# This file is part of Hypothesis, which may be found at
# https://github.com/HypothesisWorks/hypothesis/
#
# Most of this work is copyright (C) 2013-2020 David R. MacIver
# (david@drmaciver.com), but it contains contributions by others. See
# CONTRIBUTING.rst for a full list of people who may hold copyright, and
# consult the git log if you need to determine who owns an individual
# contribution.
#
# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at https://mozilla.org/MPL/2.0/.
#
# END HEADER

import ast
import enum
import json
import re
import unittest
import unittest.mock
from decimal import Decimal
from types import ModuleType
from typing import Any, List, Sequence, Set, Union

import pytest

from hypothesis.errors import InvalidArgument, MultipleFailures, Unsatisfiable
from hypothesis.extra import ghostwriter
from hypothesis.strategies import from_type, just

varied_excepts = pytest.mark.parametrize("ex", [(), ValueError, (TypeError, re.error)])


def get_test_function(source_code):
    # A helper function to get the dynamically-defined test function.
    # Note that this also tests that the module is syntatically-valid,
    # AND free from undefined names, import problems, and so on.
    namespace = {}
    exec(source_code, namespace)
    tests = [
        v
        for k, v in namespace.items()
        if k.startswith(("test_", "Test")) and not isinstance(v, ModuleType)
    ]
    assert len(tests) == 1, tests
    return tests[0]


@pytest.mark.parametrize(
    "badness", ["not an exception", BaseException, [ValueError], (Exception, "bad")]
)
def test_invalid_exceptions(badness):
    with pytest.raises(InvalidArgument):
        ghostwriter._check_except(badness)


def test_style_validation():
    ghostwriter._check_style("pytest")
    ghostwriter._check_style("unittest")
    with pytest.raises(InvalidArgument):
        ghostwriter._check_style("not a valid style")


def test_strategies_with_invalid_syntax_repr_as_nothing():
    msg = "$$ this repr is not Python syntax $$"

    class NoRepr:
        def __repr__(self):
            return msg

    s = just(NoRepr())
    assert repr(s) == f"just({msg})"
    assert ghostwriter._valid_syntax_repr(s) == "nothing()"


class AnEnum(enum.Enum):
    a = "value of AnEnum.a"
    b = "value of AnEnum.b"


def takes_enum(foo=AnEnum.a):
    # This can only fail if we use the default argument to guess
    # that any instance of that enum type should be allowed.
    assert foo != AnEnum.b


def test_ghostwriter_exploits_arguments_with_enum_defaults():
    source_code = ghostwriter.fuzz(takes_enum)
    test = get_test_function(source_code)
    with pytest.raises(AssertionError):
        test()


def timsort(seq: Sequence[int]) -> List[int]:
    return sorted(seq)


def non_type_annotation(x: 3):  # type: ignore
    pass


def annotated_any(x: Any):
    pass


space_in_name = type("a name", (type,), {"__init__": lambda self: None})


class NotResolvable:
    def __init__(self, unannotated_required):
        pass


def non_resolvable_arg(x: NotResolvable):
    pass


def test_flattens_one_of_repr():
    strat = from_type(Union[int, Sequence[int]])
    assert repr(strat).count("one_of(") > 1
    assert ghostwriter._valid_syntax_repr(strat).count("one_of(") == 1


@varied_excepts
@pytest.mark.parametrize(
    "func",
    [
        re.compile,
        json.loads,
        json.dump,
        timsort,
        ast.literal_eval,
        non_type_annotation,
        annotated_any,
        space_in_name,
        non_resolvable_arg,
    ],
)
def test_ghostwriter_fuzz(func, ex):
    source_code = ghostwriter.fuzz(func, except_=ex)
    get_test_function(source_code)


@varied_excepts
@pytest.mark.parametrize(
    "func", [re.compile, json.loads, json.dump, timsort, ast.literal_eval]
)
def test_ghostwriter_unittest_style(func, ex):
    source_code = ghostwriter.fuzz(func, except_=ex, style="unittest")
    assert issubclass(get_test_function(source_code), unittest.TestCase)


def no_annotations(foo=None, bar=False):
    pass


def test_inference_from_defaults_and_none_booleans_reprs_not_just_and_sampled_from():
    source_code = ghostwriter.fuzz(no_annotations)
    assert "@given(foo=st.none(), bar=st.booleans())" in source_code


def hopefully_hashable(foo: Set[Decimal]):
    pass


def test_no_hashability_filter():
    # In from_type, we ordinarily protect users from really weird cases like
    # `Decimal('snan')` - a unhashable value of a hashable type - but in the
    # ghostwriter we instead want to present this to the user for an explicit
    # decision.  They can pass `allow_nan=False`, fix their custom type's
    # hashing logic, or whatever else; simply doing nothing will usually work.
    source_code = ghostwriter.fuzz(hopefully_hashable)
    assert "@given(foo=st.sets(st.decimals()))" in source_code
    assert "_can_hash" not in source_code


