package com.demeng7215.dembot.utils;

import com.demeng7215.dembot.files.BotStorage;
import lombok.NonNull;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

/**
 * Checks if a temporary task has expired every 1 minute.
 * This is designed to make temporary tasks safer (eg. not banning a user forever if the bot crashes during a tempban)
 */
public final class TimeManager {

    // List of pending temp tasks' storage file paths.
    private static List<String> tempTasks;

    public static void startTimer() {

        tempTasks = new ArrayList<>();

        ScheduledExecutorService ses = Executors.newScheduledThreadPool(1);

        Runnable checkExpired = () -> {

            Iterator<String> it = tempTasks.iterator();

            while (it.hasNext()) {

                String value = it.next();
                long expiry = BotStorage.getStorage().getLong(value);

                if (expiry <= 0 || System.currentTimeMillis() >= expiry) {
                    BotStorage.getStorage().set(value, null);
                    BotStorage.saveStorage();
                    it.remove();
                    return;
                }
            }
        };

        ses.scheduleAtFixedRate(checkExpired, 0, 1, TimeUnit.MINUTES);
    }

    /**
     * Add a temporary task to check to this util.
     *
     * @param storagePath       Where the expiry time should be stored in the storage file
     * @param minutesIntoFuture Number of minutes until the temporary task expires
     */
    public static void addTempTask(@NonNull String storagePath, @NonNull int minutesIntoFuture) {

        final long expiryTime = System.currentTimeMillis() + (minutesIntoFuture * 60 * 1000);

        BotStorage.getStorage().set(storagePath, expiryTime);
        BotStorage.saveStorage();

        tempTasks.add(storagePath);
    }

    /**
     * Gets the number of minutes left in the task.
     *
     * @param storagePath Where the expiry time is stored in the storage file
     * @return 0 if the task has already expired, the number of minutes left otherwise
     */
    public static int timeLeft(@NonNull String storagePath) {
        if(!tempTasks.contains(storagePath)) return 0;
        return (int) (BotStorage.getStorage().getLong(storagePath) - System.currentTimeMillis()) / 1000 / 60;
    }
}