import ast
import copy
import sys

import astunparse
import funcsigs

from peval.core.function import Function
from peval.tools import unindent

from tests.utils import ast_to_source


def function_from_source(source, globals_=None):
    """
    A helper function to construct a Function object from a source
    with custom __future__ imports.
    """

    module = ast.parse(unindent(source))
    ast.fix_missing_locations(module)

    for stmt in module.body:
        if type(stmt) == ast.FunctionDef:
            tree = stmt
            name = stmt.name
            break
    else:
        raise ValueError("No function definitions found in the provided source")

    code_object = compile(module, '<nofile>', 'exec', dont_inherit=True)
    locals_ = {}
    eval(code_object, globals_, locals_)

    function_obj = locals_[name]
    function_obj._peval_source = astunparse.unparse(tree)

    return Function.from_object(function_obj)


global_var = 1


def global_var_writer(x):
    global global_var
    global_var = x


def global_var_reader():
    return global_var


def make_one_var_closure():
    closure_var = [1]
    def closure():
        some_local_var = 3
        closure_var[0] += 1
        return closure_var[0]
    return closure


def make_two_var_closure():
    closure_var1 = [1]
    closure_var2 = [2]
    def closure():
        some_local_var = closure_var1[0]
        closure_var2[0] += 1
        return closure_var2[0]
    return closure


def dummy_func(a, b, c=4, d=5):
    return a, b, c, d


def dummy_func_arg_groups(a, b, *args, **kwds):
    return a, b, args, kwds


def test_bind_partial_args():

    func = Function.from_object(dummy_func)

    new_func = func.bind_partial(1).eval()
    sig = funcsigs.signature(new_func)

    assert new_func(2, 3, 4) == (1, 2, 3, 4)
    assert 'a' not in sig.parameters
    assert 'b' in sig.parameters
    assert 'c' in sig.parameters
    assert 'd' in sig.parameters


def test_bind_partial_kwds():

    func = Function.from_object(dummy_func)

    new_func = func.bind_partial(1, d=10).eval()
    sig = funcsigs.signature(new_func)

    assert new_func(2, 3) == (1, 2, 3, 10)
    assert 'a' not in sig.parameters
    assert 'b' in sig.parameters
    assert 'c' in sig.parameters
    assert 'd' not in sig.parameters


def test_bind_partial_varargs():

    func = Function.from_object(dummy_func_arg_groups)

    new_func = func.bind_partial(1, 2, 3).eval()
    sig = funcsigs.signature(new_func)

    assert new_func(d=10) == (1, 2, (3,), {'d': 10})
    assert 'a' not in sig.parameters
    assert 'b' not in sig.parameters
    assert 'args' not in sig.parameters
    assert 'kwds' in sig.parameters


def test_bind_partial_varkwds():

    func = Function.from_object(dummy_func_arg_groups)

    new_func = func.bind_partial(1, 2, d=10).eval()
    sig = funcsigs.signature(new_func)

    assert new_func(3, 4) == (1, 2, (3, 4), {'d': 10})
    assert 'a' not in sig.parameters
    assert 'b' not in sig.parameters
    assert 'args' in sig.parameters
    assert 'kwds' not in sig.parameters


def test_globals_contents():

    func = Function.from_object(make_one_var_closure())

    assert 'global_var' in func.globals
    assert 'closure_var' not in func.globals


def test_closure_contents():

    func = Function.from_object(make_one_var_closure())

    assert 'global_var' not in func.closure_names
    assert 'closure_var' in func.closure_names


def test_restore_globals():

    global_var_writer(10)
    assert global_var_reader() == 10
    assert global_var == 10

    reader = Function.from_object(global_var_reader).eval()
    writer = Function.from_object(global_var_writer).eval()

    writer(20)
    assert reader() == 20
    assert global_var == 20


def test_restore_simple_closure():

    closure_ref = make_one_var_closure()
    assert closure_ref() == 2

    closure = Function.from_object(closure_ref).eval()
    assert closure() == 3
    assert closure_ref() == 4


def test_restore_modified_closure():

    def remove_first_line(node):
        assert isinstance(node, ast.FunctionDef)
        node = copy.deepcopy(node)
        node.body = node.body[1:]
        return node

