from contextlib import contextmanager

import werkzeug.test
from click.testing import CliRunner
from werkzeug.test import Client
from werkzeug.urls import url_parse

from . import _request_ctx_stack
from .cli import ScriptInfo
from .json import dumps as json_dumps


class EnvironBuilder(werkzeug.test.EnvironBuilder):
    """An :class:`~werkzeug.test.EnvironBuilder`, that takes defaults from the
    application.

    :param app: The Flask application to configure the environment from.
    :param path: URL path being requested.
    :param base_url: Base URL where the app is being served, which
        ``path`` is relative to. If not given, built from
        :data:`PREFERRED_URL_SCHEME`, ``subdomain``,
        :data:`SERVER_NAME`, and :data:`APPLICATION_ROOT`.
    :param subdomain: Subdomain name to append to :data:`SERVER_NAME`.
    :param url_scheme: Scheme to use instead of
        :data:`PREFERRED_URL_SCHEME`.
    :param json: If given, this is serialized as JSON and passed as
        ``data``. Also defaults ``content_type`` to
        ``application/json``.
    :param args: other positional arguments passed to
        :class:`~werkzeug.test.EnvironBuilder`.
    :param kwargs: other keyword arguments passed to
        :class:`~werkzeug.test.EnvironBuilder`.
    """

    def __init__(
        self,
        app,
        path="/",
        base_url=None,
        subdomain=None,
        url_scheme=None,
        *args,
        **kwargs,
    ):
        assert not (base_url or subdomain or url_scheme) or (
            base_url is not None
        ) != bool(
            subdomain or url_scheme
        ), 'Cannot pass "subdomain" or "url_scheme" with "base_url".'

        if base_url is None:
            http_host = app.config.get("SERVER_NAME") or "localhost"
            app_root = app.config["APPLICATION_ROOT"]

            if subdomain:
                http_host = f"{subdomain}.{http_host}"

            if url_scheme is None:
                url_scheme = app.config["PREFERRED_URL_SCHEME"]

            url = url_parse(path)
            base_url = (
                f"{url.scheme or url_scheme}://{url.netloc or http_host}"
                f"/{app_root.lstrip('/')}"
            )
            path = url.path

            if url.query:
                sep = b"?" if isinstance(url.query, bytes) else "?"
                path += sep + url.query

        self.app = app
        super().__init__(path, base_url, *args, **kwargs)

    def json_dumps(self, obj, **kwargs):
        """Serialize ``obj`` to a JSON-formatted string.

        The serialization will be configured according to the config associated
        with this EnvironBuilder's ``app``.
        """
        kwargs.setdefault("app", self.app)
        return json_dumps(obj, **kwargs)


class FlaskClient(Client):
    """Works like a regular Werkzeug test client but has some knowledge about
    how Flask works to defer the cleanup of the request context stack to the
    end of a ``with`` body when used in a ``with`` statement.  For general
    information about how to use this class refer to
    :class:`werkzeug.test.Client`.

    .. versionchanged:: 0.12
       `app.test_client()` includes preset default environment, which can be
       set after instantiation of the `app.test_client()` object in
       `client.environ_base`.

    Basic usage is outlined in the :doc:`/testing` chapter.
    """

    preserve_context = False

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.environ_base = {
            "REMOTE_ADDR": "127.0.0.1",
            "HTTP_USER_AGENT": f"werkzeug/{werkzeug.__version__}",
        }

    @contextmanager
    def session_transaction(self, *args, **kwargs):
        """When used in combination with a ``with`` statement this opens a
        session transaction.  This can be used to modify the session that
        the test client uses.  Once the ``with`` block is left the session is
        stored back.

