/*
    Copyright (C) 2009 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 "fmpz.h"
#include "fmpz_poly.h"
#include "ulong_extras.h"

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

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

    

    /* Check q*b + r = a, no aliasing */
    for (i = 0; i < 100 * flint_test_multiplier(); i++)
    {
        fmpz_poly_t a, b, q, r, prod;
        slong d;
        fmpz_t p;

        fmpz_init(p);
        fmpz_poly_init(a);
        fmpz_poly_init(b);
        fmpz_poly_init(q);
        fmpz_poly_init(r);
        fmpz_poly_init(prod);
        fmpz_poly_randtest(a, state, n_randint(state, 80), 100);
        fmpz_poly_randtest_not_zero(b, state, n_randint(state, 80) + 1, 100);

        fmpz_poly_pseudo_divrem_cohen(q, r, a, b);
        fmpz_poly_mul(prod, q, b);
        fmpz_poly_add(prod, prod, r);
        d = a->length - b->length + 1;
        d = FLINT_MAX(d, 0);
        fmpz_pow_ui(p, b->coeffs + b->length - 1, d);
        fmpz_poly_scalar_mul_fmpz(a, a, p);

        result = (fmpz_poly_equal(a, prod));
        if (!result)
        {
            flint_printf("FAIL (correctness):\n");
            flint_printf("a    = "), fmpz_poly_print(a), flint_printf("\n\n");
            flint_printf("b    = "), fmpz_poly_print(b), flint_printf("\n\n");
            flint_printf("prod = "), fmpz_poly_print(prod), flint_printf("\n\n");
            flint_printf("q    = "), fmpz_poly_print(q), flint_printf("\n\n");
            flint_printf("r    = "), fmpz_poly_print(r), flint_printf("\n\n");
            abort();
        }

        fmpz_clear(p);
        fmpz_poly_clear(a);
        fmpz_poly_clear(b);
        fmpz_poly_clear(q);
        fmpz_poly_clear(r);
        fmpz_poly_clear(prod);
    }

    /* Check r and a alias */
    for (i = 0; i < 50 * flint_test_multiplier(); i++)
    {
        fmpz_poly_t a, b, q, r;

        fmpz_poly_init(a);
        fmpz_poly_init(b);
        fmpz_poly_init(q);
        fmpz_poly_init(r);
        fmpz_poly_randtest(a, state, n_randint(state, 80), 100);
        fmpz_poly_randtest_not_zero(b, state, n_randint(state, 80) + 1, 100);

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

        result = (fmpz_poly_equal(a, r));
        if (!result)
        {
            flint_printf("FAIL (aliasing r, a):\n");
            fmpz_poly_print(a), flint_printf("\n\n");
            fmpz_poly_print(q), flint_printf("\n\n");
            fmpz_poly_print(r), flint_printf("\n\n");
            abort();
        }

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

    /* Check r and b alias */
    for (i = 0; i < 50 * flint_test_multiplier(); i++)
    {
        fmpz_poly_t a, b, q, r;

        fmpz_poly_init(a);
        fmpz_poly_init(b);
        fmpz_poly_init(q);
        fmpz_poly_init(r);
        fmpz_poly_randtest(a, state, n_randint(state, 80), 100);
        fmpz_poly_randtest_not_zero(b, state, n_randint(state, 80) + 1, 100);

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

        result = (fmpz_poly_equal(b, r));
        if (!result)
        {
            flint_printf("FAIL (aliasing r, b):\n");
            fmpz_poly_print(a), flint_printf("\n\n");
            fmpz_poly_print(q), flint_printf("\n\n");
            fmpz_poly_print(r), flint_printf("\n\n");
            abort();
        }

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

    /* Check q and a alias */
    for (i = 0; i < 50 * flint_test_multiplier(); i++)
    {
        fmpz_poly_t a, b, q, r;

        fmpz_poly_init(a);
        fmpz_poly_init(b);
        fmpz_poly_init(q);
        fmpz_poly_init(r);
        fmpz_poly_randtest(a, state, n_randint(state, 80), 100);
        fmpz_poly_randtest_not_zero(b, state, n_randint(state, 80) + 1, 100);

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

        result = (fmpz_poly_equal(a, q));
        if (!result)
        {
            flint_printf("FAIL (aliasing q, a):\n");
            fmpz_poly_print(a), flint_printf("\n\n");
            fmpz_poly_print(q), flint_printf("\n\n");
            fmpz_poly_print(r), flint_printf("\n\n");
            abort();
        }

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

    /* Check q and b alias */
    for (i = 0; i < 50 * flint_test_multiplier(); i++)
    {
        fmpz_poly_t a, b, q, r;

        fmpz_poly_init(a);
        fmpz_poly_init(b);
        fmpz_poly_init(q);
        fmpz_poly_init(r);
        fmpz_poly_randtest(a, state, n_randint(state, 80), 100);
        fmpz_poly_randtest_not_zero(b, state, n_randint(state, 80) + 1, 100);

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

        result = (fmpz_poly_equal(b, q));
        if (!result)
        {
            flint_printf("FAIL (aliasing q, b):\n");
            fmpz_poly_print(a), flint_printf("\n\n");
            fmpz_poly_print(q), flint_printf("\n\n");
            fmpz_poly_print(r), flint_printf("\n\n");
            abort();
        }

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

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