import sympy
import tempfile
import os
from sympy import symbols, Eq
from sympy.external import import_module
from sympy.tensor import IndexedBase, Idx
from sympy.utilities.autowrap import autowrap, ufuncify, CodeWrapError
from sympy.utilities.pytest import skip

numpy = import_module('numpy', min_module_version='1.6.1')
Cython = import_module('Cython', min_module_version='0.15.1')
f2py = import_module('numpy.f2py', __import__kwargs={'fromlist': ['f2py']})

f2pyworks = False
if f2py:
    try:
        autowrap(symbols('x'), 'f95', 'f2py')
    except (CodeWrapError, ImportError, OSError):
        f2pyworks = False
    else:
        f2pyworks = True

a, b, c = symbols('a b c')
n, m, d = symbols('n m d', integer=True)
A, B, C = symbols('A B C', cls=IndexedBase)
i = Idx('i', m)
j = Idx('j', n)
k = Idx('k', d)


def has_module(module):
    """
    Return True if module exists, otherwise run skip().

    module should be a string.
    """
    # To give a string of the module name to skip(), this function takes a
    # string.  So we don't waste time running import_module() more than once,
    # just map the three modules tested here in this dict.
    modnames = {'numpy': numpy, 'Cython': Cython, 'f2py': f2py}

    if modnames[module]:
        if module == 'f2py' and not f2pyworks:
            skip("Couldn't run f2py.")
        return True
    skip("Couldn't import %s." % module)

#
# test runners used by several language-backend combinations
#

def runtest_autowrap_twice(language, backend):
    f = autowrap((((a + b)/c)**5).expand(), language, backend)
    g = autowrap((((a + b)/c)**4).expand(), language, backend)

    # check that autowrap updates the module name.  Else, g gives the same as f
    assert f(1, -2, 1) == -1.0
    assert g(1, -2, 1) == 1.0


def runtest_autowrap_trace(language, backend):
    has_module('numpy')
    trace = autowrap(A[i, i], language, backend)
    assert trace(numpy.eye(100)) == 100


def runtest_autowrap_matrix_vector(language, backend):
    has_module('numpy')
    x, y = symbols('x y', cls=IndexedBase)
    expr = Eq(y[i], A[i, j]*x[j])
    mv = autowrap(expr, language, backend)

    # compare with numpy's dot product
    M = numpy.random.rand(10, 20)
    x = numpy.random.rand(20)
    y = numpy.dot(M, x)
    assert numpy.sum(numpy.abs(y - mv(M, x))) < 1e-13


def runtest_autowrap_matrix_matrix(language, backend):
    has_module('numpy')
    expr = Eq(C[i, j], A[i, k]*B[k, j])
    matmat = autowrap(expr, language, backend)

    # compare with numpy's dot product
    M1 = numpy.random.rand(10, 20)
    M2 = numpy.random.rand(20, 15)
    M3 = numpy.dot(M1, M2)
    assert numpy.sum(numpy.abs(M3 - matmat(M1, M2))) < 1e-13


def runtest_ufuncify(language, backend):
    has_module('numpy')
    a, b, c = symbols('a b c')
    fabc = ufuncify([a, b, c], a*b + c, backend=backend)
    facb = ufuncify([a, c, b], a*b + c, backend=backend)
    grid = numpy.linspace(-2, 2, 50)
    b = numpy.linspace(-5, 4, 50)
    c = numpy.linspace(-1, 1, 50)
    expected = grid*b + c
    numpy.testing.assert_allclose(fabc(grid, b, c), expected)
    numpy.testing.assert_allclose(facb(grid, c, b), expected)


def runtest_issue_10274(language, backend):
    expr = (a - b + c)**(13)
    tmp = tempfile.mkdtemp()
    f = autowrap(expr, language, backend, tempdir=tmp, helpers=('helper', a - b + c, (a, b, c)))
    assert f(1, 1, 1) == 1

    for file in os.listdir(tmp):
        if file.startswith("wrapped_code_") and file.endswith(".c"):
            fil = open(tmp + '/' + file)
            assert fil.read() == ("/******************************************************************************\n"
                         " *                    Code generated with sympy "+ sympy.__version__+"                     *\n"
                         " *                                                                            *\n"
                         " *              See http://www.sympy.org/ for more information.               *\n"
                         " *                                                                            *\n"
                         " *                      This file is part of 'autowrap'                       *\n"
                         " ******************************************************************************/\n"
                         "#include " + '"' + file[:-1]+ 'h"' + "\n"
                         "#include <math.h>\n"
                         "\n"
                         "double helper(double a, double b, double c) {\n"
                         "\n"
                         "   double helper_result;\n"
                         "   helper_result = a - b + c;\n"
                         "   return helper_result;\n"
                         "\n"
                         "}\n"
                         "\n"
                         "double autofunc(double a, double b, double c) {\n"
                         "\n"
                         "   double autofunc_result;\n"
                         "   autofunc_result = pow(helper(a, b, c), 13);\n"
                         "   return autofunc_result;\n"
                         "\n"
                         "}\n")

#
# tests of language-backend combinations
#

# f2py


def test_wrap_twice_f95_f2py():
    has_module('f2py')
    runtest_autowrap_twice('f95', 'f2py')


def test_autowrap_trace_f95_f2py():
    has_module('f2py')