/*
 * Copyright 2009 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 * 
 * INCLUDES MODIFICATIONS BY GOOGLE.
 */
/**
 * author Elena Semukhina
 */
package com.google.gwt.emultest.java.math;

import com.google.gwt.emultest.java.util.EmulTestBase;

import java.math.BigInteger;

/**
 * Class: java.math.BigInteger Methods: modPow, modInverse, and gcd.
 */
public class BigIntegerModPowTest extends EmulTestBase {
  /**
   * gcd: both numbers are zeros.
   */
  public void testGcdBothZeros() {
    byte rBytes[] = {0};
    BigInteger aNumber = new BigInteger("0");
    BigInteger bNumber = BigInteger.valueOf(0L);
    BigInteger result = aNumber.gcd(bNumber);
    byte resBytes[] = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 0, result.signum());
  }

  /**
   * gcd: the first number is longer.
   */
  public void testGcdFirstLonger() {
    byte aBytes[] = {
        -15, 24, 123, 56, -11, -112, -34, -98, 8, 10, 12, 14, 25, 125, -15, 28,
        -127};
    byte bBytes[] = {-12, 1, 0, 0, 0, 23, 44, 55, 66};
    int aSign = 1;
    int bSign = 1;
    byte rBytes[] = {7};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger bNumber = new BigInteger(bSign, bBytes);
    BigInteger result = aNumber.gcd(bNumber);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * gcd: the first number is zero.
   */
  public void testGcdFirstZero() {
    byte aBytes[] = {0};
    byte bBytes[] = {15, 24, 123, 57, -15, 24, 123, 57, -15, 24, 123, 57};
    int aSign = 1;
    int bSign = 1;
    byte rBytes[] = {15, 24, 123, 57, -15, 24, 123, 57, -15, 24, 123, 57};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger bNumber = new BigInteger(bSign, bBytes);
    BigInteger result = aNumber.gcd(bNumber);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * gcd: the first number is ZERO.
   */
  public void testGcdFirstZERO() {
    byte bBytes[] = {15, 24, 123, 57, -15, 24, 123, 57, -15, 24, 123, 57};
    int bSign = 1;
    byte rBytes[] = {15, 24, 123, 57, -15, 24, 123, 57, -15, 24, 123, 57};
    BigInteger aNumber = BigInteger.ZERO;
    BigInteger bNumber = new BigInteger(bSign, bBytes);
    BigInteger result = aNumber.gcd(bNumber);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * gcd: the second number is longer.
   */
  public void testGcdSecondLonger() {
    byte aBytes[] = {-12, 1, 0, 0, 0, 23, 44, 55, 66};
    byte bBytes[] = {
        -15, 24, 123, 56, -11, -112, -34, -98, 8, 10, 12, 14, 25, 125, -15, 28,
        -127};
    int aSign = 1;
    int bSign = 1;
    byte rBytes[] = {7};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger bNumber = new BigInteger(bSign, bBytes);
    BigInteger result = aNumber.gcd(bNumber);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * gcd: the second number is zero.
   */
  public void testGcdSecondZero() {
    byte aBytes[] = {15, 24, 123, 57, -15, 24, 123, 57, -15, 24, 123, 57};
    byte bBytes[] = {0};
    int aSign = 1;
    int bSign = 1;
    byte rBytes[] = {15, 24, 123, 57, -15, 24, 123, 57, -15, 24, 123, 57};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger bNumber = new BigInteger(bSign, bBytes);
    BigInteger result = aNumber.gcd(bNumber);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * modInverse: non-positive modulus.
   */
  public void testmodInverseException() {
    byte aBytes[] = {1, 2, 3, 4, 5, 6, 7};
    byte mBytes[] = {1, 2, 3};
    int aSign = 1;
    int mSign = -1;
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger modulus = new BigInteger(mSign, mBytes);
    try {
      aNumber = aNumber.modInverse(modulus);
      fail("ArithmeticException has not been caught");
    } catch (ArithmeticException e) {
      assertEquals("Improper exception message",
          "BigInteger: modulus not positive", e.getMessage());
    }
  }

