import flask
import werkzeug
from werkzeug.exceptions import BadRequest
from werkzeug.exceptions import NotFound
from werkzeug.exceptions import abort

from ddtrace.contrib import trace_utils
from ddtrace.ext import SpanTypes
from ddtrace.internal.constants import COMPONENT
from ddtrace.internal.constants import HTTP_REQUEST_BLOCKED
from ddtrace.internal.constants import STATUS_403_TYPE_AUTO
from ddtrace.internal.schema.span_attribute_schema import SpanDirection

from ...internal import core
from ...internal.schema import schematize_service_name
from ...internal.schema import schematize_url_operation
from ...internal.utils import http as http_utils


# Not all versions of flask/werkzeug have this mixin
try:
    from werkzeug.wrappers.json import JSONMixin

    _HAS_JSON_MIXIN = True
except ImportError:
    _HAS_JSON_MIXIN = False

from ddtrace import Pin
from ddtrace import config
from ddtrace.vendor.wrapt import wrap_function_wrapper as _w

from ...contrib.wsgi.wsgi import _DDWSGIMiddlewareBase
from ...internal.logger import get_logger
from ...internal.utils import get_argument_value
from ...internal.utils.importlib import func_name
from ...internal.utils.version import parse_version
from ..trace_utils import unwrap as _u
from .wrappers import _wrap_call_with_pin_check
from .wrappers import get_current_app
from .wrappers import simple_call_wrapper
from .wrappers import with_instance_pin
from .wrappers import wrap_function
from .wrappers import wrap_view


try:
    from json import JSONDecodeError
except ImportError:
    # handling python 2.X import error
    JSONDecodeError = ValueError  # type: ignore


log = get_logger(__name__)

FLASK_VERSION = "flask.version"
_BODY_METHODS = {"POST", "PUT", "DELETE", "PATCH"}

# Configure default configuration
config._add(
    "flask",
    dict(
        # Flask service configuration
        _default_service=schematize_service_name("flask"),
        collect_view_args=True,
        distributed_tracing_enabled=True,
        template_default_name="<memory>",
        trace_signals=True,
    ),
)


def get_version():
    # type: () -> str
    return getattr(flask, "__version__", "")


if _HAS_JSON_MIXIN:

    class RequestWithJson(werkzeug.Request, JSONMixin):
        pass

    _RequestType = RequestWithJson
else:
    _RequestType = werkzeug.Request

# Extract flask version into a tuple e.g. (0, 12, 1) or (1, 0, 2)
# DEV: This makes it so we can do `if flask_version >= (0, 12, 0):`
# DEV: Example tests:
#      (0, 10, 0) > (0, 10)
#      (0, 10, 0) >= (0, 10, 0)
#      (0, 10, 1) >= (0, 10)
#      (0, 11, 1) >= (0, 10)
#      (0, 11, 1) >= (0, 10, 2)
#      (1, 0, 0) >= (0, 10)
#      (0, 9) == (0, 9)
#      (0, 9, 0) != (0, 9)
#      (0, 8, 5) <= (0, 9)
flask_version_str = getattr(flask, "__version__", "")
flask_version = parse_version(flask_version_str)


class _FlaskWSGIMiddleware(_DDWSGIMiddlewareBase):
    _request_call_name = schematize_url_operation("flask.request", protocol="http", direction=SpanDirection.INBOUND)
    _application_call_name = "flask.application"
    _response_call_name = "flask.response"

    def _wrapped_start_response(self, start_response, ctx, status_code, headers, exc_info=None):
        core.dispatch("flask.start_response.pre", (flask.request, ctx, config.flask, status_code, headers))
        if not core.get_item(HTTP_REQUEST_BLOCKED):
            headers_from_context = ""
            result = core.dispatch_with_results("flask.start_response", ("Flask",)).waf
            if result:
                headers_from_context = result.value
            if core.get_item(HTTP_REQUEST_BLOCKED):
                # response code must be set here, or it will be too late
                block_config = core.get_item(HTTP_REQUEST_BLOCKED)
                desired_type = block_config.get("type", "auto")
                status = block_config.get("status_code", 403)
                if desired_type == "none":
                    response_headers = []
                else:
                    if block_config.get("type", "auto") == "auto":
                        ctype = "text/html" if "text/html" in headers_from_context else "text/json"
                    else:
                        ctype = "text/" + block_config["type"]
                    response_headers = [("content-type", ctype)]
                result = start_response(str(status), response_headers)
                core.dispatch("flask.start_response.blocked", (ctx, config.flask, response_headers, status))
            else:
                result = start_response(status_code, headers)
        else:
            result = start_response(status_code, headers)
        return result

    def _request_call_modifier(self, ctx, parsed_headers=None):
        environ = ctx.get_item("environ")
        # Create a werkzeug request from the `environ` to make interacting with it easier
        # DEV: This executes before a request context is created
        request = _RequestType(environ)

        req_body = None
        result = core.dispatch_with_results(
            "flask.request_call_modifier",
            (
                ctx,
                config.flask,
                request,
                environ,
                _HAS_JSON_MIXIN,
                FLASK_VERSION,
                flask_version_str,
                BadRequest,
            ),
        ).request_body
        if result:
            req_body = result.value
        core.dispatch("flask.request_call_modifier.post", (ctx, config.flask, request, req_body))


def patch():
    """
    Patch `flask` module for tracing
    """
    # Check to see if we have patched Flask yet or not
    if getattr(flask, "_datadog_patch", False):
        return
    flask._datadog_patch = True

