class NotSubscriptable: ...

# snapshot: not-subscriptable
a = NotSubscriptable()[0]

error[not-subscriptable]: Cannot subscript object of type `NotSubscriptable` with no `__getitem__` method
 --> src/mdtest_snippet.py:4:5
  |
4 | a = NotSubscriptable()[0]
  |     ^^^^^^^^^^^^^^^^^^^^^
  |

class NotSubscriptable:
    __getitem__ = None

# TODO: this would be more user-friendly if the `call-non-callable` diagnostic was
# transformed into a `not-subscriptable` diagnostic with a subdiagnostic explaining
# that this was because `__getitem__` was possibly not callable
#
# error: [call-non-callable] "Method `__getitem__` of type `None | Unknown` may not be callable on object of type `NotSubscriptable`"
a = NotSubscriptable()[0]

class Identity:
    def __getitem__(self, index: int) -> int:
        return index

reveal_type(Identity()[0])  # revealed: int

def _(flag: bool):
    class Identity:
        if flag:
            def __getitem__(self, index: int) -> int:
                return index

        else:
            def __getitem__(self, index: int) -> str:
                return str(index)

    reveal_type(Identity()[0])  # revealed: int | str

class Identity:
    def __getitem__(self, index: int) -> int:
        return index

a = Identity()
# error: [invalid-argument-type] "Method `__getitem__` of type `bound method Identity.__getitem__(index: int) -> int` cannot be called with key of type `Literal["a"]` on object of type `Identity`"
a["a"]

class NoGetitem:
    def __setitem__(self, index: int, value: int) -> None:
        pass

a = NoGetitem()
a[0] = 0

class NoSetitem: ...

a = NoSetitem()
a[0] = 0  # error: "Cannot assign to a subscript on an object of type `NoSetitem`"

class NoSetitem:
    __setitem__ = None

a = NoSetitem()
a[0] = 0  # error: "Method `__setitem__` of type `None | Unknown` may not be callable on object of type `NoSetitem`"

class Identity:
    def __setitem__(self, index: int, value: int) -> None:
        pass

a = Identity()
a[0] = 0

class Identity:
    def __setitem__(self, index: int, value: int) -> None:
        pass

a = Identity()
# error: [invalid-assignment] "Invalid subscript assignment with key of type `Literal["a"]` and value of type `Literal[0]` on object of type `Identity`"
a["a"] = 0