Automation/app/src/main/java/com/jens/automation2/receivers/CalendarReceiver.java

package com.jens.automation2.receivers;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.SystemClock;

import androidx.annotation.NonNull;

import com.jens.automation2.AutomationService;
import com.jens.automation2.Miscellaneous;
import com.jens.automation2.Rule;
import com.jens.automation2.Trigger;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

public class CalendarReceiver extends BroadcastReceiver implements AutomationListenerInterface
{
    static CalendarReceiver calendarReceiverInstance = null;
    static boolean calendarReceiverActive = false;
    static IntentFilter calendarIntentFilter = null;
    private static AutomationService automationServiceRef;
    private static Intent calendarIntent = null;

    public static final int AVAILABILITY_OUT_OF_OFFICE = 4;
    public static final int AVAILABILITY_WORKING_ELSEWHERE = 5;
    public static final String calendarAlarmAction = "ALARM_FOR_CALENDAR";

    static List<AndroidCalendar> calendarsCache = null;
    static List<CalendarEvent> calendarEventsCache = null;

    static Timer timer = null;
    static TimerTask timerTask = null;
    static Calendar nextWakeup = null;
    static AlarmManager alarmManager = null;
    static boolean alarmHasChanged = false;

    public static CalendarReceiver getInstance()
    {
        if(calendarReceiverInstance == null)
            calendarReceiverInstance = new CalendarReceiver();

        return calendarReceiverInstance;
    }

    @Override
    public void onReceive(Context context, Intent intent)
    {
        if(intent.getAction().equalsIgnoreCase(Intent.ACTION_PROVIDER_CHANGED))
        {
            Miscellaneous.logEvent("i", "CalendarReceiver", "Received " + intent.getAction(), 5);

            calendarsCache = null;
            calendarEventsCache = null;

            checkForRules(context);
            armOrRearmTimer();
        }
        else if(intent.getAction().equalsIgnoreCase(calendarAlarmAction))
        {
            Miscellaneous.logEvent("i", "AlarmReceiver", "Received alarm for calendar receiver.", 5);
            routineAtAlarm();
        }
    }

    private static void checkForRules(Context context)
    {
        ArrayList<Rule> ruleCandidates = Rule.findRuleCandidates(Trigger.Trigger_Enum.calendarEvent);
        for(int i = 0; i < ruleCandidates.size(); i++)
        {
            if(ruleCandidates.get(i).getsGreenLight(context))
                ruleCandidates.get(i).activate(AutomationService.getInstance(), false);
        }
    }

    @Override
    public void startListener(AutomationService automationService)
    {
        if(!calendarReceiverActive)
        {
            if(calendarReceiverInstance == null)
                calendarReceiverInstance = new CalendarReceiver();

            if(calendarIntentFilter == null)
            {
                calendarIntentFilter = new IntentFilter();
                calendarIntentFilter.addAction(Intent.ACTION_PROVIDER_CHANGED);
//                calendarIntentFilter.addDataScheme("content");
            }

            AutomationService.getInstance().registerReceiver(calendarReceiverInstance, calendarIntentFilter);

            calendarReceiverActive = true;
        }
    }

    @Override
    public void stopListener(AutomationService automationService)
    {
        if(calendarReceiverActive)
        {
            if(calendarReceiverInstance != null)
            {
                AutomationService.getInstance().unregisterReceiver(calendarReceiverInstance);
                calendarReceiverInstance = null;
            }

            calendarReceiverActive = false;
        }
    }

    @Override
    public boolean isListenerRunning()
    {
        return calendarReceiverActive;
    }

    @Override
    public Trigger.Trigger_Enum[] getMonitoredTrigger()
    {
        return new Trigger.Trigger_Enum[]{Trigger.Trigger_Enum.calendarEvent};
    }

    public static class AndroidCalendar
    {
        public int calendarId;
        public String displayName;
        public String accountString;

