package labs.applications;

import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.Order;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestMethodOrder;
import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.Random;


/**
 * Correctness and performance tests for Applications.EventSequencer
 *
 * @author Nathan Sprague
 *
 */
@TestMethodOrder(OrderAnnotation.class)
public class EventSequencerTest {

  /**
   * Generate random numbers with no repeats in a given range.
   */
  public ArrayList<Integer> randomSample(int min, int max, int howMany) {
    Random gen = new Random(100101);
    HashSet<Integer> seen = new HashSet<>();
    ArrayList<Integer> result = new ArrayList<>();

    while (result.size() < howMany) {
      int next = gen.nextInt(max - min) + min;
      if (!seen.contains(next)) {
        seen.add(next);
        result.add(next);
      }
    }
    return result;
  }


  @Test
  @Order(1)
  public void testCorrectness() {

    Applications.EventSequencer sequencer = new Applications.EventSequencer();
    String events = "ABCDEFGHIJKLMNOPQRSTUV";
    String moreEvents = "XYZ";

    for (int i = 0; i < events.length(); i++) {
      sequencer.addEvent(i * 2, events.substring(i, i + 1));
    }

    assertEquals("A", sequencer.nextEvent()); // 0
    assertEquals("B", sequencer.nextEvent()); // 2
    assertEquals("C", sequencer.nextEvent()); // 4
    assertEquals("D", sequencer.nextEvent()); // 6

    for (int i = 0; i < moreEvents.length(); i++) {
      sequencer.addEvent(9 - 2 * i, moreEvents.substring(i, i + 1)); // 9, 7, 5
    }

    assertEquals("Y", sequencer.nextEvent()); // 7
    assertEquals("E", sequencer.nextEvent()); // 8
    assertEquals("X", sequencer.nextEvent()); // 9
    assertEquals("F", sequencer.nextEvent()); // 10

  }

  @Test
  @Order(2)
  public void testPerformance() {
    long addTime = 0;
    int addCounter = 0;
    long getTime = 0;
    int getCounter = 0;
    int numEvents = 1000000;
    int maxTime = 100000000;

    Applications.EventSequencer sequencer = new Applications.EventSequencer();

    ArrayList<Integer> times = randomSample(1, maxTime, numEvents);

    long start = System.nanoTime();
    for (int time : times) {
      sequencer.addEvent(time, "Some Event");
      addCounter++;
    }
    addTime += (System.nanoTime() - start);


    start = System.nanoTime();
    for (int i = 0; i < numEvents / 2; i++) {
      String event = sequencer.nextEvent();
      getCounter++;
    }
    getTime += (System.nanoTime() - start);


    // Half of these will be before.
    times = randomSample(maxTime / 2, maxTime + maxTime / 2, numEvents);

    start = System.nanoTime();
    for (int time : times) {
      sequencer.addEvent(time, "Some Event");
      addCounter++;
    }
    addTime += (System.nanoTime() - start);


    start = System.nanoTime();
    for (int i = 0; i < numEvents / 2; i++) {
      String event = sequencer.nextEvent();
      getCounter++;
    }
    getTime += (System.nanoTime() - start);

    System.out.printf("TOTAL TIME: %.2f seconds.\n", (addTime + getTime) / 1000000000.0);

    System.out.printf(
        "Add:  %8d operations performed in %4.2f seconds, %8.3f microseconds per call.\n",
        addCounter, addTime / 1000000000.0, addTime / 1000.0 / addCounter);

    System.out.printf(
        "Next: %8d operations performed in %4.2f seconds, %8.3f microseconds per call.\n",
        getCounter, getTime / 1000000000.0, getTime / 1000.0 / getCounter);

  }

}