/*
 * Copyright (C) 2017 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.systemui;

import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Handler;
import android.os.IBinder;
import android.os.RemoteException;
import android.os.UserHandle;
import android.util.Log;
import com.android.systemui.shared.recents.model.IOverviewProxy;
import com.android.systemui.statusbar.policy.DeviceProvisionedController;
import com.android.systemui.statusbar.policy.DeviceProvisionedController.DeviceProvisionedListener;

/**
 * Class to send information from overview to launcher with a binder.
 */
public class OverviewProxyService {

    private static final String TAG = "OverviewProxyService";
    private static final long BACKOFF_MILLIS = 5000;

    private final Context mContext;
    private final Handler mHandler;
    private final Runnable mConnectionRunnable = this::startConnectionToCurrentUser;
    private final DeviceProvisionedController mDeviceProvisionedController
            = Dependency.get(DeviceProvisionedController.class);

    private IOverviewProxy mOverviewProxy;
    private int mConnectionBackoffAttempts;

    private final ServiceConnection mOverviewServiceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            if (service != null) {
                mConnectionBackoffAttempts = 0;
                mOverviewProxy = IOverviewProxy.Stub.asInterface(service);
                // Listen for launcher's death
                try {
                    service.linkToDeath(mOverviewServiceDeathRcpt, 0);
                } catch (RemoteException e) {
                    Log.e(TAG, "Lost connection to launcher service", e);
                }
            }
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            // Do nothing
        }
    };

    private final DeviceProvisionedListener mDeviceProvisionedCallback =
                new DeviceProvisionedListener() {
            @Override
            public void onDeviceProvisionedChanged() {
                if (mDeviceProvisionedController.isCurrentUserSetup()) {
                    startConnectionToCurrentUser();
                }
            }

            @Override
            public void onUserSwitched() {
                disconnectFromLauncherService();
                mConnectionBackoffAttempts = 0;
                startConnectionToCurrentUser();
            }
        };

    // This is the death handler for the binder from the launcher service
    private final IBinder.DeathRecipient mOverviewServiceDeathRcpt = new IBinder.DeathRecipient() {
        @Override
        public void binderDied() {
            mOverviewProxy = null;
        }
    };

    public OverviewProxyService(Context context) {
        mContext = context;
        mHandler = new Handler();
        mConnectionBackoffAttempts = 0;
        mDeviceProvisionedController.addCallback(mDeviceProvisionedCallback);
    }

    public void startConnectionToCurrentUser() {
        // If user has not setup yet or already connected, do not try to connect
        if (!mDeviceProvisionedController.isCurrentUserSetup() || mOverviewProxy != null) {
            return;
        }
        mHandler.removeCallbacks(mConnectionRunnable);
        Intent launcherServiceIntent = new Intent();
        launcherServiceIntent.setComponent(ComponentName.unflattenFromString(
                mContext.getString(R.string.config_overviewServiceComponent)));
        boolean bound = mContext.bindServiceAsUser(launcherServiceIntent,
                mOverviewServiceConnection, Context.BIND_AUTO_CREATE,
                UserHandle.getUserHandleForUid(mDeviceProvisionedController.getCurrentUser()));
        if (!bound) {
            // Retry after exponential backoff timeout
            final long timeoutMs = (long) Math.scalb(BACKOFF_MILLIS, mConnectionBackoffAttempts);
            mHandler.postDelayed(mConnectionRunnable, timeoutMs);
            mConnectionBackoffAttempts++;
        }
    }

    public IOverviewProxy getProxy() {
        return mOverviewProxy;
    }

    private void disconnectFromLauncherService() {
        mContext.unbindService(mOverviewServiceConnection);
        mOverviewProxy = null;
    }
}