"""Tests for tools for solving inequalities and systems of inequalities. """

from sympy import (And, Eq, FiniteSet, Ge, Gt, Interval, Le, Lt, Ne, oo,
                   Or, S, sin, sqrt, Symbol, Union, Integral, Sum,
                   Function, Poly, PurePoly, pi, root)
from sympy.solvers.inequalities import (reduce_inequalities,
                                        solve_poly_inequality as psolve,
                                        reduce_rational_inequalities,
                                        solve_univariate_inequality as isolve,
                                        reduce_abs_inequality)
from sympy.polys.rootoftools import RootOf
from sympy.solvers.solvers import solve
from sympy.abc import x, y

from sympy.utilities.pytest import raises, slow


inf = oo.evalf()


def test_solve_poly_inequality():
    assert psolve(Poly(0, x), '==') == [S.Reals]
    assert psolve(Poly(1, x), '==') == [S.EmptySet]
    assert psolve(PurePoly(x + 1, x), ">") == [Interval(-1, oo, True, False)]


def test_reduce_poly_inequalities_real_interval():
    assert reduce_rational_inequalities(
        [[Eq(x**2, 0)]], x, relational=False) == FiniteSet(0)
    assert reduce_rational_inequalities(
        [[Le(x**2, 0)]], x, relational=False) == FiniteSet(0)
    assert reduce_rational_inequalities(
        [[Lt(x**2, 0)]], x, relational=False) == S.EmptySet
    assert reduce_rational_inequalities(
        [[Ge(x**2, 0)]], x, relational=False) == \
        S.Reals if x.is_real else Interval(-oo, oo)
    assert reduce_rational_inequalities(
        [[Gt(x**2, 0)]], x, relational=False) == \
        FiniteSet(0).complement(S.Reals)
    assert reduce_rational_inequalities(
        [[Ne(x**2, 0)]], x, relational=False) == \
        FiniteSet(0).complement(S.Reals)

    assert reduce_rational_inequalities(
        [[Eq(x**2, 1)]], x, relational=False) == FiniteSet(-1, 1)
    assert reduce_rational_inequalities(
        [[Le(x**2, 1)]], x, relational=False) == Interval(-1, 1)
    assert reduce_rational_inequalities(
        [[Lt(x**2, 1)]], x, relational=False) == Interval(-1, 1, True, True)
    assert reduce_rational_inequalities(
        [[Ge(x**2, 1)]], x, relational=False) == \
        Union(Interval(-oo, -1), Interval(1, oo))
    assert reduce_rational_inequalities(
        [[Gt(x**2, 1)]], x, relational=False) == \
        Interval(-1, 1).complement(S.Reals)
    assert reduce_rational_inequalities(
        [[Ne(x**2, 1)]], x, relational=False) == \
        FiniteSet(-1, 1).complement(S.Reals)
    assert reduce_rational_inequalities([[Eq(
        x**2, 1.0)]], x, relational=False) == FiniteSet(-1.0, 1.0).evalf()
    assert reduce_rational_inequalities(
        [[Le(x**2, 1.0)]], x, relational=False) == Interval(-1.0, 1.0)
    assert reduce_rational_inequalities([[Lt(
        x**2, 1.0)]], x, relational=False) == Interval(-1.0, 1.0, True, True)
    assert reduce_rational_inequalities(
        [[Ge(x**2, 1.0)]], x, relational=False) == \
        Union(Interval(-inf, -1.0), Interval(1.0, inf))
    assert reduce_rational_inequalities(
        [[Gt(x**2, 1.0)]], x, relational=False) == \
        Union(Interval(-inf, -1.0, right_open=True),
        Interval(1.0, inf, left_open=True))
    assert reduce_rational_inequalities([[Ne(
        x**2, 1.0)]], x, relational=False) == \
        FiniteSet(-1.0, 1.0).complement(S.Reals)

    s = sqrt(2)

