import java.util.ArrayList;
import java.util.Comparator;
import java.util.Iterator;
import java.util.PriorityQueue;

public class RealTimeScheduler {
    private int totalTime;
    private ArrayList<Task> tasks;
    private PriorityQueue<Task> scheduleQueue;


    private class TaskComparator implements Comparator<Task>{

        @Override
        public int compare(Task o1, Task o2) {
            double priorityTask1 = 1 / o1.getPeriod();
            double priorityTask2 = 1 / o2.getPeriod();

            return (int)(o1.getPeriod() - o2.getPeriod());
        }
    }

    public RealTimeScheduler(int totalTime, ArrayList<Task> tasks) {
        this.totalTime = totalTime;
        this.tasks = tasks;
        this.scheduleQueue = new PriorityQueue<>(tasks.size(), new TaskComparator());
    }


    private ArrayList<Task> getTasksAtGivenTimePeriod(int clock){
        ArrayList<Task> tasksAtTimePeriod = new ArrayList<>();
        for(Task t : this.tasks){
            if((clock - t.getRelease())% t.getPeriod() == 0){
                tasksAtTimePeriod.add(new Task(clock, t.getExecution(), t.getDeadline(), t.getPeriod(), t.getId()));
            }
        }
        return tasksAtTimePeriod;
    }

    private void work(int clock){
        Task t = this.scheduleQueue.peek();
        if (t == null){
            return;
        }
        t.work();

        if(t.hasFinishedWork()){
            System.out.println("Time = " + clock + " Thread with id = " + t.getId() + " has finished working");
            this.scheduleQueue.remove(t);
        }
    }

    public void simulate(){
        int clock = 1;
        this.scheduleQueue.addAll(tasks);
        while(clock <= this.totalTime){

            //find threads that are missing the deadline
            for(Iterator<Task> it = this.scheduleQueue.iterator(); it.hasNext();){
                Task ta = it.next();
                if(clock - ta.getRelease() > ta.getDeadline()){
                    System.out.println("Time = " + clock + " Thread with id = " + ta.getId() + " has missed its deadline");
                    it.remove();
                }
            }

            work(clock);



            ArrayList<Task> ts = getTasksAtGivenTimePeriod(clock);
            if (ts.size() != 0){
                this.scheduleQueue.addAll(ts);
            }
            clock++;
        }

        System.out.println("Time has ended!");

    }


}