# ================================================================================
# Copyright (c) 2017-2020 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=========================================================
#

"""read and use the config"""

import base64
import copy
import json
import logging
import logging.config
import os

from .onap.audit import Audit
from .utils import Utils

LOGS_DIR = 'logs'

try:
    os.makedirs(LOGS_DIR, mode=0o770, exist_ok=True)
except Exception:
    pass

logging.basicConfig(
    filename=os.path.join(LOGS_DIR, 'policy_handler.log'),
    format=('%(asctime)s.%(msecs)03d %(levelname)+8s ' +
            '%(threadName)s %(name)s.%(funcName)s: %(message)s'),
    datefmt='%Y%m%d_%H%M%S', level=logging.DEBUG)

_LOGGER = Utils.get_logger(__file__)

class Settings(object):
    """settings of module or an application
    that is the config filtered by the collection of config-keys.

    keeps track of changes versus the previous set_config unless committed
    """
    def __init__(self, *config_keys):
        """provide the collection of top level keys in config to limit the config"""
        self._config_keys = config_keys
        self._changed = False
        self._config = None
        self._prev_config = None

    def __str__(self):
        """get str of the config"""
        if not self._changed:
            return Audit.json_dumps({
                "config_keys": self._config_keys,
                "config": self._config
            })

        return Audit.json_dumps({
            "config_keys": self._config_keys,
            "changed": self._changed,
            "config": self._config,
            "prev_config": self._prev_config
        })

    def is_loaded(self):
        """whether loaded already"""
        return bool(self._config)

    def commit_change(self):
        """set the prev config to the latest config"""
        self._prev_config = copy.deepcopy(self._config)
        self._changed = False

    def _set_changed(self):
        """determine whether the config changed"""
        self._changed = not (self._prev_config
                             and Utils.are_the_same(self._prev_config, self._config,
                                                    Audit.json_dumps))

    def set_config(self, config, auto_commit=False):
        """update the config"""
        self.commit_change()

        if isinstance(config, Settings):
            config = config._config

        if not isinstance(config, dict):
            config = {}

        self._config = copy.deepcopy(dict((k, v) for (k, v) in config.items()
                                          if not self._config_keys or k in self._config_keys))

        if auto_commit:
            self.commit_change()
        else:
            self._set_changed()

    def is_changed(self):
        """whether the config has changed"""
        return self._changed

    def get_by_key(self, config_key, default=None):
        """get the latest sub config by config_key and whether it has changed"""
        if not config_key or not isinstance(config_key, str):
            return False, default

        value = copy.deepcopy(self._config.get(config_key, default))
        if not self._prev_config:
            return True, value
        prev_value = self._prev_config.get(config_key, default)
        return self._changed and not Utils.are_the_same(prev_value, value, Audit.json_dumps), value

    def update(self, config_key, value=None):
        """set the latest sub config by config_key and determine whether the config has changed"""
        if not config_key:
            return

        self._config[config_key] = copy.deepcopy(value)
        self._set_changed()


class Config(object):
    """main config of the application"""
    CONFIG_FILE_PATH = "etc/config.json"
    LOGGER_CONFIG_FILE_PATH = "etc/common_logger.config"
    SERVICE_NAME_POLICY_HANDLER = "policy_handler"

    FIELD_SYSTEM = "system"
    FIELD_CONSUL_URL = "consul_url"
    FIELD_WSERVICE_PORT = "wservice_port"
    FIELD_TLS = "tls"
    FIELD_POLICY_ENGINE = "policy_engine"
    DMAAP_MR = "dmaap_mr"
    POOL_CONNECTIONS = "pool_connections"
    DEPLOY_HANDLER = "deploy_handler"
    THREAD_POOL_SIZE = "thread_pool_size"
    POLICY_RETRY_COUNT = "policy_retry_count"
    POLICY_RETRY_SLEEP = "policy_retry_sleep"
    RECONFIGURE = "reconfigure"
    TIMER_INTERVAL = "interval"
    REQUESTS_VERIFY = "verify"
    TLS_CA_MODE = "tls_ca_mode"
    TLS_WSS_CA_MODE = "tls_wss_ca_mode"
    TLS_CA_MODE_DO_NOT_VERIFY = "do_not_verify"
    TIMEOUT_IN_SECS = "timeout_in_secs"
    CONSUL_TIMEOUT_IN_SECS = "consul_timeout_in_secs"
    WS_PING_INTERVAL_IN_SECS = "ws_ping_interval_in_secs"
    DEFAULT_TIMEOUT_IN_SECS = 60
    SERVICE_ACTIVATOR = "service_activator"
    MODE_OF_OPERATION = "mode_of_operation"
    PDP_API_VERSION = "PDP_API_VERSION"
    QUERY_TIMEOUT = "timeout"
    PDP_USER = "PDP_USER"
    PDP_PWD = "PDP_PWD"
    DMAAP_MR_USER = "DMAAP_MR_USER"
    DMAAP_MR_PWD = "DMAAP_MR_PWD"