    Pin().onto(flask.Flask)
    core.dispatch("flask.patch", (flask_version,))
    # flask.app.Flask methods that have custom tracing (add metadata, wrap functions, etc)
    _w("flask", "Flask.wsgi_app", patched_wsgi_app)
    _w("flask", "Flask.dispatch_request", request_patcher("dispatch_request"))
    _w("flask", "Flask.preprocess_request", request_patcher("preprocess_request"))
    _w("flask", "Flask.add_url_rule", patched_add_url_rule)
    _w("flask", "Flask.endpoint", patched_endpoint)

    _w("flask", "Flask.finalize_request", patched_finalize_request)

    if flask_version >= (2, 0, 0):
        _w("flask", "Flask.register_error_handler", patched_register_error_handler)
    else:
        _w("flask", "Flask._register_error_handler", patched__register_error_handler)

    # flask.blueprints.Blueprint methods that have custom tracing (add metadata, wrap functions, etc)
    _w("flask", "Blueprint.register", patched_blueprint_register)
    _w("flask", "Blueprint.add_url_rule", patched_blueprint_add_url_rule)

    flask_hooks = [
        "before_request",
        "after_request",
        "teardown_request",
        "teardown_appcontext",
    ]
    if flask_version < (2, 3, 0):
        flask_hooks.append("before_first_request")

    for hook in flask_hooks:
        _w("flask", "Flask.{}".format(hook), patched_flask_hook)
    _w("flask", "after_this_request", patched_flask_hook)

    flask_app_traces = [
        "process_response",
        "handle_exception",
        "handle_http_exception",
        "handle_user_exception",
        "do_teardown_request",
        "do_teardown_appcontext",
        "send_static_file",
    ]
    if flask_version < (2, 2, 0):
        flask_app_traces.append("try_trigger_before_first_request_functions")

    for name in flask_app_traces:
        _w("flask", "Flask.{}".format(name), simple_call_wrapper("flask.{}".format(name)))
    # flask static file helpers
    _w("flask", "send_file", simple_call_wrapper("flask.send_file"))

    # flask.json.jsonify
    _w("flask", "jsonify", patched_jsonify)

    _w("flask.templating", "_render", patched_render)
    _w("flask", "render_template", _build_render_template_wrapper("render_template"))
    _w("flask", "render_template_string", _build_render_template_wrapper("render_template_string"))

    bp_hooks = [
        "after_app_request",
        "after_request",
        "before_app_request",
        "before_request",
        "teardown_request",
        "teardown_app_request",
    ]
    if flask_version < (2, 3, 0):
        bp_hooks.append("before_app_first_request")

    for hook in bp_hooks:
        _w("flask", "Blueprint.{}".format(hook), patched_flask_hook)

    if config.flask["trace_signals"]:
        signals = [
            "template_rendered",
            "request_started",
            "request_finished",
            "request_tearing_down",
            "got_request_exception",
            "appcontext_tearing_down",
        ]
        # These were added in 0.11.0
        if flask_version >= (0, 11):
            signals.append("before_render_template")

        # These were added in 0.10.0
        if flask_version >= (0, 10):
            signals.append("appcontext_pushed")
            signals.append("appcontext_popped")
            signals.append("message_flashed")

        for signal in signals:
            module = "flask"

            # v0.9 missed importing `appcontext_tearing_down` in `flask/__init__.py`
            #  https://github.com/pallets/flask/blob/0.9/flask/__init__.py#L35-L37
            #  https://github.com/pallets/flask/blob/0.9/flask/signals.py#L52
            # DEV: Version 0.9 doesn't have a patch version
            if flask_version <= (0, 9) and signal == "appcontext_tearing_down":
                module = "flask.signals"

