import functools
import inspect
import itertools
import os
import re
import unittest
from types import FunctionType
from typing import Any, Callable, Dict, Optional, Set, TypeVar, Union
from typing import ContextManager
from unittest.mock import patch

import boto3
import botocore
import responses
from botocore.config import Config
from botocore.handlers import BUILTIN_HANDLERS

from moto import settings
from .base_backend import BackendDict
from .botocore_stubber import BotocoreStubber
from .custom_responses_mock import (
    get_response_mock,
    CallbackResponse,
    not_implemented_callback,
    reset_responses_mock,
)
from .model_instances import reset_model_data

DEFAULT_ACCOUNT_ID = "123456789012"
CALLABLE_RETURN = TypeVar("CALLABLE_RETURN")


class BaseMockAWS(ContextManager["BaseMockAWS"]):
    nested_count = 0
    mocks_active = False

    def __init__(self, backends: BackendDict):
        from moto.instance_metadata import instance_metadata_backends
        from moto.moto_api._internal.models import moto_api_backend

        self.backends = backends

        self.backends_for_urls = []
        default_account_id = DEFAULT_ACCOUNT_ID
        default_backends = [
            instance_metadata_backends[default_account_id]["global"],
            moto_api_backend,
        ]
        backend_default_account = self.backends[default_account_id]
        if "us-east-1" in backend_default_account:
            # We only need to know the URL for a single region - they will be the same everywhere
            self.backends_for_urls.append(backend_default_account["us-east-1"])
        elif "global" in backend_default_account:
            # If us-east-1 is not available, it's probably a global service
            self.backends_for_urls.append(backend_default_account["global"])
        self.backends_for_urls.extend(default_backends)

        self.FAKE_KEYS = {
            "AWS_ACCESS_KEY_ID": "foobar_key",
            "AWS_SECRET_ACCESS_KEY": "foobar_secret",
        }
        self.ORIG_KEYS: Dict[str, Optional[str]] = {}
        self.default_session_mock = patch("boto3.DEFAULT_SESSION", None)

        if self.__class__.nested_count == 0:
            self.reset()  # type: ignore[attr-defined]

    def __call__(
        self,
        func: Callable[..., "BaseMockAWS"],
        reset: bool = True,
        remove_data: bool = True,
    ) -> Callable[..., "BaseMockAWS"]:
        if inspect.isclass(func):
            return self.decorate_class(func)  # type: ignore
        return self.decorate_callable(func, reset, remove_data)

    def __enter__(self) -> "BaseMockAWS":
        self.start()
        return self

    def __exit__(self, *args: Any) -> None:
        self.stop()

    def start(self, reset: bool = True) -> None:
        if not self.__class__.mocks_active:
            self.default_session_mock.start()
            self.mock_env_variables()
            self.__class__.mocks_active = True

        self.__class__.nested_count += 1
        if reset:
            for backend in self.backends.values():
                backend.reset()

        self.enable_patching(reset)  # type: ignore[attr-defined]

    def stop(self, remove_data: bool = True) -> None:
        self.__class__.nested_count -= 1

        if self.__class__.nested_count < 0:
            raise RuntimeError("Called stop() before start().")

        if self.__class__.nested_count == 0:
            if self.__class__.mocks_active:
                try:
                    self.default_session_mock.stop()
                except RuntimeError:
                    # We only need to check for this exception in Python 3.7
                    # https://bugs.python.org/issue36366
                    pass
                self.unmock_env_variables()
                self.__class__.mocks_active = False
                if remove_data:
                    # Reset the data across all backends
                    for backend in self.backends.values():
                        backend.reset()
                    # Remove references to all model instances that were created
                    reset_model_data()
            self.disable_patching()  # type: ignore[attr-defined]

    def decorate_callable(
        self, func: Callable[..., "BaseMockAWS"], reset: bool, remove_data: bool
    ) -> Callable[..., "BaseMockAWS"]:
        def wrapper(*args: Any, **kwargs: Any) -> "BaseMockAWS":
            self.start(reset=reset)
            try:
                result = func(*args, **kwargs)
            finally:
                self.stop(remove_data=remove_data)
            return result

        functools.update_wrapper(wrapper, func)
        wrapper.__wrapped__ = func  # type: ignore[attr-defined]
        return wrapper

    def decorate_class(self, klass: type) -> object:
        direct_methods = get_direct_methods_of(klass)
        defined_classes = set(
            x for x, y in klass.__dict__.items() if inspect.isclass(y)
        )

        # Get a list of all userdefined superclasses
        superclasses = [
            c for c in klass.__mro__ if c not in [unittest.TestCase, object]
        ]
        # Get a list of all userdefined methods
        supermethods = list(
            itertools.chain(*[get_direct_methods_of(c) for c in superclasses])
        )
        # Check whether the user has overridden the setUp-method
        has_setup_method = (
            ("setUp" in supermethods and unittest.TestCase in klass.__mro__)
            or "setup" in supermethods
            or "setup_method" in supermethods
        )

        for attr in itertools.chain(direct_methods, defined_classes):
            if attr.startswith("_"):
                continue

            attr_value = getattr(klass, attr)
            if not hasattr(attr_value, "__call__"):
                continue
            if not hasattr(attr_value, "__name__"):
                continue

