package mvd.jester.tests;

import java.math.RoundingMode;
import java.util.HashMap;
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.model.DagTask;
import mvd.jester.model.Segment;
import mvd.jester.model.SortedTaskSet;
import mvd.jester.model.SystemManager;
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(final SystemManager manager) {
        super(manager);
        this.responseTimes = new HashMap<>();
        this.priorityManager = new RateMonotonic();
    }

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

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

        return new SchedulingInfo(responseTimes.values());
    }

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

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

        do {
            previousResponseTime = responseTime;
            double taskInterference = 0;

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

            taskInterference /= manager.getNumberOfProcessors();
            final double selfInterference = getSelfInterference(task);

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

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

        return responseTime;
    }


    private double getSelfInterference(final DagTask task) {
        // final long numberOfThreads = task.getNumberOfThreads();
        // TODO: Change back to number of threads
        final long numberOfThreads = manager.getNumberOfProcessors();

        double interference = task.getWorkload() - task.getCriticalPath();
        interference /= numberOfThreads;

        return interference;
    }


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

            double workload = 0;

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

            final double interference = amountOfJobs * workload;

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

}