        @NonNull
        @Override
        public String toString()
        {
            return displayName + " (" + accountString + ")";
        }
    }

    public static class CalendarEvent
    {
        public AndroidCalendar calendar;
        public int calendarId;
        public String eventId;
        public String title;
        public String description;
        public String location;
        public String availability;
        public Calendar start, end;
        public boolean allDay;

        public boolean isCurrentlyActive()
        {
            Calendar now = Calendar.getInstance();
            return now.getTimeInMillis() >= start.getTimeInMillis() && now.getTimeInMillis() < end.getTimeInMillis();
        }

        @NonNull
        @Override
        public String toString()
        {
            return title;
        }
    }

    public static List<AndroidCalendar> readCalendars(Context context)
    {
        if(calendarsCache == null)
        {
            calendarsCache = new ArrayList<>();

            Cursor cursor;

            cursor = context.getContentResolver().query(
                    Uri.parse("content://com.android.calendar/calendars"),
                    new String[]{ "_id", "calendar_displayName", "ownerAccount",  },
                    null, null, null);

            cursor.moveToFirst();
            // fetching calendars name
            String CNames[] = new String[cursor.getCount()];

            List<AndroidCalendar> calendarlist = new ArrayList<>();

            for (int i = 0; i < CNames.length; i++)
            {
                try
                {
                    AndroidCalendar calendar = new AndroidCalendar();
                    calendar.calendarId = Integer.parseInt(cursor.getString(0));
                    calendar.displayName = cursor.getString(1);
                    calendar.accountString = cursor.getString(2);

                    calendarsCache.add(calendar);
                }
                catch (Exception e)
                {
                }
                cursor.moveToNext();
            }

            if (cursor != null)
                cursor.close();
        }

        return calendarsCache;
    }

    public static List<CalendarEvent> readCalendarEvents(Context context, boolean includePastEvents)
    {
        if(calendarEventsCache == null)
        {
            calendarEventsCache = new ArrayList<>();

            Cursor cursor;

                cursor = context.getContentResolver().query(
                            Uri.parse("content://com.android.calendar/events"),
                            new String[] { "calendar_id", "_id", "title", "description", "allDay", "dtstart", "dtend", "eventLocation", "availability" },
                            null, null, null);

            cursor.moveToFirst();
            // fetching calendars name
            String CNames[] = new String[cursor.getCount()];

            Calendar now = Calendar.getInstance();

            for (int i = 0; i < CNames.length; i++)
            {
                try
                {
                    CalendarEvent event = new CalendarEvent();
                    event.calendarId = Integer.parseInt(cursor.getString(0));

                    for(AndroidCalendar cal : readCalendars(context))
                    {
                        if(cal.calendarId == event.calendarId)
                        {
                            event.calendar = cal;
                            break;
                        }
                    }

                    event.eventId = cursor.getString(1);
                    event.title = cursor.getString(2);
                    event.description = cursor.getString(3);
                    event.allDay = cursor.getString(4).equals("1");
                    event.start = Miscellaneous.calendarFromLong(Long.parseLong(cursor.getString(5)));
                    event.end = Miscellaneous.calendarFromLong(Long.parseLong(cursor.getString(6)));
                    event.location = cursor.getString(7);
                    event.availability = cursor.getString(8);

                    if(includePastEvents || event.end.getTimeInMillis() > now.getTimeInMillis())
                        calendarEventsCache.add(event);
                }
                catch (Exception e)
                {}
                cursor.moveToNext();
            }

            if(cursor != null)
                cursor.close();

        }

        return calendarEventsCache;
    }

    protected static void routineAtAlarm()
    {
        checkForRules(Miscellaneous.getAnyContext());

