# -*- coding: utf-8 -*-
"""
ceph dashboard mgr plugin (based on CherryPy)
"""
from __future__ import absolute_import

import collections
import errno
import logging
import os
import socket
import ssl
import sys
import tempfile
import threading
import time
from typing import TYPE_CHECKING, Optional
from urllib.parse import urlparse

if TYPE_CHECKING:
    if sys.version_info >= (3, 8):
        from typing import Literal
    else:
        from typing_extensions import Literal

from mgr_module import CLIReadCommand, CLIWriteCommand, HandleCommandResult, \
    MgrModule, MgrStandbyModule, NotifyType, Option, _get_localized_key
from mgr_util import ServerConfigException, build_url, \
    create_self_signed_cert, get_default_addr, verify_tls_files

from . import mgr
from .controllers import Router, json_error_page
from .grafana import push_local_dashboards
from .services.auth import AuthManager, AuthManagerTool, JwtManager
from .services.exception import dashboard_exception_handler
from .services.rgw_client import configure_rgw_credentials
from .services.sso import SSO_COMMANDS, handle_sso_command
from .settings import handle_option_command, options_command_list, options_schema_list
from .tools import NotificationQueue, RequestLoggingTool, TaskManager, \
    prepare_url_prefix, str_to_bool

try:
    import cherrypy
    from cherrypy._cptools import HandlerWrapperTool
except ImportError:
    # To be picked up and reported by .can_run()
    cherrypy = None

from .services.sso import load_sso_db

if cherrypy is not None:
    from .cherrypy_backports import patch_cherrypy
    patch_cherrypy(cherrypy.__version__)

# pylint: disable=wrong-import-position
from .plugins import PLUGIN_MANAGER, debug, feature_toggles, motd  # isort:skip # noqa E501 # pylint: disable=unused-import

PLUGIN_MANAGER.hook.init()


# cherrypy likes to sys.exit on error.  don't let it take us down too!
# pylint: disable=W0613
def os_exit_noop(*args):
    pass


# pylint: disable=W0212
os._exit = os_exit_noop


logger = logging.getLogger(__name__)


class CherryPyConfig(object):
    """
    Class for common server configuration done by both active and
    standby module, especially setting up SSL.
    """

    def __init__(self):
        self._stopping = threading.Event()
        self._url_prefix = ""

        self.cert_tmp = None
        self.pkey_tmp = None

    def shutdown(self):
        self._stopping.set()

    @property
    def url_prefix(self):
        return self._url_prefix

    @staticmethod
    def update_cherrypy_config(config):
        PLUGIN_MANAGER.hook.configure_cherrypy(config=config)
        cherrypy.config.update(config)

    # pylint: disable=too-many-branches
    def _configure(self):
        """
        Configure CherryPy and initialize self.url_prefix

        :returns our URI
        """
        server_addr = self.get_localized_module_option(  # type: ignore
            'server_addr', get_default_addr())
        use_ssl = self.get_localized_module_option('ssl', True)  # type: ignore
        if not use_ssl:
            server_port = self.get_localized_module_option('server_port', 8080)  # type: ignore
        else:
            server_port = self.get_localized_module_option('ssl_server_port', 8443)  # type: ignore

        if server_addr is None:
            raise ServerConfigException(
                'no server_addr configured; '
                'try "ceph config set mgr mgr/{}/{}/server_addr <ip>"'
                .format(self.module_name, self.get_mgr_id()))  # type: ignore
        self.log.info('server: ssl=%s host=%s port=%d', 'yes' if use_ssl else 'no',  # type: ignore
                      server_addr, server_port)

        # Initialize custom handlers.
        cherrypy.tools.authenticate = AuthManagerTool()
        self.configure_cors()
        cherrypy.tools.plugin_hooks_filter_request = cherrypy.Tool(
            'before_handler',
            lambda: PLUGIN_MANAGER.hook.filter_request_before_handler(request=cherrypy.request),
            priority=1)
        cherrypy.tools.request_logging = RequestLoggingTool()
        cherrypy.tools.dashboard_exception_handler = HandlerWrapperTool(dashboard_exception_handler,
                                                                        priority=31)

        cherrypy.log.access_log.propagate = False
        cherrypy.log.error_log.propagate = False

