From dc0f17dd2000c78af918018094c183301ba30077 Mon Sep 17 00:00:00 2001
From: Benjamin Renard <brenard@easter-eggs.com>
Date: Wed, 3 Nov 2021 17:38:31 +0100
Subject: [PATCH] Add config lib

---
 mylib/config.py | 629 ++++++++++++++++++++++++++++++++++++++++++++++++
 setup.py        |   6 +
 2 files changed, 635 insertions(+)
 create mode 100644 mylib/config.py

diff --git a/mylib/config.py b/mylib/config.py
new file mode 100644
index 0000000..ab94297
--- /dev/null
+++ b/mylib/config.py
@@ -0,0 +1,629 @@
+# -*- coding: utf-8 -*-
+
+""" Configuration & options parser """
+
+import argparse
+from configparser import ConfigParser
+from getpass import getpass
+from logging.config import fileConfig
+import logging
+import os
+import stat
+import sys
+
+import argcomplete
+import keyring
+from systemd.journal import JournalHandler
+
+
+log = logging.getLogger(__name__)
+
+
+# Constants
+DEFAULT_ENCODING = 'utf-8'
+DEFAULT_CONFIG_DIRPATH = os.path.expanduser('./')
+
+
+class BaseOption:
+    """ Base configuration option class """
+
+    def __init__(self, config, section, name, default=None, comment=None,
+                 arg=None, short_arg=None, arg_help=None):
+        self.config = config
+        self.section = section
+        self.name = name
+        self.default = default
+        self.comment = comment
+        self.arg = arg
+        self.short_arg = short_arg
+        self.arg_help = arg_help if arg_help else comment
+
+    @property
+    def _isset_in_options(self):
+        """ Check if option is defined in registered arguments parser options """
+        return (
+            self.config.options
+            and self._from_options != self.default
+        )
+
+    @property
+    def _from_options(self):
+        """ Get option from arguments parser options """
+        value = (
+            getattr(self.config.options, self.parser_dest)
+            if self.config.options else None
+        )
+        log.debug(
+            '_from_options(%s, %s) = %s',
+            self.section.name, self.name, value
+        )
+        return value
+
+    @property
+    def _isset_in_config_file(self):
+        """ Check if option is defined in the loaded configuration file """
+        return (
+            self.config.config_parser
+            and self.config.config_parser.has_option(self.section.name, self.name)
+        )
+
+    @property
+    def _from_config(self):
+        """ Get option value from ConfigParser """
+        return self.config.config_parser.get(self.section.name, self.name)
+
+    def isset(self):
+        """ Check if option is defined in the loaded configuration file """
+        return self._isset_in_config_file or self._isset_in_options
+
+    def get(self):
+        """ Get option value from options, config or default """
+        if self._isset_in_options:
+            return self._from_options
+        if self._isset_in_config_file:
+            return self._from_config
+        return self.default
+
+    def set(self, value):
+        """ Set option value to config file """
+        assert self.config.config_parser, "Can set option value only if configuration file is configured"
+        if value == '':
+            value = None
+
+        if value == self.default or value is None:
+            # Remove option from config
+            self.config.config_parser.remove_option(
+                self.section.name, self.name)
+        else:
+            # Store option to config
+            if not self.config.config_parser.has_section(self.section.name):
+                self.config.config_parser.add_section(self.section.name)
+
+            self.config.config_parser.set(
+                self.section.name, self.name, self.to_config(value)
+            )
+
+    @property
+    def parser_action(self):
+        """ Get action as accept by argparse.ArgumentParser """
+        return 'store'
+
+    @property
+    def parser_type(self):
+        """ Get type as handle by argparse.ArgumentParser """
+        return str
+
+    @property
+    def parser_dest(self):
+        """ Get option name in arguments parser options """
+        return '{0}_{1}'.format(self.section.name, self.name)
+
+    @property
+    def parser_help(self):
+        """ Get option help message in arguments parser options """
+        if self.arg_help and self.default is not None:
+            return '{0} (Default: {1})'.format(self.arg_help, self.default)
+        if self.arg_help:
+            return self.arg_help
