ExceptionToResourceMapping.java

package com.smartandroid.sa.eventbus;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import android.util.Log;

/**
 * Maps throwables to texts for error dialogs. Use Config to configure the
 * mapping.
 * 
 * @author Markus
 */
public class ExceptionToResourceMapping {

	public final Map<Class<? extends Throwable>, Integer> throwableToMsgIdMap;

	public ExceptionToResourceMapping() {
		throwableToMsgIdMap = new HashMap<Class<? extends Throwable>, Integer>();
	}

	/** Looks at the exception and its causes trying to find an ID. */
	public Integer mapThrowable(final Throwable throwable) {
		Throwable throwableToCheck = throwable;
		int depthToGo = 20;

		while (true) {
			Integer resId = mapThrowableFlat(throwableToCheck);
			if (resId != null) {
				return resId;
			} else {
				throwableToCheck = throwableToCheck.getCause();
				depthToGo--;
				if (depthToGo <= 0 || throwableToCheck == throwable
						|| throwableToCheck == null) {
					Log.d(EventBus.TAG,
							"No specific message ressource ID found for "
									+ throwable);
					// return config.defaultErrorMsgId;
					return null;
				}
			}
		}

	}

	/** Mapping without checking the cause (done in mapThrowable). */
	protected Integer mapThrowableFlat(Throwable throwable) {
		Class<? extends Throwable> throwableClass = throwable.getClass();
		Integer resId = throwableToMsgIdMap.get(throwableClass);
		if (resId == null) {
			Class<? extends Throwable> closestClass = null;
			Set<Entry<Class<? extends Throwable>, Integer>> mappings = throwableToMsgIdMap
					.entrySet();
			for (Entry<Class<? extends Throwable>, Integer> mapping : mappings) {
				Class<? extends Throwable> candidate = mapping.getKey();
				if (candidate.isAssignableFrom(throwableClass)) {
					if (closestClass == null
							|| closestClass.isAssignableFrom(candidate)) {
						closestClass = candidate;
						resId = mapping.getValue();
					}
				}
			}

		}
		return resId;
	}

	public ExceptionToResourceMapping addMapping(
			Class<? extends Throwable> clazz, int msgId) {
		throwableToMsgIdMap.put(clazz, msgId);
		return this;
	}

}