from sympy import exp, symbols, sqrt, I, pi, Mul, Integer, Wild
from sympy.matrices import Matrix

from sympy.physics.quantum.gate import (XGate, YGate, ZGate, random_circuit,
        CNOT, IdentityGate, H, X, Y, S, T, Z, SwapGate, gate_simp, gate_sort,
        CNotGate, TGate, HadamardGate, PhaseGate, UGate, CGate)
from sympy.physics.quantum.commutator import Commutator
from sympy.physics.quantum.anticommutator import AntiCommutator
from sympy.physics.quantum.represent import represent
from sympy.physics.quantum.qapply import qapply
from sympy.physics.quantum.qubit import Qubit, IntQubit, qubit_to_matrix, \
    matrix_to_qubit
from sympy.physics.quantum.matrixutils import matrix_to_zero
from sympy.physics.quantum.matrixcache import sqrt2_inv
from sympy.physics.quantum import Dagger


def test_gate():
    """Test a basic gate."""
    h = HadamardGate(1)
    assert h.min_qubits == 2
    assert h.nqubits == 1

    i0 = Wild('i0')
    i1 = Wild('i1')
    h0_w1 = HadamardGate(i0)
    h0_w2 = HadamardGate(i0)
    h1_w1 = HadamardGate(i1)

    assert h0_w1 == h0_w2
    assert h0_w1 != h1_w1
    assert h1_w1 != h0_w2

    cnot_10_w1 = CNOT(i1, i0)
    cnot_10_w2 = CNOT(i1, i0)
    cnot_01_w1 = CNOT(i0, i1)

    assert cnot_10_w1 == cnot_10_w2
    assert cnot_10_w1 != cnot_01_w1
    assert cnot_10_w2 != cnot_01_w1


def test_UGate():
    a, b, c, d = symbols('a,b,c,d')
    uMat = Matrix([[a, b], [c, d]])

    # Test basic case where gate exists in 1-qubit space
    u1 = UGate((0,), uMat)
    assert represent(u1, nqubits=1) == uMat
    assert qapply(u1*Qubit('0')) == a*Qubit('0') + c*Qubit('1')
    assert qapply(u1*Qubit('1')) == b*Qubit('0') + d*Qubit('1')

    # Test case where gate exists in a larger space
    u2 = UGate((1,), uMat)
    u2Rep = represent(u2, nqubits=2)
    for i in range(4):
        assert u2Rep*qubit_to_matrix(IntQubit(i, 2)) == \
            qubit_to_matrix(qapply(u2*IntQubit(i, 2)))


def test_cgate():
    """Test the general CGate."""
    # Test single control functionality
    CNOTMatrix = Matrix(
        [[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]])
    assert represent(CGate(1, XGate(0)), nqubits=2) == CNOTMatrix

    # Test multiple control bit functionality
    ToffoliGate = CGate((1, 2), XGate(0))
    assert represent(ToffoliGate, nqubits=3) == \
        Matrix(
            [[1, 0, 0, 0, 0, 0, 0, 0], [0, 1, 0, 0, 0, 0, 0, 0], [0, 0, 1, 0, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0], [0, 0, 0, 0, 1, 0, 0, 0], [0, 0, 0, 0, 0,
        1, 0, 0], [0, 0, 0, 0, 0, 0, 0, 1],
    [0, 0, 0, 0, 0, 0, 1, 0]])

    ToffoliGate = CGate((3, 0), XGate(1))
    assert qapply(ToffoliGate*Qubit('1001')) == \
        matrix_to_qubit(represent(ToffoliGate*Qubit('1001'), nqubits=4))
    assert qapply(ToffoliGate*Qubit('0000')) == \
        matrix_to_qubit(represent(ToffoliGate*Qubit('0000'), nqubits=4))

    CYGate = CGate(1, YGate(0))
    CYGate_matrix = Matrix(
        ((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 0, -I), (0, 0, I, 0)))
    # Test 2 qubit controlled-Y gate decompose method.
    assert represent(CYGate.decompose(), nqubits=2) == CYGate_matrix

    CZGate = CGate(0, ZGate(1))
    CZGate_matrix = Matrix(
        ((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, -1)))
    assert qapply(CZGate*Qubit('11')) == -Qubit('11')
    assert matrix_to_qubit(represent(CZGate*Qubit('11'), nqubits=2)) == \
        -Qubit('11')
    # Test 2 qubit controlled-Z gate decompose method.
    assert represent(CZGate.decompose(), nqubits=2) == CZGate_matrix

    CPhaseGate = CGate(0, PhaseGate(1))
    assert qapply(CPhaseGate*Qubit('11')) == \
        I*Qubit('11')
    assert matrix_to_qubit(represent(CPhaseGate*Qubit('11'), nqubits=2)) == \
        I*Qubit('11')

