/*

 * Copyright 2003-2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

/*

 * @test

 * @bug 4851776 4907265 6177836

 * @summary Some tests for the divide methods.

 * @author Joseph D. Darcy

 * @compile -source 1.5 DivideTests.java

 * @run main DivideTests

 */

import java.math.*;

import static java.math.BigDecimal.*;

public class DivideTests {

    // Preliminary exact divide method; could be used for comparison

    // purposes.

    BigDecimal anotherDivide(BigDecimal dividend, BigDecimal divisor) {

        /*

         * Handle zero cases first.

         */

        if (divisor.signum() == 0) {   // x/0

            if (dividend.signum() == 0)    // 0/0

                throw new ArithmeticException("Division undefined");  // NaN

            throw new ArithmeticException("Division by zero");

        }

        if (dividend.signum() == 0)        // 0/y

            return BigDecimal.ZERO;

        else {

            /*

             * Determine if there is a result with a terminating

             * decimal expansion.  Putting aside overflow and

             * underflow considerations, the existance of an exact

             * result only depends on the ratio of the intVal's of the

             * dividend (i.e. this) and and divisor since the scales

             * of the argument just affect where the decimal point

             * lies.

             *

             * For the ratio of (a = this.intVal) and (b =

             * divisor.intVal) to have a finite decimal expansion,

             * once a/b is put in lowest terms, b must be equal to

             * (2^i)*(5^j) for some integer i,j >= 0.  Therefore, we

             * first compute to see if b_prime =(b/gcd(a,b)) is equal

             * to (2^i)*(5^j).

             */

            BigInteger TWO  = BigInteger.valueOf(2);

            BigInteger FIVE = BigInteger.valueOf(5);

            BigInteger TEN  = BigInteger.valueOf(10);

            BigInteger divisorIntvalue  = divisor.scaleByPowerOfTen(divisor.scale()).toBigInteger().abs();

            BigInteger dividendIntvalue = dividend.scaleByPowerOfTen(dividend.scale()).toBigInteger().abs();

            BigInteger b_prime = divisorIntvalue.divide(dividendIntvalue.gcd(divisorIntvalue));

            boolean goodDivisor = false;

            int i=0, j=0;

            badDivisor: {

                while(! b_prime.equals(BigInteger.ONE) ) {

                    int b_primeModTen = b_prime.mod(TEN).intValue() ;

                    switch(b_primeModTen) {

                    case 0:

                        // b_prime divisible by 10=2*5, increment i and j

                        i++;

                        j++;

                        b_prime = b_prime.divide(TEN);

                        break;

                    case 5:

                        // b_prime divisible by 5, increment j

                        j++;

                        b_prime = b_prime.divide(FIVE);

                        break;

                    case 2:

                    case 4:

                    case 6:

                    case 8:

                        // b_prime divisible by 2, increment i

                        i++;

                        b_prime = b_prime.divide(TWO);

                        break;

                    default: // hit something we shouldn't have

                        b_prime = BigInteger.ONE; // terminate loop

                        break badDivisor;

                    }

                }

                goodDivisor = true;

            }

            if( ! goodDivisor ) {

                throw new ArithmeticException("Non terminating decimal expansion");

            }

            else {

                // What is a rule for determining how many digits are

                // needed?  Once that is determined, cons up a new

                // MathContext object and pass it on to the divide(bd,

                // mc) method; precision == ?, roundingMode is unnecessary.

                // Are we sure this is the right scale to use?  Should

                // also determine a precision-based method.