        # Apply the 'global' CherryPy configuration.
        config = {
            'engine.autoreload.on': False,
            'server.socket_host': server_addr,
            'server.socket_port': int(server_port),
            'error_page.default': json_error_page,
            'tools.request_logging.on': True,
            'tools.gzip.on': True,
            'tools.gzip.mime_types': [
                # text/html and text/plain are the default types to compress
                'text/html', 'text/plain',
                # We also want JSON and JavaScript to be compressed
                'application/json',
                'application/*+json',
                'application/javascript',
            ],
            'tools.json_in.on': True,
            'tools.json_in.force': True,
            'tools.plugin_hooks_filter_request.on': True,
        }

        if use_ssl:
            # SSL initialization
            cert = self.get_localized_store("crt")  # type: ignore
            if cert is not None:
                self.cert_tmp = tempfile.NamedTemporaryFile()
                self.cert_tmp.write(cert.encode('utf-8'))
                self.cert_tmp.flush()  # cert_tmp must not be gc'ed
                cert_fname = self.cert_tmp.name
            else:
                cert_fname = self.get_localized_module_option('crt_file')  # type: ignore

            pkey = self.get_localized_store("key")  # type: ignore
            if pkey is not None:
                self.pkey_tmp = tempfile.NamedTemporaryFile()
                self.pkey_tmp.write(pkey.encode('utf-8'))
                self.pkey_tmp.flush()  # pkey_tmp must not be gc'ed
                pkey_fname = self.pkey_tmp.name
            else:
                pkey_fname = self.get_localized_module_option('key_file')  # type: ignore

            verify_tls_files(cert_fname, pkey_fname)

            # Create custom SSL context to disable TLS 1.0 and 1.1.
            context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
            context.load_cert_chain(cert_fname, pkey_fname)
            if sys.version_info >= (3, 7):
                context.minimum_version = ssl.TLSVersion.TLSv1_2
            else:
                context.options |= ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1

            config['server.ssl_module'] = 'builtin'
            config['server.ssl_certificate'] = cert_fname
            config['server.ssl_private_key'] = pkey_fname
            config['server.ssl_context'] = context

        self.update_cherrypy_config(config)

        self._url_prefix = prepare_url_prefix(self.get_module_option(  # type: ignore
            'url_prefix', default=''))

        if server_addr in ['::', '0.0.0.0']:
            server_addr = self.get_mgr_ip()  # type: ignore
        base_url = build_url(
            scheme='https' if use_ssl else 'http',
            host=server_addr,
            port=server_port,
        )
        uri = f'{base_url}{self.url_prefix}/'
        return uri

    def await_configuration(self):
        """
        Block until configuration is ready (i.e. all needed keys are set)
        or self._stopping is set.

        :returns URI of configured webserver
        """
        while not self._stopping.is_set():
            try:
                uri = self._configure()
            except ServerConfigException as e:
                self.log.info(  # type: ignore
                    "Config not ready to serve, waiting: {0}".format(e)
                )
                # Poll until a non-errored config is present
                self._stopping.wait(5)
            else:
                self.log.info("Configured CherryPy, starting engine...")  # type: ignore
                return uri

    def configure_cors(self):
        """
        Allow CORS requests if the cross_origin_url option is set.
        """
        cross_origin_url = mgr.get_localized_module_option('cross_origin_url', '')
        if cross_origin_url:
            cherrypy.tools.CORS = cherrypy.Tool('before_handler', self.cors_tool)
            config = {
                'tools.CORS.on': True,
            }
            self.update_cherrypy_config(config)

    def cors_tool(self):
        '''
        Handle both simple and complex CORS requests

        Add CORS headers to each response. If the request is a CORS preflight
        request swap out the default handler with a simple, single-purpose handler
        that verifies the request and provides a valid CORS response.
        '''
        req_head = cherrypy.request.headers
        resp_head = cherrypy.response.headers

        # Always set response headers necessary for 'simple' CORS.
        req_header_cross_origin_url = req_head.get('Access-Control-Allow-Origin')
        cross_origin_urls = mgr.get_localized_module_option('cross_origin_url', '')
        cross_origin_url_list = [url.strip() for url in cross_origin_urls.split(',')]
        if req_header_cross_origin_url in cross_origin_url_list:
            resp_head['Access-Control-Allow-Origin'] = req_header_cross_origin_url
        resp_head['Access-Control-Expose-Headers'] = 'GET, POST'
        resp_head['Access-Control-Allow-Credentials'] = 'true'