            # DEV: Patch `receivers_for` instead of `connect` to ensure we don't mess with `disconnect`
            _w(module, "{}.receivers_for".format(signal), patched_signal_receivers_for(signal))


def unpatch():
    if not getattr(flask, "_datadog_patch", False):
        return
    flask._datadog_patch = False

    props = [
        # Flask
        "Flask.wsgi_app",
        "Flask.dispatch_request",
        "Flask.add_url_rule",
        "Flask.endpoint",
        "Flask.preprocess_request",
        "Flask.process_response",
        "Flask.handle_exception",
        "Flask.handle_http_exception",
        "Flask.handle_user_exception",
        "Flask.do_teardown_request",
        "Flask.do_teardown_appcontext",
        "Flask.send_static_file",
        # Flask Hooks
        "Flask.before_request",
        "Flask.after_request",
        "Flask.teardown_request",
        "Flask.teardown_appcontext",
        # Blueprint
        "Blueprint.register",
        "Blueprint.add_url_rule",
        # Blueprint Hooks
        "Blueprint.after_app_request",
        "Blueprint.after_request",
        "Blueprint.before_app_request",
        "Blueprint.before_request",
        "Blueprint.teardown_request",
        "Blueprint.teardown_app_request",
        # Signals
        "template_rendered.receivers_for",
        "request_started.receivers_for",
        "request_finished.receivers_for",
        "request_tearing_down.receivers_for",
        "got_request_exception.receivers_for",
        "appcontext_tearing_down.receivers_for",
        # Top level props
        "after_this_request",
        "send_file",
        "jsonify",
        "render_template",
        "render_template_string",
        "templating._render",
    ]

    props.append("Flask.finalize_request")

    if flask_version >= (2, 0, 0):
        props.append("Flask.register_error_handler")
    else:
        props.append("Flask._register_error_handler")

    # These were added in 0.11.0
    if flask_version >= (0, 11):
        props.append("before_render_template.receivers_for")

    # These were added in 0.10.0
    if flask_version >= (0, 10):
        props.append("appcontext_pushed.receivers_for")
        props.append("appcontext_popped.receivers_for")
        props.append("message_flashed.receivers_for")

    # These were removed in 2.2.0
    if flask_version < (2, 2, 0):
        props.append("Flask.try_trigger_before_first_request_functions")

    # These were removed in 2.3.0
    if flask_version < (2, 3, 0):
        props.append("Flask.before_first_request")
        props.append("Blueprint.before_app_first_request")

    for prop in props:
        # Handle 'flask.request_started.receivers_for'
        obj = flask

        # v0.9.0 missed importing `appcontext_tearing_down` in `flask/__init__.py`
        #  https://github.com/pallets/flask/blob/0.9/flask/__init__.py#L35-L37
        #  https://github.com/pallets/flask/blob/0.9/flask/signals.py#L52
        # DEV: Version 0.9 doesn't have a patch version
        if flask_version <= (0, 9) and prop == "appcontext_tearing_down.receivers_for":
            obj = flask.signals

        if "." in prop:
            attr, _, prop = prop.partition(".")
            obj = getattr(obj, attr, object())
        _u(obj, prop)


@with_instance_pin
def patched_wsgi_app(pin, wrapped, instance, args, kwargs):
    # This wrapper is the starting point for all requests.
    # DEV: This is safe before this is the args for a WSGI handler
    #   https://www.python.org/dev/peps/pep-3333/
    environ, start_response = args
    middleware = _FlaskWSGIMiddleware(wrapped, pin.tracer, config.flask, pin)
    return middleware(environ, start_response)


def patched_finalize_request(wrapped, instance, args, kwargs):
    """
    Wrapper for flask.app.Flask.finalize_request
    """
    rv = wrapped(*args, **kwargs)
    response = None
    headers = None
    if getattr(rv, "is_sequence", False):
        response = rv.response
        headers = rv.headers
    core.dispatch("flask.finalize_request.post", (response, headers))
    return rv


def patched_blueprint_register(wrapped, instance, args, kwargs):
    """
    Wrapper for flask.blueprints.Blueprint.register

    This wrapper just ensures the blueprint has a pin, either set manually on
    itself from the user or inherited from the application
    """
    app = get_argument_value(args, kwargs, 0, "app")
    # Check if this Blueprint has a pin, otherwise clone the one from the app onto it
    pin = Pin.get_from(instance)
    if not pin:
        pin = Pin.get_from(app)
        if pin:
            pin.clone().onto(instance)
    return wrapped(*args, **kwargs)


def patched_blueprint_add_url_rule(wrapped, instance, args, kwargs):
    pin = Pin._find(wrapped, instance)
    if not pin:
        return wrapped(*args, **kwargs)

    def _wrap(rule, endpoint=None, view_func=None, **kwargs):
        if view_func:
            pin.clone().onto(view_func)
        return wrapped(rule, endpoint=endpoint, view_func=view_func, **kwargs)

    return _wrap(*args, **kwargs)


def patched_add_url_rule(wrapped, instance, args, kwargs):
    """Wrapper for flask.app.Flask.add_url_rule to wrap all views attached to this app"""

