# -*- coding: utf-8 -*-
#
# This file is part of Glances.
#
# Copyright (C) 2016 Nicolargo <nicolas@nicolargo.com>
#
# Glances is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Glances is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

"""Manage the Glances client browser (list of Glances server)."""

import json
import socket

from glances.compat import Fault, ProtocolError, ServerProxy
from glances.autodiscover import GlancesAutoDiscoverServer
from glances.client import GlancesClient, GlancesClientTransport
from glances.logger import logger
from glances.password_list import GlancesPasswordList as GlancesPassword
from glances.static_list import GlancesStaticServer
from glances.outputs.glances_curses_browser import GlancesCursesBrowser


class GlancesClientBrowser(object):

    """This class creates and manages the TCP client browser (servers list)."""

    def __init__(self, config=None, args=None):
        # Store the arg/config
        self.args = args
        self.config = config
        self.static_server = None
        self.password = None

        # Load the configuration file
        self.load()

        # Start the autodiscover mode (Zeroconf listener)
        if not self.args.disable_autodiscover:
            self.autodiscover_server = GlancesAutoDiscoverServer()
        else:
            self.autodiscover_server = None

        # Init screen
        self.screen = GlancesCursesBrowser(args=self.args)

    def load(self):
        """Load server and password list from the confiuration file."""
        # Init the static server list (if defined)
        self.static_server = GlancesStaticServer(config=self.config)

        # Init the password list (if defined)
        self.password = GlancesPassword(config=self.config)

    def get_servers_list(self):
        """Return the current server list (list of dict).

        Merge of static + autodiscover servers list.
        """
        ret = []

        if self.args.browser:
            ret = self.static_server.get_servers_list()
            if self.autodiscover_server is not None:
                ret = self.static_server.get_servers_list() + self.autodiscover_server.get_servers_list()

        return ret

    def __get_uri(self, server):
        """Return the URI for the given server dict."""
        # Select the connection mode (with or without password)
        if server['password'] != "":
            if server['status'] == 'PROTECTED':
                # Try with the preconfigure password (only if status is PROTECTED)
                clear_password = self.password.get_password(server['name'])
                if clear_password is not None:
                    server['password'] = self.password.sha256_hash(clear_password)
            return 'http://{}:{}@{}:{}'.format(server['username'], server['password'],
                                               server['ip'], server['port'])
        else:
            return 'http://{}:{}'.format(server['ip'], server['port'])

    def __serve_forever(self):
        """Main client loop."""
        while True:
            # No need to update the server list
            # It's done by the GlancesAutoDiscoverListener class (autodiscover.py)
            # Or define staticaly in the configuration file (module static_list.py)
            # For each server in the list, grab elementary stats (CPU, LOAD, MEM, OS...)
            # logger.debug(self.get_servers_list())
            try:
                for v in self.get_servers_list():
                    # Do not retreive stats for statics server
                    # Why ? Because for each offline servers, the timeout will be reached
                    # So ? The curse interface freezes
                    if v['type'] == 'STATIC' and v['status'] in ['UNKNOWN', 'SNMP', 'OFFLINE']:
                        continue

                    # Get the server URI
                    uri = self.__get_uri(v)

                    # Try to connect to the server
                    t = GlancesClientTransport()
                    t.set_timeout(3)

                    # Get common stats
                    try:
                        s = ServerProxy(uri, transport=t)
                    except Exception as e:
                        logger.warning(
                            "Client browser couldn't create socket {}: {}".format(uri, e))
                    else:
                        # Mandatory stats
                        try:
                            # CPU%
                            cpu_percent = 100 - json.loads(s.getCpu())['idle']
                            v['cpu_percent'] = '{:.1f}'.format(cpu_percent)
                            # MEM%
                            v['mem_percent'] = json.loads(s.getMem())['percent']
                            # OS (Human Readable name)
                            v['hr_name'] = json.loads(s.getSystem())['hr_name']
                        except (socket.error, Fault, KeyError) as e:
                            logger.debug(
                                "Error while grabbing stats form {}: {}".format(uri, e))
                            v['status'] = 'OFFLINE'
                        except ProtocolError as e:
                            if e.errcode == 401:
                                # Error 401 (Authentication failed)
                                # Password is not the good one...
                                v['password'] = None
                                v['status'] = 'PROTECTED'
                            else:
                                v['status'] = 'OFFLINE'
                            logger.debug("Cannot grab stats from {} ({} {})".format(uri, e.errcode, e.errmsg))
                        else:
                            # Status
                            v['status'] = 'ONLINE'

