# Copyright (c) 2017-2020 Wind River Systems, 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.

import json
import logging
from django.core.cache import cache

logger = logging.getLogger(__name__)

# note: memcached key length should be < 250, the value < 1MB


def flush_cache_by_url(resource_url):
    try:
        # this is to invalidate similar cache data blindly
        resource_wo_query = resource_url.split("?", 1)[0]
        aaikey = "AAI_" + resource_wo_query
        cache.delete(aaikey)

        # AAI entry keys: flush all entries with same prefix
        aaikeylist = json.loads(cache.get("AAIKeys", '[]'))
        aaikeyset = set([])
        for k in aaikeylist:
            if k.find(aaikey) >= 0:
                cache.delete(k)
            else:
                aaikeyset.add(k)
        cache.set("AAIKeys", json.dumps(list(aaikeyset)))
    except:
        pass  # silently drop any exception


def get_cache_by_url(resource_url):
    try:
        if filter_cache_by_url(resource_url):
            value = cache.get("AAI_" + resource_url)
            # logger.debug("Find cache the resource: %s, %s" %( resource_url, value))
            return json.loads(value) if value else None
        else:
            return None
    except Exception as e:
        logger.error("get_cache_by_url exception: %s" % str(e))
        return None


def set_cache_by_url(resource_url, resource_in_json):
    try:
        # filter out unmanaged AAI resource
        if filter_cache_by_url(resource_url):
            # cache the resource for 24 hours
            # logger.debug("Cache the resource: "+ resource_url)
            aaikey = "AAI_" + resource_url
            cache.set(aaikey, json.dumps(resource_in_json), 3600 * 24)
            # AAI entry keys
            aaikeylist = json.loads(cache.get("AAIKeys", '[]'))
            aaikeyset = set(aaikeylist)
            aaikeyset.add(aaikey)
            cache.set("AAIKeys", json.dumps(list(aaikeyset)))
    except Exception as e:
        logger.error("set_cache_by_url exception: %s" % str(e))


def filter_cache_by_url(resource_url):
    # cannot cache url with query string, e.g. depth=all
    if resource_url.find(r"?") >= 0:
        return False
    # hardcoded filter: cloud region only
    if resource_url.find(r"cloud-infrastructure/cloud-regions/cloud-region") >= 0:
        return True
    else:
        return False