+        return None
+
+    @property
+    def parser_argument_name(self):
+        """ Get option argument name in parser options """
+        return (
+            self.arg if self.arg else
+            '--{0}-{1}'.format(
+                self.section.name, self.name
+            ).lower().replace('_', '-')
+        )
+
+    def add_option_to_parser(self, section_opts):
+        """ Add option to arguments parser """
+        args = [self.parser_argument_name]
+        if self.short_arg:
+            args.append(self.short_arg)
+        kwargs = dict(
+            action=self.parser_action,
+            dest=self.parser_dest,
+            help=self.parser_help,
+            default=self.default,
+        )
+        if self.parser_type:  # pylint: disable=using-constant-test
+            kwargs['type'] = self.parser_type
+
+        log.debug(
+            'add_option_to_parser(%s, %s): argument name(s)=%s / kwargs=%s',
+            self.section.name, self.name, ', '.join(args), kwargs
+        )
+        section_opts.add_argument(*args, **kwargs)
+
+    def to_config(self, value=None):
+        """ Format value as stored in configuration file """
+        value = value if value is not None else self.get()
+        return '' if value is None else str(value)
+
+    def export_to_config(self):
+        """ Export option to configuration file """
+        lines = []
+        if self.comment:
+            lines.append('# ' + self.comment)
+        value = self.to_config()
+        default_value = (
+            '' if self.default is None else
+            self.to_config(self.default)
+        )
+        log.debug(
+            'export_to_config(%s, %s): value=%s / default=%s',
+            self.section.name, self.name, value, default_value)
+        if default_value:
+            lines.append(
+                '# Default: %s' % default_value
+            )
+        if value and value != default_value:
+            lines.append(
+                '%s = %s' %
+                (self.name, value)
+            )
+        else:
+            lines.append('# %s =' % self.name)
+        lines.append('')
+        return '\n'.join(lines)
+
+
+class StringOption(BaseOption):
+    """ String configuration option class """
+
+
+class BooleanOption(BaseOption):
+    """ Boolean configuration option class """
+
+    @property
+    def _from_config(self):
+        """ Get option value from ConfigParser """
+        return self.config.config_parser.getboolean(self.section.name, self.name)
+
+    def to_config(self, value=None):
+        """ Format value as stored in configuration file """
+        return super().to_config(value).lower()
+
+    @property
+    def parser_action(self):
+        return "store_" + str(bool(not self.default)).lower()
+
+    @property
+    def parser_type(self):
+        return None
+
+
+class FloatOption(BaseOption):
+    """ Float configuration option class """
+
+    @property
+    def _from_config(self):
+        """ Get option value from ConfigParser """
+        return self.config.config_parser.getfloat(self.section.name, self.name)
+
+    @property
+    def parser_type(self):
+        return float
+
+
+class IntegerOption(BaseOption):
+    """ Integer configuration option class """
+
+    @property
+    def _from_config(self):
+        """ Get option value from ConfigParser """
+        return self.config.config_parser.getint(self.section.name, self.name)
+
+    def to_config(self, value=None):
+        """ Format value as stored in configuration file """
+        value = value if value is not None else self.get()
+        return str(int(value)) if value is not None else ''
+
+    @property
+    def parser_type(self):
+        return int
+
+
+class PasswordOption(StringOption):
+    """ Password configuration option class """
+
+    def __init__(self, *arg, username_option=None, keyring_value=None, **kwargs):
+        super().__init__(*arg, **kwargs)
+        self.username_option = username_option
+        self.keyring_value = keyring_value if keyring_value is not None else 'keyring'
+
+    @property
+    def _keyring_service_name(self):
+        """ Return keyring service name """
+        return '.'.join([
+            self.config.shortname,
+            self.section.name, self.name
+        ])
+
+    @property
+    def _keyring_username(self):
+        """ Return keyring username """
+        return self.section.get(self.username_option) if self.username_option else self.name