    assert reduce_rational_inequalities([[Lt(
        x**2 - 1, 0), Gt(x**2 - 1, 0)]], x, relational=False) == S.EmptySet
    assert reduce_rational_inequalities([[Le(x**2 - 1, 0), Ge(
        x**2 - 1, 0)]], x, relational=False) == FiniteSet(-1, 1)
    assert reduce_rational_inequalities(
        [[Le(x**2 - 2, 0), Ge(x**2 - 1, 0)]], x, relational=False
        ) == Union(Interval(-s, -1, False, False), Interval(1, s, False, False))
    assert reduce_rational_inequalities(
        [[Le(x**2 - 2, 0), Gt(x**2 - 1, 0)]], x, relational=False
        ) == Union(Interval(-s, -1, False, True), Interval(1, s, True, False))
    assert reduce_rational_inequalities(
        [[Lt(x**2 - 2, 0), Ge(x**2 - 1, 0)]], x, relational=False
        ) == Union(Interval(-s, -1, True, False), Interval(1, s, False, True))
    assert reduce_rational_inequalities(
        [[Lt(x**2 - 2, 0), Gt(x**2 - 1, 0)]], x, relational=False
        ) == Union(Interval(-s, -1, True, True), Interval(1, s, True, True))
    assert reduce_rational_inequalities(
        [[Lt(x**2 - 2, 0), Ne(x**2 - 1, 0)]], x, relational=False
        ) == Union(Interval(-s, -1, True, True), Interval(-1, 1, True, True),
        Interval(1, s, True, True))


def test_reduce_poly_inequalities_complex_relational():
    assert reduce_rational_inequalities(
        [[Eq(x**2, 0)]], x, relational=True) == Eq(x, 0)
    assert reduce_rational_inequalities(
        [[Le(x**2, 0)]], x, relational=True) == Eq(x, 0)
    assert reduce_rational_inequalities(
        [[Lt(x**2, 0)]], x, relational=True) == False
    assert reduce_rational_inequalities(
        [[Ge(x**2, 0)]], x, relational=True) == And(Lt(-oo, x), Lt(x, oo))
    assert reduce_rational_inequalities(
        [[Gt(x**2, 0)]], x, relational=True) == \
        And(Or(And(Lt(-oo, x), Lt(x, 0)), And(Lt(0, x), Lt(x, oo))))
    assert reduce_rational_inequalities(
        [[Ne(x**2, 0)]], x, relational=True) == \
        And(Or(And(Lt(-oo, x), Lt(x, 0)), And(Lt(0, x), Lt(x, oo))))

    for one in (S(1), S(1.0)):
        inf = one*oo
        assert reduce_rational_inequalities(
            [[Eq(x**2, one)]], x, relational=True) == \
            Or(Eq(x, -one), Eq(x, one))
        assert reduce_rational_inequalities(
            [[Le(x**2, one)]], x, relational=True) == \
            And(And(Le(-one, x), Le(x, one)))
        assert reduce_rational_inequalities(
            [[Lt(x**2, one)]], x, relational=True) == \
            And(And(Lt(-one, x), Lt(x, one)))
        assert reduce_rational_inequalities(
            [[Ge(x**2, one)]], x, relational=True) == \
            And(Or(And(Le(one, x), Lt(x, inf)), And(Le(x, -one), Lt(-inf, x))))
        assert reduce_rational_inequalities(
            [[Gt(x**2, one)]], x, relational=True) == \
            And(Or(And(Lt(-inf, x), Lt(x, -one)), And(Lt(one, x), Lt(x, inf))))
        assert reduce_rational_inequalities(
            [[Ne(x**2, one)]], x, relational=True) == \
            Or(And(Lt(-inf, x), Lt(x, -one)),
               And(Lt(-one, x), Lt(x, one)),
               And(Lt(one, x), Lt(x, inf)))


def test_reduce_rational_inequalities_real_relational():
    assert reduce_rational_inequalities([], x) == False
    assert reduce_rational_inequalities(
        [[(x**2 + 3*x + 2)/(x**2 - 16) >= 0]], x, relational=False) == \
        Union(Interval.open(-oo, -4), Interval(-2, -1), Interval.open(4, oo))

