import configparser
import os
import sys


class Conf(object):
    _confobj = None
    _cfgfiles = []
    debug = None

    def __init__(self, filename=None, debug=None, force_filename=False):
        if debug:
            self.set_debug(debug)
        self._confobj = configparser.ConfigParser(dict(HOME=os.environ.get('HOME')))
        filenames = []
        if not force_filename:
            # default config files are $HOME/etc/userconfig2.conf and
            # {sys.prefix}/etc/userconfig2.conf
            if os.path.isfile(f'{os.environ.get("HOME")}/etc/userconfig2.conf'):
                filenames.append(f'{os.environ.get("HOME")}/etc/userconfig2.conf')
            if os.path.isfile(f'{sys.prefix}/etc/userconfig2.conf'):
                filenames.append(f'{sys.prefix}/etc/userconfig2.conf')
        # supplied filename will be read last, has highest priority
        if filename:
            filenames.append(filename)
        ret = self.set_filenames(filenames)
        if not ret:
            raise ValueError(f'Cannot open either configuration file: {",".join(filenames)}')

    def set_debug(self, debug):
        self.debug = debug

    def set_filenames(self, filenames):
        ret = self._confobj.read(filenames)
        if len(ret) == 0:
            return None
        self._cfgfiles = ret
        if self.debug:
            self.debug.stdout("Read config files: %s" % ", ".join(filenames), 2)
        return ret

    def get(self, option, boolean=False, section='userconfig'):
        try:
            if boolean:
                return self._confobj.getboolean(section, option)
            else:
                return self._confobj.get(section, option)
        except (configparser.NoOptionError, configparser.NoSectionError) as e:
            raise ValueError(f'Option {option} does not exist in section {section}: {e}')

    def set(self, option, value, section='userconfig'):
        try:
            self._confobj.set(section, option, value)
        except configparser.NoSectionError as e:
            raise ValueError(f'Section {section} does not exist: {e}')

    def get_items(self, section='userconfig'):
        try:
            return self._confobj.items(section)
        except configparser.NoSectionError as e:
            raise ValueError(f'Section {section} does not exist: {e}')

    def check(self, option, section='userconfig'):
        return self._confobj.has_option(section, option)

    def sections(self):
        return self._confobj.sections()