/*
    Copyright (C) 2010 William Hart

    This file is part of FLINT.

    FLINT is free software: you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License (LGPL) as published
    by the Free Software Foundation; either version 2.1 of the License, or
    (at your option) any later version.  See <https://www.gnu.org/licenses/>.
*/

#include <stdio.h>
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "nmod_poly.h"
#include "ulong_extras.h"

int
main(void)
{
    int i, result;
    FLINT_TEST_INIT(state);
    

    flint_printf("divrem_divconquer....");
    fflush(stdout);

    /* Check result of divrem */
    for (i = 0; i < 100 * flint_test_multiplier(); i++)
    {
        nmod_poly_t a, b, q, r, prod;

        mp_limb_t n;
        do n = n_randtest(state);
        while (!n_is_probabprime(n));

        nmod_poly_init(a, n);
        nmod_poly_init(b, n);
        nmod_poly_init(q, n);
        nmod_poly_init(r, n);
        nmod_poly_init(prod, n);
        
        nmod_poly_randtest(a, state, n_randint(state, 2000));
        do nmod_poly_randtest(b, state, n_randint(state, 2000));
        while (b->length == 0);

        nmod_poly_divrem_divconquer(q, r, a, b);
        nmod_poly_mul(prod, q, b);
        nmod_poly_add(prod, prod, r);

        result = (nmod_poly_equal(a, prod));
        if (!result)
        {
            flint_printf("FAIL:\n");
            nmod_poly_print(a), flint_printf("\n\n");
            nmod_poly_print(prod), flint_printf("\n\n");
            nmod_poly_print(q), flint_printf("\n\n");
            nmod_poly_print(r), flint_printf("\n\n");
            flint_printf("n = %wd\n", n);
            abort();
        }
 
        nmod_poly_clear(a);
        nmod_poly_clear(b);
        nmod_poly_clear(q);
        nmod_poly_clear(r);
        nmod_poly_clear(prod);
    }

    /* Check aliasing of a and q */
    for (i = 0; i < 100 * flint_test_multiplier(); i++)
    {
        nmod_poly_t a, b, q, r;

        mp_limb_t n;
        do n = n_randtest(state);
        while (!n_is_probabprime(n));

        nmod_poly_init(a, n);
        nmod_poly_init(b, n);
        nmod_poly_init(q, n);
        nmod_poly_init(r, n);
        nmod_poly_randtest(a, state, n_randint(state, 2000));
        do nmod_poly_randtest(b, state, n_randint(state, 2000));
        while (b->length == 0);

        nmod_poly_divrem_divconquer(q, r, a, b);
        nmod_poly_divrem_divconquer(a, r, a, b);

        result = (nmod_poly_equal(a, q));
        if (!result)
        {
            flint_printf("FAIL:\n");
            nmod_poly_print(a), flint_printf("\n\n");
            nmod_poly_print(b), flint_printf("\n\n");
            nmod_poly_print(q), flint_printf("\n\n");
            nmod_poly_print(r), flint_printf("\n\n");
            flint_printf("n = %wd\n", n);
            abort();
        }

        nmod_poly_clear(a);
        nmod_poly_clear(b);
        nmod_poly_clear(q);
        nmod_poly_clear(r);
    }

    /* Check aliasing of b and q */
    for (i = 0; i < 100 * flint_test_multiplier(); i++)
    {
        nmod_poly_t a, b, q, r;

        mp_limb_t n;
        do n = n_randtest(state);
        while (!n_is_probabprime(n));

        nmod_poly_init(a, n);
        nmod_poly_init(b, n);
        nmod_poly_init(q, n);
        nmod_poly_init(r, n);
        nmod_poly_randtest(a, state, n_randint(state, 2000));
        do nmod_poly_randtest(b, state, n_randint(state, 2000));
        while (b->length == 0);

        nmod_poly_divrem_divconquer(q, r, a, b);
        nmod_poly_divrem_divconquer(b, r, a, b);

        result = (nmod_poly_equal(b, q));
        if (!result)
        {
            flint_printf("FAIL:\n");
            nmod_poly_print(a), flint_printf("\n\n");
            nmod_poly_print(b), flint_printf("\n\n");
            nmod_poly_print(q), flint_printf("\n\n");
            nmod_poly_print(r), flint_printf("\n\n");
            flint_printf("n = %wd\n", n);
            abort();
        }

        nmod_poly_clear(a);
        nmod_poly_clear(b);
        nmod_poly_clear(q);
        nmod_poly_clear(r);
    }

    /* Check aliasing of a and r */
    for (i = 0; i < 100 * flint_test_multiplier(); i++)
    {
        nmod_poly_t a, b, q, r;

        mp_limb_t n;
        do n = n_randtest(state);
        while (!n_is_probabprime(n));

        nmod_poly_init(a, n);
        nmod_poly_init(b, n);
        nmod_poly_init(q, n);
        nmod_poly_init(r, n);
        nmod_poly_randtest(a, state, n_randint(state, 2000));
        do nmod_poly_randtest(b, state, n_randint(state, 2000));
        while (b->length == 0);

        nmod_poly_divrem_divconquer(q, r, a, b);
        nmod_poly_divrem_divconquer(q, a, a, b);

        result = (nmod_poly_equal(a, r));
        if (!result)
        {
            flint_printf("FAIL:\n");
            nmod_poly_print(a), flint_printf("\n\n");
            nmod_poly_print(b), flint_printf("\n\n");
            nmod_poly_print(q), flint_printf("\n\n");
            nmod_poly_print(r), flint_printf("\n\n");
            flint_printf("n = %wd\n", n);
            abort();
        }

        nmod_poly_clear(a);
        nmod_poly_clear(b);
        nmod_poly_clear(q);
        nmod_poly_clear(r);
    }

    /* Check aliasing of b and r */
    for (i = 0; i < 100 * flint_test_multiplier(); i++)
    {
        nmod_poly_t a, b, q, r;

        mp_limb_t n;
        do n = n_randtest(state);
        while (!n_is_probabprime(n));

        nmod_poly_init(a, n);
        nmod_poly_init(b, n);
        nmod_poly_init(q, n);
        nmod_poly_init(r, n);
        nmod_poly_randtest(a, state, n_randint(state, 2000));
        do nmod_poly_randtest(b, state, n_randint(state, 2000));
        while (b->length == 0);

        nmod_poly_divrem_divconquer(q, r, a, b);
        nmod_poly_divrem_divconquer(q, b, a, b);

        result = (nmod_poly_equal(b, r));
        if (!result)
        {
            flint_printf("FAIL:\n");
            nmod_poly_print(a), flint_printf("\n\n");
            nmod_poly_print(b), flint_printf("\n\n");
            nmod_poly_print(q), flint_printf("\n\n");
            nmod_poly_print(r), flint_printf("\n\n");
            flint_printf("n = %wd\n", n);
            abort();
        }

        nmod_poly_clear(a);
        nmod_poly_clear(b);
        nmod_poly_clear(q);
        nmod_poly_clear(r);
    }

    FLINT_TEST_CLEANUP(state);
    
    flint_printf("PASS\n");
    return 0;
}