    assert reduce_rational_inequalities(
        [[((-2*x - 10)*(3 - x))/((x**2 + 5)*(x - 2)**2) < 0]], x,
        relational=False) == \
        Union(Interval.open(-5, 2), Interval.open(2, 3))

    assert reduce_rational_inequalities([[(x + 1)/(x - 5) <= 0]], x,
        relational=False) == \
        Interval.Ropen(-1, 5)

    assert reduce_rational_inequalities([[(x**2 + 4*x + 3)/(x - 1) > 0]], x,
        relational=False) == \
        Union(Interval.open(-3, -1), Interval.open(1, oo))

    assert reduce_rational_inequalities([[(x**2 - 16)/(x - 1)**2 < 0]], x,
        relational=False) == \
        Union(Interval.open(-4, 1), Interval.open(1, 4))

    assert reduce_rational_inequalities([[(3*x + 1)/(x + 4) >= 1]], x,
        relational=False) == \
        Union(Interval.open(-oo, -4), Interval.Ropen(S(3)/2, oo))

    assert reduce_rational_inequalities([[(x - 8)/x <= 3 - x]], x,
        relational=False) == \
        Union(Interval.Lopen(-oo, -2), Interval.Lopen(0, 4))


def test_reduce_abs_inequalities():
    e = abs(x - 5) < 3
    ans = And(Lt(2, x), Lt(x, 8))
    assert reduce_inequalities(e) == ans
    assert reduce_inequalities(e, x) == ans
    assert reduce_inequalities(abs(x - 5)) == Eq(x, 5)
    assert reduce_inequalities(
        abs(2*x + 3) >= 8) == Or(And(Le(S(5)/2, x), Lt(x, oo)),
        And(Le(x, -S(11)/2), Lt(-oo, x)))
    assert reduce_inequalities(abs(x - 4) + abs(
        3*x - 5) < 7) == And(Lt(S(1)/2, x), Lt(x, 4))
    assert reduce_inequalities(abs(x - 4) + abs(3*abs(x) - 5) < 7) == \
        Or(And(S(-2) < x, x < -1), And(S(1)/2 < x, x < 4))

    nr = Symbol('nr', real=False)
    raises(TypeError, lambda: reduce_inequalities(abs(nr - 5) < 3))


def test_reduce_inequalities_general():
    assert reduce_inequalities(Ge(sqrt(2)*x, 1)) == And(sqrt(2)/2 <= x, x < oo)
    assert reduce_inequalities(PurePoly(x + 1, x) > 0) == And(S(-1) < x, x < oo)


def test_reduce_inequalities_boolean():
    assert reduce_inequalities(
        [Eq(x**2, 0), True]) == Eq(x, 0)
    assert reduce_inequalities([Eq(x**2, 0), False]) == False


def test_reduce_inequalities_multivariate():
    assert reduce_inequalities([Ge(x**2, 1), Ge(y**2, 1)]) == And(
        Or(And(Le(1, x), Lt(x, oo)), And(Le(x, -1), Lt(-oo, x))),
        Or(And(Le(1, y), Lt(y, oo)), And(Le(y, -1), Lt(-oo, y))))


def test_reduce_inequalities_errors():
    raises(NotImplementedError, lambda: reduce_inequalities(Ge(sin(x) + x, 1)))
    raises(NotImplementedError, lambda: reduce_inequalities(Ge(x**2*y + y, 1)))


def test_hacky_inequalities():
    assert reduce_inequalities(x + y < 1, symbols=[x]) == (x < 1 - y)
    assert reduce_inequalities(x + y >= 1, symbols=[x]) == (x >= 1 - y)


def test_issue_6343():
    eq = -3*x**2/2 - 45*x/4 + S(33)/2 > 0
    assert reduce_inequalities(eq) == \
        And(x < -S(15)/4 + sqrt(401)/4, -sqrt(401)/4 - S(15)/4 < x)


