#  BSD 3-Clause License
#
#  Copyright (c) 2012, the Sentry Team, see AUTHORS for more details
#  Copyright (c) 2019, Elasticsearch BV
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#  modification, are permitted provided that the following conditions are met:
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#  * Redistributions of source code must retain the above copyright notice, this
#    list of conditions and the following disclaimer.
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#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution.
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#    contributors may be used to endorse or promote products derived from
#    this software without specific prior written permission.
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#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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from __future__ import absolute_import

import logging
import threading
from types import FunctionType
from typing import Optional

import wrapt
from django.apps import apps
from django.conf import settings as django_settings
from django.http import HttpRequest, HttpResponse

import elasticapm
from elasticapm.conf import constants
from elasticapm.contrib.django.client import client, get_client
from elasticapm.utils import build_name_with_http_method_prefix, get_name_from_func

try:
    from importlib import import_module
except ImportError:
    from django.utils.importlib import import_module

try:
    from django.utils.deprecation import MiddlewareMixin
except ImportError:
    # no-op class for Django < 1.10
    class MiddlewareMixin(object):
        pass


def _is_ignorable_404(uri):
    """
    Returns True if the given request *shouldn't* notify the site managers.
    """
    urls = getattr(django_settings, "IGNORABLE_404_URLS", ())
    return any(pattern.search(uri) for pattern in urls)


class ElasticAPMClientMiddlewareMixin(object):
    @property
    def client(self):
        try:
            app = apps.get_app_config("elasticapm")
            return app.client
        except LookupError:
            return get_client()


class Catch404Middleware(MiddlewareMixin, ElasticAPMClientMiddlewareMixin):
    def process_response(self, request, response):
        if response.status_code != 404 or _is_ignorable_404(request.get_full_path()):
            return response
        if django_settings.DEBUG and not self.client.config.debug:
            return response
        data = {"level": logging.INFO, "logger": "http404"}
        result = self.client.capture(
            "Message",
            request=request,
            param_message={"message": "Page Not Found: %s", "params": [request.build_absolute_uri()]},
            logger_name="http404",
            level=logging.INFO,
        )
        request._elasticapm = {"service_name": data.get("service_name", self.client.config.service_name), "id": result}
        return response


def get_name_from_middleware(wrapped, instance):
    name = [type(instance).__name__, wrapped.__name__]
    if type(instance).__module__:
        name = [type(instance).__module__] + name
    return ".".join(name)


def process_request_wrapper(wrapped, instance, args, kwargs):
    response = wrapped(*args, **kwargs)
    try:
        if response is not None:
            request = args[0]
            elasticapm.set_transaction_name(
                build_name_with_http_method_prefix(get_name_from_middleware(wrapped, instance), request)
            )
    except Exception:
        pass
    return response


def process_response_wrapper(wrapped, instance, args, kwargs):
    response = wrapped(*args, **kwargs)
    try:
        request, original_response = args
        # if we haven't set the name in a view, and this middleware created
        # a new response object, it's logged as the responsible transaction
        # name
        if not getattr(request, "_elasticapm_name_set", False) and response is not original_response:
            elasticapm.set_transaction_name(
                build_name_with_http_method_prefix(get_name_from_middleware(wrapped, instance), request)
            )
    except Exception:
        pass
    return response


class TracingMiddleware(MiddlewareMixin, ElasticAPMClientMiddlewareMixin):
    _elasticapm_instrumented = False
    _instrumenting_lock = threading.Lock()

    def __init__(self, *args, **kwargs) -> None:
        super(TracingMiddleware, self).__init__(*args, **kwargs)
        if not self._elasticapm_instrumented:
            with self._instrumenting_lock:
                if not self._elasticapm_instrumented:
                    if self.client.config.instrument_django_middleware:
                        self.instrument_middlewares()

                    TracingMiddleware._elasticapm_instrumented = True

    def instrument_middlewares(self) -> None:
        middlewares = getattr(django_settings, "MIDDLEWARE", None) or getattr(
            django_settings, "MIDDLEWARE_CLASSES", None
        )
        if middlewares:
            for middleware_path in middlewares:
                module_path, class_name = middleware_path.rsplit(".", 1)
                try:
                    module = import_module(module_path)
                    middleware_class = getattr(module, class_name)
                    if middleware_class == type(self):
                        # don't instrument ourselves
                        continue
                    if hasattr(middleware_class, "process_request"):
                        wrapt.wrap_function_wrapper(middleware_class, "process_request", process_request_wrapper)
                    if hasattr(middleware_class, "process_response"):
                        wrapt.wrap_function_wrapper(middleware_class, "process_response", process_response_wrapper)
                except ImportError:
                    client.logger.warning("Can't instrument middleware %s", middleware_path)

    def process_view(self, request: HttpRequest, view_func: FunctionType, view_args: list, view_kwargs: dict) -> None:
        elasticapm.set_transaction_name(self.get_transaction_name(request, view_func), override=False)
        request._elasticapm_name_set = True

    def process_response(self, request: HttpRequest, response: HttpResponse):
        if django_settings.DEBUG and not self.client.config.debug:
            return response
        try:
            if hasattr(response, "status_code"):
                if not getattr(request, "_elasticapm_name_set", False):
                    elasticapm.set_transaction_name(self.get_transaction_name(request), override=False)
                elasticapm.set_context(
                    lambda: self.client.get_data_from_request(request, constants.TRANSACTION), "request"
                )
                elasticapm.set_context(
                    lambda: self.client.get_data_from_response(response, constants.TRANSACTION), "response"
                )
                elasticapm.set_context(lambda: self.client.get_user_info(request), "user")
                elasticapm.set_transaction_result("HTTP {}xx".format(response.status_code // 100), override=False)
                elasticapm.set_transaction_outcome(http_status_code=response.status_code, override=False)
        except Exception:
            self.client.error_logger.error("Exception during timing of request", exc_info=True)
        return response

    def get_transaction_name(self, request: HttpRequest, view_func: Optional[FunctionType] = None) -> str:
        transaction_name = ""
        if self.client.config.django_transaction_name_from_route and hasattr(request.resolver_match, "route"):
            r = request.resolver_match
            # if no route is defined (e.g. for the root URL), fall back on url_name and then function name
            transaction_name = r.route or r.url_name or get_name_from_func(r.func)
        elif view_func:
            transaction_name = get_name_from_func(view_func)
        if transaction_name:
            transaction_name = build_name_with_http_method_prefix(transaction_name, request)
        return transaction_name


class ErrorIdMiddleware(MiddlewareMixin):
    """
    Appends the X-ElasticAPM-ErrorId response header for referencing a message within
    the ElasticAPM datastore.
    """

    def process_response(self, request, response):
        if not getattr(request, "_elasticapm", None):
            return response
        response["X-ElasticAPM-ErrorId"] = request._elasticapm["id"]
        return response


class LogMiddleware(MiddlewareMixin):
    # Create a thread local variable to store the session in for logging
    thread = threading.local()

    def process_request(self, request) -> None:
        self.thread.request = request
