# ================================================================================
# Copyright (c) 2017-2018 AT&T Intellectual Property. All rights reserved.
# ================================================================================
# 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.
# ============LICENSE_END=========================================================
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# ECOMP is a trademark and service mark of AT&T Intellectual Property.

"""send policy-update notification to deployment-handler"""

import json
import logging
from copy import copy, deepcopy
from threading import Lock

import requests

from .config import Config, Settings
from .customize import CustomizerUser
from .discovery import DiscoveryClient
from .onap.audit import (REQUEST_X_ECOMP_REQUESTID, AuditHttpCode,
                         AuditResponseCode, Metrics)
from .policy_consts import (CATCH_UP, LATEST_POLICIES, POLICIES,
                            POLICY_FILTER_MATCHES, POLICY_FILTERS,
                            REMOVED_POLICIES, TARGET_ENTITY)


class PolicyUpdateMessage(object):
    """class for messages to deployment-handler on policy-update"""
    BYTES_IN_MB = 1 << 2 * 10

    def __init__(self, latest_policies=None,
                 removed_policies=None, policy_filter_matches=None, catch_up=True):
        """init"""
        self._catch_up = catch_up
        self._latest_policies = deepcopy(latest_policies or {})
        self._removed_policies = copy(removed_policies or {})
        self._policy_filter_matches = deepcopy(policy_filter_matches or {})

        self._message = {
            CATCH_UP: self._catch_up,
            LATEST_POLICIES: self._latest_policies,
            REMOVED_POLICIES: self._removed_policies,
            POLICY_FILTER_MATCHES: self._policy_filter_matches
        }
        self.msg_length = 0
        self._calc_stats()

    def _calc_stats(self):
        """generate the message and calc stats"""
        self.msg_length = len(json.dumps(self._message))

    def empty(self):
        """checks whether have any data"""
        return (not self._latest_policies
                and not self._removed_policies
                and not self._policy_filter_matches)

    def add(self, policy_id, latest_policy=None, policy_filter_ids=None, removed_policy=None):
        """add the parts from the other message to the current message"""
        if not policy_id or not (latest_policy or policy_filter_ids or removed_policy):
            return

        if latest_policy:
            self._latest_policies[policy_id] = deepcopy(latest_policy)

        if policy_filter_ids is not None:
            if policy_id not in self._policy_filter_matches:
                self._policy_filter_matches[policy_id] = {}
            self._policy_filter_matches[policy_id].update(policy_filter_ids)

        if removed_policy is not None:
            self._removed_policies[policy_id] = removed_policy

        self._calc_stats()

    def get_message(self):
        """expose the copy of the message"""
        return deepcopy(self._message)

    def __str__(self):
        """to string"""
        return json.dumps(self._message)

    def _iter_over_removed_policies(self):
        """generator of iterator over removed_policies"""
        for (policy_id, value) in self._removed_policies.items():
            yield (policy_id, value)

    def _iter_over_latest_policies(self):
        """generator of iterator over latest_policies and policy_filter_matches"""
        for (policy_id, policy) in self._latest_policies.items():
            yield (policy_id, policy, self._policy_filter_matches.get(policy_id))

    def gen_segmented_messages(self, max_msg_length_mb):
        """
        Break the policy-update message into a list of segmented messages.

        Each segmented message should not exceed the max_msg_length_mb from config.
        """
        max_msg_length_mb = (max_msg_length_mb or 10) * PolicyUpdateMessage.BYTES_IN_MB

        messages = []
        curr_message = PolicyUpdateMessage(catch_up=self._catch_up)

        for (policy_id, value) in self._iter_over_removed_policies():
            if (not curr_message.empty()
                    and (len(policy_id) + len(str(value)) + curr_message.msg_length
                         > max_msg_length_mb)):
                messages.append(curr_message.get_message())
                curr_message = PolicyUpdateMessage(catch_up=self._catch_up)
            curr_message.add(policy_id, removed_policy=value)

