# Copyright [2017] [Red Hat, Inc.]
#
# 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.


import hashlib
import json
import os
import tempfile
from collections import defaultdict
from functools import partial

import kubernetes.dynamic
import kubernetes.dynamic.discovery
from ansible_collections.kubernetes.core.plugins.module_utils.client.resource import (
    ResourceList,
)
from kubernetes import __version__
from kubernetes.dynamic.exceptions import (
    ResourceNotFoundError,
    ResourceNotUniqueError,
    ServiceUnavailableError,
)


class Discoverer(kubernetes.dynamic.discovery.Discoverer):
    def __init__(self, client, cache_file):
        self.client = client
        default_cache_file_name = "k8srcp-{0}.json".format(
            hashlib.sha256(self.__get_default_cache_id()).hexdigest()
        )
        self.__cache_file = cache_file or os.path.join(
            tempfile.gettempdir(), default_cache_file_name
        )
        self.__init_cache()

    def __get_default_cache_id(self):
        user = self.__get_user()
        if user:
            cache_id = "{0}-{1}".format(self.client.configuration.host, user)
        else:
            cache_id = self.client.configuration.host
        return cache_id.encode("utf-8")

    def __get_user(self):
        # This is intended to provide a portable method for getting a username.
        # It could, and maybe should, be replaced by getpass.getuser() but, due
        # to a lack of portability testing the original code is being left in
        # place.
        if hasattr(os, "getlogin"):
            try:
                user = os.getlogin()
                if user:
                    return str(user)
            except OSError:
                pass
        if hasattr(os, "getuid"):
            try:
                user = os.getuid()
                if user:
                    return str(user)
            except OSError:
                pass
        user = os.environ.get("USERNAME")
        if user:
            return str(user)
        return None

    def __init_cache(self, refresh=False):
        if refresh or not os.path.exists(self.__cache_file):
            self._cache = {"library_version": __version__}
            refresh = True
        else:
            try:
                with open(self.__cache_file, "r") as f:
                    self._cache = json.load(f, cls=partial(CacheDecoder, self.client))
                if self._cache.get("library_version") != __version__:
                    # Version mismatch, need to refresh cache
                    self.invalidate_cache()
            except Exception:
                self.invalidate_cache()
        self._load_server_info()
        self.discover()
        if refresh:
            self._write_cache()

    def get_resources_for_api_version(self, prefix, group, version, preferred):
        """returns a dictionary of resources associated with provided (prefix, group, version)"""

        resources = defaultdict(list)
        subresources = defaultdict(dict)

        path = "/".join(filter(None, [prefix, group, version]))
        try:
            resources_response = self.client.request("GET", path).resources or []
        except ServiceUnavailableError:
            resources_response = []

        resources_raw = list(
            filter(lambda resource: "/" not in resource["name"], resources_response)
        )
        subresources_raw = list(
            filter(lambda resource: "/" in resource["name"], resources_response)
        )
        for subresource in subresources_raw:
            resource, name = subresource["name"].split("/", 1)
            subresources[resource][name] = subresource

        for resource in resources_raw:
            # Prevent duplicate keys
            for key in ("prefix", "group", "api_version", "client", "preferred"):
                resource.pop(key, None)

            resourceobj = kubernetes.dynamic.Resource(
                prefix=prefix,
                group=group,
                api_version=version,
                client=self.client,
                preferred=preferred,
                subresources=subresources.get(resource["name"]),
                **resource
            )
            resources[resource["kind"]].append(resourceobj)

            resource_lookup = {
                "prefix": prefix,
                "group": group,
                "api_version": version,
                "kind": resourceobj.kind,
                "name": resourceobj.name,
            }
            resource_list = ResourceList(
                self.client,
                group=group,
                api_version=version,
                base_kind=resource["kind"],
                base_resource_lookup=resource_lookup,
            )
            resources[resource_list.kind].append(resource_list)
        return resources

    def get(self, **kwargs):
        """
        Same as search, but will throw an error if there are multiple or no
        results. If there are multiple results and only one is an exact match
        on api_version, that resource will be returned.
        """
        results = self.search(**kwargs)
        # If there are multiple matches, prefer exact matches on api_version
        if len(results) > 1 and kwargs.get("api_version"):
            results = [
                result
                for result in results
                if result.group_version == kwargs["api_version"]
            ]
        # If there are multiple matches, prefer non-List kinds
        if len(results) > 1 and not all(isinstance(x, ResourceList) for x in results):
            results = [
                result for result in results if not isinstance(result, ResourceList)
            ]
        # if multiple resources are found that share a GVK, prefer the one with the most supported verbs
        if (
            len(results) > 1
            and len(set((x.group_version, x.kind) for x in results)) == 1
        ):
            if len(set(len(x.verbs) for x in results)) != 1:
                results = [max(results, key=lambda x: len(x.verbs))]
        if len(results) == 1:
            return results[0]
        elif not results:
            raise ResourceNotFoundError("No matches found for {0}".format(kwargs))
        else:
            raise ResourceNotUniqueError(
                "Multiple matches found for {0}: {1}".format(kwargs, results)
            )


class LazyDiscoverer(Discoverer, kubernetes.dynamic.LazyDiscoverer):
    def __init__(self, client, cache_file):
        Discoverer.__init__(self, client, cache_file)
        self.__update_cache = False

    @property
    def update_cache(self):
        self.__update_cache


class CacheDecoder(json.JSONDecoder):
    def __init__(self, client, *args, **kwargs):
        self.client = client
        json.JSONDecoder.__init__(self, object_hook=self.object_hook, *args, **kwargs)

    def object_hook(self, obj):
        if "_type" not in obj:
            return obj
        _type = obj.pop("_type")
        if _type == "Resource":
            return kubernetes.dynamic.Resource(client=self.client, **obj)
        elif _type == "ResourceList":
            return ResourceList(self.client, **obj)
        elif _type == "ResourceGroup":
            return kubernetes.dynamic.discovery.ResourceGroup(
                obj["preferred"], resources=self.object_hook(obj["resources"])
            )
        return obj