config.py

import io
import json
import logging
import inspect
import sys
import os

from utility_functions import (
    recursive_dictionary_update,
    path,
    Singleton
)


class ConfigurationManager(object):
    __metaclass__ = Singleton

    logger = logging.getLogger('starrypy.config.ConfigurationManager')
    log_format = logging.Formatter(
        '%(asctime)s - %(levelname)s - %(name)s # %(message)s'
    )
    logfile_handle = logging.FileHandler('config.log')
    logfile_handle.setLevel(9)
    logger.addHandler(logfile_handle)
    logfile_handle.setFormatter(log_format)

    def __init__(self):
        default_config_path = path.preauthChild(
            os.path.join('config', 'config.json.default')
        )
        self.config_path = path.preauthChild(
            os.path.join('config', 'config.json')
        )
        if default_config_path.exists():
            try:
                with default_config_path.open() as default_config:
                    default = json.load(default_config)
            except ValueError as e:
                print 'Error: %s' % e
                self.logger.critical(
                    'The configuration defaults file (config.json.default) '
                    'contains invalid JSON. Please run it against a JSON '
                    'linter, such as http://jsonlint.com. Shutting down.'
                )
                sys.exit()
        else:
            self.logger.critical(
                'The configuration defaults file (config.json.default)'
                ' doesn\'t exist! Shutting down.'
            )
            sys.exit()

        if self.config_path.exists():
            try:
                with self.config_path.open() as c:
                    config = json.load(c)
                    self.config = recursive_dictionary_update(default, config)
            except ValueError as e:
                print 'Error: %s' % e
                self.logger.critical(
                    'The configuration file (config.json) contains invalid '
                    'JSON. Please run it against a JSON linter, such as '
                    'http://jsonlint.com. Shutting down.'
                )
                sys.exit()
        else:
            self.logger.warning(
                'The configuration file (config.json)'
                ' doesn\'t exist! Creating one from defaults.'
            )
            try:
                with self.config_path.open('w') as f:
                    json.dump(
                        default,
                        f,
                        indent=4,
                        separators=(',', ': '),
                        sort_keys=True,
                        ensure_ascii=False
                    )
            except IOError:
                self.logger.critical(
                    'Couldn\'t write a default configuration file. '
                    'Please check that StarryPy has write access in the '
                    'config/ directory.'
                )
                self.logger.critical('Exiting...')
                sys.exit()
            self.logger.warning(
                'StarryPy will now exit. Please examine config.json '
                'and adjust the variables appropriately.'
            )
            sys.exit()

        self.logger.debug('Created configuration manager.')
        self.save()

    def save(self):
        try:
            with io.open(self.config_path.path, 'w') as config:
                self.logger.debug('Writing configuration file.')
                config.write(
                    json.dumps(
                        self.config,
                        indent=4,
                        separators=(',', ': '),
                        sort_keys=True,
                        ensure_ascii=False
                    )
                )
        except Exception as e:
            self.logger.critical(
                'Tried to save the configuration file, failed.\n%s', str(e)
            )
            raise

    def __getattr__(self, item):
        if item in ['config', 'config_path']:
            return super(ConfigurationManager, self).__getattribute__(item)

        elif item == 'plugin_config':
            caller = inspect.stack()[1][0].f_locals['self'].__class__.name
            if caller in self.config['plugin_config']:
                return self.config['plugin_config'][caller]
            else:
                return {}

        else:
            if item in self.config:
                return self.config[item]
            else:
                self.logger.error(
                    'Couldn\'t find configuration option %s in '
                    'configuration file.', item
                )
                raise AttributeError

    def __setattr__(self, key, value):
        if key == 'config':
            super(ConfigurationManager, self).__setattr__(key, value)
            self.save()
        elif key == 'config_path':
            super(ConfigurationManager, self).__setattr__(key, value)
        elif key == 'plugin_config':
            caller = inspect.stack()[1][0].f_locals['self'].__class__.name
            self.config['plugin_config'][caller] = value
            self.save()
        else:
            self.config[key] = value
            self.save()