    def _wrap(rule, endpoint=None, view_func=None, **kwargs):
        if view_func:
            # TODO: `if hasattr(view_func, 'view_class')` then this was generated from a `flask.views.View`
            #   should we do something special with these views? Change the name/resource? Add tags?
            view_func = wrap_view(instance, view_func, name=endpoint, resource=rule)

        return wrapped(rule, endpoint=endpoint, view_func=view_func, **kwargs)

    return _wrap(*args, **kwargs)


def patched_endpoint(wrapped, instance, args, kwargs):
    """Wrapper for flask.app.Flask.endpoint to ensure all endpoints are wrapped"""
    endpoint = kwargs.get("endpoint", args[0])

    def _wrapper(func):
        return wrapped(endpoint)(wrap_function(instance, func, resource=endpoint))

    return _wrapper


def patched_flask_hook(wrapped, instance, args, kwargs):
    func = get_argument_value(args, kwargs, 0, "f")
    return wrapped(wrap_function(instance, func))


def traced_render_template(wrapped, instance, args, kwargs):
    return _build_render_template_wrapper("render_template")(wrapped, instance, args, kwargs)


def traced_render_template_string(wrapped, instance, args, kwargs):
    return _build_render_template_wrapper("render_template_string")(wrapped, instance, args, kwargs)


def _build_render_template_wrapper(name):
    name = "flask.%s" % name

    def traced_render(wrapped, instance, args, kwargs):
        pin = Pin._find(wrapped, instance, get_current_app())
        if not pin or not pin.enabled():
            return wrapped(*args, **kwargs)
        with core.context_with_data(
            "flask.render_template",
            span_name=name,
            pin=pin,
            flask_config=config.flask,
            tags={COMPONENT: config.flask.integration_name},
            span_type=SpanTypes.TEMPLATE,
            call_key=[name + ".call", "current_span"],
        ) as ctx, ctx.get_item(name + ".call"):
            return wrapped(*args, **kwargs)

    return traced_render


def patched_render(wrapped, instance, args, kwargs):
    pin = Pin._find(wrapped, instance, get_current_app())

    if not pin.enabled:
        return wrapped(*args, **kwargs)

    def _wrap(template, context, app):
        core.dispatch("flask.render", (template, config.flask))
        return wrapped(*args, **kwargs)

    return _wrap(*args, **kwargs)


def patched__register_error_handler(wrapped, instance, args, kwargs):
    def _wrap(key, code_or_exception, f):
        return wrapped(key, code_or_exception, wrap_function(instance, f))

    return _wrap(*args, **kwargs)


def patched_register_error_handler(wrapped, instance, args, kwargs):
    def _wrap(code_or_exception, f):
        return wrapped(code_or_exception, wrap_function(instance, f))

    return _wrap(*args, **kwargs)


def _block_request_callable(call):
    core.set_item(HTTP_REQUEST_BLOCKED, STATUS_403_TYPE_AUTO)
    core.dispatch("flask.blocked_request_callable", (call,))
    ctype = "text/html" if "text/html" in flask.request.headers.get("Accept", "").lower() else "text/json"
    abort(flask.Response(http_utils._get_blocked_template(ctype), content_type=ctype, status=403))


def request_patcher(name):
    @with_instance_pin
    def _patched_request(pin, wrapped, instance, args, kwargs):
        with core.context_with_data(
            "flask._patched_request",
            span_name=".".join(("flask", name)),
            pin=pin,
            service=trace_utils.int_service(pin, config.flask, pin),
            flask_config=config.flask,
            flask_request=flask.request,
            block_request_callable=_block_request_callable,
            ignored_exception_type=NotFound,
            call_key="flask_request_call",
            tags={COMPONENT: config.flask.integration_name},
        ) as ctx, ctx.get_item("flask_request_call"):
            core.dispatch("flask._patched_request", (ctx,))
            return wrapped(*args, **kwargs)

    return _patched_request


def patched_signal_receivers_for(signal):
    def outer(wrapped, instance, args, kwargs):
        sender = get_argument_value(args, kwargs, 0, "sender")
        # See if they gave us the flask.app.Flask as the sender
        app = None
        if isinstance(sender, flask.Flask):
            app = sender
        for receiver in wrapped(*args, **kwargs):
            yield _wrap_call_with_pin_check(receiver, app, func_name(receiver), signal=signal)

    return outer


def patched_jsonify(wrapped, instance, args, kwargs):
    pin = Pin._find(wrapped, instance, get_current_app())
    if not pin or not pin.enabled():
        return wrapped(*args, **kwargs)

    with core.context_with_data(
        "flask.jsonify",
        span_name="flask.jsonify",
        flask_config=config.flask,
        tags={COMPONENT: config.flask.integration_name},
        pin=pin,
        call_key="flask_jsonify_call",
    ) as ctx, ctx.get_item("flask_jsonify_call"):
        return wrapped(*args, **kwargs)