package mvd.jester.tests;

import java.math.RoundingMode;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import com.google.common.math.LongMath;
import mvd.jester.info.SchedulingInfo;
import mvd.jester.info.TerminationInfo;
import mvd.jester.info.TerminationInfo.Level;
import mvd.jester.model.DagTask;
import mvd.jester.model.Segment;
import mvd.jester.model.SortedTaskSet;
import mvd.jester.model.Task;
import mvd.jester.priority.PriorityManager;
import mvd.jester.priority.RateMonotonic;

/**
 * SchmidMottok
 */
public class SchmidMottok extends AbstractTest<DagTask> {

    private final Map<Task, TerminationInfo> responseTimes;
    private final PriorityManager priorityManager;

    public SchmidMottok(long numberOfProcessors) {
        super(numberOfProcessors);
        this.responseTimes = new HashMap<>();
        this.priorityManager = new RateMonotonic();
    }

    @Override
    public PriorityManager getPriorityManager() {
        return priorityManager;
    }

    @Override
    public SchedulingInfo runSchedulabilityCheck(SortedTaskSet<DagTask> tasks) {
        responseTimes.clear();
        for (DagTask t : tasks) {
            long responseTime = calculateResponseTime(tasks, t);
            responseTimes.put(t, new TerminationInfo(t.getDeadline(), responseTime, Level.HIGH));
        }

        return new SchedulingInfo(new HashSet<>(responseTimes.values()),
                tasks.getParallelTaskRatio(), tasks.getUtilization());
    }

    @Override
    public String getName() {
        return "SchmidMottok";
    }

    private long calculateResponseTime(Set<DagTask> tasks, DagTask task) {
        long minimumWcet = task.getCriticalPath();
        long responseTime = minimumWcet;
        long previousResponseTime = 0;

        do {
            previousResponseTime = responseTime;
            double taskInterference = 0;

            for (DagTask t : tasks) {
                if (t.getPeriod() < task.getPeriod()) {
                    long numberOfThreads = t.getNumberOfThreads();
                    for (int p = 0; p < numberOfThreads; ++p) {
                        taskInterference += Math.min(getTaskInterference(t, responseTime, p + 1),
                                responseTime - minimumWcet + 1);
                    }
                }
            }

            taskInterference /= numberOfProcessors;
            double selfInterference = getSelfInterference(task);

            long totalInterference = (long) Math.floor(taskInterference + selfInterference);

            responseTime = minimumWcet + totalInterference;
        } while (previousResponseTime != responseTime);

        return responseTime;
    }


    private double getSelfInterference(DagTask task) {
        double interference = 0;
        long numberOfThreads = task.getNumberOfThreads();

        for (Segment s : task.getWorkloadDistribution()) {
            interference += (double) (s.getNumberOfJobs() - 1) * s.getJobWcet();
        }

        interference /= numberOfThreads;

        return interference;
    }


    private double getTaskInterference(DagTask task, long interval, long parallelism) {
        if (responseTimes.containsKey(task)) {
            long responseTime = responseTimes.get(task).getResponseTime();
            long minWcet = task.getCriticalPath();
            long period = task.getPeriod();
            long amountOfJobs =
                    (LongMath.divide(interval + responseTime - minWcet, period, RoundingMode.FLOOR)
                            + 1);

            double workload = 0;

            for (Segment s : task.getWorkloadDistribution()) {
                long numberOfThreads = s.getNumberOfJobs() > 1 ? task.getNumberOfThreads() : 1;
                if (numberOfThreads >= parallelism) {
                    workload += s.getNumberOfJobs() * s.getJobWcet() / numberOfThreads;
                }
            }

            double interference = amountOfJobs * workload;

            return interference;
        } else {
            throw new RuntimeException("Task was not found in task set!");
        }
    }

}