# -*- coding: utf-8 -*-
#
# This file is part of Glances.
#
# Copyright (C) 2019 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 configuration file."""

import os
import sys
import multiprocessing
from io import open
import re

from glances.compat import ConfigParser, NoOptionError, system_exec
from glances.globals import BSD, LINUX, MACOS, SUNOS, WINDOWS
from glances.logger import logger


def user_config_dir():
    r"""Return the per-user config dir (full path).

    - Linux, *BSD, SunOS: ~/.config/glances
    - macOS: ~/Library/Application Support/glances
    - Windows: %APPDATA%\glances
    """
    if WINDOWS:
        path = os.environ.get('APPDATA')
    elif MACOS:
        path = os.path.expanduser('~/Library/Application Support')
    else:
        path = os.environ.get('XDG_CONFIG_HOME') or os.path.expanduser('~/.config')
    if path is None:
        path = ''
    else:
        path = os.path.join(path, 'glances')

    return path


def user_cache_dir():
    r"""Return the per-user cache dir (full path).

    - Linux, *BSD, SunOS: ~/.cache/glances
    - macOS: ~/Library/Caches/glances
    - Windows: {%LOCALAPPDATA%,%APPDATA%}\glances\cache
    """
    if WINDOWS:
        path = os.path.join(os.environ.get('LOCALAPPDATA') or os.environ.get('APPDATA'),
                            'glances', 'cache')
    elif MACOS:
        path = os.path.expanduser('~/Library/Caches/glances')
    else:
        path = os.path.join(os.environ.get('XDG_CACHE_HOME') or os.path.expanduser('~/.cache'),
                            'glances')

    return path


def system_config_dir():
    r"""Return the system-wide config dir (full path).

    - Linux, SunOS: /etc/glances
    - *BSD, macOS: /usr/local/etc/glances
    - Windows: %APPDATA%\glances
    """
    if LINUX or SUNOS:
        path = '/etc'
    elif BSD or MACOS:
        path = '/usr/local/etc'
    else:
        path = os.environ.get('APPDATA')
    if path is None:
        path = ''
    else:
        path = os.path.join(path, 'glances')

    return path


class Config(object):

    """This class is used to access/read config file, if it exists.

    :param config_dir: the path to search for config file
    :type config_dir: str or None
    """

    def __init__(self, config_dir=None):
        self.config_dir = config_dir
        self.config_filename = 'glances.conf'
        self._loaded_config_file = None

        # Re patern for optimize research of `foo`
        self.re_pattern = re.compile('(\`.+?\`)')

        self.parser = ConfigParser()
        self.read()

    def config_file_paths(self):
        r"""Get a list of config file paths.

        The list is built taking into account of the OS, priority and location.

        * custom path: /path/to/glances
        * Linux, SunOS: ~/.config/glances, /etc/glances
        * *BSD: ~/.config/glances, /usr/local/etc/glances
        * macOS: ~/Library/Application Support/glances, /usr/local/etc/glances
        * Windows: %APPDATA%\glances

        The config file will be searched in the following order of priority:
            * /path/to/file (via -C flag)
            * user's home directory (per-user settings)
            * system-wide directory (system-wide settings)
        """
        paths = []

        if self.config_dir:
            paths.append(self.config_dir)

        paths.append(os.path.join(user_config_dir(), self.config_filename))
        paths.append(os.path.join(system_config_dir(), self.config_filename))

        return paths

    def read(self):
        """Read the config file, if it exists. Using defaults otherwise."""
        for config_file in self.config_file_paths():
            logger.info('Search glances.conf file in {}'.format(config_file))
            if os.path.exists(config_file):
                try:
                    with open(config_file, encoding='utf-8') as f:
                        self.parser.read_file(f)
                        self.parser.read(f)
                    logger.info("Read configuration file '{}'".format(config_file))
                except UnicodeDecodeError as err:
                    logger.error("Can not read configuration file '{}': {}".format(config_file, err))
                    sys.exit(1)
                # Save the loaded configuration file path (issue #374)
                self._loaded_config_file = config_file
                break

        # Quicklook
        if not self.parser.has_section('quicklook'):
            self.parser.add_section('quicklook')
        self.set_default_cwc('quicklook', 'cpu')
        self.set_default_cwc('quicklook', 'mem')
        self.set_default_cwc('quicklook', 'swap')

