"""
A simple example of server sent events.
"""

import asyncio
from datetime import datetime

import pkg_resources
import uvicorn

from bareasgi import (
    Application,
    text_writer,
    HttpRequest,
    HttpResponse
)


async def index(_request: HttpRequest) -> HttpResponse:
    """Redirect to the index page"""
    return HttpResponse(303, [(b'Location', b'/test')])

async def test_page(request: HttpRequest) -> HttpResponse:
    """A request handler which provides the page to respond to server sent events"""
    return HttpResponse(
        200,
        [(b'content-type', b'text/html')],
        text_writer(request.info['html'])
    )

async def test_events(_response: HttpRequest) -> HttpResponse:
    """A request handler which provides server sent events"""

    async def send_events():
        is_cancelled = False
        while not is_cancelled:
            try:
                print('Sending event')
                yield f'data: {datetime.now()}\n\n\n'.encode('utf-8')
                # Defeat buffering by giving the server a nudge.
                yield ':\n\n\n'.encode('utf-8')
                await asyncio.sleep(1)
            except asyncio.CancelledError:
                print('Cancelled')
                is_cancelled = True
            except:  # pylint: disable=bare-except
                print('Failed')

    headers = [
        (b'cache-control', b'no-cache'),
        (b'content-type', b'text/event-stream'),
        (b'connection', b'keep-alive')
    ]

    return HttpResponse(200, headers, send_events())


if __name__ == "__main__":
    html_filename = pkg_resources.resource_filename(__name__, "server_sent_events.html")
    with open(html_filename, 'rt', encoding='utf-8') as file_ptr:
        html = file_ptr.read()

    app = Application(info=dict(html=html))

    app.http_router.add({'GET'}, '/', index)
    app.http_router.add({'GET'}, '/test', test_page)
    app.http_router.add({'GET'}, '/events', test_events)

    uvicorn.run(app, port=9009)