package org.sleuthkit.autopsy.imagegallery.datamodel;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import java.util.Collections;
import java.util.Set;
import java.util.logging.Level;
import org.sleuthkit.autopsy.coreutils.Logger;
import org.sleuthkit.datamodel.TskCoreException;

/**
 * Manages a cache of hashset hits as a map from fileID to hashset names.
 * Initial/invalid values are loaded from the backing DrawableDB
 */
public class HashSetManager {

    /**
     * The db that initial values are loaded from.
     */
    private DrawableDB db = null;

    /**
     * the internal cache from fileID to a set of hashset names.
     */
    private final LoadingCache<Long, Set<String>> hashSetCache = CacheBuilder.newBuilder().build(CacheLoader.from(this::getHashSetsForFileHelper));

    /**
     * assign the given db to back this hashset manager.
     *
     * @param db
     */
    public void setDb(DrawableDB db) {
        this.db = db;
        hashSetCache.invalidateAll();
    }

    /**
     * helper method to load hashset hits for the given fileID from the db
     *
     * @param fileID
     *
     * @return the names of the hashsets the given fileID is in
     */
    private Set<String> getHashSetsForFileHelper(long fileID) {
        try {
            return db.getHashSetsForFile(fileID);
        } catch (TskCoreException ex) {
            Logger.getLogger(HashSetManager.class.getName()).log(Level.SEVERE, "Failed to get Hash Sets for file", ex); //NON-NLS
            return Collections.emptySet();
        }
    }

    /**
     * is the given fileID in any hashset
     *
     * @param fileID
     *
     * @return true if the file is in any hashset
     */
    public boolean isInAnyHashSet(long fileID) {
        return getHashSetsForFile(fileID).isEmpty() == false;
    }

    /**
     * get the names of the hash sets the given fileId is in
     *
     * @param fileID
     *
     * @return a set containging the names of the hash sets for the given file
     */
    public Set<String> getHashSetsForFile(long fileID) {
        return hashSetCache.getUnchecked(fileID);
    }

    /**
     * invalidate the cached hashset names for the given fileID
     *
     * @param fileID the fileID to invalidate in the cache
     */
    public void invalidateHashSetsForFile(long fileID) {
        hashSetCache.invalidate(fileID);
    }
}