        # CPU
        if not self.parser.has_section('cpu'):
            self.parser.add_section('cpu')
        self.set_default_cwc('cpu', 'user')
        self.set_default_cwc('cpu', 'system')
        self.set_default_cwc('cpu', 'steal')
        # By default I/O wait should be lower than 1/number of CPU cores
        iowait_bottleneck = (1.0 / multiprocessing.cpu_count()) * 100.0
        self.set_default_cwc('cpu', 'iowait',
                             [str(iowait_bottleneck - (iowait_bottleneck * 0.20)),
                              str(iowait_bottleneck - (iowait_bottleneck * 0.10)),
                              str(iowait_bottleneck)])
        # Context switches bottleneck identification #1212
        ctx_switches_bottleneck = (500000 * 0.10) * multiprocessing.cpu_count()
        self.set_default_cwc('cpu', 'ctx_switches',
                             [str(ctx_switches_bottleneck - (ctx_switches_bottleneck * 0.20)),
                              str(ctx_switches_bottleneck - (ctx_switches_bottleneck * 0.10)),
                              str(ctx_switches_bottleneck)])

        # Per-CPU
        if not self.parser.has_section('percpu'):
            self.parser.add_section('percpu')
        self.set_default_cwc('percpu', 'user')
        self.set_default_cwc('percpu', 'system')

        # Load
        if not self.parser.has_section('load'):
            self.parser.add_section('load')
        self.set_default_cwc('load', cwc=['0.7', '1.0', '5.0'])

        # Mem
        if not self.parser.has_section('mem'):
            self.parser.add_section('mem')
        self.set_default_cwc('mem')

        # Swap
        if not self.parser.has_section('memswap'):
            self.parser.add_section('memswap')
        self.set_default_cwc('memswap')

        # NETWORK
        if not self.parser.has_section('network'):
            self.parser.add_section('network')
        self.set_default_cwc('network', 'rx')
        self.set_default_cwc('network', 'tx')

        # FS
        if not self.parser.has_section('fs'):
            self.parser.add_section('fs')
        self.set_default_cwc('fs')

        # Sensors
        if not self.parser.has_section('sensors'):
            self.parser.add_section('sensors')
        self.set_default_cwc('sensors', 'temperature_core', cwc=['60', '70', '80'])
        self.set_default_cwc('sensors', 'temperature_hdd', cwc=['45', '52', '60'])
        self.set_default_cwc('sensors', 'battery', cwc=['80', '90', '95'])

        # Process list
        if not self.parser.has_section('processlist'):
            self.parser.add_section('processlist')
        self.set_default_cwc('processlist', 'cpu')
        self.set_default_cwc('processlist', 'mem')

    @property
    def loaded_config_file(self):
        """Return the loaded configuration file."""
        return self._loaded_config_file

    def as_dict(self):
        """Return the configuration as a dict"""
        dictionary = {}
        for section in self.parser.sections():
            dictionary[section] = {}
            for option in self.parser.options(section):
                dictionary[section][option] = self.parser.get(section, option)
        return dictionary

    def sections(self):
        """Return a list of all sections."""
        return self.parser.sections()

    def items(self, section):
        """Return the items list of a section."""
        return self.parser.items(section)

    def has_section(self, section):
        """Return info about the existence of a section."""
        return self.parser.has_section(section)

    def set_default_cwc(self, section,
                        option_header=None,
                        cwc=['50', '70', '90']):
        """Set default values for careful, warning and critical."""
        if option_header is None:
            header = ''
        else:
            header = option_header + '_'
        self.set_default(section, header + 'careful', cwc[0])
        self.set_default(section, header + 'warning', cwc[1])
        self.set_default(section, header + 'critical', cwc[2])

    def set_default(self, section, option,
                    default):
        """If the option did not exist, create a default value."""
        if not self.parser.has_option(section, option):
            self.parser.set(section, option, default)

    def get_value(self, section, option,
                  default=None):
        """Get the value of an option, if it exists.

        If it did not exist, then return the default value.

        It allows user to define dynamic configuration key (see issue#1204)
        Dynamic vlaue should starts and end with the ` char
        Example: prefix=`hostname`
        """
        ret = default
        try:
            ret = self.parser.get(section, option)
        except NoOptionError:
            pass

        # Search a substring `foo` and replace it by the result of its exec
        if ret is not None:
            try:
                match = self.re_pattern.findall(ret)
                for m in match:
                    ret = ret.replace(m, system_exec(m[1:-1]))
            except TypeError:
                pass
        return ret

    def get_int_value(self, section, option, default=0):
        """Get the int value of an option, if it exists."""
        try:
            return self.parser.getint(section, option)
        except NoOptionError:
            return int(default)

    def get_float_value(self, section, option, default=0.0):
        """Get the float value of an option, if it exists."""
        try:
            return self.parser.getfloat(section, option)
        except NoOptionError:
            return float(default)

    def get_bool_value(self, section, option, default=True):
        """Get the bool value of an option, if it exists."""
        try:
            return self.parser.getboolean(section, option)
        except NoOptionError:
            return bool(default)