            # Check if this is a classmethod. If so, skip patching
            if inspect.ismethod(attr_value) and attr_value.__self__ is klass:
                continue

            # Check if this is a staticmethod. If so, skip patching
            for cls in inspect.getmro(klass):
                if attr_value.__name__ not in cls.__dict__:
                    continue
                bound_attr_value = cls.__dict__[attr_value.__name__]
                if not isinstance(bound_attr_value, staticmethod):
                    break
            else:
                # It is a staticmethod, skip patching
                continue

            try:
                # Special case for UnitTests-class
                is_test_method = attr.startswith(unittest.TestLoader.testMethodPrefix)
                should_reset = False
                should_remove_data = False
                if attr in ["setUp", "setup_method"]:
                    should_reset = True
                elif not has_setup_method and is_test_method:
                    should_reset = True
                    should_remove_data = True
                else:
                    # Method is unrelated to the test setup
                    # Method is a test, but was already reset while executing the setUp-method
                    pass
                kwargs = {"reset": should_reset, "remove_data": should_remove_data}
                setattr(klass, attr, self(attr_value, **kwargs))
            except TypeError:
                # Sometimes we can't set this for built-in types
                continue
        return klass

    def mock_env_variables(self) -> None:
        # "Mock" the AWS credentials as they can't be mocked in Botocore currently
        # self.env_variables_mocks = mock.patch.dict(os.environ, FAKE_KEYS)
        # self.env_variables_mocks.start()
        for k, v in self.FAKE_KEYS.items():
            self.ORIG_KEYS[k] = os.environ.get(k, None)
            os.environ[k] = v

    def unmock_env_variables(self) -> None:
        # This doesn't work in Python2 - for some reason, unmocking clears the entire os.environ dict
        # Obviously bad user experience, and also breaks pytest - as it uses PYTEST_CURRENT_TEST as an env var
        # self.env_variables_mocks.stop()
        for k, v in self.ORIG_KEYS.items():
            if v:
                os.environ[k] = v
            else:
                del os.environ[k]


def get_direct_methods_of(klass: object) -> Set[str]:
    return set(
        x
        for x, y in klass.__dict__.items()
        if isinstance(y, (FunctionType, classmethod, staticmethod))
    )


RESPONSES_METHODS = [
    responses.GET,
    responses.DELETE,
    responses.HEAD,
    responses.OPTIONS,
    responses.PATCH,
    responses.POST,
    responses.PUT,
]

botocore_mock = responses.RequestsMock(
    assert_all_requests_are_fired=False,
    target="botocore.vendored.requests.adapters.HTTPAdapter.send",
)

responses_mock = get_response_mock()

BOTOCORE_HTTP_METHODS = ["GET", "DELETE", "HEAD", "OPTIONS", "PATCH", "POST", "PUT"]


botocore_stubber = BotocoreStubber()
BUILTIN_HANDLERS.append(("before-send", botocore_stubber))


def patch_client(client: botocore.client.BaseClient) -> None:
    """
    Explicitly patch a boto3-client
    """
    """
    Adding the botocore_stubber to the BUILTIN_HANDLERS, as above, will mock everything as long as the import ordering is correct
     - user:   start mock_service decorator
     - system: imports core.model
     - system: adds the stubber to the BUILTIN_HANDLERS
     - user:   create a boto3 client - which will use the BUILTIN_HANDLERS

    But, if for whatever reason the imports are wrong and the client is created first, it doesn't know about our stub yet
    This method can be used to tell a client that it needs to be mocked, and append the botocore_stubber after creation
    :param client:
    :return:
    """
    if isinstance(client, botocore.client.BaseClient):
        # Check if our event handler was already registered
        try:
            event_emitter = client._ruleset_resolver._event_emitter._emitter
            all_handlers = event_emitter._handlers._root["children"]
            handler_trie = list(all_handlers["before-send"].values())[1]
            handlers_list = handler_trie.first + handler_trie.middle + handler_trie.last
            if botocore_stubber in handlers_list:
                # No need to patch - this client already has the botocore_stubber registered
                return
        except:  # noqa: E722 Do not use bare except
            # Because we're accessing all kinds of private methods, the API may change and newer versions of botocore may throw an exception
            # One of our tests will fail if this happens (test_patch_can_be_called_on_a_mocked_client)
            # If this happens for a user, just continue and hope for the best
            #  - in 99% of the cases there are no duplicate event handlers, so it doesn't matter if the check fails
            pass

        client.meta.events.register("before-send", botocore_stubber)
    else:
        raise Exception(f"Argument {client} should be of type boto3.client")