    system_name = SERVICE_NAME_POLICY_HANDLER
    wservice_port = 25577
    _pdp_api_version = os.environ.get(PDP_API_VERSION)
    consul_url = "http://consul:8500"
    consul_timeout_in_secs = DEFAULT_TIMEOUT_IN_SECS
    tls_cacert_file = None
    tls_server_cert_file = None
    tls_private_key_file = None
    tls_server_ca_chain_file = None
    _pdp_authorization = None
    _dmaap_mr_authorization = None

    _local_config = Settings()
    discovered_config = Settings()

    @staticmethod
    def _get_tls_file_path(tls_config, cert_directory, tls_name):
        """calc file path and verify its existance"""
        file_name = tls_config.get(tls_name)
        if not file_name:
            return None
        tls_file_path = os.path.join(cert_directory, file_name)
        if not os.path.isfile(tls_file_path) or not os.access(tls_file_path, os.R_OK):
            _LOGGER.error("invalid %s: %s", tls_name, tls_file_path)
            return None
        return tls_file_path

    @staticmethod
    def _set_tls_config(tls_config):
        """verify and set tls certs in config"""
        try:
            Config.tls_cacert_file = None
            Config.tls_server_cert_file = None
            Config.tls_private_key_file = None
            Config.tls_server_ca_chain_file = None

            if not (tls_config and isinstance(tls_config, dict)):
                _LOGGER.info("no tls in config: %s", json.dumps(tls_config))
                return

            cert_directory = tls_config.get("cert_directory")

            if not (cert_directory and isinstance(cert_directory, str)):
                _LOGGER.warning("unexpected tls.cert_directory: %r", cert_directory)
                return

            cert_directory = os.path.join(
                os.path.dirname(os.path.dirname(os.path.realpath(__file__))), cert_directory)
            if not (cert_directory and os.path.isdir(cert_directory)):
                _LOGGER.warning("ignoring invalid cert_directory: %s", cert_directory)
                return

            Config.tls_cacert_file = Config._get_tls_file_path(tls_config, cert_directory, "cacert")
            Config.tls_server_cert_file = Config._get_tls_file_path(tls_config, cert_directory,
                                                                    "server_cert")
            Config.tls_private_key_file = Config._get_tls_file_path(tls_config, cert_directory,
                                                                    "private_key")
            Config.tls_server_ca_chain_file = Config._get_tls_file_path(tls_config, cert_directory,
                                                                        "server_ca_chain")

        finally:
            _LOGGER.info("tls_cacert_file = %s", Config.tls_cacert_file)
            _LOGGER.info("tls_server_cert_file = %s", Config.tls_server_cert_file)
            _LOGGER.info("tls_private_key_file = %s", Config.tls_private_key_file)
            _LOGGER.info("tls_server_ca_chain_file = %s", Config.tls_server_ca_chain_file)

    @staticmethod
    def init_config(file_path=None):
        """read and store the config from config file"""
        if Config._local_config.is_loaded():
            _LOGGER.info("config already inited: %s", Config._local_config)
            return

        if not file_path:
            file_path = Config.CONFIG_FILE_PATH

        loaded_config = None
        if os.access(file_path, os.R_OK):
            with open(file_path, 'r') as config_json:
                loaded_config = json.load(config_json)

        if not loaded_config:
            _LOGGER.warning("config not loaded from file: %s", file_path)
            return

        _LOGGER.info("config loaded from file(%s): %s", file_path, Audit.json_dumps(loaded_config))
        logging_config = loaded_config.get("logging")
        if logging_config:
            logging.config.dictConfig(logging_config)

        Config.wservice_port = loaded_config.get(Config.FIELD_WSERVICE_PORT, Config.wservice_port)
        Config.consul_url = os.environ.get(
            "CONSUL_URL", loaded_config.get(Config.FIELD_CONSUL_URL, Config.consul_url)).rstrip("/")
        Config.consul_timeout_in_secs = loaded_config.get(Config.CONSUL_TIMEOUT_IN_SECS)
        if not Config.consul_timeout_in_secs or Config.consul_timeout_in_secs < 1:
            Config.consul_timeout_in_secs = Config.DEFAULT_TIMEOUT_IN_SECS

