# Copyright (C) 2011-2012  Patrick Totzke <patricktotzke@gmail.com>
# This file is released under the GNU GPL, version 3 or a later revision.
# For further details see the COPYING file

import logging

from configobj  import (ConfigObj, ConfigObjError, flatten_errors,
                        get_extra_values)
from validate   import Validator

from .errors import ConfigError


def read_config(configs = None, specpath=None, checks=None,
                report_extra=False):
    """
    get a (validated) config object for given config file path.

    :param configs: list of configurations; each configuration is either a path
        to a config file or a list of lines to parse as configuration
    :type configs: list
    :param specpath: path to spec-file
    :type specpath: str
    :param checks: custom checks to use for validator.
        see `validate docs <http://www.voidspace.org.uk/python/validate.html>`_
    :type checks: dict str->callable,
    :param report_extra: log if a setting is not present in the spec file
    :type report_extra: boolean
    :raises: :class:`~alot.settings.errors.ConfigError`
    :rtype: `configobj.ConfigObj`
    """
    checks = checks or {}

    config = ConfigObj(configspec = specpath)

    for cf in configs:
        try:
            c = ConfigObj(infile = cf, configspec = specpath,
                               file_error = True, encoding = 'UTF8')
        except ConfigObjError as e:
            msg = 'Error when parsing `%s`:\n%s' % (cf, e)
            logging.error(msg)
            raise ConfigError(msg)
        except IOError:
            raise ConfigError('Could not read %s and/or %s' % (cf, specpath))
        except UnboundLocalError:
            # this works around a bug in configobj
            msg = '%s is malformed. Check for sections without parents..' % cf
            raise ConfigError(msg)
        config.merge(c)

    if specpath:
        validator = Validator()
        validator.functions.update(checks)
        try:
            results = config.validate(validator, preserve_errors=True)
        except ConfigObjError as e:
            raise ConfigError(str(e))

        if results is not True:
            error_msg = ''
            for (section_list, key, res) in flatten_errors(config, results):
                if key is not None:
                    if res is False:
                        msg = 'key "%s" in section "%s" is missing.'
                        msg = msg % (key, ', '.join(section_list))
                    else:
                        msg = 'key "%s" in section "%s" failed validation: %s'
                        msg = msg % (key, ', '.join(section_list), res)
                else:
                    msg = 'section "%s" is missing' % '.'.join(section_list)
                error_msg += msg + '\n'
            raise ConfigError(error_msg)

        extra_values = get_extra_values(config) if report_extra else None
        if extra_values:
            msg = ['Unknown values were found in the config. Please check for '
                   'typos if a specified setting does not seem to work:']
            for sections, val in extra_values:
                if sections:
                    msg.append('%s: %s' % ('->'.join(sections), val))
                else:
                    msg.append(str(val))
            logging.info('\n'.join(msg))
    return config