        for (policy_id, policy, policy_filter_ids) in self._iter_over_latest_policies():
            if (not curr_message.empty()
                    and (2 * len(policy_id) + len(json.dumps(policy))
                         + len(json.dumps(policy_filter_ids))
                         + curr_message.msg_length > max_msg_length_mb)):
                messages.append(curr_message.get_message())
                curr_message = PolicyUpdateMessage(catch_up=self._catch_up)
            curr_message.add(policy_id, latest_policy=policy, policy_filter_ids=policy_filter_ids)

        if not curr_message.empty():
            messages.append(curr_message.get_message())

        msg_count = len(messages)
        if msg_count > 1:
            msg_count = "/" + str(msg_count)
            for idx, msg in enumerate(messages):
                msg["data_segment"] = str((idx+1)) + msg_count

        return messages


class DeployHandler(object):
    """calling the deployment-handler web apis"""
    _logger = logging.getLogger("policy_handler.deploy_handler")
    DEFAULT_TARGET_ENTITY = "deployment_handler"

    _lazy_inited = False
    _lock = Lock()
    _settings = Settings(Config.POOL_CONNECTIONS, Config.DEPLOY_HANDLER)

    _requests_session = None
    _url = None
    _url_policy = None
    _max_msg_length_mb = 10
    _query = {}
    _target_entity = None
    _custom_kwargs = None
    _server_instance_uuid = None
    server_instance_changed = False

    @staticmethod
    def _init(audit):
        """set config"""
        DeployHandler._custom_kwargs = (CustomizerUser.get_customizer()
                                        .get_deploy_handler_kwargs(audit))
        if (not DeployHandler._custom_kwargs
                or not isinstance(DeployHandler._custom_kwargs, dict)):
            DeployHandler._custom_kwargs = {}

        if not DeployHandler._requests_session:
            DeployHandler._requests_session = requests.Session()

        changed, pool_size = DeployHandler._settings.get_by_key(Config.POOL_CONNECTIONS, 10)
        if changed:
            DeployHandler._requests_session.mount(
                'https://', requests.adapters.HTTPAdapter(pool_connections=pool_size,
                                                          pool_maxsize=pool_size))
            DeployHandler._requests_session.mount(
                'http://', requests.adapters.HTTPAdapter(pool_connections=pool_size,
                                                         pool_maxsize=pool_size))

        _, config_dh = DeployHandler._settings.get_by_key(Config.DEPLOY_HANDLER)
        if config_dh and isinstance(config_dh, dict):
            # dns based routing to deployment-handler
            # config for policy-handler >= 2.4.0
            # "deploy_handler" : {
            #     "target_entity" : "deployment_handler",
            #     "url" : "http://deployment_handler:8188",
            #     "max_msg_length_mb" : 10,
            #     "query" : {
            #         "cfy_tenant_name" : "default_tenant"
            #     }
            # }
            DeployHandler._target_entity = config_dh.get(TARGET_ENTITY,
                                                         DeployHandler.DEFAULT_TARGET_ENTITY)
            DeployHandler._url = config_dh.get("url")
            DeployHandler._max_msg_length_mb = config_dh.get("max_msg_length_mb",
                                                             DeployHandler._max_msg_length_mb)
            DeployHandler._query = deepcopy(config_dh.get("query", {}))
            DeployHandler._logger.info("dns based routing to %s: url(%s)",
                                       DeployHandler._target_entity, DeployHandler._url)

        if not DeployHandler._url:
            # discover routing to deployment-handler at consul-services
            if not isinstance(config_dh, dict):
                # config for policy-handler <= 2.3.1
                # "deploy_handler" : "deployment_handler"
                DeployHandler._target_entity = str(config_dh or DeployHandler.DEFAULT_TARGET_ENTITY)
            DeployHandler._url = DiscoveryClient.get_service_url(audit,
                                                                 DeployHandler._target_entity)

        DeployHandler._url_policy = str(DeployHandler._url or "") + '/policy'
        DeployHandler._logger.info("got %s policy url(%s): %s", DeployHandler._target_entity,
                                   DeployHandler._url_policy, DeployHandler._settings)

