import asyncio

from aiohttp import web
from aiopg.sa import create_engine
from db import dsn, tbl


async def list_view(request):
    engine = request.app['engine']
    body = ''
    async with engine.acquire() as conn:
        async for row in conn.execute(tbl.select()):
            body += '<p>{}: {}</p>\n'.format(row.id, row.val)
    return web.Response(body=body.encode())


async def finish_controller(app):
    print('closing engine')
    engine = app['engine']
    engine.close()
    await engine.wait_closed()


def app(loop=None):
    loop = loop or asyncio.get_event_loop()
    _app = web.Application(loop=loop)
    _app['engine'] = loop.run_until_complete(create_engine(dsn, loop=loop))
    _app.register_on_finish(finish_controller)
    _app.router.add_route('GET', '/', list_view)
    return _app


if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    the_app = app(loop)
    handler = the_app.make_handler()
    f = loop.create_server(handler, '0.0.0.0', 8000)
    srv = loop.run_until_complete(f)
    print('serving on', srv.sockets[0].getsockname())
    try:
        loop.run_forever()
    except KeyboardInterrupt:
        pass
    finally:
        srv.close()
        loop.run_until_complete(srv.wait_closed())
        loop.run_until_complete(handler.finish_connections(1.0))
        loop.run_until_complete(the_app.finish())
        loop.close()