import aiohttp_jinja2
from aiohttp.web import Application
from aiohttp_babel.locale import (load_gettext_translations,
                                  set_default_locale,
                                  set_locale_detector)
from aiohttp_babel.middlewares import babel_middleware, _
set_default_locale('en_GB')  # set default locale, if necessary
# load compiled locales
load_gettext_translations('/path/to/locales', 'domain')
# you can use your own locale detection method, if necessary.
# aiohttp_babel checks cookie parameter `locale` or `Accept-Language`
# header by default.
def detector(request):
    if request.url.host == 'es.example.com':
        return 'es'
    elif request.url.host == 'zh.example.com':
        return 'zh'
    else:
        return 'en'
set_locale_detector(detector)
jinja_loader = jinja2.FileSystemLoader('./templates')
app = Application(middlewares=[babel_middleware])
aiohttp_jinja2.setup(app, loader=jinja_loader)
jinja_env = aiohttp_jinja2.get_env(app)
jinja_env.globals['_'] = _