#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright (C) 2015 GNS3 Technologies Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


"""
Start the program. Use main.py to load it.
"""

import os
import datetime
import sys
import locale
import argparse
import psutil


from gns3server.web.web_server import WebServer
from gns3server.web.logger import init_logger
from gns3server.version import __version__
from gns3server.config import Config
from gns3server.crash_report import CrashReport

import logging
log = logging.getLogger(__name__)


def locale_check():
    """
    Checks if this application runs with a correct locale (i.e. supports UTF-8 encoding) and attempt to fix
    if this is not the case.

    This is to prevent UnicodeEncodeError with unicode paths when using standard library I/O operation
    methods (e.g. os.stat() or os.path.*) which rely on the system or user locale.

    More information can be found there: http://seasonofcode.com/posts/unicode-i-o-and-locales-in-python.html
    or there: http://robjwells.com/post/61198832297/get-your-us-ascii-out-of-my-face
    """

    # no need to check on Windows or when this application is frozen
    if sys.platform.startswith("win") or hasattr(sys, "frozen"):
        return

    language = encoding = None
    try:
        language, encoding = locale.getlocale()
    except ValueError as e:
        log.error("Could not determine the current locale: {}".format(e))
    if not language and not encoding:
        try:
            log.warning("Could not find a default locale, switching to C.UTF-8...")
            locale.setlocale(locale.LC_ALL, ("C", "UTF-8"))
        except locale.Error as e:
            log.error("Could not switch to the C.UTF-8 locale: {}".format(e))
            raise SystemExit
    elif encoding != "UTF-8":
        log.warning("Your locale {}.{} encoding is not UTF-8, switching to the UTF-8 version...".format(language, encoding))
        try:
            locale.setlocale(locale.LC_ALL, (language, "UTF-8"))
        except locale.Error as e:
            log.error("Could not set an UTF-8 encoding for the {} locale: {}".format(language, e))
            raise SystemExit
    else:
        log.info("Current locale is {}.{}".format(language, encoding))


def parse_arguments(argv):
    """
    Parse command line arguments and override local configuration

    :params args: Array of command line arguments
    """

    parser = argparse.ArgumentParser(description="GNS3 server version {}".format(__version__))
    parser.add_argument("-v", "--version", help="show the version", action="version", version=__version__)
    parser.add_argument("--host", help="run on the given host/IP address")
    parser.add_argument("--port", help="run on the given port", type=int)
    parser.add_argument("--ssl", action="store_true", help="run in SSL mode")
    parser.add_argument("--config", help="Configuration file")
    parser.add_argument("--certfile", help="SSL cert file")
    parser.add_argument("--certkey", help="SSL key file")
    parser.add_argument("--record", help="save curl requests into a file (for developers)")
    parser.add_argument("-L", "--local", action="store_true", help="local mode (allows some insecure operations)")
    parser.add_argument("-A", "--allow", action="store_true", help="allow remote connections to local console ports")
    parser.add_argument("-q", "--quiet", action="store_true", help="do not show logs on stdout")
    parser.add_argument("-d", "--debug", action="store_true", help="show debug logs")
    parser.add_argument("--shell", action="store_true", help="start a shell inside the server (debugging purpose only you need to install ptpython before)")
    parser.add_argument("--log", help="send output to logfile instead of console")
    parser.add_argument("--logmaxsize", help="maximum logfile size in bytes (default is 10MB)")
    parser.add_argument("--logbackupcount", help="number of historical log files to keep (default is 10)")
    parser.add_argument("--logcompression", action="store_true", help="compress inactive (historical) logs")
    parser.add_argument("--daemon", action="store_true", help="start as a daemon")
    parser.add_argument("--pid", help="store process pid")
    parser.add_argument("--profile", help="Settings profile (blank will use default settings files)")

    args = parser.parse_args(argv)
    if args.config:
        Config.instance(files=[args.config], profile=args.profile)
    else:
        Config.instance(profile=args.profile)

    config = Config.instance().get_section_config("Server")
    defaults = {
        "host": config.get("host", "0.0.0.0"),
        "port": config.get("port", 3080),
        "ssl": config.getboolean("ssl", False),
        "certfile": config.get("certfile", ""),
        "certkey": config.get("certkey", ""),
        "record": config.get("record", ""),
        "local": config.getboolean("local", False),
        "allow": config.getboolean("allow_remote_console", False),
        "quiet": config.getboolean("quiet", False),
        "debug": config.getboolean("debug", False),
        "logfile": config.getboolean("logfile", ""),
        "logmaxsize": config.get("logmaxsize", 10000000),  # default is 10MB
        "logbackupcount": config.get("logbackupcount", 10),
        "logcompression": config.getboolean("logcompression", False)
    }