        # Non-simple CORS preflight request; short-circuit the normal handler.
        if cherrypy.request.method == 'OPTIONS':
            req_header_origin_url = req_head.get('Origin')
            if req_header_origin_url in cross_origin_url_list:
                resp_head['Access-Control-Allow-Origin'] = req_header_origin_url
            ac_method = req_head.get('Access-Control-Request-Method', None)

            allowed_methods = ['GET', 'POST']
            allowed_headers = [
                'Content-Type',
                'Authorization',
                'Accept',
                'Access-Control-Allow-Origin'
            ]

            if ac_method and ac_method in allowed_methods:
                resp_head['Access-Control-Allow-Methods'] = ', '.join(allowed_methods)
                resp_head['Access-Control-Allow-Headers'] = ', '.join(allowed_headers)

                resp_head['Connection'] = 'keep-alive'
                resp_head['Access-Control-Max-Age'] = '3600'

            # CORS requests should short-circuit the other tools.
            cherrypy.response.body = ''.encode('utf8')
            cherrypy.response.status = 200
            cherrypy.serving.request.handler = None

            # Needed to avoid the auth_tool check.
            if cherrypy.request.config.get('tools.sessions.on', False):
                cherrypy.session['token'] = True
            return True


if TYPE_CHECKING:
    SslConfigKey = Literal['crt', 'key']


class Module(MgrModule, CherryPyConfig):
    """
    dashboard module entrypoint
    """

    COMMANDS = [
        {
            'cmd': 'dashboard set-jwt-token-ttl '
                   'name=seconds,type=CephInt',
            'desc': 'Set the JWT token TTL in seconds',
            'perm': 'w'
        },
        {
            'cmd': 'dashboard get-jwt-token-ttl',
            'desc': 'Get the JWT token TTL in seconds',
            'perm': 'r'
        },
        {
            "cmd": "dashboard create-self-signed-cert",
            "desc": "Create self signed certificate",
            "perm": "w"
        },
        {
            "cmd": "dashboard grafana dashboards update",
            "desc": "Push dashboards to Grafana",
            "perm": "w",
        },
    ]
    COMMANDS.extend(options_command_list())
    COMMANDS.extend(SSO_COMMANDS)
    PLUGIN_MANAGER.hook.register_commands()

    MODULE_OPTIONS = [
        Option(name='server_addr', type='str', default=get_default_addr()),
        Option(name='server_port', type='int', default=8080),
        Option(name='ssl_server_port', type='int', default=8443),
        Option(name='jwt_token_ttl', type='int', default=28800),
        Option(name='url_prefix', type='str', default=''),
        Option(name='key_file', type='str', default=''),
        Option(name='crt_file', type='str', default=''),
        Option(name='ssl', type='bool', default=True),
        Option(name='standby_behaviour', type='str', default='redirect',
               enum_allowed=['redirect', 'error']),
        Option(name='standby_error_status_code', type='int', default=500,
               min=400, max=599),
        Option(name='redirect_resolve_ip_addr', type='bool', default=False),
        Option(name='cross_origin_url', type='str', default=''),
    ]
    MODULE_OPTIONS.extend(options_schema_list())
    for options in PLUGIN_MANAGER.hook.get_options() or []:
        MODULE_OPTIONS.extend(options)

    NOTIFY_TYPES = [NotifyType.clog]

    __pool_stats = collections.defaultdict(lambda: collections.defaultdict(
        lambda: collections.deque(maxlen=10)))  # type: dict

    def __init__(self, *args, **kwargs):
        super(Module, self).__init__(*args, **kwargs)
        CherryPyConfig.__init__(self)

        mgr.init(self)

        self._stopping = threading.Event()
        self.shutdown_event = threading.Event()
        self.ACCESS_CTRL_DB = None
        self.SSO_DB = None
        self.health_checks = {}

    @classmethod
    def can_run(cls):
        if cherrypy is None:
            return False, "Missing dependency: cherrypy"

        if not os.path.exists(cls.get_frontend_path()):
            return False, ("Frontend assets not found at '{}': incomplete build?"
                           .format(cls.get_frontend_path()))

        return True, ""

    @classmethod
    def get_frontend_path(cls):
        current_dir = os.path.dirname(os.path.abspath(__file__))
        return os.path.join(current_dir, 'frontend/dist')

    def serve(self):

        if 'COVERAGE_ENABLED' in os.environ:
            import coverage
            __cov = coverage.Coverage(config_file="{}/.coveragerc"
                                      .format(os.path.dirname(__file__)),
                                      data_suffix=True)
            __cov.start()
            cherrypy.engine.subscribe('after_request', __cov.save)
            cherrypy.engine.subscribe('stop', __cov.stop)

