/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * 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.android.storagemanager.overlay;

import android.content.Context;
import android.text.TextUtils;
import android.util.Log;

import com.android.storagemanager.R;
import com.android.tools.r8.keepanno.annotations.KeepItemKind;
import com.android.tools.r8.keepanno.annotations.KeepTarget;
import com.android.tools.r8.keepanno.annotations.UsesReflection;

/**
 * Abstract class for creating feature controllers. Allows OEM implementations to define their own
 * factories with their own controllers containing whatever code is needed to implement
 * the features. To provide a factory implementation, implementors should override
 * {@link R.string#config_featureFactory} in their override.
 */
public abstract class FeatureFactory {
    private static final String LOG_TAG = "FeatureFactory";
    private static final boolean DEBUG = false;

    private static FeatureFactory sFactory;

    /**
     * Returns a factory for creating feature controllers. Creates the factory if it does not
     * already exist. Uses the value of {@link R.string#config_featureFactory} to instantiate a
     * factory implementation.
     */
    @UsesReflection(
            description = "This method instantiates subclasses of FeatureFactory via reflection.",
            value = {
                @KeepTarget(
                        kind = KeepItemKind.CLASS_AND_MEMBERS,
                        instanceOfClassConstantExclusive = FeatureFactory.class,
                        methodName = "<init>")
            })
    public static FeatureFactory getFactory(Context context) {
        if (sFactory != null) {
            return sFactory;
        }

        if (DEBUG) Log.d(LOG_TAG, "getFactory");
        final String clsName = context.getString(R.string.config_featureFactory);
        if (TextUtils.isEmpty(clsName)) {
            throw new UnsupportedOperationException("No feature factory configured");
        }
        try {
            sFactory = (FeatureFactory) context.getClassLoader().loadClass(clsName).newInstance();
        } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
            throw new FactoryNotFoundException(e);
        }

        if (DEBUG) Log.d(LOG_TAG, "started " + sFactory.getClass().getSimpleName());
        return sFactory;
    }

    /**
     * Return a provider which adds additional deletion services to the Deletion Helper.
     */
    public abstract DeletionHelperFeatureProvider getDeletionHelperFeatureProvider();

    /**
     * Returns a provider which provides a periodic storage management job.
     */
    public abstract StorageManagementJobProvider getStorageManagementJobProvider();

    public static class FactoryNotFoundException extends RuntimeException {
        public FactoryNotFoundException(Throwable throwable) {
            super("Unable to create factory. Did you misconfigure Proguard?", throwable);
        }
    }
}