        DeployHandler._settings.commit_change()
        DeployHandler._lazy_inited = bool(DeployHandler._url)

    @staticmethod
    def reconfigure(audit):
        """reconfigure"""
        with DeployHandler._lock:
            DeployHandler._settings.set_config(Config.discovered_config)
            if not DeployHandler._settings.is_changed():
                DeployHandler._settings.commit_change()
                return False

            DeployHandler._lazy_inited = False
            DeployHandler._init(audit)
        return True

    @staticmethod
    def _lazy_init(audit):
        """set config"""
        if DeployHandler._lazy_inited:
            return

        with DeployHandler._lock:
            if DeployHandler._lazy_inited:
                return

            DeployHandler._settings.set_config(Config.discovered_config)
            DeployHandler._init(audit)

    @staticmethod
    def policy_update(audit, policy_update_message):
        """
        segments the big policy_update_message limited by size
        and sequatially sends each segment as put to deployment-handler at /policy.

        param policy_update_message is of PolicyUpdateMessage type
        """
        if not policy_update_message or policy_update_message.empty():
            return

        DeployHandler._lazy_init(audit)

        str_metrics = "policy_update {0}".format(str(policy_update_message))

        metrics_total = Metrics(
            aud_parent=audit,
            targetEntity="{0} total policy_update".format(DeployHandler._target_entity),
            targetServiceName=DeployHandler._url_policy)

        metrics_total.metrics_start("started {}".format(str_metrics))
        messages = policy_update_message.gen_segmented_messages(DeployHandler._max_msg_length_mb)
        for message in messages:
            DeployHandler._policy_update(audit, message)
            if not audit.is_success():
                break
        metrics_total.metrics("done {}".format(str_metrics))

    @staticmethod
    def _policy_update(audit, message):
        """
        sends the put message to deployment-handler at /policy

        detects whether server_instance_changed condition on deployment-handler
        that is the cause to catch_up
        """
        if not message:
            return

        metrics = Metrics(aud_parent=audit, targetEntity=DeployHandler._target_entity,
                          targetServiceName=DeployHandler._url_policy)
        headers = {REQUEST_X_ECOMP_REQUESTID : metrics.request_id}

        log_action = "put to {0} at {1}".format(
            DeployHandler._target_entity, DeployHandler._url_policy)
        log_data = " msg={} headers={}, params={}".format(json.dumps(message), json.dumps(headers),
                                                          json.dumps(DeployHandler._query))
        log_line = log_action + log_data
        DeployHandler._logger.info(log_line)
        metrics.metrics_start(log_line)

        if not DeployHandler._url:
            error_msg = "no url found to {0}".format(log_line)
            DeployHandler._logger.error(error_msg)
            metrics.set_http_status_code(AuditHttpCode.SERVICE_UNAVAILABLE_ERROR.value)
            audit.set_http_status_code(AuditHttpCode.SERVICE_UNAVAILABLE_ERROR.value)
            metrics.metrics(error_msg)
            return

        res = None
        try:
            with DeployHandler._lock:
                session = DeployHandler._requests_session
                url = DeployHandler._url_policy
                params = deepcopy(DeployHandler._query)
                custom_kwargs = deepcopy(DeployHandler._custom_kwargs)

            res = session.put(url, json=message,
                              headers=headers, params=params, **custom_kwargs)
        except Exception as ex:
            error_code = (AuditHttpCode.SERVICE_UNAVAILABLE_ERROR.value
                          if isinstance(ex, requests.exceptions.RequestException)
                          else AuditHttpCode.SERVER_INTERNAL_ERROR.value)
            error_msg = ("failed to {0} {1}: {2}{3}"
                         .format(log_action, type(ex).__name__, str(ex), log_data))
            DeployHandler._logger.exception(error_msg)
            metrics.set_http_status_code(error_code)
            audit.set_http_status_code(error_code)
            metrics.metrics(error_msg)
            return

        metrics.set_http_status_code(res.status_code)
        audit.set_http_status_code(res.status_code)

        log_line = "response {0} from {1}: text={2}{3}".format(res.status_code, log_action,
                                                               res.text, log_data)
        metrics.metrics(log_line)

        if res.status_code != requests.codes.ok:
            DeployHandler._logger.error(log_line)
            return