  /**
   * modInverse: negative number.
   */
  public void testmodInverseNeg1() {
    byte aBytes[] = {
        15, 24, 123, 56, -11, -112, -34, -98, 8, 10, 12, 14, 25, 125, -15, 28,
        -127};
    byte mBytes[] = {2, 122, 45, 36, 100};
    int aSign = -1;
    int mSign = 1;
    byte rBytes[] = {0, -41, 4, -91, 27};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger modulus = new BigInteger(mSign, mBytes);
    BigInteger result = aNumber.modInverse(modulus);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * modInverse: negative number (another case: x < 0).
   */
  public void testmodInverseNeg2() {
    byte aBytes[] = {-15, 24, 123, 57, -15, 24, 123, 57, -15, 24, 123, 57};
    byte mBytes[] = {122, 2, 4, 122, 2, 4};
    byte rBytes[] = {85, 47, 127, 4, -128, 45};
    BigInteger aNumber = new BigInteger(aBytes);
    BigInteger modulus = new BigInteger(mBytes);
    BigInteger result = aNumber.modInverse(modulus);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * modInverse: non-invertible number.
   */
  public void testmodInverseNonInvertible() {
    byte aBytes[] = {
        -15, 24, 123, 56, -11, -112, -34, -98, 8, 10, 12, 14, 25, 125, -15, 28,
        -127};
    byte mBytes[] = {-12, 1, 0, 0, 0, 23, 44, 55, 66};
    int aSign = 1;
    int mSign = 1;
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger modulus = new BigInteger(mSign, mBytes);
    try {
      aNumber = aNumber.modInverse(modulus);
      fail("ArithmeticException has not been caught");
    } catch (ArithmeticException e) {
      assertEquals("Improper exception message", "BigInteger not invertible.",
          e.getMessage());
    }
  }

  /**
   * modInverse: positive number.
   */
  public void testmodInversePos1() {
    byte aBytes[] = {
        24, 123, 56, -11, -112, -34, -98, 8, 10, 12, 14, 25, 125, -15, 28, -127};
    byte mBytes[] = {122, 45, 36, 100, 122, 45};
    int aSign = 1;
    int mSign = 1;
    byte rBytes[] = {47, 3, 96, 62, 87, 19};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger modulus = new BigInteger(mSign, mBytes);
    BigInteger result = aNumber.modInverse(modulus);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * modInverse: positive number (another case: a < 0).
   */
  public void testmodInversePos2() {
    byte aBytes[] = {
        15, 24, 123, 56, -11, -112, -34, -98, 8, 10, 12, 14, 25, 125, -15, 28,
        -127};
    byte mBytes[] = {2, 122, 45, 36, 100};
    int aSign = 1;
    int mSign = 1;
    byte rBytes[] = {1, -93, 40, 127, 73};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger modulus = new BigInteger(mSign, mBytes);
    BigInteger result = aNumber.modInverse(modulus);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * modPow: non-positive modulus.
   */
  public void testModPowException() {
    byte aBytes[] = {1, 2, 3, 4, 5, 6, 7};
    byte eBytes[] = {1, 2, 3, 4, 5};
    byte mBytes[] = {1, 2, 3};
    int aSign = 1;
    int eSign = 1;
    int mSign = -1;
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger exp = new BigInteger(eSign, eBytes);
    BigInteger modulus = new BigInteger(mSign, mBytes);
    try {
      aNumber = aNumber.modPow(exp, modulus);
      fail("ArithmeticException has not been caught");
    } catch (ArithmeticException e) {
      assertEquals("Improper exception message",
          "BigInteger: modulus not positive", e.getMessage());
    }
  }

  /**
   * modPow: negative exponent.
   */
  public void testModPowNegExp() {
    byte aBytes[] = {-127, 100, 56, 7, 98, -1, 39, -128, 127, 75, 48, -7};
    byte eBytes[] = {27, -15, 65, 39};
    byte mBytes[] = {-128, 2, 3, 4, 5};
    int aSign = 1;
    int eSign = -1;
    int mSign = 1;
    byte rBytes[] = {12, 118, 46, 86, 92};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger exp = new BigInteger(eSign, eBytes);
    BigInteger modulus = new BigInteger(mSign, mBytes);
    BigInteger result = aNumber.modPow(exp, modulus);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }

  /**
   * modPow: positive exponent.
   */
  public void testModPowPosExp() {
    byte aBytes[] = {-127, 100, 56, 7, 98, -1, 39, -128, 127, 75, 48, -7};
    byte eBytes[] = {27, -15, 65, 39};
    byte mBytes[] = {-128, 2, 3, 4, 5};
    int aSign = 1;
    int eSign = 1;
    int mSign = 1;
    byte rBytes[] = {113, 100, -84, -28, -85};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger exp = new BigInteger(eSign, eBytes);
    BigInteger modulus = new BigInteger(mSign, mBytes);
    BigInteger result = aNumber.modPow(exp, modulus);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for (int i = 0; i < resBytes.length; i++) {
      assertEquals("Byte " + i, rBytes[i], resBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
  }
}