def patch_resource(resource: Any) -> None:
    """
    Explicitly patch a boto3-resource
    """
    if hasattr(resource, "meta") and isinstance(
        resource.meta, boto3.resources.factory.ResourceMeta
    ):
        patch_client(resource.meta.client)
    else:
        raise Exception(f"Argument {resource} should be of type boto3.resource")


class BotocoreEventMockAWS(BaseMockAWS):
    def reset(self) -> None:
        botocore_stubber.reset()
        reset_responses_mock(responses_mock)

    def enable_patching(
        self, reset: bool = True  # pylint: disable=unused-argument
    ) -> None:
        # Circumvent circular imports
        from .utils import convert_flask_to_responses_response

        botocore_stubber.enabled = True
        for method in BOTOCORE_HTTP_METHODS:
            for backend in self.backends_for_urls:
                for key, value in backend.urls.items():
                    pattern = re.compile(key)
                    botocore_stubber.register_response(method, pattern, value)

        if not hasattr(responses_mock, "_patcher") or not hasattr(
            responses_mock._patcher, "target"
        ):
            responses_mock.start()

        for method in RESPONSES_METHODS:
            # for backend in default_backends.values():
            for backend in self.backends_for_urls:
                for key, value in backend.urls.items():
                    responses_mock.add(
                        CallbackResponse(
                            method=method,
                            url=re.compile(key),
                            callback=convert_flask_to_responses_response(value),
                        )
                    )
            responses_mock.add(
                CallbackResponse(
                    method=method,
                    url=re.compile(r"https?://.+\.amazonaws.com/.*"),
                    callback=not_implemented_callback,
                )
            )
            botocore_mock.add(
                CallbackResponse(
                    method=method,
                    url=re.compile(r"https?://.+\.amazonaws.com/.*"),
                    callback=not_implemented_callback,
                )
            )

    def disable_patching(self) -> None:
        botocore_stubber.enabled = False
        self.reset()

        try:
            responses_mock.stop()
        except RuntimeError:
            pass


MockAWS = BotocoreEventMockAWS


class ServerModeMockAWS(BaseMockAWS):
    RESET_IN_PROGRESS = False

    def __init__(self, *args: Any, **kwargs: Any):
        self.test_server_mode_endpoint = settings.test_server_mode_endpoint()
        super().__init__(*args, **kwargs)

    def reset(self) -> None:
        call_reset_api = os.environ.get("MOTO_CALL_RESET_API")
        if not call_reset_api or call_reset_api.lower() != "false":
            if not ServerModeMockAWS.RESET_IN_PROGRESS:
                ServerModeMockAWS.RESET_IN_PROGRESS = True
                import requests

                requests.post(f"{self.test_server_mode_endpoint}/moto-api/reset")
                ServerModeMockAWS.RESET_IN_PROGRESS = False

    def enable_patching(self, reset: bool = True) -> None:
        if self.__class__.nested_count == 1 and reset:
            # Just started
            self.reset()

        from boto3 import client as real_boto3_client, resource as real_boto3_resource

        def fake_boto3_client(*args: Any, **kwargs: Any) -> botocore.client.BaseClient:
            region = self._get_region(*args, **kwargs)
            if region:
                if "config" in kwargs:
                    kwargs["config"].__dict__["user_agent_extra"] += " region/" + region
                else:
                    config = Config(user_agent_extra="region/" + region)
                    kwargs["config"] = config
            if "endpoint_url" not in kwargs:
                kwargs["endpoint_url"] = self.test_server_mode_endpoint
            return real_boto3_client(*args, **kwargs)

        def fake_boto3_resource(*args: Any, **kwargs: Any) -> Any:
            if "endpoint_url" not in kwargs:
                kwargs["endpoint_url"] = self.test_server_mode_endpoint
            return real_boto3_resource(*args, **kwargs)

        self._client_patcher = patch("boto3.client", fake_boto3_client)
        self._resource_patcher = patch("boto3.resource", fake_boto3_resource)
        self._client_patcher.start()
        self._resource_patcher.start()

    def _get_region(self, *args: Any, **kwargs: Any) -> Optional[str]:
        if "region_name" in kwargs:
            return kwargs["region_name"]
        if type(args) == tuple and len(args) == 2:
            _, region = args
            return region
        return None

    def disable_patching(self) -> None:
        if self._client_patcher:
            self._client_patcher.stop()
            self._resource_patcher.stop()


class base_decorator:
    mock_backend = MockAWS

    def __init__(self, backends: BackendDict):
        self.backends = backends

    def __call__(
        self, func: Optional[Callable[..., Any]] = None
    ) -> Union[BaseMockAWS, Callable[..., BaseMockAWS]]:
        if settings.TEST_SERVER_MODE:
            mocked_backend: BaseMockAWS = ServerModeMockAWS(self.backends)
        else:
            mocked_backend = self.mock_backend(self.backends)

        if func:
            return mocked_backend(func)
        else:
            return mocked_backend
