package cgeo.geocaching;

import cgeo.geocaching.DataStore.StorageLocation;
import cgeo.geocaching.connector.gc.Tile;
import cgeo.geocaching.enumerations.CacheType;
import cgeo.geocaching.geopoint.Viewport;
import cgeo.geocaching.utils.LeastRecentlyUsedMap;
import cgeo.geocaching.utils.LeastRecentlyUsedMap.RemoveHandler;
import cgeo.geocaching.utils.Log;

import org.apache.commons.lang3.StringUtils;

import java.util.HashSet;
import java.util.Set;

/**
 * Cache for Caches. Every cache is stored in memory while c:geo is active to
 * speed up the app and to minimize network request - which are slow.
 */
public class CacheCache {

    private static final int MAX_CACHED_CACHES = 1000;
    final private LeastRecentlyUsedMap<String, Geocache> cachesCache;

    public CacheCache() {
        cachesCache = new LeastRecentlyUsedMap.LruCache<>(MAX_CACHED_CACHES);
        cachesCache.setRemoveHandler(new CacheRemoveHandler());
    }

    public synchronized void removeAllFromCache() {
        cachesCache.clear();
    }

    /**
     * @param geocode
     *            Geocode of the cache to remove from the cache
     */
    public void removeCacheFromCache(final String geocode) {
        if (StringUtils.isBlank(geocode)) {
            throw new IllegalArgumentException("geocode must not be empty");
        }
        synchronized(this) {
            cachesCache.remove(geocode);
        }
    }

    /**
     * "Store" a cache in the CacheCache. If the cache is already in the CacheCache the cache gets replaced.
     *
     * @param cache
     *            Cache
     *
     */
    public void putCacheInCache(final Geocache cache) {
        if (cache == null) {
            throw new IllegalArgumentException("cache must not be null");
        }
        if (StringUtils.isBlank(cache.getGeocode())) {
            throw new IllegalArgumentException("geocode must not be empty");
        }
        synchronized(this) {
            cache.addStorageLocation(StorageLocation.CACHE);
            cachesCache.put(cache.getGeocode(), cache);
        }
    }

    /**
     * @param geocode
     *            Geocode of the cache to retrieve from the cache
     * @return cache if found, null else
     */
    public Geocache getCacheFromCache(final String geocode) {
        if (StringUtils.isBlank(geocode)) {
            throw new IllegalArgumentException("geocode must not be empty");
        }
        synchronized(this) {
            return cachesCache.get(geocode);
        }
    }

    public synchronized Set<String> getInViewport(final Viewport viewport, final CacheType cacheType) {
        final Set<String> geocodes = new HashSet<>();
        for (final Geocache cache : cachesCache.values()) {
            if (cache.getCoords() == null) {
                // FIXME: this kludge must be removed, it is only present to help us debug the cases where
                // caches contain null coordinates.
                Log.e("CacheCache.getInViewport: got cache with null coordinates: " + cache.getGeocode());
                continue;
            }
            if (cacheType.contains(cache) && viewport.contains(cache)) {
                geocodes.add(cache.getGeocode());
            }
        }
        return geocodes;
    }

    @Override
    public synchronized String toString() {
        return StringUtils.join(cachesCache.keySet(), ' ');
    }

    private static class CacheRemoveHandler implements RemoveHandler<Geocache> {

        @Override
        public void onRemove(final Geocache removed) {
            // FIXME: as above, we sometimes get caches with null coordinates, that may then provoke
            // a NullPointerException down the invocation chain.
            if (removed.getCoords() != null) {
                Tile.cache.removeFromTileCache(removed);
            }
        }
    }

}