contact " +
                                                           "support@dcache.org", e);
        }
    }

    /**
     * Returns a database backed map of all StorageInfo objects.
     */
    StoredMap<String,StorageInfo> getStorageInfoMap()
    {
        return views.getStorageInfoMap();
    }

    /**
     * Returns a database backed map of all state objects.
     */
    StoredMap<String,CacheRepositoryEntryState> getStateMap()
    {
        return views.getStateMap();
    }

    /** Closes the database. */
    @Override
    public void close()
    {
        try {
            database.close();
        } catch (DatabaseException e) {
            LOGGER.error("Ignored: Could not close database: " + e.getMessage());
        }
    }

    @Override
    public synchronized boolean isOk()
    {
        Path tmp = dir.resolve(".repository_is_ok");
        try {
            Files.deleteIfExists(tmp);
            Files.createFile(tmp);

            if (database.isFailed()) {
                return false;
            }

            return true;
        } catch (IOException e) {
            LOGGER.error("Failed to touch " + tmp + ": " + e.getMessage());
            return false;
        }
    }

    public boolean isValid()
    {
        return database.getEnvironment().isValid();
    }

    public EnvironmentConfig getConfig()
    {
        return database.getEnvironment().getConfig();
    }

    public Transaction beginTransaction()
    {
        return database.getEnvironment().beginTransaction(null, null);
    }

    public abstract void setLastModifiedTime(PnfsId pnfsId, long time) throws IOException;

    public abstract long getFileSize(PnfsId pnfsId) throws IOException;

    public abstract URI getUri(PnfsId pnfsId);

    public abstract RepositoryChannel openChannel(PnfsId pnfsId, IoMode mode) throws IOException;
}