package fr.uge.set;

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

import java.lang.reflect.Modifier;
import java.lang.reflect.RecordComponent;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.stream.IntStream;

import static org.junit.jupiter.api.Assertions.assertAll;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTimeoutPreemptively;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

@SuppressWarnings("static-method")
public class IntHashSetTest {
  @Nested
  public class Q1 {

    @Test
    public void entryIsNotDeclaredInThePackage() {
      assertThrows(ClassNotFoundException.class, () -> Class.forName("fr.uge.set.Entry"));
    }

    @Test
    public void entryIsDeclaredInsideIntHashSet() {
      assertTrue(Arrays.stream(IntHashSet.class.getDeclaredClasses())
          .anyMatch(type -> type.getName().equals("fr.uge.set.IntHashSet$Entry")));
    }

    @Test
    public void entryIsARecord() throws ClassNotFoundException {
      var type = Class.forName("fr.uge.set.IntHashSet$Entry");
      assertTrue(type.isRecord());
    }

    @Test
    public void entryIsStaticAndPrivateAndFinal() throws ClassNotFoundException {
      var type = Class.forName("fr.uge.set.IntHashSet$Entry");
      var modifiers = type.getModifiers();
      assertAll(
          () -> assertTrue(Modifier.isPrivate(modifiers)),
          () -> assertTrue(Modifier.isStatic(modifiers)),
          () -> assertTrue(Modifier.isFinal(modifiers))
      );
    }

    @Test
    public void entryHasTwoComponentsValueAndNext() throws ClassNotFoundException {
      var type = Class.forName("fr.uge.set.IntHashSet$Entry");
      var components = type.getRecordComponents();
      assertNotNull(components);
      assertEquals(List.of("value", "next"), Arrays.stream(components).map(RecordComponent::getName).toList());
    }
  }


  @Nested
  public class Q3 {

    @Test
    public void shouldAddOne() {
      var set = new IntHashSet();
      set.add(1);
      assertEquals(1, set.size());
    }

    @Test
    public void shouldAddAnInteger() {
      var set = new IntHashSet();
      set.add(31_133);
      assertEquals(1, set.size());
    }

    @Test
    public void shouldAddWithoutErrors() {
      var set = new IntHashSet();
      IntStream.range(0, 100).map(i -> i * 2 + 1).forEach(set::add);
      assertEquals(100, set.size());
    }

    @Test
    public void shouldNotTakeTooLongToAddTheSameNumberMultipleTimes() {
      var set = new IntHashSet();
      assertTimeoutPreemptively(
          Duration.ofMillis(5_000),
          () -> IntStream.range(0, 1_000_000).map(i -> 42).forEach(set::add));
      assertEquals(1, set.size());
    }

    @Test
    public void shouldAnswerZeroWhenAskingForSizeOfEmptySet() {
      var set = new IntHashSet();
      assertEquals(0, set.size());
    }

    @Test
    public void shouldNotAddTwiceTheSameAndComputeSizeAccordingly() {
      var set = new IntHashSet();
      set.add(3);
      assertEquals(1, set.size());
      set.add(-777);
      assertEquals(2, set.size());
      set.add(3);
      assertEquals(2, set.size());
      set.add(-777);
      assertEquals(2, set.size());
      set.add(11);
      assertEquals(3, set.size());
      set.add(3);
      assertEquals(3, set.size());
    }
  }


  @Nested
  public class Q4 {

    @Test
    public void shouldDoNoThingWhenForEachCalledOnEmptySet() {
      var set = new IntHashSet();
      set.forEach(__ -> fail("should not be called"));
    }

    @Test
    public void shouldCompteTheSumOfAllTheElementsInASetUsingForEachAngGetTheSameAsTheFormula() {
      var length = 100;
      var set = new IntHashSet();
      IntStream.range(0, length).forEach(set::add);
      var sum = new int[] {0};
      set.forEach(value -> sum[0] += value);
      assertEquals(length * (length - 1) / 2, sum[0]);
    }

    @Test
    public void shouldComputeIndenticalSetAndHashSetUsingForEachAndHaveSameSize() {
      var set = new IntHashSet();
      IntStream.range(0, 100).forEach(set::add);
      var hashSet = new HashSet<Integer>();
      set.forEach(hashSet::add);
      assertEquals(set.size(), hashSet.size());
    }

    @Test
    public void shouldAddAllTheElementsOfASetToAListUsingForEach() {
      var set = new IntHashSet();
      IntStream.range(0, 100).forEach(set::add);
      var list = new ArrayList<Integer>();
      set.forEach(list::add);
      list.sort(null);
      IntStream.range(0, 100).forEach(i -> assertEquals(i, list.get(i)));
    }

    @Test
    public void shouldNotUseNullAsAParameterForForEach() {
      var set = new IntHashSet();
      assertThrows(NullPointerException.class, () -> set.forEach(null));
    }

    @Test
    public void shouldNotUseNullAsAParameterForForEach2() {
      var set = new IntHashSet();
      set.add(4);
      assertThrows(NullPointerException.class, () -> set.forEach(null));
    }
  }


  @Nested
  public class Q5 {

    @Test
    public void shouldNotFindAnythingContainedInAnEmptySet() {
      var set = new IntHashSet();
      assertFalse(set.contains(4));
      assertFalse(set.contains(7));
      assertFalse(set.contains(1));
      assertFalse(set.contains(0));
      assertEquals(0, set.size());
    }

    @Test
    public void shouldNotFindAnIntegerBeforeAddingItButShouldFindItAfter() {
      var set = new IntHashSet();
      for (int i = 0; i < 10; i++) {
        assertFalse(set.contains(i));
        set.add(i);
        assertTrue(set.contains(i));
      }
      assertEquals(10, set.size());
    }

    @Test
    public void shoulAddAndTestContainsForAnExtremalValue() {
      var set = new IntHashSet();
      assertFalse(set.contains(Integer.MIN_VALUE));
      set.add(Integer.MIN_VALUE);
      assertTrue(set.contains(Integer.MIN_VALUE));
      set.add(Integer.MAX_VALUE);
      assertTrue(set.contains(Integer.MAX_VALUE));
      assertEquals(2, set.size());
    }
  }
}