    closure_ref = make_two_var_closure()
    assert closure_ref() == 3

    closure = Function.from_object(closure_ref)
    closure = closure.replace(tree=remove_first_line(closure.tree)).eval()

    assert closure() == 4
    assert closure_ref() == 5


def recursive_outer(x):
    if x > 1:
        return recursive_outer(x - 1)
    else:
        return x


def make_recursive():
    def recursive_inner(x):
        if x > 2:
            return recursive_inner(x - 1)
        else:
            return x
    return recursive_inner


def test_recursive_call():
    # When evaluated inside a fake closure (to detect closure variables),
    # the function name will be included in the list of closure variables
    # (if it is used in the body of the function).
    # So if the function was not a closure to begin with,
    # the corresponding cell will be missing.
    # This tests checks that Function evaluates non-closure functions
    # without a fake closure to prevent that.

    func = Function.from_object(recursive_outer)
    func = func.replace()
    func = func.eval()
    assert func(10) == 1

    func = Function.from_object(make_recursive())
    func = func.replace()
    func = func.eval()
    assert func(10) == 2


def test_construct_from_eval():
    # Test that the function returned from Function.eval()
    # can be used to construct a new Function object.
    func = Function.from_object(dummy_func).eval()
    func2 = Function.from_object(func).eval()
    assert func2(1, 2, c=10) == (1, 2, 10, 5)


# The decorator must be in the global namespace,
# see Known Limitations in the docs.
def tag(f):
    vars(f)['_tag'] = True
    return f


def test_reapply_decorators():

    @tag
    def tagged(x):
        return x

    func = Function.from_object(tagged).eval()

    assert '_tag' in vars(func) and vars(func)['_tag']


def test_detect_future_features():

    # Test that the presence of a future feature is detected

    src = """
        from __future__ import division
        def f():
            return 1 / 2
        """

    func = function_from_source(src)
    assert func.future_features.division


    # Test that the absence of a future feature is detected
    # (Does not test much in Py3, since all the future features are enabled by default).

    src = """
        def f():
            return 1 / 2
        """

    func = function_from_source(src)
    if sys.version_info >= (3,):
        assert func.future_features.division
    else:
        assert not func.future_features.division


def test_preserve_future_features():

    # Test that the presence of a future feature is preserved after re-evaluation

    src = """
        from __future__ import division
        def f():
            return 1 / 2
        """

    func = function_from_source(src)
    new_func_obj = func.eval()
    new_func = Function.from_object(new_func_obj)

    assert new_func.future_features.division
    assert new_func_obj() == 0.5


    # Test that the absence of a future feature is preserved after re-evaluation
    # (Does not test much in Py3, since all the future features are enabled by default).

    src = """
        def f():
            return 1 / 2
        """

    func = function_from_source(src)
    new_func_obj = func.eval()
    new_func = Function.from_object(new_func_obj)

    if sys.version_info >= (3,):
        assert new_func.future_features.division
        assert new_func_obj() == 0.5
    else:
        assert not new_func.future_features.division
        assert new_func_obj() == 0


def test_compile_ast():
    function = Function.from_object(sample_fn)
    compiled_fn = function.eval()
    assert compiled_fn(3, -9) == sample_fn(3, -9)
    assert compiled_fn(3, -9, 'z', zzz=map) == sample_fn(3, -9, 'z', zzz=map)


def test_get_source():
    function = Function.from_object(sample_fn)
    source = ast_to_source(function.tree)

    expected_source = unindent(
        """
        def sample_fn(x, y, foo='bar', **kw):
            if (foo == 'bar'):
                return (x + y)
            else:
                return kw['zzz']
        """)

    assert source == expected_source


def sample_fn(x, y, foo='bar', **kw):
    if foo == 'bar':
        return x + y
    else:
        return kw['zzz']


def sample_fn2(x, y, foo='bar', **kw):
    if foo == 'bar':
        return x - y
    else:
        return kw['zzz']


def sample_fn3(x, y, foo='bar', **kwargs):
    if foo == 'bar':
        return x + y
    else:
        return kwargs['zzz']