    # Test that the dagger, inverse, and power of CGate is evaluated properly
    assert Dagger(CZGate) == CZGate
    assert pow(CZGate, 1) == Dagger(CZGate)
    assert Dagger(CZGate) == CZGate.inverse()
    assert Dagger(CPhaseGate) != CPhaseGate
    assert Dagger(CPhaseGate) == CPhaseGate.inverse()
    assert Dagger(CPhaseGate) == pow(CPhaseGate, -1)
    assert pow(CPhaseGate, -1) == CPhaseGate.inverse()


def test_UGate_CGate_combo():
    a, b, c, d = symbols('a,b,c,d')
    uMat = Matrix([[a, b], [c, d]])
    cMat = Matrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, a, b], [0, 0, c, d]])

    # Test basic case where gate exists in 1-qubit space.
    u1 = UGate((0,), uMat)
    cu1 = CGate(1, u1)
    assert represent(cu1, nqubits=2) == cMat
    assert qapply(cu1*Qubit('10')) == a*Qubit('10') + c*Qubit('11')
    assert qapply(cu1*Qubit('11')) == b*Qubit('10') + d*Qubit('11')
    assert qapply(cu1*Qubit('01')) == Qubit('01')
    assert qapply(cu1*Qubit('00')) == Qubit('00')

    # Test case where gate exists in a larger space.
    u2 = UGate((1,), uMat)
    u2Rep = represent(u2, nqubits=2)
    for i in range(4):
        assert u2Rep*qubit_to_matrix(IntQubit(i, 2)) == \
            qubit_to_matrix(qapply(u2*IntQubit(i, 2)))


def test_represent_hadamard():
    """Test the representation of the hadamard gate."""
    circuit = HadamardGate(0)*Qubit('00')
    answer = represent(circuit, nqubits=2)
    # Check that the answers are same to within an epsilon.
    assert answer == Matrix([sqrt2_inv, sqrt2_inv, 0, 0])


def test_represent_xgate():
    """Test the representation of the X gate."""
    circuit = XGate(0)*Qubit('00')
    answer = represent(circuit, nqubits=2)
    assert Matrix([0, 1, 0, 0]) == answer


def test_represent_ygate():
    """Test the representation of the Y gate."""
    circuit = YGate(0)*Qubit('00')
    answer = represent(circuit, nqubits=2)
    assert answer[0] == 0 and answer[1] == I and \
        answer[2] == 0 and answer[3] == 0


def test_represent_zgate():
    """Test the representation of the Z gate."""
    circuit = ZGate(0)*Qubit('00')
    answer = represent(circuit, nqubits=2)
    assert Matrix([1, 0, 0, 0]) == answer


def test_represent_phasegate():
    """Test the representation of the S gate."""
    circuit = PhaseGate(0)*Qubit('01')
    answer = represent(circuit, nqubits=2)
    assert Matrix([0, I, 0, 0]) == answer


def test_represent_tgate():
    """Test the representation of the T gate."""
    circuit = TGate(0)*Qubit('01')
    assert Matrix([0, exp(I*pi/4), 0, 0]) == represent(circuit, nqubits=2)


def test_compound_gates():
    """Test a compound gate representation."""
    circuit = YGate(0)*ZGate(0)*XGate(0)*HadamardGate(0)*Qubit('00')
    answer = represent(circuit, nqubits=2)
    assert Matrix([I/sqrt(2), I/sqrt(2), 0, 0]) == answer


def test_cnot_gate():
    """Test the CNOT gate."""
    circuit = CNotGate(1, 0)
    assert represent(circuit, nqubits=2) == \
        Matrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]])
    circuit = circuit*Qubit('111')
    assert matrix_to_qubit(represent(circuit, nqubits=3)) == \
        qapply(circuit)

    circuit = CNotGate(1, 0)
    assert Dagger(circuit) == circuit
    assert Dagger(Dagger(circuit)) == circuit
    assert circuit*circuit == 1


def test_gate_sort():
    """Test gate_sort."""
    for g in (X, Y, Z, H, S, T):
        assert gate_sort(g(2)*g(1)*g(0)) == g(0)*g(1)*g(2)
    e = gate_sort(X(1)*H(0)**2*CNOT(0, 1)*X(1)*X(0))
    assert e == H(0)**2*CNOT(0, 1)*X(0)*X(1)**2
    assert gate_sort(Z(0)*X(0)) == -X(0)*Z(0)
    assert gate_sort(Z(0)*X(0)**2) == X(0)**2*Z(0)
    assert gate_sort(Y(0)*H(0)) == -H(0)*Y(0)
    assert gate_sort(Y(0)*X(0)) == -X(0)*Y(0)
    assert gate_sort(Z(0)*Y(0)) == -Y(0)*Z(0)
    assert gate_sort(T(0)*S(0)) == S(0)*T(0)
    assert gate_sort(Z(0)*S(0)) == S(0)*Z(0)
    assert gate_sort(Z(0)*T(0)) == T(0)*Z(0)
    assert gate_sort(Z(0)*CNOT(0, 1)) == CNOT(0, 1)*Z(0)
    assert gate_sort(S(0)*CNOT(0, 1)) == CNOT(0, 1)*S(0)
    assert gate_sort(T(0)*CNOT(0, 1)) == CNOT(0, 1)*T(0)
    assert gate_sort(X(1)*CNOT(0, 1)) == CNOT(0, 1)*X(1)
    # This takes a long time and should only be uncommented once in a while.
    # nqubits = 5
    # ngates = 10
    # trials = 10
    # for i in range(trials):
    #     c = random_circuit(ngates, nqubits)
    #     assert represent(c, nqubits=nqubits) == \
    #            represent(gate_sort(c), nqubits=nqubits)