        AuthManager.initialize()
        load_sso_db()

        uri = self.await_configuration()
        if uri is None:
            # We were shut down while waiting
            return

        # Publish the URI that others may use to access the service we're
        # about to start serving
        self.set_uri(uri)

        mapper, parent_urls = Router.generate_routes(self.url_prefix)

        config = {}
        for purl in parent_urls:
            config[purl] = {
                'request.dispatch': mapper
            }

        cherrypy.tree.mount(None, config=config)

        PLUGIN_MANAGER.hook.setup()

        cherrypy.engine.start()
        NotificationQueue.start_queue()
        TaskManager.init()
        logger.info('Engine started.')
        update_dashboards = str_to_bool(
            self.get_module_option('GRAFANA_UPDATE_DASHBOARDS', 'False'))
        if update_dashboards:
            logger.info('Starting Grafana dashboard task')
            TaskManager.run(
                'grafana/dashboards/update',
                {},
                push_local_dashboards,
                kwargs=dict(tries=10, sleep=60),
            )
        # wait for the shutdown event
        self.shutdown_event.wait()
        self.shutdown_event.clear()
        NotificationQueue.stop()
        cherrypy.engine.stop()
        logger.info('Engine stopped')

    def shutdown(self):
        super(Module, self).shutdown()
        CherryPyConfig.shutdown(self)
        logger.info('Stopping engine...')
        self.shutdown_event.set()

    def _set_ssl_item(self, item_label: str, item_key: 'SslConfigKey' = 'crt',
                      mgr_id: Optional[str] = None, inbuf: Optional[str] = None):
        if inbuf is None:
            return -errno.EINVAL, '', f'Please specify the {item_label} with "-i" option'

        if mgr_id is not None:
            self.set_store(_get_localized_key(mgr_id, item_key), inbuf)
        else:
            self.set_store(item_key, inbuf)
        return 0, f'SSL {item_label} updated', ''

    @CLIWriteCommand("dashboard set-ssl-certificate")
    def set_ssl_certificate(self, mgr_id: Optional[str] = None, inbuf: Optional[str] = None):
        return self._set_ssl_item('certificate', 'crt', mgr_id, inbuf)

    @CLIWriteCommand("dashboard set-ssl-certificate-key")
    def set_ssl_certificate_key(self, mgr_id: Optional[str] = None, inbuf: Optional[str] = None):
        return self._set_ssl_item('certificate key', 'key', mgr_id, inbuf)

    @CLIWriteCommand("dashboard create-self-signed-cert")
    def set_mgr_created_self_signed_cert(self):
        cert, pkey = create_self_signed_cert('IT', 'ceph-dashboard')
        result = HandleCommandResult(*self.set_ssl_certificate(inbuf=cert))
        if result.retval != 0:
            return result

        result = HandleCommandResult(*self.set_ssl_certificate_key(inbuf=pkey))
        if result.retval != 0:
            return result
        return 0, 'Self-signed certificate created', ''

    @CLIWriteCommand("dashboard set-rgw-credentials")
    def set_rgw_credentials(self):
        try:
            configure_rgw_credentials()
        except Exception as error:
            return -errno.EINVAL, '', str(error)

        return 0, 'RGW credentials configured', ''

    @CLIWriteCommand("dashboard set-login-banner")
    def set_login_banner(self, inbuf: str):
        '''
        Set the custom login banner read from -i <file>
        '''
        item_label = 'login banner file'
        if inbuf is None:
            return HandleCommandResult(
                -errno.EINVAL,
                stderr=f'Please specify the {item_label} with "-i" option'
            )
        mgr.set_store('custom_login_banner', inbuf)
        return HandleCommandResult(stdout=f'{item_label} added')

    @CLIReadCommand("dashboard get-login-banner")
    def get_login_banner(self):
        '''
        Get the custom login banner text
        '''
        banner_text = mgr.get_store('custom_login_banner')
        if banner_text is None:
            return HandleCommandResult(stdout='No login banner set')
        else:
            return HandleCommandResult(stdout=banner_text)