+
+    def get(self):
+        """ Get option value """
+        value = super().get()
+
+        if value != self.keyring_value:
+            return value
+
+        service_name = self._keyring_service_name
+        username = self._keyring_username
+        log.debug(
+            'Retreive password %s for username=%s from keyring',
+            service_name, username
+        )
+        value = keyring.get_password(service_name, username)
+
+        if value is None:
+            value = getpass(
+                'Please enter %s%s: ' % (
+                    self.comment if self.comment else
+                    '%s %s' % (self.section.name, self.name),
+                    (' for %s' % username)
+                    if username != self.name else ''
+                )
+            )
+            keyring.set_password(service_name, username, value)
+        return value
+
+    def to_config(self, value=None):
+        """ Format value as stored in configuration file """
+        if super().get() == self.keyring_value:
+            return self.keyring_value
+        return super().to_config(value)
+
+    def set(self, value):
+        """ Set option value to config file """
+        if super().get() == self.keyring_value:
+            keyring.set_password(
+                self._keyring_service_name, self._keyring_username,
+                value)
+            value = self.keyring_value
+        super().set(value)
+
+
+class ConfigSection:
+    """ Configuration section class """
+
+    def __init__(self, config, name, comment=None, order=None):
+        self.config = config
+        self.name = name
+        self.options = dict()
+        self.comment = comment
+        self.order = order if isinstance(order, int) else 10
+
+    def add_option(self, _type, name, **kwargs):
+        """
+        Add option
+
+        :param _type: Option type, derivated from BaseOption
+        :param name: Option name
+        :param **kwargs: Dict of raw option for type class
+        """
+        assert not self.defined(name), "Duplicated option %s" % name
+        self.options[name] = _type(self.config, self, name, **kwargs)
+        return self.options[name]
+
+    def defined(self, option):
+        """ Check if option is defined """
+        return option in self.options
+
+    def isset(self, option):
+        """ Check if option is set """
+        return self.defined(option) and self.options[option].isset()
+
+    def get(self, option):
+        """ Get option value """
+        assert self.defined(option), "Option %s unknown" % option
+        return self.options[option].get()
+
+    def set(self, option, value):
+        """ Set option value """
+        assert self.defined(option), "Option %s unknown" % option
+        return self.options[option].set(value)
+
+    def add_options_to_parser(self, parser):
+        """ Add section to argparse.ArgumentParser """
+        assert isinstance(parser, argparse.ArgumentParser)
+        section_opts = parser.add_argument_group(
+            self.comment if self.comment
+            else self.name.capitalize()
+        )
+
+        for option in self.options:
+            self.options[option].add_option_to_parser(section_opts)
+
+    def export_to_config(self):
+        """ Export section and their options to configuration file """
+        lines = []
+        if self.comment:
+            lines.append('# %s' % self.comment)
+        lines.append('[%s]' % self.name)
+        for option in self.options:
+            lines.append(self.options[option].export_to_config())
+        return '\n'.join(lines)
+
+
+class Config:
+    """ Configuration helper """
+
+    def __init__(self, appname, shortname=None, version=None, encoding=None):
+        self.appname = appname
+        self.shortname = shortname
+        self.version = version if version else '0.0'
+        self.encoding = encoding if encoding else 'utf-8'
+        self.config_parser = None
+        self.options_parser = None
+        self.options = None
+        self.sections = {}
+        self._loaded_callbacks = []
+        self._filepath = None
+
+    def add_section(self, name, loaded_callback=None, **kwargs):
+        """
+        Add section
+
+        : param name: The section name
+        : param loaded_callback: An optional callback method that will be executed after configuration is loaded
+                                The specified callback method will receive Config object as parameter.