        ::

            with client.session_transaction() as session:
                session['value'] = 42

        Internally this is implemented by going through a temporary test
        request context and since session handling could depend on
        request variables this function accepts the same arguments as
        :meth:`~flask.Flask.test_request_context` which are directly
        passed through.
        """
        if self.cookie_jar is None:
            raise RuntimeError(
                "Session transactions only make sense with cookies enabled."
            )
        app = self.application
        environ_overrides = kwargs.setdefault("environ_overrides", {})
        self.cookie_jar.inject_wsgi(environ_overrides)
        outer_reqctx = _request_ctx_stack.top
        with app.test_request_context(*args, **kwargs) as c:
            session_interface = app.session_interface
            sess = session_interface.open_session(app, c.request)
            if sess is None:
                raise RuntimeError(
                    "Session backend did not open a session. Check the configuration"
                )

            # Since we have to open a new request context for the session
            # handling we want to make sure that we hide out own context
            # from the caller.  By pushing the original request context
            # (or None) on top of this and popping it we get exactly that
            # behavior.  It's important to not use the push and pop
            # methods of the actual request context object since that would
            # mean that cleanup handlers are called
            _request_ctx_stack.push(outer_reqctx)
            try:
                yield sess
            finally:
                _request_ctx_stack.pop()

            resp = app.response_class()
            if not session_interface.is_null_session(sess):
                session_interface.save_session(app, sess, resp)
            headers = resp.get_wsgi_headers(c.request.environ)
            self.cookie_jar.extract_wsgi(c.request.environ, headers)

    def open(self, *args, **kwargs):
        as_tuple = kwargs.pop("as_tuple", False)
        buffered = kwargs.pop("buffered", False)
        follow_redirects = kwargs.pop("follow_redirects", False)

        if (
            not kwargs
            and len(args) == 1
            and isinstance(args[0], (werkzeug.test.EnvironBuilder, dict))
        ):
            environ = self.environ_base.copy()

            if isinstance(args[0], werkzeug.test.EnvironBuilder):
                environ.update(args[0].get_environ())
            else:
                environ.update(args[0])

            environ["flask._preserve_context"] = self.preserve_context
        else:
            kwargs.setdefault("environ_overrides", {})[
                "flask._preserve_context"
            ] = self.preserve_context
            kwargs.setdefault("environ_base", self.environ_base)
            builder = EnvironBuilder(self.application, *args, **kwargs)

            try:
                environ = builder.get_environ()
            finally:
                builder.close()

        return Client.open(
            self,
            environ,
            as_tuple=as_tuple,
            buffered=buffered,
            follow_redirects=follow_redirects,
        )

    def __enter__(self):
        if self.preserve_context:
            raise RuntimeError("Cannot nest client invocations")
        self.preserve_context = True
        return self

    def __exit__(self, exc_type, exc_value, tb):
        self.preserve_context = False

        # Normally the request context is preserved until the next
        # request in the same thread comes. When the client exits we
        # want to clean up earlier. Pop request contexts until the stack
        # is empty or a non-preserved one is found.
        while True:
            top = _request_ctx_stack.top

            if top is not None and top.preserved:
                top.pop()
            else:
                break


class FlaskCliRunner(CliRunner):
    """A :class:`~click.testing.CliRunner` for testing a Flask app's
    CLI commands. Typically created using
    :meth:`~flask.Flask.test_cli_runner`. See :ref:`testing-cli`.
    """

    def __init__(self, app, **kwargs):
        self.app = app
        super().__init__(**kwargs)

    def invoke(self, cli=None, args=None, **kwargs):
        """Invokes a CLI command in an isolated environment. See
        :meth:`CliRunner.invoke <click.testing.CliRunner.invoke>` for
        full method documentation. See :ref:`testing-cli` for examples.

        If the ``obj`` argument is not given, passes an instance of
        :class:`~flask.cli.ScriptInfo` that knows how to load the Flask
        app being tested.

        :param cli: Command object to invoke. Default is the app's
            :attr:`~flask.app.Flask.cli` group.
        :param args: List of strings to invoke the command with.

        :return: a :class:`~click.testing.Result` object.
        """
        if cli is None:
            cli = self.app.cli

        if "obj" not in kwargs:
            kwargs["obj"] = ScriptInfo(create_app=lambda: self.app)

        return super().invoke(cli, args, **kwargs)