def test_gate_simp():
    """Test gate_simp."""
    e = H(0)*X(1)*H(0)**2*CNOT(0, 1)*X(1)**3*X(0)*Z(3)**2*S(4)**3
    assert gate_simp(e) == H(0)*CNOT(0, 1)*S(4)*X(0)*Z(4)
    assert gate_simp(X(0)*X(0)) == 1
    assert gate_simp(Y(0)*Y(0)) == 1
    assert gate_simp(Z(0)*Z(0)) == 1
    assert gate_simp(H(0)*H(0)) == 1
    assert gate_simp(T(0)*T(0)) == S(0)
    assert gate_simp(S(0)*S(0)) == Z(0)
    assert gate_simp(Integer(1)) == Integer(1)
    assert gate_simp(X(0)**2 + Y(0)**2) == Integer(2)


def test_swap_gate():
    """Test the SWAP gate."""
    swap_gate_matrix = Matrix(
        ((1, 0, 0, 0), (0, 0, 1, 0), (0, 1, 0, 0), (0, 0, 0, 1)))
    assert represent(SwapGate(1, 0).decompose(), nqubits=2) == swap_gate_matrix
    assert qapply(SwapGate(1, 3)*Qubit('0010')) == Qubit('1000')
    nqubits = 4
    for i in range(nqubits):
        for j in range(i):
            assert represent(SwapGate(i, j), nqubits=nqubits) == \
                represent(SwapGate(i, j).decompose(), nqubits=nqubits)


def test_one_qubit_commutators():
    """Test single qubit gate commutation relations."""
    for g1 in (IdentityGate, X, Y, Z, H, T, S):
        for g2 in (IdentityGate, X, Y, Z, H, T, S):
            e = Commutator(g1(0), g2(0))
            a = matrix_to_zero(represent(e, nqubits=1, format='sympy'))
            b = matrix_to_zero(represent(e.doit(), nqubits=1, format='sympy'))
            assert a == b

            e = Commutator(g1(0), g2(1))
            assert e.doit() == 0


def test_one_qubit_anticommutators():
    """Test single qubit gate anticommutation relations."""
    for g1 in (IdentityGate, X, Y, Z, H):
        for g2 in (IdentityGate, X, Y, Z, H):
            e = AntiCommutator(g1(0), g2(0))
            a = matrix_to_zero(represent(e, nqubits=1, format='sympy'))
            b = matrix_to_zero(represent(e.doit(), nqubits=1, format='sympy'))
            assert a == b
            e = AntiCommutator(g1(0), g2(1))
            a = matrix_to_zero(represent(e, nqubits=2, format='sympy'))
            b = matrix_to_zero(represent(e.doit(), nqubits=2, format='sympy'))
            assert a == b


def test_cnot_commutators():
    """Test commutators of involving CNOT gates."""
    assert Commutator(CNOT(0, 1), Z(0)).doit() == 0
    assert Commutator(CNOT(0, 1), T(0)).doit() == 0
    assert Commutator(CNOT(0, 1), S(0)).doit() == 0
    assert Commutator(CNOT(0, 1), X(1)).doit() == 0
    assert Commutator(CNOT(0, 1), CNOT(0, 1)).doit() == 0
    assert Commutator(CNOT(0, 1), CNOT(0, 2)).doit() == 0
    assert Commutator(CNOT(0, 2), CNOT(0, 1)).doit() == 0
    assert Commutator(CNOT(1, 2), CNOT(1, 0)).doit() == 0


def test_random_circuit():
    c = random_circuit(10, 3)
    assert isinstance(c, Mul)
    m = represent(c, nqubits=3)
    assert m.shape == (8, 8)
    assert isinstance(m, Matrix)


def test_hermitian_XGate():
    x = XGate(1, 2)
    x_dagger = Dagger(x)

    assert (x == x_dagger)


def test_hermitian_YGate():
    y = YGate(1, 2)
    y_dagger = Dagger(y)

    assert (y == y_dagger)


def test_hermitian_ZGate():
    z = ZGate(1, 2)
    z_dagger = Dagger(z)

    assert (z == z_dagger)


def test_unitary_XGate():
    x = XGate(1, 2)
    x_dagger = Dagger(x)

    assert (x*x_dagger == 1)


def test_unitary_YGate():
    y = YGate(1, 2)
    y_dagger = Dagger(y)

    assert (y*y_dagger == 1)


def test_unitary_ZGate():
    z = ZGate(1, 2)
    z_dagger = Dagger(z)

    assert (z*z_dagger == 1)