                MathContext mc = new MathContext(dividend.precision() +

                                                 (int)Math.ceil(

                                                      10.0*divisor.precision()/3.0),

                                                 RoundingMode.UNNECESSARY);

                // Should do some more work here to rescale, etc.

                return dividend.divide(divisor, mc);

            }

        }

    }

    public static int powersOf2and5() {

        int failures = 0;

        for(int i = 0; i < 6; i++) {

            int powerOf2 = (int)StrictMath.pow(2.0, i);

            for(int j = 0; j < 6; j++) {

                int powerOf5 = (int)StrictMath.pow(5.0, j);

                int product;

                BigDecimal bd;

                try {

                    bd = BigDecimal.ONE.divide(new BigDecimal(product=powerOf2*powerOf5));

                } catch (ArithmeticException e) {

                    failures++;

                    System.err.println((new BigDecimal(powerOf2)).toString() + " / " +

                                       (new BigDecimal(powerOf5)).toString() + " threw an exception.");

                    e.printStackTrace();

                }

                try {

                    bd = new BigDecimal(powerOf2).divide(new BigDecimal(powerOf5));

                } catch (ArithmeticException e) {

                    failures++;

                    System.err.println((new BigDecimal(powerOf2)).toString() + " / " +

                                       (new BigDecimal(powerOf5)).toString() + " threw an exception.");

                    e.printStackTrace();

                }

                try {

                    bd = new BigDecimal(powerOf5).divide(new BigDecimal(powerOf2));

                } catch (ArithmeticException e) {

                    failures++;

                    System.err.println((new BigDecimal(powerOf5)).toString() + " / " +

                                       (new BigDecimal(powerOf2)).toString() + " threw an exception.");

                    e.printStackTrace();

                }

            }

        }

        return failures;

    }

    public static int nonTerminating() {

        int failures = 0;

        int[] primes = {1, 3, 7, 13, 17};

        // For each pair of prime products, verify the ratio of

        // non-equal products has a non-terminating expansion.

        for(int i = 0; i < primes.length; i++) {

            for(int j = i+1; j < primes.length; j++) {

                for(int m = 0; m < primes.length; m++) {

                    for(int n = m+1; n < primes.length; n++) {

                        int dividend = primes[i] * primes[j];

                        int divisor  = primes[m] * primes[n];

                        if ( ((dividend/divisor) * divisor) != dividend ) {

                            try {

                                BigDecimal quotient = (new BigDecimal(dividend).

                                                       divide(new BigDecimal(divisor)));

                                failures++;

                                System.err.println("Exact quotient " + quotient.toString() +

                                                   " returned for non-terminating fraction " +

                                                   dividend + " / " + divisor + ".");

                            }

                            catch (ArithmeticException e) {

                                ; // Correct result

                            }

                        }

                    }

                }

            }

        }

        return failures;

    }

    public static int properScaleTests(){

        int failures = 0;

        BigDecimal[][] testCases = {

            {new BigDecimal("1"),       new BigDecimal("5"),            new BigDecimal("2e-1")},

            {new BigDecimal("1"),       new BigDecimal("50e-1"),        new BigDecimal("2e-1")},

            {new BigDecimal("10e-1"),   new BigDecimal("5"),            new BigDecimal("2e-1")},

            {new BigDecimal("1"),       new BigDecimal("500e-2"),       new BigDecimal("2e-1")},

            {new BigDecimal("100e-2"),  new BigDecimal("5"),            new BigDecimal("20e-2")},

            {new BigDecimal("1"),       new BigDecimal("32"),           new BigDecimal("3125e-5")},

            {new BigDecimal("1"),       new BigDecimal("64"),           new BigDecimal("15625e-6")},

            {new BigDecimal("1.0000000"),       new BigDecimal("64"),   new BigDecimal("156250e-7")},

        };

        for(BigDecimal[] tc : testCases) {

            BigDecimal quotient;

            if (! (quotient = tc[0].divide(tc[1])).equals(tc[2]) ) {

                failures++;

                System.err.println("Unexpected quotient from " + tc[0] + " / " + tc[1] +

                                   "; expected " + tc[2] + " got " + quotient);

            }

        }

        return failures;

    }

    public static int trailingZeroTests() {

        int failures = 0;

        MathContext mc = new MathContext(3, RoundingMode.FLOOR);

        BigDecimal[][] testCases = {

            {new BigDecimal("19"),      new BigDecimal("100"),          new BigDecimal("0.19")},

            {new BigDecimal("21"),      new BigDecimal("110"),          new BigDecimal("0.190")},

        };

        for(BigDecimal[] tc : testCases) {

            BigDecimal quotient;

            if (! (quotient = tc[0].divide(tc[1], mc)).equals(tc[2]) ) {

                failures++;

                System.err.println("Unexpected quotient from " + tc[0] + " / " + tc[1] +

                                   "; expected " + tc[2] + " got " + quotient);

            }

        }

        return failures;

    }

    public static int scaledRoundedDivideTests() {

        int failures = 0;

        // Tests of the traditional scaled divide under different

        // rounding modes.

