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

import java.util.Arrays;

public class SimpleTest {

    private final Investment invest = new MyInvestment();

    private int profit(int[] values, BuySell p) {
        return values[p.sell()] - values[p.buy()];
    }

    @Test
    public void testExample() {
        int[] numbers = new int[]{9,1,5};
        Assertions.assertEquals(new BuySell(1,2), invest.bestInvestment(numbers), "Incorrect buy/sell for input: " + Arrays.toString(numbers) + ".");
    }

    @Test
    public void testNoBuy() {
        int[] numbers = new int[]{5, 4, 4, 4, 3, 3, 2, 1};
        Assertions.assertNull(invest.bestInvestment(numbers), "Incorrect buy/sell for input: " + Arrays.toString(numbers) + ".");
    }

    @Test
    public void testOneDay() {
        int[] numbers = new int[]{1};
        Assertions.assertNull(invest.bestInvestment(numbers), "Incorrect buy/sell for input: " + Arrays.toString(numbers) + ".");
    }

    @Test
    public void testEmpty() {
        int[] numbers = new int[]{};
        Assertions.assertNull(invest.bestInvestment(numbers), "Incorrect buy/sell for input: " + Arrays.toString(numbers) + ".");
    }

    @Test
    public void testMerge() {
        int[] numbers = new int[]{5, 1, 1, 1, 20, 10, 10, 5};
        BuySell actual = invest.bestInvestment(numbers);
        Assertions.assertEquals(19, profit(numbers, actual), "Incorrect buy/sell for input: " + Arrays.toString(numbers) + ".");
    }

    @Test
    public void testLeft() {
        int[] numbers = new int[]{1, 1, 20, 1, 1, 1, 1, 1};
        BuySell actual = invest.bestInvestment(numbers);
        Assertions.assertEquals(19, profit(numbers, actual), "Incorrect buy/sell for input: " + Arrays.toString(numbers) + ".");
    }

    @Test
    public void testRight() {
        int[] numbers = new int[]{1, 1, 1, 1, 1, 1, 20, 1};
        BuySell actual = invest.bestInvestment(numbers);
        Assertions.assertEquals(19, profit(numbers, actual), "Incorrect buy/sell for input: " + Arrays.toString(numbers) + ".");
    }
}