    @CLIWriteCommand("dashboard unset-login-banner")
    def unset_login_banner(self):
        '''
        Unset the custom login banner
        '''
        mgr.set_store('custom_login_banner', None)
        return HandleCommandResult(stdout='Login banner removed')

    def handle_command(self, inbuf, cmd):
        # pylint: disable=too-many-return-statements
        res = handle_option_command(cmd, inbuf)
        if res[0] != -errno.ENOSYS:
            return res
        res = handle_sso_command(cmd)
        if res[0] != -errno.ENOSYS:
            return res
        if cmd['prefix'] == 'dashboard set-jwt-token-ttl':
            self.set_module_option('jwt_token_ttl', str(cmd['seconds']))
            return 0, 'JWT token TTL updated', ''
        if cmd['prefix'] == 'dashboard get-jwt-token-ttl':
            ttl = self.get_module_option('jwt_token_ttl', JwtManager.JWT_TOKEN_TTL)
            return 0, str(ttl), ''
        if cmd['prefix'] == 'dashboard grafana dashboards update':
            push_local_dashboards()
            return 0, 'Grafana dashboards updated', ''

        return (-errno.EINVAL, '', 'Command not found \'{0}\''
                .format(cmd['prefix']))

    def notify(self, notify_type: NotifyType, notify_id):
        NotificationQueue.new_notification(str(notify_type), notify_id)

    def get_updated_pool_stats(self):
        df = self.get('df')
        pool_stats = {p['id']: p['stats'] for p in df['pools']}
        now = time.time()
        for pool_id, stats in pool_stats.items():
            for stat_name, stat_val in stats.items():
                self.__pool_stats[pool_id][stat_name].append((now, stat_val))

        return self.__pool_stats

    def config_notify(self):
        """
        This method is called whenever one of our config options is changed.
        """
        PLUGIN_MANAGER.hook.config_notify()

    def refresh_health_checks(self):
        self.set_health_checks(self.health_checks)


class StandbyModule(MgrStandbyModule, CherryPyConfig):
    def __init__(self, *args, **kwargs):
        super(StandbyModule, self).__init__(*args, **kwargs)
        CherryPyConfig.__init__(self)
        self.shutdown_event = threading.Event()

        # We can set the global mgr instance to ourselves even though
        # we're just a standby, because it's enough for logging.
        mgr.init(self)

    def serve(self):
        uri = self.await_configuration()
        if uri is None:
            # We were shut down while waiting
            return

        module = self

        class Root(object):
            @cherrypy.expose
            def default(self, *args, **kwargs):
                if module.get_module_option('standby_behaviour', 'redirect') == 'redirect':
                    active_uri = module.get_active_uri()

                    if cherrypy.request.path_info.startswith('/api/prometheus_receiver'):
                        module.log.debug("Suppressed redirecting alert to active '%s'",
                                         active_uri)
                        cherrypy.response.status = 204
                        return None

                    if active_uri:
                        if module.get_module_option('redirect_resolve_ip_addr'):
                            p_result = urlparse(active_uri)
                            hostname = str(p_result.hostname)
                            fqdn_netloc = p_result.netloc.replace(
                                hostname, socket.getfqdn(hostname))
                            active_uri = p_result._replace(netloc=fqdn_netloc).geturl()

                        module.log.info("Redirecting to active '%s'", active_uri)
                        raise cherrypy.HTTPRedirect(active_uri)
                    else:
                        template = """
                    <html>
                        <!-- Note: this is only displayed when the standby
                             does not know an active URI to redirect to, otherwise
                             a simple redirect is returned instead -->
                        <head>
                            <title>Ceph</title>
                            <meta http-equiv="refresh" content="{delay}">
                        </head>
                        <body>
                            No active ceph-mgr instance is currently running
                            the dashboard. A failover may be in progress.
                            Retrying in {delay} seconds...
                        </body>
                    </html>
                        """
                        return template.format(delay=5)
                else:
                    status = module.get_module_option('standby_error_status_code', 500)
                    raise cherrypy.HTTPError(status, message="Keep on looking")

        cherrypy.tree.mount(Root(), "{}/".format(self.url_prefix), {})
        self.log.info("Starting engine...")
        cherrypy.engine.start()
        self.log.info("Engine started...")
        # Wait for shutdown event
        self.shutdown_event.wait()
        self.shutdown_event.clear()
        cherrypy.engine.stop()
        self.log.info("Engine stopped.")

    def shutdown(self):
        CherryPyConfig.shutdown(self)

        self.log.info("Stopping engine...")
        self.shutdown_event.set()
        self.log.info("Stopped engine...")