                            # Optional stats (load is not available on Windows OS)
                            try:
                                # LOAD
                                load_min5 = json.loads(s.getLoad())['min5']
                                v['load_min5'] = '{:.2f}'.format(load_min5)
                            except Exception as e:
                                logger.warning(
                                    "Error while grabbing stats form {}: {}".format(uri, e))
            # List can change size during iteration...
            except RuntimeError:
                logger.debug(
                    "Server list dictionnary change inside the loop (wait next update)")

            # Update the screen (list or Glances client)
            if self.screen.active_server is None:
                #  Display the Glances browser
                self.screen.update(self.get_servers_list())
            else:
                # Display the Glances client for the selected server
                logger.debug("Selected server: {}".format(self.get_servers_list()[self.screen.active_server]))

                # Connection can take time
                # Display a popup
                self.screen.display_popup(
                    'Connect to {}:{}'.format(v['name'], v['port']), duration=1)

                # A password is needed to access to the server's stats
                if self.get_servers_list()[self.screen.active_server]['password'] is None:
                    # First of all, check if a password is available in the [passwords] section
                    clear_password = self.password.get_password(v['name'])
                    if (clear_password is None or self.get_servers_list()
                            [self.screen.active_server]['status'] == 'PROTECTED'):
                        # Else, the password should be enter by the user
                        # Display a popup to enter password
                        clear_password = self.screen.display_popup(
                            'Password needed for {}: '.format(v['name']), is_input=True)
                    # Store the password for the selected server
                    if clear_password is not None:
                        self.set_in_selected('password', self.password.sha256_hash(clear_password))

                # Display the Glance client on the selected server
                logger.info("Connect Glances client to the {} server".format(
                    self.get_servers_list()[self.screen.active_server]['key']))

                # Init the client
                args_server = self.args

                # Overwrite connection setting
                args_server.client = self.get_servers_list()[self.screen.active_server]['ip']
                args_server.port = self.get_servers_list()[self.screen.active_server]['port']
                args_server.username = self.get_servers_list()[self.screen.active_server]['username']
                args_server.password = self.get_servers_list()[self.screen.active_server]['password']
                client = GlancesClient(config=self.config, args=args_server, return_to_browser=True)

                # Test if client and server are in the same major version
                if not client.login():
                    self.screen.display_popup(
                        "Sorry, cannot connect to '{}'\n"
                        "See 'glances.log' for more details".format(v['name']))

                    # Set the ONLINE status for the selected server
                    self.set_in_selected('status', 'OFFLINE')
                else:
                    # Start the client loop
                    # Return connection type: 'glances' or 'snmp'
                    connection_type = client.serve_forever()

                    try:
                        logger.debug("Disconnect Glances client from the {} server".format(
                            self.get_servers_list()[self.screen.active_server]['key']))
                    except IndexError:
                        # Server did not exist anymore
                        pass
                    else:
                        # Set the ONLINE status for the selected server
                        if connection_type == 'snmp':
                            self.set_in_selected('status', 'SNMP')
                        else:
                            self.set_in_selected('status', 'ONLINE')

                # Return to the browser (no server selected)
                self.screen.active_server = None

    def serve_forever(self):
        """Wrapper to the serve_forever function.

        This function will restore the terminal to a sane state
        before re-raising the exception and generating a traceback.
        """
        try:
            return self.__serve_forever()
        finally:
            self.end()

    def set_in_selected(self, key, value):
        """Set the (key, value) for the selected server in the list."""
        # Static list then dynamic one
        if self.screen.active_server >= len(self.static_server.get_servers_list()):
            self.autodiscover_server.set_server(
                self.screen.active_server - len(self.static_server.get_servers_list()),
                key, value)
        else:
            self.static_server.set_server(self.screen.active_server, key, value)

    def end(self):
        """End of the client browser session."""
        self.screen.end()