    parser.set_defaults(**defaults)
    return parser.parse_args(argv)


def set_config(args):

    config = Config.instance()
    server_config = config.get_section_config("Server")
    server_config["local"] = str(args.local)
    server_config["allow_remote_console"] = str(args.allow)
    server_config["host"] = args.host
    server_config["port"] = str(args.port)
    server_config["ssl"] = str(args.ssl)
    server_config["certfile"] = args.certfile
    server_config["certkey"] = args.certkey
    server_config["record"] = args.record
    server_config["debug"] = str(args.debug)
    server_config["shell"] = str(args.shell)
    config.set_section_config("Server", server_config)


def pid_lock(path):
    """
    Write the file in a file on the system.
    Check if the process is not already running.
    """

    if os.path.exists(path):
        pid = None
        try:
            with open(path) as f:
                try:
                    pid = int(f.read())
                    os.kill(pid, 0)  # kill returns an error if the process is not running
                except (OSError, SystemError, ValueError):
                    pid = None
        except OSError as e:
            log.critical("Can't open pid file %s: %s", pid, str(e))
            sys.exit(1)

        if pid:
            log.critical("GNS3 is already running pid: %d", pid)
            sys.exit(1)

    try:
        with open(path, 'w+') as f:
            f.write(str(os.getpid()))
    except OSError as e:
        log.critical("Can't write pid file %s: %s", path, str(e))
        sys.exit(1)


def kill_ghosts():
    """
    Kill process from previous GNS3 session
    """
    detect_process = ["vpcs", "traceng", "ubridge", "dynamips"]
    for proc in psutil.process_iter():
        try:
            name = proc.name().lower().split(".")[0]
            if name in detect_process:
                proc.kill()
                log.warning("Killed ghost process %s", name)
        except (OSError, psutil.NoSuchProcess, psutil.AccessDenied):
            pass


def run():
    args = parse_arguments(sys.argv[1:])

    if args.daemon and sys.platform.startswith("win"):
        log.critical("Daemon is not supported on Windows")
        sys.exit(1)

    if args.pid:
        pid_lock(args.pid)
        kill_ghosts()

    level = logging.INFO
    if args.debug:
        level = logging.DEBUG

    user_log = init_logger(level, logfile=args.log, max_bytes=int(args.logmaxsize), backup_count=int(args.logbackupcount),
                           compression=args.logcompression, quiet=args.quiet)
    user_log.info("GNS3 server version {}".format(__version__))
    current_year = datetime.date.today().year
    user_log.info("Copyright (c) 2007-{} GNS3 Technologies Inc.".format(current_year))

    for config_file in Config.instance().get_config_files():
        user_log.info("Config file {} loaded".format(config_file))

    set_config(args)
    server_config = Config.instance().get_section_config("Server")

    if server_config.getboolean("local"):
        log.warning("Local mode is enabled. Beware, clients will have full control on your filesystem")

    if server_config.getboolean("auth"):
        user = server_config.get("user", "").strip()
        if not user:
            log.critical("HTTP authentication is enabled but no username is configured")
            return
        log.info("HTTP authentication is enabled with username '{}'".format(user))

    # we only support Python 3 version >= 3.8
    if sys.version_info < (3, 8, 0):
        raise SystemExit("Python 3.8 or higher is required")

    user_log.info("Running with Python {major}.{minor}.{micro} and has PID {pid}".format(major=sys.version_info[0], minor=sys.version_info[1],
                                                                                         micro=sys.version_info[2], pid=os.getpid()))

    try:
        import truststore
        truststore.inject_into_ssl()
        log.info("Using system certificate store for SSL connections")
    except ImportError:
        pass

    # check for the correct locale (UNIX/Linux only)
    locale_check()

    try:
        os.getcwd()
    except FileNotFoundError:
        log.critical("The current working directory doesn't exist")
        return

    CrashReport.instance()
    host = server_config["host"]
    port = int(server_config["port"])

    server = WebServer.instance(host, port)
    try:
        server.run()
    except OSError as e:
        # This is to ignore OSError: [WinError 0] The operation completed successfully exception on Windows.
        if not sys.platform.startswith("win") or not e.winerror == 0:
            raise
    except Exception as e:
        log.critical("Critical error while running the server: {}".format(e), exc_info=1)
        CrashReport.instance().capture_exception()
        return
    finally:
        if args.pid:
            log.info("Remove PID file %s", args.pid)
            try:
                os.remove(args.pid)
            except OSError as e:
                log.critical("Can't remove pid file %s: %s", args.pid, str(e))
