# Copyright The OpenTelemetry Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from functools import cached_property
from logging import getLogger
from os import environ

from opentelemetry.instrumentation.dependencies import (
    get_dist_dependency_conflicts,
)
from opentelemetry.instrumentation.distro import BaseDistro, DefaultDistro
from opentelemetry.instrumentation.environment_variables import (
    OTEL_PYTHON_CONFIGURATOR,
    OTEL_PYTHON_DISABLED_INSTRUMENTATIONS,
    OTEL_PYTHON_DISTRO,
)
from opentelemetry.instrumentation.version import __version__
from opentelemetry.util._importlib_metadata import (
    EntryPoint,
    distributions,
    entry_points,
)

_logger = getLogger(__name__)


class _EntryPointDistFinder:
    @cached_property
    def _mapping(self):
        return {
            self._key_for(ep): dist
            for dist in distributions()
            for ep in dist.entry_points
        }

    def dist_for(self, entry_point: EntryPoint):
        dist = getattr(entry_point, "dist", None)
        if dist:
            return dist

        return self._mapping.get(self._key_for(entry_point))

    @staticmethod
    def _key_for(entry_point: EntryPoint):
        return f"{entry_point.group}:{entry_point.name}:{entry_point.value}"


def _load_distro() -> BaseDistro:
    distro_name = environ.get(OTEL_PYTHON_DISTRO, None)
    for entry_point in entry_points(group="opentelemetry_distro"):
        try:
            # If no distro is specified, use first to come up.
            if distro_name is None or distro_name == entry_point.name:
                distro = entry_point.load()()
                if not isinstance(distro, BaseDistro):
                    _logger.debug(
                        "%s is not an OpenTelemetry Distro. Skipping",
                        entry_point.name,
                    )
                    continue
                _logger.debug(
                    "Distribution %s will be configured", entry_point.name
                )
                return distro
        except Exception as exc:  # pylint: disable=broad-except
            _logger.exception(
                "Distribution %s configuration failed", entry_point.name
            )
            raise exc
    return DefaultDistro()


def _load_instrumentors(distro):
    package_to_exclude = environ.get(OTEL_PYTHON_DISABLED_INSTRUMENTATIONS, [])
    entry_point_finder = _EntryPointDistFinder()
    if isinstance(package_to_exclude, str):
        package_to_exclude = package_to_exclude.split(",")
        # to handle users entering "requests , flask" or "requests, flask" with spaces
        package_to_exclude = [x.strip() for x in package_to_exclude]

    for entry_point in entry_points(group="opentelemetry_pre_instrument"):
        entry_point.load()()

    for entry_point in entry_points(group="opentelemetry_instrumentor"):
        if entry_point.name in package_to_exclude:
            _logger.debug(
                "Instrumentation skipped for library %s", entry_point.name
            )
            continue

        try:
            entry_point_dist = entry_point_finder.dist_for(entry_point)
            conflict = get_dist_dependency_conflicts(entry_point_dist)
            if conflict:
                _logger.debug(
                    "Skipping instrumentation %s: %s",
                    entry_point.name,
                    conflict,
                )
                continue

            # tell instrumentation to not run dep checks again as we already did it above
            distro.load_instrumentor(entry_point, skip_dep_check=True)
            _logger.debug("Instrumented %s", entry_point.name)
        except Exception as exc:  # pylint: disable=broad-except
            _logger.exception("Instrumenting of %s failed", entry_point.name)
            raise exc

    for entry_point in entry_points(group="opentelemetry_post_instrument"):
        entry_point.load()()


def _load_configurators():
    configurator_name = environ.get(OTEL_PYTHON_CONFIGURATOR, None)
    configured = None
    for entry_point in entry_points(group="opentelemetry_configurator"):
        if configured is not None:
            _logger.warning(
                "Configuration of %s not loaded, %s already loaded",
                entry_point.name,
                configured,
            )
            continue
        try:
            if (
                configurator_name is None
                or configurator_name == entry_point.name
            ):
                entry_point.load()().configure(
                    auto_instrumentation_version=__version__
                )  # type: ignore
                configured = entry_point.name
            else:
                _logger.warning(
                    "Configuration of %s not loaded because %s is set by %s",
                    entry_point.name,
                    configurator_name,
                    OTEL_PYTHON_CONFIGURATOR,
                )
        except Exception as exc:  # pylint: disable=broad-except
            _logger.exception("Configuration of %s failed", entry_point.name)
            raise exc
