PluginBundleManager.java

/*
 * ttrss-reader-fork for Android
 *
 * Copyright (C) 2010 Nils Braden
 * Copyright 2013 two forty four a.m. LLC <http://www.twofortyfouram.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * <http://www.apache.org/licenses/LICENSE-2.0>
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and limitations under the License.
 */

package org.ttrssreader.imageCache.bundle;

import org.ttrssreader.utils.Utils;

import android.content.Context;
import android.os.Bundle;
import android.util.Log;

/**
 * Class for managing the {@link com.twofortyfouram.locale.Intent#EXTRA_BUNDLE} for this plug-in.
 */
public final class PluginBundleManager {

	private static final String TAG = PluginBundleManager.class.getSimpleName();

	/**
	 * Type: {@code String}.
	 * <p>
	 * String message to display in a Toast message.
	 */
	public static final String BUNDLE_EXTRA_IMAGES = "org.ttrssreader.FETCH_IMAGES"; //$NON-NLS-1$
	public static final String BUNDLE_EXTRA_NOTIFICATION = "org.ttrssreader.SHOW_NOTIFICATION"; //$NON-NLS-1$

	/**
	 * Type: {@code int}.
	 * <p>
	 * versionCode of the plug-in that saved the Bundle.
	 */
	/*
	 * This extra is not strictly required, however it makes backward and forward compatibility significantly
	 * easier. For example, suppose a bug is found in how some version of the plug-in stored its Bundle. By
	 * having the version, the plug-in can better detect when such bugs occur.
	 */
	private static final String BUNDLE_EXTRA_INT_VERSION_CODE = "org.ttrssreader.INT_VERSION_CODE"; //$NON-NLS-1$

	/**
	 * Method to verify the content of the bundle are correct.
	 * <p>
	 * This method will not mutate {@code bundle}.
	 *
	 * @param bundle bundle to verify. May be null, which will always return false.
	 * @return true if the Bundle is valid, false if the bundle is invalid.
	 */
	public static boolean isBundleValid(final Bundle bundle) {
		if (null == bundle) {
			return false;
		}

		/*
		 * Make sure the expected extras exist
		 */
		if (!bundle.containsKey(BUNDLE_EXTRA_IMAGES)) {
			Log.e(TAG, String.format("bundle must contain extra %s", BUNDLE_EXTRA_IMAGES)); //$NON-NLS-1$
			return false;
		}
		if (!bundle.containsKey(BUNDLE_EXTRA_NOTIFICATION)) {
			Log.e(TAG, String.format("bundle must contain extra %s", BUNDLE_EXTRA_NOTIFICATION)); //$NON-NLS-1$
			return false;
		}
		if (!bundle.containsKey(BUNDLE_EXTRA_INT_VERSION_CODE)) {
			Log.e(TAG, String.format("bundle must contain extra %s", BUNDLE_EXTRA_INT_VERSION_CODE)); //$NON-NLS-1$
			return false;
		}

		/*
		 * Make sure the correct number of extras exist. Run this test after checking for specific Bundle
		 * extras above so that the error message is more useful. (E.g. the caller will see what extras are
		 * missing, rather than just a message that there is the wrong number).
		 */
		if (3 != bundle.keySet().size()) {
			Log.e(TAG, String.format("bundle must contain 3 keys, but currently contains %d keys: %s",
					bundle.keySet().size(), bundle.keySet())); //$NON-NLS-1$
			return false;
		}

		if (bundle.getInt(BUNDLE_EXTRA_INT_VERSION_CODE, 0) != bundle.getInt(BUNDLE_EXTRA_INT_VERSION_CODE, 1)) {
			Log.e(TAG, String.format("bundle extra %s appears to be the wrong type.  It must be an int",
					BUNDLE_EXTRA_INT_VERSION_CODE)); //$NON-NLS-1$
			return false;
		}

		return true;
	}

	/**
	 * @param context Application context.
	 * @return A plug-in bundle.
	 */
	public static Bundle generateBundle(final Context context, final boolean fetchImages,
			final boolean showNotification) {
		final Bundle result = new Bundle();
		result.putInt(BUNDLE_EXTRA_INT_VERSION_CODE, Utils.getAppVersionCode(context));
		result.putBoolean(BUNDLE_EXTRA_IMAGES, fetchImages);
		result.putBoolean(BUNDLE_EXTRA_NOTIFICATION, showNotification);

		return result;
	}

	/**
	 * Private constructor prevents instantiation
	 *
	 * @throws UnsupportedOperationException because this class cannot be instantiated.
	 */
	private PluginBundleManager() {
		throw new UnsupportedOperationException("This class is non-instantiable"); //$NON-NLS-1$
	}

}