/*
 * Copyright (C) 2010 ZXing authors
 *
 * 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.google.zxing.client.android;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.Handler;

/**
 * Finishes an context after a period of inactivity if the device is on battery power.
 */
public final class InactivityTimer {

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

    private static final long INACTIVITY_DELAY_MS = 5 * 60 * 1000L;

    private final Context context;
    private final BroadcastReceiver powerStatusReceiver;
    private boolean registered = false;
    private Handler handler;
    private Runnable callback;
    private boolean onBattery;

    public InactivityTimer(Context context, Runnable callback) {
        this.context = context;
        this.callback = callback;

        powerStatusReceiver = new PowerStatusReceiver();
        handler = new Handler();
    }

    /**
     * Trigger activity, resetting the timer.
     */
    public void activity() {
        cancelCallback();
        if (onBattery) {
            handler.postDelayed(callback, INACTIVITY_DELAY_MS);
        }
    }

    /**
     * Start the activity timer.
     */
    public void start() {
        registerReceiver();
        activity();
    }

    /**
     * Cancel the activity timer.
     */
    public void cancel() {
        cancelCallback();
        unregisterReceiver();
    }

    private void unregisterReceiver() {
        if (registered) {
            context.unregisterReceiver(powerStatusReceiver);
            registered = false;
        }
    }

    private void registerReceiver() {
        if (!registered) {
            context.registerReceiver(powerStatusReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));
            registered = true;
        }
    }

    private void cancelCallback() {
        handler.removeCallbacksAndMessages(null);
    }

    private void onBattery(boolean onBattery) {
        this.onBattery = onBattery;

        // To make sure we're still running
        if (registered) {
            // This will either cancel or reschedule, depending on the battery status.
            activity();
        }
    }

    private final class PowerStatusReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (Intent.ACTION_BATTERY_CHANGED.equals(intent.getAction())) {
                // 0 indicates that we're on battery
                final boolean onBatteryNow = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1) <= 0;
                // post on handler to run in main thread
                handler.post(() -> onBattery(onBatteryNow));
            }
        }
    }
}