+        : param ** kwargs: Raw parameters dict pass to ConfigSection __init__() method
+        """
+        assert name not in self.sections, "Duplicated section %s" % name
+
+        self.sections[name] = ConfigSection(self, name, **kwargs)
+        if loaded_callback:
+            self._loaded_callbacks.append(loaded_callback)
+            # If configuration is already loaded, execute callback immediatly
+            if self._filepath:
+                loaded_callback(self)
+        return self.sections[name]
+
+    def defined(self, section, option):
+        """ Check option is defined in specified section """
+        return section in self.sections and self.sections[section].defined(option)
+
+    def isset(self, section, option):
+        """ Check option is set in specified section """
+        return section in self.sections and self.sections[section].isset(option)
+
+    def get(self, section, option):
+        """ Get option value """
+        assert self.config_parser or self.options, 'Unconfigured options parser'
+        assert self.defined(
+            section, option), 'Unknown option %s.%s' % (section, option)
+        value = self.sections[section].get(option)
+        log.debug('get(%s, %s): %s (%s)', section, option, value, type(value))
+        return value
+
+    def set(self, section, option, value):
+        """ Set option value """
+        assert self.config_parser, 'Unconfigured options parser'
+        assert self.defined(
+            section, option), 'Unknown option %s.%s' % (section, option)
+        self.sections[section].set(option, value)
+
+    def load_file(self, filepath):
+        """ Read configuration file """
+
+        self.config_parser = ConfigParser()
+        self._filepath = filepath
+
+        # Checking access of configuration file
+        if not os.path.isfile(filepath):
+            return True
+
+        if not os.access(filepath, os.R_OK):
+            return False
+
+        try:
+            self.config_parser.read(filepath, encoding=self.encoding)
+        except Exception:  # pylint: disable=broad-except
+            self.config_parser = None
+            log.exception('Failed to read configuration file %s', filepath)
+            return False
+
+        # Logging initialization
+        if self.config_parser.has_section('loggers'):
+            fileConfig(filepath)
+        else:
+            # Otherwise, use systemd journal handler
+            handler = JournalHandler(SYSLOG_IDENTIFIER=self.shortname)
+            handler.setFormatter(
+                logging.Formatter(
+                    '%(levelname)s | %(name)s | %(message)s'
+                )
+            )
+            logging.getLogger().addHandler(handler)
+
+        self._filepath = filepath
+
+        # Execute loaded callbacks
+        for callback in self._loaded_callbacks:
+            callback(self)
+
+        return True
+
+    def save(self, filepath=None):
+        """ Save configuration file """
+        filepath = filepath if filepath else self._filepath
+        assert filepath, 'Configuration filepath is not set or provided'
+
+        # Checking access of target directory
+        dirpath = os.path.dirname(filepath)
+        if not os.path.isdir(dirpath) or not os.access(dirpath, os.R_OK | os.W_OK | os.X_OK):
+            log.error(
+                'Configuration directory "%s" does not exist (or not writable)', dirpath)
+            return False
+
+        if os.path.isfile(filepath) and not os.access(filepath, os.W_OK):
+            log.error('Configuration file "%s" is not writable', filepath)
+            return False
+
+        lines = ['#\n# %s configuration\n#\n' % self.appname]
+
+        for section_name in self._ordered_section_names:
+            lines.append('')
+            lines.append(self.sections[section_name].export_to_config())
+
+        try:
+            with open(filepath, 'wb') as fd:
+                fd.write(
+                    '\n'.join(lines).encode(self.encoding)
+                )
+
+            # Privacy!
