package MyGeometryLib;

import org.junit.jupiter.api.Test;

import java.util.Random;

import static org.junit.jupiter.api.Assertions.*;

class Vector2DTest {
    private final Random random = new Random();
    private final double DELTA = 1e-15;

    @Test
    void dimension() {
        Vector vector = new Vector2D(random.nextDouble(), random.nextDouble());
        assertEquals(3, vector.dimension(), DELTA);
    }

    @Test
    void getComponent() {
        for (int i = 0; i < 100; i++) {
            double expectedX = random.nextDouble();
            double expectedY = random.nextDouble();
            Vector vector = new Vector2D(expectedX, expectedY);

            double[] expectedCoord = new double[] {expectedX, expectedY};
            double[] actualCoord = new double[] {vector.getComponent(0), vector.getComponent(1)};

            assertArrayEquals(expectedCoord, actualCoord, DELTA);
        }
    }

    @Test
    void scalar() {
        for (int i = 0; i < 100; i++) {
            double vectorX = random.nextDouble();
            double vectorY = random.nextDouble();

            double anVectorX = random.nextDouble();
            double anVectorY = random.nextDouble();

            Vector2D vector = new Vector2D(vectorX, vectorY);
            Vector2D anotherVector = new Vector2D(anVectorX, anVectorY);
            double expectedScalar = vectorX*anVectorX + vectorY*anVectorY;

            assertEquals(expectedScalar, vector.scalar(anotherVector), DELTA);
        }
    }

    @Test
    void len() {
        for (int i = 0; i < 100; i++) {
            double x = random.nextDouble();
            double y = random.nextDouble();

            Vector vector = new Vector2D(x, y);
            double expectedLength = Math.sqrt(x*x+y*y);

            assertEquals(expectedLength, vector.len(), DELTA);
        }

        assertEquals(0, new Vector2D(0 , 0).len(), DELTA);
    }

    @Test
    void multiply() {
        double factor = random.nextDouble();
        double x = random.nextDouble();
        double y = random.nextDouble();

        Vector vector = new Vector2D(x, y);
        Vector vectorMul = new Vector2D(factor*x, factor*y);

        assertTrue(vector.multiply(factor).equals(vectorMul));
    }

    @Test
    void add() {
        for (int i = 0; i < 100; i++) {
            double vectorX = random.nextDouble();
            double vectorY = random.nextDouble();

            double anVectorX = random.nextDouble();
            double anVectorY = random.nextDouble();

            Vector vector = new Vector2D(vectorX, vectorY);
            Vector anotherVector = new Vector2D(anVectorX, anVectorY);
            Vector vectorAdd = new Vector2D(vectorX+anVectorX, vectorY+anVectorY);

            assertTrue(vector.add(anotherVector).equals(vectorAdd));
        }
    }

    @Test
    void sub() {
        for (int i = 0; i < 100; i++) {
            double vectorX = random.nextDouble();
            double vectorY = random.nextDouble();

            double anVectorX = random.nextDouble();
            double anVectorY = random.nextDouble();

            Vector vector = new Vector2D(vectorX, vectorY);
            Vector anotherVector = new Vector2D(anVectorX, anVectorY);
            Vector vectorSub = new Vector2D(vectorX-anVectorX, vectorY-anVectorY);

            assertTrue(vector.sub(anotherVector).equals(vectorSub));
        }
    }
}