package cgeo.geocaching.sorting;
import cgeo.geocaching.connector.gc.GCConstants;
import cgeo.geocaching.models.Geocache;
import cgeo.geocaching.utils.Log;
import org.apache.commons.lang3.StringUtils;
/**
* abstract super implementation for all cache comparators
*
*/
abstract class AbstractCacheComparator implements CacheComparator {
@Override
public final int compare(final Geocache cache1, final Geocache cache2) {
try {
final boolean canCompare1 = canCompare(cache1);
final boolean canCompare2 = canCompare(cache2);
if (!canCompare1) {
return canCompare2 ? 1 : fallbackToGeocode(cache1, cache2);
}
return canCompare2 ? compareCaches(cache1, cache2) : -1;
} catch (final Exception e) {
Log.e("AbstractCacheComparator.compare", e);
// This may violate the Comparator interface if the exception is not systematic.
return fallbackToGeocode(cache1, cache2);
}
}
private static int fallbackToGeocode(final Geocache cache1, final Geocache cache2) {
final int comparePrefix = StringUtils.compareIgnoreCase(StringUtils.substring(cache1.getGeocode(), 0, 2), StringUtils.substring(cache2.getGeocode(), 0, 2));
if (comparePrefix == 0) {
return (int) (GCConstants.gccodeToGCId(cache1.getGeocode())
- GCConstants.gccodeToGCId(cache2.getGeocode()));
}
return comparePrefix;
}
/**
* Check necessary preconditions (like missing fields) before running the comparison itself.
* Caches not filling the conditions will be placed last, sorted by Geocode.
*
* The default implementation returns {@code true} and can be overridden if needed in sub classes.
*
* @param cache
* the cache to be sorted
*
* @return {@code true} if the cache holds the necessary data to be compared meaningfully
*/
protected boolean canCompare(final Geocache cache) {
return true;
}
/**
* Compares two caches. Logging and exception handling is implemented outside this method already.
* <p/>
* A cache is smaller than another cache if it is desirable to show it first when presented to the user.
* For example, a highly rated cache must be considered smaller than a poorly rated one.
*
* @return an integer < 0 if cache1 is less than cache2, 0 if they are equal, and > 0 if cache1 is greater than
* cache2.
*/
protected abstract int compareCaches(final Geocache cache1, final Geocache cache2);
@Override
public boolean isAutoManaged() {
return false;
}
}