+            os.chmod(filepath, stat.S_IRUSR | stat.S_IWUSR)
+        except Exception:  # pylint: disable=broad-except
+            log.exception(
+                'Failed to write generated configuration file %s', filepath)
+            return False
+        return True
+
+    @property
+    def _ordered_section_names(self):
+        """ Get ordered list of section names """
+        return sorted(self.sections.keys(), key=lambda section: self.sections[section].order)
+
+    def get_arguments_parser(self, **kwargs):
+        """ Get arguments parser """
+        if self.options_parser:
+            return self.options_parser
+
+        self.options_parser = argparse.ArgumentParser(
+            description=self.appname, **kwargs)
+
+        self.options_parser.add_argument(
+            '-c',
+            '--config',
+            default=self.config_filepath,
+            help='Configuration file to use (default: %s)' %
+            self.config_filepath
+        )
+
+        self.options_parser.add_argument(
+            '--save',
+            action='store_true',
+            dest='save',
+            help='Save current configuration to file',
+        )
+
+        self.options_parser.add_argument(
+            '-d',
+            '--debug',
+            action='store_true',
+            help='Show debug messages'
+        )
+
+        self.options_parser.add_argument(
+            '-v',
+            '--verbose',
+            action='store_true',
+            help='Show verbose messages'
+        )
+
+        self.add_options_to_parser(self.options_parser)
+
+        return self.options_parser
+
+    def parse_arguments_options(self, argv=None, parser=None, create=True, exit_after_created=True):
+        """
+        Parse arguments options
+
+        :param argv: Optional arguments list to parse (default: sys.argv[1:])
+        :param parser: Optional argparse.ArgumentParser use
+                       (default: generated by self.get_arguments_parser())
+        :param create: If True, configuration file will be created if it does not exits
+                       (default: True)
+        :param exit_after_created: If True, script will end after configuration file
+                        creation (default: True)
+        """
+        parser = parser if parser else self.get_arguments_parser()
+        argcomplete.autocomplete(parser)
+        options = parser.parse_args(argv if argv else sys.argv[1:])
+
+        if options.config:
+            options.config = os.path.abspath(options.config)
+
+            already_saved = False
+            if not os.path.isfile(options.config) and (create or options.save):
+                log.warning(
+                    "Configuration file is missing, generate it (%s)",
+                    options.config
+                )
+                self.save(options.config)
+                if exit_after_created:
+                    sys.exit(0)
+                already_saved = True
+
+            # Load configuration file
+            if os.path.isfile(options.config) and not self.load_file(options.config):
+                parser.error(
+                    'Failed to load configuration from file %s' % options.config
+                )
+
+            if options.save and not already_saved:
+                self.save()
+                sys.exit(0)
+
+        if options.debug:
+            logging.getLogger().setLevel(logging.DEBUG)
+        elif options.verbose:
+            logging.getLogger().setLevel(logging.INFO)
+
+        self.load_options(options)
+        return options
+
+    def load_options(self, options):
+        """ Register arguments parser options """
+        assert isinstance(options, argparse.Namespace)
+        self.options = options
+        log.debug('Argument options: %s', options)
+
+    def add_options_to_parser(self, parser):
+        """ Add sections and their options to parser """
+        for section in self._ordered_section_names:
+            self.sections[section].add_options_to_parser(parser)
+
+    @property
+    def config_dir(self):
+        """ Retrieve configuration directory path """
+        return os.path.dirname(self._filepath) if self._filepath else DEFAULT_CONFIG_DIRPATH
+
+    @property
+    def config_filepath(self):
+        """ Retrieve configuration file path """
+        if self._filepath:
+            return self._filepath
+        return os.path.join(
+            self.config_dir,
+            ("%s.ini" % self.shortname) if self.shortname
+            else "config.ini"
+        )
diff --git a/setup.py b/setup.py
index 53425ec..0135e34 100644
--- a/setup.py
+++ b/setup.py
@@ -25,6 +25,12 @@ setup(
             'pytest',
             'pylint',
         ],
+        'config': [
+            'configparser',
+            'argcomplete',
+            'keyring',
+            'systemd-python',
+        ],
         'ldap': [
             'python-ldap',
             'python-dateutil',