        DeployHandler._logger.info(log_line)
        result = res.json() or {}
        DeployHandler._server_instance_changed(result, metrics)


    @staticmethod
    def get_deployed_policies(audit):
        """
        Retrieves policies and policy-filters from components
        that were deployed by deployment-handler
        """
        DeployHandler._lazy_init(audit)
        metrics = Metrics(aud_parent=audit, targetEntity=DeployHandler._target_entity,
                          targetServiceName=DeployHandler._url_policy)
        headers = {REQUEST_X_ECOMP_REQUESTID : metrics.request_id}

        log_action = "get {0}: {1}".format(DeployHandler._target_entity, DeployHandler._url_policy)
        log_data = " headers={}, params={}".format(json.dumps(headers),
                                                   json.dumps(DeployHandler._query))
        log_line = log_action + log_data
        DeployHandler._logger.info(log_line)
        metrics.metrics_start(log_line)

        if not DeployHandler._url:
            error_msg = "no url found to {0}".format(log_line)
            DeployHandler._logger.error(error_msg)
            metrics.set_http_status_code(AuditHttpCode.SERVICE_UNAVAILABLE_ERROR.value)
            audit.set_http_status_code(AuditHttpCode.SERVICE_UNAVAILABLE_ERROR.value)
            metrics.metrics(error_msg)
            return None, None

        res = None
        try:
            with DeployHandler._lock:
                session = DeployHandler._requests_session
                url = DeployHandler._url_policy
                params = deepcopy(DeployHandler._query)
                custom_kwargs = deepcopy(DeployHandler._custom_kwargs)

            res = session.get(url, headers=headers, params=params, **custom_kwargs)
        except Exception as ex:
            error_code = (AuditHttpCode.SERVICE_UNAVAILABLE_ERROR.value
                          if isinstance(ex, requests.exceptions.RequestException)
                          else AuditHttpCode.SERVER_INTERNAL_ERROR.value)
            error_msg = ("failed to {0} {1}: {2}{3}"
                         .format(log_action, type(ex).__name__, str(ex), log_data))
            DeployHandler._logger.exception(error_msg)
            metrics.set_http_status_code(error_code)
            audit.set_http_status_code(error_code)
            metrics.metrics(error_msg)
            return None, None

        metrics.set_http_status_code(res.status_code)
        audit.set_http_status_code(res.status_code)

        log_line = ("response {0} from {1}: text={2}{3}"
                    .format(res.status_code, log_action, res.text, log_data))
        metrics.metrics(log_line)

        if res.status_code != requests.codes.ok:
            DeployHandler._logger.error(log_line)
            return None, None

        result = res.json() or {}
        DeployHandler._server_instance_changed(result, metrics)

        policies = result.get(POLICIES, {})
        policy_filters = result.get(POLICY_FILTERS, {})
        if not policies and not policy_filters:
            audit.set_http_status_code(AuditHttpCode.DATA_NOT_FOUND_ERROR.value)
            DeployHandler._logger.warning(audit.warn(
                "found no deployed policies or policy-filters: {}".format(log_line),
                error_code=AuditResponseCode.DATA_ERROR))
            return policies, policy_filters

        DeployHandler._logger.info(log_line)
        return policies, policy_filters

    @staticmethod
    def _server_instance_changed(result, metrics):
        """Checks whether the deployment-handler instance changed since last call."""
        prev_server_instance_uuid = DeployHandler._server_instance_uuid
        DeployHandler._server_instance_uuid = result.get("server_instance_uuid")

        if (prev_server_instance_uuid
                and prev_server_instance_uuid != DeployHandler._server_instance_uuid):
            DeployHandler.server_instance_changed = True

            DeployHandler._logger.info(metrics.info(
                "deployment_handler_changed: {1} != {0}"
                .format(prev_server_instance_uuid, DeployHandler._server_instance_uuid)))