@pytest.mark.parametrize(
    "gw,args",
    [
        (ghostwriter.fuzz, ["not callable"]),
        (ghostwriter.idempotent, ["not callable"]),
        (ghostwriter.roundtrip, []),
        (ghostwriter.roundtrip, ["not callable"]),
        (ghostwriter.equivalent, [sorted]),
        (ghostwriter.equivalent, [sorted, "not callable"]),
    ],
)
def test_invalid_func_inputs(gw, args):
    with pytest.raises(InvalidArgument):
        gw(*args)


def test_run_ghostwriter_fuzz():
    # Our strategy-guessing code works for all the arguments to sorted,
    # and we handle positional-only arguments in calls correctly too.
    source_code = ghostwriter.fuzz(sorted)
    assert "st.nothing()" not in source_code
    get_test_function(source_code)()


class MyError(UnicodeDecodeError):
    pass


@pytest.mark.parametrize(
    "exceptions,output",
    [
        # Discard subclasses of other exceptions to catch, including non-builtins,
        # and replace OSError aliases with OSError.
        ((Exception, UnicodeError), "Exception"),
        ((UnicodeError, MyError), "UnicodeError"),
        ((IOError,), "OSError"),
        ((IOError, UnicodeError), "(OSError, UnicodeError)"),
    ],
)
def test_exception_deduplication(exceptions, output):
    _, body = ghostwriter._make_test_body(
        lambda: None, ghost="", test_body="pass", except_=exceptions, style="pytest"
    )
    assert f"except {output}:" in body


def test_run_ghostwriter_roundtrip():
    # This test covers the whole lifecycle: first, we get the default code.
    # The first argument is unknown, so we fail to draw from st.nothing()
    source_code = ghostwriter.roundtrip(json.dumps, json.loads)
    with pytest.raises(Unsatisfiable):
        get_test_function(source_code)()

    # Replacing that nothing() with a strategy for JSON allows us to discover
    # two possible failures: `nan` is not equal to itself, and if dumps is
    # passed allow_nan=False it is a ValueError to pass a non-finite float.
    source_code = source_code.replace(
        "st.nothing()",
        "st.recursive(st.one_of(st.none(), st.booleans(), st.floats(), st.text()), "
        "lambda v: st.lists(v, max_size=2) | st.dictionaries(st.text(), v, max_size=2)"
        ", max_leaves=2)",
    )
    try:
        get_test_function(source_code)()
    except (AssertionError, ValueError, MultipleFailures):
        pass

    # Finally, restricting ourselves to finite floats makes the test pass!
    source_code = source_code.replace(
        "st.floats()", "st.floats(allow_nan=False, allow_infinity=False)"
    )
    get_test_function(source_code)()


@varied_excepts
@pytest.mark.parametrize("func", [sorted, timsort])
def test_ghostwriter_idempotent(func, ex):
    source_code = ghostwriter.idempotent(func, except_=ex)
    test = get_test_function(source_code)
    if "=st.nothing()" in source_code:
        with pytest.raises(Unsatisfiable):
            test()
    else:
        test()


def test_overlapping_args_use_union_of_strategies():
    def f(arg: int) -> None:
        pass

    def g(arg: float) -> None:
        pass

    source_code = ghostwriter.equivalent(f, g)
    assert "arg=st.one_of(st.integers(), st.floats())" in source_code


def test_module_with_mock_does_not_break():
    # Before we added an explicit check for unspec'd mocks, they would pass
    # through the initial validation and then fail when used in more detailed
    # logic in the ghostwriter machinery.
    ghostwriter.magic(unittest.mock)


def compose_types(x: type, y: type):
    pass


def test_unrepr_identity_elem():
    # Works with inferred identity element
    source_code = ghostwriter.binary_operation(compose_types)
    exec(source_code, {})
    # and also works with explicit identity element
    source_code = ghostwriter.binary_operation(compose_types, identity=type)
    exec(source_code, {})