package com.eveningoutpost.dexdrip.G5Model;

// jamorham

import com.eveningoutpost.dexdrip.Models.JoH;
import com.eveningoutpost.dexdrip.Models.UserError;
import com.eveningoutpost.dexdrip.UtilityModels.Constants;
import com.eveningoutpost.dexdrip.UtilityModels.PersistentStore;

import static com.eveningoutpost.dexdrip.UtilityModels.BgGraphBuilder.DEXCOM_PERIOD;

public class DexSyncKeeper {

    private static final String TAG = DexTimeKeeper.class.getSimpleName();
    private static final String DEX_SYNC_STORE = "DEX_SYNC_STORE-";
    private static final long OLDEST_POSSIBLE = 1533839836123L;
    private static final long GRACE_TIME = 5000;
    private static final long VALIDITY_PERIOD = Constants.DAY_IN_MS;


    // store sync time as now
    public static void store(final String transmitterId) {
        store(transmitterId, JoH.tsl());
    }

    // store sync time
    public static void store(final String transmitterId, final long when) {

        if ((transmitterId == null) || (transmitterId.length() != 6)) {
            UserError.Log.e(TAG, "Invalid dex transmitter in store: " + transmitterId);
            return;
        }

        if (when < OLDEST_POSSIBLE) {
            UserError.Log.wtf(TAG, "Invalid timestamp to store: " + JoH.dateTimeText(when));
            return;
        }

        PersistentStore.setLong(DEX_SYNC_STORE + transmitterId, when);
        UserError.Log.d(TAG, "Sync time updated to: " + JoH.dateTimeText(when));
    }

    // anticpiate next wake up from now
    public static long anticipate(final String transmitterId) {
        return anticipate(transmitterId, JoH.tsl());
    }

    // anticipate next wake up from time
    // -1 means we don't know anything
    static long anticipate(final String transmitterId, final long now) {
        final long last = PersistentStore.getLong(DEX_SYNC_STORE + transmitterId);
        if (last < OLDEST_POSSIBLE) {
            return -1;
        }
        if (last > now) {
            UserError.Log.e(TAG, "Anticipation time in the future! cannot use: " + JoH.dateTimeText(last));
            return -1; // can't be in the future
        }

        if (now - last > VALIDITY_PERIOD) {
            UserError.Log.e(TAG, "Anticipation time too old to use: " + JoH.dateTimeText(last));
            return -1;
        }

        final long modulo = (now - last) % DEXCOM_PERIOD;
        if ((modulo < GRACE_TIME) && ((now - last) > GRACE_TIME)) return now;
        final long next = now + (DEXCOM_PERIOD - modulo);
        return next;
    }

    public static boolean isReady(final String transmitterId) {
        return anticipate(transmitterId, JoH.tsl()) != -1;
    }

    // are we outside connection window?
    // TODO also handle waking up before window PRE_GRACE_TIME = 20seconds?
    public static boolean outsideWindow(final String transmitterId) {
        final long now = JoH.tsl();
        final long next = anticipate(transmitterId, now);
        return next != now;
    }

}