def i18n(ctx, update=False):
    '''Extract translatable strings'''
    header('Extract translatable strings')

    info('Extract Python strings')
    lrun('python setup.py extract_messages')

    # Fix crowdin requiring Language with `2-digit` iso code in potfile
    # to produce 2-digit iso code pofile
    # Opening the catalog also allows to set extra metadata
    potfile = join(ROOT, 'udata', 'translations', '{}.pot'.format(I18N_DOMAIN))
    with open(potfile, 'rb') as infile:
        catalog = read_po(infile, 'en')
    catalog.copyright_holder = 'Open Data Team'
    catalog.msgid_bugs_address = 'i18n@opendata.team'
    catalog.language_team = 'Open Data Team <i18n@opendata.team>'
    catalog.last_translator = 'Open Data Team <i18n@opendata.team>'
    catalog.revision_date = datetime.now(LOCALTZ)
    with open(potfile, 'wb') as outfile:
        write_po(outfile, catalog, width=80)

    if update:
        lrun('python setup.py update_catalog')

    info('Extract JavaScript strings')
    keys = set()
    catalog = {}
    catalog_filename = join(ROOT, 'js', 'locales',
                            '{}.en.json'.format(I18N_DOMAIN))
    if exists(catalog_filename):
        with codecs.open(catalog_filename, encoding='utf8') as f:
            catalog = json.load(f)

    globs = '*.js', '*.vue', '*.hbs'
    regexps = [
        re.compile(r'(?:|\.|\s|\{)_\(\s*(?:"|\')(.*?)(?:"|\')\s*(?:\)|,)'),  # JS _('trad')
        re.compile(r'v-i18n="(.*?)"'),  # Vue.js directive v-i18n="trad"
        re.compile(r'"\{\{\{?\s*\'(.*?)\'\s*\|\s*i18n\}\}\}?"'),  # Vue.js filter {{ 'trad'|i18n }}
        re.compile(r'{{_\s*"(.*?)"\s*}}'),  # Handlebars {{_ "trad" }}
        re.compile(r'{{_\s*\'(.*?)\'\s*}}'),  # Handlebars {{_ 'trad' }}
        re.compile(r'\:[a-z0-9_\-]+="\s*_\(\'(.*?)\'\)\s*"'),  # Vue.js binding :prop="_('trad')"
    ]

    for directory, _, _ in os.walk(join(ROOT, 'js')):
        glob_patterns = (iglob(join(directory, g)) for g in globs)
        for filename in itertools.chain(*glob_patterns):
            print('Extracting messages from {0}'.format(green(filename)))
            content = codecs.open(filename, encoding='utf8').read()
            for regexp in regexps:
                for match in regexp.finditer(content):
                    key = match.group(1)
                    key = key.replace('\\n', '\n')
                    keys.add(key)
                    if key not in catalog:
                        catalog[key] = key

    # Remove old/not found translations
    for key in catalog.keys():
        if key not in keys:
            del catalog[key]

    with codecs.open(catalog_filename, 'w', encoding='utf8') as f:
        json.dump(catalog, f, sort_keys=True, indent=4, ensure_ascii=False,
                  encoding='utf8', separators=(',', ': '))
Extract translatable strings