#  BSD 3-Clause License
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#  Copyright (c) 2019, Elasticsearch BV
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"""
Instrumentation for Tornado
"""

import elasticapm
from elasticapm.conf import constants
from elasticapm.instrumentation.packages.asyncio.base import AbstractInstrumentedModule, AsyncAbstractInstrumentedModule
from elasticapm.traces import capture_span
from elasticapm.utils.disttracing import TraceParent
from elasticapm.utils.logging import get_logger

logger = get_logger("elasticapm.instrument")


class TornadoBaseInstrumentedModule(AbstractInstrumentedModule):
    def instrument(self) -> None:
        try:
            import tornado

            if tornado.version_info[0] < 6:
                logger.debug("Skipping instrumentation of %s. Tornado is only supported with version 6.0+", self.name)
                return
        except ImportError:
            pass
        super().instrument()


class TornadoRequestExecuteInstrumentation(TornadoBaseInstrumentedModule, AsyncAbstractInstrumentedModule):
    name = "tornado_request_execute"
    creates_transactions = True
    instrument_list = [("tornado.web", "RequestHandler._execute")]

    async def call(self, module, method, wrapped, instance, args, kwargs):
        if not hasattr(instance.application, "elasticapm_client"):
            # If tornado was instrumented but not as the main framework
            # (i.e. in Flower), we should skip it.
            return await wrapped(*args, **kwargs)

        # Late import to avoid ImportErrors
        from elasticapm.contrib.tornado.utils import get_data_from_request, get_data_from_response

        request = instance.request
        client = instance.application.elasticapm_client
        should_ignore = client.should_ignore_url(request.path)
        if not should_ignore:
            # In tornado 6.5.3 the __in__ protocol for the headers is case-sensitive so we need to normalize them
            normalized_headers = {k.lower(): v for k, v in request.headers.items()}
            trace_parent = TraceParent.from_headers(normalized_headers)
            client.begin_transaction("request", trace_parent=trace_parent)
            elasticapm.set_context(
                lambda: get_data_from_request(instance, request, client.config, constants.TRANSACTION), "request"
            )
            # TODO: Can we somehow incorporate the routing rule itself here?
            elasticapm.set_transaction_name("{} {}".format(request.method, type(instance).__name__), override=False)

        ret = await wrapped(*args, **kwargs)

        if not should_ignore:
            elasticapm.set_context(
                lambda: get_data_from_response(instance, client.config, constants.TRANSACTION), "response"
            )
            status = instance.get_status()
            result = "HTTP {}xx".format(status // 100)
            elasticapm.set_transaction_result(result, override=False)
            elasticapm.set_transaction_outcome(http_status_code=status)
            client.end_transaction()

        return ret


class TornadoHandleRequestExceptionInstrumentation(TornadoBaseInstrumentedModule):
    name = "tornado_handle_request_exception"

    instrument_list = [("tornado.web", "RequestHandler._handle_request_exception")]

    def call(self, module, method, wrapped, instance, args, kwargs):
        if not hasattr(instance.application, "elasticapm_client"):
            # If tornado was instrumented but not as the main framework
            # (i.e. in Flower), we should skip it.
            return wrapped(*args, **kwargs)

        # Late import to avoid ImportErrors
        from tornado.web import Finish, HTTPError

        from elasticapm.contrib.tornado.utils import get_data_from_request

        e = args[0]
        if isinstance(e, Finish):
            # Not an error; Finish is an exception that ends a request without an error response
            return wrapped(*args, **kwargs)

        client = instance.application.elasticapm_client
        request = instance.request
        client.capture_exception(
            context={"request": get_data_from_request(instance, request, client.config, constants.ERROR)}
        )
        elasticapm.set_transaction_outcome(constants.OUTCOME.FAILURE)
        if isinstance(e, HTTPError):
            elasticapm.set_transaction_result("HTTP {}xx".format(int(e.status_code / 100)), override=False)
            elasticapm.set_context({"status_code": e.status_code}, "response")
        else:
            elasticapm.set_transaction_result("HTTP 5xx", override=False)
            elasticapm.set_context({"status_code": 500}, "response")

        return wrapped(*args, **kwargs)


class TornadoRenderInstrumentation(TornadoBaseInstrumentedModule):
    name = "tornado_render"

    instrument_list = [("tornado.web", "RequestHandler.render")]

    def call(self, module, method, wrapped, instance, args, kwargs):
        if "template_name" in kwargs:
            name = kwargs["template_name"]
        else:
            name = args[0]

        with capture_span(name, span_type="template", span_subtype="tornado", span_action="render"):
            return wrapped(*args, **kwargs)
