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package com.github.ibole.infrastructure.common.utils;

import java.math.BigInteger;

/*********************************************************************************************
 * .
 * 
 * 
 * 
 * Copyright 2016, iBole Inc. All rights reserved.
 * 
 * 

 * 
 *********************************************************************************************/


/**
 * Numbers utilities.
 */
public final class Numbers {
  /**
   * Safely convert a {@literal long} to an {@literal int}.
   * 
   * If the {@literal long} is greater than {@link Integer#MAX_VALUE} then {@link Integer#MAX_VALUE}
   * is returned.
   * 
   * If the {@literal long} is lesser than {@link Integer#MIN_VALUE} then {@link Integer#MIN_VALUE}
   * is returned.
   * 

   * Implementation use {@literal BigInteger}s. See {@link Math#toIntExact(long)} for a throwing
   * equivalent.
   * 
   * @param aLong A {@literal long}
   * 
   * @return Converted {@literal int}
   */
  public static int safeIntValueOf(long aLong) {
    return safeIntValueOf(BigInteger.valueOf(aLong));
  }

  /**
   * Safely compute the sum of the given {@literal long}s.
   * 
   * If the sum of all the {@literal long}s is greater than {@link Long#MAX_VALUE} then
   * {@link Long#MAX_VALUE} is returned.
   * 

   * If the sum of all the {@literal long}s is lesser than {@link Long#MIN_VALUE} then
   * {@link Long#MIN_VALUE} is returned.
   * 

   * Implementation use {@literal BigInteger}s. See {@link Math#addExact(long, long)} for a throwing
   * equivalent.
   * 
   * @param longs {@literal long}s to sum
   * 
   * @return Computed sum
   */
  public static long safeLongValueOfSum(long... longs) {
    BigInteger bigint = BigInteger.ZERO;
    for (long each : longs) {
      bigint = bigint.add(BigInteger.valueOf(each));
    }
    return safeLongValueOf(bigint);
  }

  /**
   * Safely compute the product of the given {@literal long}s.
   * 
   * If the product of all the {@literal long}s is greater than {@link Long#MAX_VALUE} then
   * {@link Long#MAX_VALUE} is returned.
   * 

   * If the product of all the {@literal long}s is lesser than {@link Long#MIN_VALUE} then
   * {@link Long#MIN_VALUE} is returned.
   * 
   * Implementation use {@literal BigInteger}s. See {@link Math#multiplyExact(long, long)} for a
   * throwing equivalent.
   * 
   * @param longs {@literal long}s to multiply
   * 
   * @return Computed product
   */
  public static long safeLongValueOfMultiply(long... longs) {
    BigInteger bigint = BigInteger.ONE;
    for (long each : longs) {
      bigint = bigint.multiply(BigInteger.valueOf(each));
    }
    return safeLongValueOf(bigint);
  }

  private static int safeIntValueOf(BigInteger bigint) {
    try {
      return bigint.intValueExact();
    } catch (ArithmeticException tooBIG) {
      return bigint.signum() == 1 ? Integer.MAX_VALUE : Integer.MIN_VALUE;
    }
  }

  private static long safeLongValueOf(BigInteger bigint) {
    try {
      return bigint.longValueExact();
    } catch (ArithmeticException tooBIG) {
      return bigint.signum() == 1 ? Long.MAX_VALUE : Long.MIN_VALUE;
    }
  }

  private Numbers() {}
}