def test_issue_8235():
    assert reduce_inequalities(x**2 - 1 < 0) == \
        And(S(-1) < x, x < S(1))
    assert reduce_inequalities(x**2 - 1 <= 0) == \
        And(S(-1) <= x, x <= 1)
    assert reduce_inequalities(x**2 - 1 > 0) == \
        Or(And(-oo < x, x < -1), And(x < oo, S(1) < x))
    assert reduce_inequalities(x**2 - 1 >= 0) == \
        Or(And(-oo < x, x <= S(-1)), And(S(1) <= x, x < oo))

    eq = x**8 + x - 9  # we want RootOf solns here
    sol = solve(eq >= 0)
    tru = Or(And(RootOf(eq, 1) <= x, x < oo), And(-oo < x, x <= RootOf(eq, 0)))
    assert sol == tru

    # recast vanilla as real
    assert solve(sqrt((-x + 1)**2) < 1) == And(S(0) < x, x < 2)


def test_issue_5526():
    assert reduce_inequalities(S(0) <=
        x + Integral(y**2, (y, 1, 3)) - 1, [x]) == \
        (-Integral(y**2, (y, 1, 3)) + 1 <= x)
    f = Function('f')
    e = Sum(f(x), (x, 1, 3))
    assert reduce_inequalities(S(0) <= x + e + y**2, [x]) == \
        (-y**2 - Sum(f(x), (x, 1, 3)) <= x)


def test_solve_univariate_inequality():
    assert isolve(x**2 >= 4, x, relational=False) == Union(Interval(-oo, -2),
        Interval(2, oo))
    assert isolve(x**2 >= 4, x) == Or(And(Le(2, x), Lt(x, oo)), And(Le(x, -2),
        Lt(-oo, x)))
    assert isolve((x - 1)*(x - 2)*(x - 3) >= 0, x, relational=False) == \
        Union(Interval(1, 2), Interval(3, oo))
    assert isolve((x - 1)*(x - 2)*(x - 3) >= 0, x) == \
        Or(And(Le(1, x), Le(x, 2)), And(Le(3, x), Lt(x, oo)))
    # issue 2785:
    assert isolve(x**3 - 2*x - 1 > 0, x, relational=False) == \
        Union(Interval(-1, -sqrt(5)/2 + S(1)/2, True, True),
              Interval(S(1)/2 + sqrt(5)/2, oo, True, True))
    # issue 2794:
    assert isolve(x**3 - x**2 + x - 1 > 0, x, relational=False) == \
        Interval(1, oo, True)

    # XXX should be limited in domain, e.g. between 0 and 2*pi
    assert isolve(sin(x) < S.Half, x) == \
        Or(And(-oo < x, x < pi/6), And(5*pi/6 < x, x < oo))
    assert isolve(sin(x) > S.Half, x) == And(pi/6 < x, x < 5*pi/6)

    # numerical testing in valid() is needed
    assert isolve(x**7 - x - 2 > 0, x) == \
        And(RootOf(x**7 - x - 2, 0) < x, x < oo)

    # handle numerator and denominator; although these would be handled as
    # rational inequalities, these test confirm that the right thing is done
    # when the domain is EX (e.g. when 2 is replaced with sqrt(2))
    assert isolve(1/(x - 2) > 0, x) == And(S(2) < x, x < oo)
    den = ((x - 1)*(x - 2)).expand()
    assert isolve((x - 1)/den <= 0, x) == \
        Or(And(-oo < x, x < 1), And(S(1) < x, x < 2))


@slow
def test_slow_general_univariate():
    r = RootOf(x**5 - x**2 + 1, 0)
    assert solve(sqrt(x) + 1/root(x, 3) > 1) == \
        Or(And(S(0) < x, x < r**6), And(r**6 < x, x < oo))


def test_issue_8545():
    eq = 1 - x - abs(1 - x)
    ans = And(Lt(1, x), Lt(x, oo))
    assert reduce_abs_inequality(eq, '<', x) == ans
    eq = 1 - x - sqrt((1 - x)**2)
    assert reduce_inequalities(eq < 0) == ans


def test_issue_8974():
    assert isolve(-oo < x, x) == And(-oo < x, x < oo)
    assert isolve(oo > x, x) == And(-oo < x, x < oo)
