import configparser
import io
import os
import re
import shutil
import subprocess


_locale_re = re.compile(r'^(?!#\s|)$')
_locale_def_re = re.compile(r'([^.]*)[^@]*(.*)')


class Locale(object):
    def __init__(self, locales_xml):
        self.xml = locales_xml
        self.syslocales = {}
        self.userlocales = []
        self.rawlocales = None
        self._localevars = configparser.ConfigParser()
        self._localevars.optionxform = str
        self._localevars['BASE'] = {}
        self._initVars()

    def _initVars(self):
        for l in self.xml.findall('locale'):
            locale = l.text.strip()
            self._localevars['BASE'][l.attrib['name'].strip()] = locale
            if locale not in self.userlocales:
                self.userlocales.append(locale)
        if not self.userlocales:
            self.userlocales = ['en_US', 'en_US.UTF-8']
        return()

    def _verify(self, chroot_base):
        localegen = os.path.join(chroot_base, 'etc', 'locale.gen')  # This *should* be brand new.
        with open(localegen, 'r') as fh:
            self.rawlocales = fh.read().splitlines()
        for idx, line in enumerate(self.rawlocales[:]):
            if _locale_re.search(line) or line.strip() == '':
                continue
            locale, charset = line.split()
            locale = locale.replace('#', '')
            self.syslocales[locale] = charset
            if locale in self.userlocales:
                # "Uncomment" the locale (self.writeConf() actually writes the change)
                self.rawlocales[idx] = '{0} {1}'.format(locale, charset)
        userl = set(self.userlocales)
        sysl = set(self.syslocales.keys())
        if (userl - sysl):
            raise ValueError('non-existent locale specified')
        return()

    def writeConf(self, chroot_base):
        # We basically recreate locale-gen in python here, more or less.
        self._verify(chroot_base)
        localegen = os.path.join(chroot_base, 'etc', 'locale.gen')
        localedbdir = os.path.join(chroot_base, 'usr', 'lib', 'locale')
        localesrcdir = os.path.join(chroot_base, 'usr', 'share', 'i18n')
        with open(localegen, 'w') as fh:
            fh.write('# Generated by AIF-NG.\n\n')
            fh.write('\n'.join(self.rawlocales))
            fh.write('\n')
        # If only the locale DB wasn't in a hopelessly binary format.
        for root, dirs, files in os.walk(localedbdir):
            for f in files:
                fpath = os.path.join(root, f)
                os.remove(fpath)
            for d in dirs:
                dpath = os.path.join(root, d)
                shutil.rmtree(dpath)
        # TODO: logging
        for locale in self.userlocales:
            lpath = os.path.join(localesrcdir, 'locales', locale)
            charset = self.syslocales[locale]
            if os.path.isfile(lpath):
                ldef_name = locale
            else:
                ldef_name = _locale_def_re.sub(r'\g<1>\g<2>', locale)
                lpath = os.path.join(localesrcdir, 'locales', ldef_name)
            env = dict(os.environ).copy()
            env['I18NPATH'] = localesrcdir
            subprocess.run(['localedef',
                            '--force',
                            # These are overridden by a prefix env var.
                            # '--inputfile={0}'.format(lpath),
                            # '--charmap={0}'.format(os.path.join(localesrcdir, 'charmaps', charset)),
                            '--inputfile={0}'.format(ldef_name),
                            '--charmap={0}'.format(charset),
                            '--alias-file={0}'.format(os.path.join(chroot_base,
                                                                   'usr', 'share', 'locale', 'locale.alias')),
                            '--prefix={0}'.format(chroot_base),
                            locale],
                           env = env)
        cfg = os.path.join(chroot_base, 'etc', 'locale.conf')
        # And now we write the variables.
        # We have to strip out the section from the ini.
        cfgbuf = io.StringIO()
        self._localevars.write(cfgbuf, space_around_delimiters = False)
        cfgbuf.seek(0, 0)
        with open(cfg, 'w') as fh:
            for line in cfgbuf.readlines():
                if line.startswith('[BASE]') or line.strip() == '':
                    continue
                fh.write(line)
        os.chmod(cfg, 0o0644)
        os.chown(cfg, 0, 0)
        return()