// Copyright (c) 2019, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package backport;

import com.android.tools.r8.TestBase;
import com.android.tools.r8.TestParameters;
import com.android.tools.r8.TestRuntime.CfVm;
import com.android.tools.r8.desugar.backports.AbstractBackportTest;
import java.math.BigInteger;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

@RunWith(Parameterized.class)
public final class StrictMathBackportJava9Test extends AbstractBackportTest {
  @Parameters(name = "{0}")
  public static Iterable<?> data() {
    return TestBase.getTestParameters()
        .withDexRuntimes()
        .withCfRuntimesStartingFromIncluding(CfVm.JDK9)
        .withAllApiLevelsAlsoForCf()
        .build();
  }

  public StrictMathBackportJava9Test(TestParameters parameters) {
    super(parameters, Math.class, StrictMathBackportJava9Main.class);
    // Note: None of the methods in this test exist in the latest android.jar. If/when they ship in
    // an actual API level, migrate these tests to StrictMathBackportTest.
  }

  public static class StrictMathBackportJava9Main {

    public static void main(String[] args) {
      testMultiplyExactLongInt();
      testMultiplyFull();
      testFloorDivLongInt();
      testFloorModLongInt();
    }

    public static void testMultiplyExactLongInt() {
      assertEquals(8L, StrictMath.multiplyExact(2L, 4));
      assertEquals(Long.MAX_VALUE, StrictMath.multiplyExact(Long.MAX_VALUE, 1));
      assertEquals(Long.MIN_VALUE, StrictMath.multiplyExact(Long.MIN_VALUE / 2L, 2));
      try {
        throw new AssertionError(StrictMath.multiplyExact(Long.MAX_VALUE, 2));
      } catch (ArithmeticException expected) {
      }
      try {
        throw new AssertionError(StrictMath.multiplyExact(Long.MIN_VALUE, 2));
      } catch (ArithmeticException expected) {
      }
    }

    public static void testMultiplyFull() {
      assertEquals(8L, StrictMath.multiplyFull(2, 4));
      assertEquals(
          4611686014132420609L, StrictMath.multiplyFull(Integer.MAX_VALUE, Integer.MAX_VALUE));
      assertEquals(
          -4611686016279904256L, StrictMath.multiplyFull(Integer.MAX_VALUE, Integer.MIN_VALUE));
      assertEquals(
          4611686018427387904L, StrictMath.multiplyFull(Integer.MIN_VALUE, Integer.MIN_VALUE));
    }

    public static void testMultiplyHigh() {
      long[] interestingValues = {
        Long.MIN_VALUE,
        Long.MAX_VALUE,
        Integer.MIN_VALUE,
        Integer.MAX_VALUE,
        Short.MIN_VALUE,
        Short.MAX_VALUE,
        Byte.MIN_VALUE,
        Byte.MAX_VALUE,
        0L,
        -1L,
        1L,
        -42L,
        42L
      };
      for (long x : interestingValues) {
        for (long y : interestingValues) {
          long expected =
              BigInteger.valueOf(x).multiply(BigInteger.valueOf(y)).shiftRight(64).longValue();
          assertEquals(expected, StrictMath.multiplyHigh(x, y));
        }
      }
    }

    public static void testFloorDivLongInt() {
      assertEquals(1L, StrictMath.floorDiv(4L, 4));
      assertEquals(1L, StrictMath.floorDiv(-4L, -4));
      assertEquals(-1L, StrictMath.floorDiv(-4L, 4));
      assertEquals(-1L, StrictMath.floorDiv(4L, -4));

      assertEquals(1L, StrictMath.floorDiv(4L, 3));
      assertEquals(1L, StrictMath.floorDiv(-4L, -3));
      assertEquals(-2L, StrictMath.floorDiv(-4L, 3));
      assertEquals(-2L, StrictMath.floorDiv(4L, -3));

      // Spec edge case: result is actually MAX_VALUE+1 which becomes MIN_VALUE.
      assertEquals(Long.MIN_VALUE, StrictMath.floorDiv(Long.MIN_VALUE, -1));
    }

    public static void testFloorModLongInt() {
      assertEquals(0, StrictMath.floorMod(4L, 4));
      assertEquals(0, StrictMath.floorMod(-4L, -4));
      assertEquals(0, StrictMath.floorMod(-4L, 4));
      assertEquals(0, StrictMath.floorMod(4L, -4));

      assertEquals(1, StrictMath.floorMod(4L, 3));
      assertEquals(-1, StrictMath.floorMod(-4L, -3));
      assertEquals(2, StrictMath.floorMod(-4L, 3));
      assertEquals(-2, StrictMath.floorMod(4L, -3));
    }

    private static void assertEquals(int expected, int actual) {
      if (expected != actual) {
        throw new AssertionError("Expected <" + expected + "> but was <" + actual + '>');
      }
    }

    private static void assertEquals(long expected, long actual) {
      if (expected != actual) {
        throw new AssertionError("Expected <" + expected + "> but was <" + actual + '>');
      }
    }
  }
}