        // Set next timer
        calculateNextWakeup();
        armOrRearmTimer();
    }

    private static void armOrRearmTimer()
    {
        PendingIntent pi = null;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
        {
            if (alarmManager == null)
            {
                alarmManager = (AlarmManager) Miscellaneous.getAnyContext().getSystemService(Context.ALARM_SERVICE);
            }

            if(pi == null)
            {
                Intent intent = new Intent(Miscellaneous.getAnyContext(), CalendarReceiver.class);
                intent.setAction(calendarAlarmAction);
                pi = PendingIntent.getBroadcast(AutomationService.getInstance(), 0, intent, 0);
            }
        }
        else
        {
            timerTask = new TimerTask()
            {
                @Override
                public void run()
                {
                    routineAtAlarm();
                }
            };

            if(timer != null)
            {
                timer.cancel();
                timer.purge();
            }
            timer = new Timer();
        }

        if(nextWakeup == null)
        {
            readCalendarEvents(Miscellaneous.getAnyContext(), false);
            calculateNextWakeup();
        }

        // If it's now filled, go on
        if(nextWakeup != null)
        {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
            {
                if (Build.VERSION.SDK_INT < Build.VERSION_CODES.S || (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S && alarmManager.canScheduleExactAlarms()))
                {
                    try
                    {
                        alarmManager.cancel(pi);
                    }
                    catch (Exception e)
                    {

                    }
                    Miscellaneous.logEvent("i", "armOrRearmTimer()", "Setting calendar alarm for " + nextWakeup.toString(), 5);
                    alarmManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, nextWakeup.getTimeInMillis(), pi);

                    //alarmManager.setExactAndAllowWhileIdle(AlarmManager.ELAPSED_REALTIME_WAKEUP, nextWakeup.getTimeInMillis(), pi);
                }
            }
            else
                timer.schedule(timerTask, nextWakeup.getTimeInMillis());
        }
    }

    private static void calculateNextWakeup()
    {
        Calendar now = Calendar.getInstance();
        if (nextWakeup != null && nextWakeup.getTimeInMillis() < now.getTimeInMillis())
            nextWakeup = null;

        List<CalendarEvent> events = readCalendarEvents(Miscellaneous.getAnyContext(), false);
        if (events.size() > 0)
        {
            for (CalendarEvent event : events)
            {
                if (event.isCurrentlyActive())
                {
                    if (nextWakeup == null || event.end.getTimeInMillis() < nextWakeup.getTimeInMillis())
                    {
                        nextWakeup = event.end;
                        Miscellaneous.logEvent("i", "calculateNextWakeupForCalendar()", "Chose end of event " + event.title + " as next wakeup.", 5);
                        if(!alarmHasChanged)
                            alarmHasChanged = true;
                    }
                }
                else
                {
                    if (nextWakeup == null || event.start.getTimeInMillis() < nextWakeup.getTimeInMillis())
                    {
                        nextWakeup = event.start;
                        Miscellaneous.logEvent("i", "calculateNextWakeupForCalendar()", "Chose start of event " + event.title + " as next wakeup.", 5);
                        if(!alarmHasChanged)
                            alarmHasChanged = true;
                    }
                }
            }
        }
        //else
        //  we expect to be called byOnReceive() when new items exist
    }

    public static void startCalendarReceiver(final AutomationService automationServiceRef)
    {
        if (!calendarReceiverActive)
        {
            CalendarReceiver.automationServiceRef = automationServiceRef;

            if (calendarReceiverInstance == null)
                calendarReceiverInstance = new CalendarReceiver();

            if (calendarIntentFilter == null)
            {
                calendarIntentFilter = new IntentFilter();
                calendarIntentFilter.addAction(Intent.ACTION_PROVIDER_CHANGED);
                calendarIntentFilter.addDataScheme("content");
                calendarIntentFilter.addDataAuthority("com.android.calendar", null);
            }

            calendarIntent = automationServiceRef.registerReceiver(calendarReceiverInstance, calendarIntentFilter);

            calendarReceiverActive = true;

            armOrRearmTimer();
        }
    }
}