        // Encode rounding mode and scale for the divide in a

        // BigDecimal with the significand equal to the rounding mode

        // and the scale equal to the number's scale.

        // {dividend, dividisor, rounding, quotient}

        BigDecimal a = new BigDecimal("31415");

        BigDecimal a_minus = a.negate();

        BigDecimal b = new BigDecimal("10000");

        BigDecimal c = new BigDecimal("31425");

        BigDecimal c_minus = c.negate();

        BigDecimal[][] testCases = {

            {a,         b,      BigDecimal.valueOf(ROUND_UP, 3),        new BigDecimal("3.142")},

            {a_minus,   b,      BigDecimal.valueOf(ROUND_UP, 3),        new BigDecimal("-3.142")},

            {a,         b,      BigDecimal.valueOf(ROUND_DOWN, 3),      new BigDecimal("3.141")},

            {a_minus,   b,      BigDecimal.valueOf(ROUND_DOWN, 3),      new BigDecimal("-3.141")},

            {a,         b,      BigDecimal.valueOf(ROUND_CEILING, 3),   new BigDecimal("3.142")},

            {a_minus,   b,      BigDecimal.valueOf(ROUND_CEILING, 3),   new BigDecimal("-3.141")},

            {a,         b,      BigDecimal.valueOf(ROUND_FLOOR, 3),     new BigDecimal("3.141")},

            {a_minus,   b,      BigDecimal.valueOf(ROUND_FLOOR, 3),     new BigDecimal("-3.142")},

            {a,         b,      BigDecimal.valueOf(ROUND_HALF_UP, 3),   new BigDecimal("3.142")},

            {a_minus,   b,      BigDecimal.valueOf(ROUND_HALF_UP, 3),   new BigDecimal("-3.142")},

            {a,         b,      BigDecimal.valueOf(ROUND_DOWN, 3),      new BigDecimal("3.141")},

            {a_minus,   b,      BigDecimal.valueOf(ROUND_DOWN, 3),      new BigDecimal("-3.141")},

            {a,         b,      BigDecimal.valueOf(ROUND_HALF_EVEN, 3), new BigDecimal("3.142")},

            {a_minus,   b,      BigDecimal.valueOf(ROUND_HALF_EVEN, 3), new BigDecimal("-3.142")},

            {c,         b,      BigDecimal.valueOf(ROUND_HALF_EVEN, 3), new BigDecimal("3.142")},

            {c_minus,   b,      BigDecimal.valueOf(ROUND_HALF_EVEN, 3), new BigDecimal("-3.142")},

        };

        for(BigDecimal tc[] : testCases) {

            int scale = tc[2].scale();

            int rm = tc[2].unscaledValue().intValue();

            BigDecimal quotient = tc[0].divide(tc[1], scale, rm);

            if (!quotient.equals(tc[3])) {

                failures++;

                System.err.println("Unexpected quotient from " + tc[0] + " / " + tc[1] +

                                   " scale " + scale + " rounding mode " + RoundingMode.valueOf(rm) +

                                   "; expected " + tc[3] + " got " + quotient);

            }

        }

        return failures;

    }

    public static void main(String argv[]) {

        int failures = 0;

        failures += powersOf2and5();

        failures += nonTerminating();

        failures += properScaleTests();

        failures += trailingZeroTests();

        failures += scaledRoundedDivideTests();

        if (failures > 0) {

            throw new RuntimeException("Incurred " + failures +

                                       " failures while testing exact divide.");

        }

    }

}