/*
 * Copyright (C) 2014 SCVNGR, Inc. d/b/a LevelUp
 *
 * 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 com.scvngr.levelup.core.util.bundle;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.Nullable;

import com.scvngr.levelup.core.annotation.LevelUpApi;
import com.scvngr.levelup.core.annotation.LevelUpApi.Contract;
import com.scvngr.levelup.core.util.LogManager;

import net.jcip.annotations.ThreadSafe;

/**
 * Helper class to scrub Bundles of invalid extras. This is a workaround for
 * <a href="http://code.google.com/p/android/issues/detail?id=16006">Android issue #16006</a>.
 */
@LevelUpApi(contract = Contract.INTERNAL)
@ThreadSafe
public final class BundleScrubber {
    /**
     * Scrubs Intents for private serializable subclasses in the Intent extras. If the Intent's
     * extras contain a private serializable subclass, the Bundle is cleared. The Bundle will not be
     * set to null. If the Bundle is null, has no extras, or the extras do not contain a private
     * serializable subclass, the Bundle is not mutated.
     *
     * @param intent {@code Intent} to scrub. This parameter may be mutated if scrubbing is
     *            necessary.
     * @return true if the Intent was scrubbed, false if the Intent was not modified.
     */
    public static boolean scrub(@Nullable final Intent intent) {
        if (null == intent) {
            return false;
        }

        return scrub(intent.getExtras());
    }

    /**
     * Scrubs Bundles for private serializable subclasses in the extras. If the Bundle's extras
     * contain a private serializable subclass, the Bundle is cleared. If the Bundle is null, has no
     * extras, or the extras do not contain a private serializable subclass, the Bundle is not
     * mutated.
     *
     * @param bundle {@code Bundle} to scrub. This parameter may be mutated if scrubbing is
     *            necessary.
     * @return true if the Bundle was scrubbed, false if the Bundle was not modified.
     */
    public static boolean scrub(@Nullable final Bundle bundle) {
        if (null == bundle) {
            return false;
        }

        /*
         * Note: This is a hack to work around a private serializable classloader attack.
         */
        try {
            // if a private serializable exists, this will throw an exception
            bundle.containsKey(null);
        } catch (final Exception e) {
            LogManager.e("Private serializable attack detected; deleting all extras", e);

            bundle.clear();
            return true;
        }

        return false;
    }

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