        Config._pdp_api_version = os.environ.get(
            Config.PDP_API_VERSION, loaded_config.get(Config.PDP_API_VERSION.lower()))

        pdp_user = os.environ.get(Config.PDP_USER)
        pdp_pwd = os.environ.get(Config.PDP_PWD)
        if pdp_user and pdp_pwd:
            Config._pdp_authorization = "Basic {}".format(base64.b64encode(
                ("{}:{}".format(pdp_user, pdp_pwd)).encode()).decode("utf-8"))

        dmaap_mr_user = os.environ.get(Config.DMAAP_MR_USER)
        dmaap_mr_pwd = os.environ.get(Config.DMAAP_MR_PWD)
        if dmaap_mr_user and dmaap_mr_pwd:
            Config._dmaap_mr_authorization = "Basic {}".format(base64.b64encode(
                ("{}:{}".format(dmaap_mr_user, dmaap_mr_pwd)).encode()).decode("utf-8"))

        local_config = loaded_config.get(Config.SERVICE_NAME_POLICY_HANDLER, {})
        Config.system_name = local_config.get(Config.FIELD_SYSTEM, Config.system_name)

        Config._set_tls_config(local_config.get(Config.FIELD_TLS))

        Config._local_config.set_config(local_config, auto_commit=True)

    @staticmethod
    def _overwrite_discovered_config(audit, discovered_config):
        """replace the secrets in discovered_config with data from environment"""
        changes = []
        if Config._pdp_authorization:
            pdp_cfg = discovered_config.get("policy_engine", {})
            if pdp_cfg.get("url", "").lower().startswith("https:"):
                pdp_cfg.get("headers", {})["Authorization"] = Config._pdp_authorization
                changes.append("pdp_authorization")

        if Config._dmaap_mr_authorization:
            dmaap_mr_cfg = discovered_config.get("dmaap_mr", {})
            if dmaap_mr_cfg.get("url", "").lower().startswith("https:"):
                dmaap_mr_cfg.get("headers", {})["Authorization"] = Config._dmaap_mr_authorization
                changes.append("dmaap_mr_authorization")

        if changes:
            _LOGGER.info(audit.info("overwritten discovered config: {}".format(", ".join(changes))))


    @staticmethod
    def discover(audit):
        """bring the config settings from the discovery service"""
        discovery_key = Config.system_name
        from .discovery import DiscoveryClient
        new_config = DiscoveryClient.get_value(audit, discovery_key)

        if not new_config or not isinstance(new_config, dict):
            _LOGGER.warning(audit.warn("unexpected config from discovery: {}".format(new_config)))
            return

        _LOGGER.debug(audit.debug("loaded config from discovery({}): {}".format(
            discovery_key, Audit.json_dumps(new_config))))
        discovered_config = new_config.get(Config.SERVICE_NAME_POLICY_HANDLER)

        Config._overwrite_discovered_config(audit, discovered_config)

        Config.discovered_config.set_config(discovered_config)
        _LOGGER.info(audit.info("config from discovery: {}".format(Config.discovered_config)))


    @staticmethod
    def get_tls_verify(tls_ca_mode=None):
        """
        generate verify value based on tls_ca_mode

        tls_ca_mode can be one of:

        "cert_directory" - use the cacert.pem stored locally in cert_directory.
        this is the default if cacert.pem file is found

        "os_ca_bundle" - use the public ca_bundle provided by linux system.
        this is the default if cacert.pem file not found

        "do_not_verify" - special hack to turn off the verification by cacert and hostname
        """
        if tls_ca_mode == Config.TLS_CA_MODE_DO_NOT_VERIFY:
            return False

        if tls_ca_mode == "os_ca_bundle" or not Config.tls_cacert_file:
            return True

        return Config.tls_cacert_file

    @staticmethod
    def get_requests_kwargs(tls_ca_mode=None):
        """generate kwargs with verify for requests based on the tls_ca_mode"""
        return {Config.REQUESTS_VERIFY: Config.get_tls_verify(tls_ca_mode)}

    @staticmethod
    def is_pdp_api_default(log_status=True):
        """whether to use the old (2018) or the default pdp API (started in 2019)"""
        is_default = (Config._pdp_api_version is None)
        if log_status:
            _LOGGER.info("_pdp_api_version(%s) default(%s)", Config._pdp_api_version, is_default)
        return is_default