import sys, os, asyncio, json, argparse
import aiohttp, aiohttp_jinja2, jinja2
from aiohttp import web
# from urllib.parse import urlparse, unquote as urlunquote, quote as urlquote


async def index (request):
    ws = web.WebSocketResponse()
    ws_ready = ws.can_prepare(request)
    if not ws_ready.ok:
        return aiohttp_jinja2.render_template(request.app['template'], request, {})

    await ws.prepare(request)
    # print('index.Websocket connection ready')
    connections = request.app['websockets']
    connections.append(ws)
    
    await ws.send_str(json.dumps({'src': 'connect', 'connections': len(connections)}))
    print ("{} active connections".format(len(connections)))

    # incoming messages
    async for msg in ws:
        print ("index.got msg")
        if msg.type == aiohttp.WSMsgType.TEXT:
            print(msg.data)
            if msg.data == 'close':
                await ws.close()
            # else:
            #     await ws.send_str(msg.data + '/answer')

    # if the connection closes, the above loop simply finishes
    # and we arrive here
    connections.remove(ws)
    print ("{} active connections".format(len(connections)))
    return ws

# The following is a fusion of:
# https://stackoverflow.com/questions/31510190/aysncio-cannot-read-stdin-on-windows#36785819
# https://docs.aiohttp.org/en/stable/web_advanced.html#background-tasks
async def listen_to_stdin(app):
    loop = asyncio.get_event_loop()
    try:
        while True:
            line = await loop.run_in_executor(None, sys.stdin.readline)
            for ws in app['websockets']:
                await ws.send_str(json.dumps({'src': 'stdin', 'line': line.rstrip()}))
    except asyncio.CancelledError:
        pass
    finally:
        pass

async def start_background_tasks(app):
    app['stdin_listener'] = asyncio.create_task(listen_to_stdin(app))

async def cleanup_background_tasks(app):
    app['stdin_listener'].cancel()
    await app['stdin_listener']

def main ():
    ap = argparse.ArgumentParser("make & serve")
    ap.add_argument("--host", default="localhost")
    ap.add_argument("--port", type=int, default=8080)
    ap.add_argument("--static", nargs=2, default=None, action="append")
    ap.add_argument("--template", default="pipeserver.html", help="Template for web page to serve")
    args = ap.parse_args()

    # On Windows, the default event loop is SelectorEventLoop which does not support run_in_executor. ProactorEventLoop should be used instead.
    if sys.platform == 'win32':
        loop = asyncio.ProactorEventLoop()
        asyncio.set_event_loop(loop)

    app = web.Application()
    app['websockets'] = []
    template_path, app['template'] = os.path.split(args.template)
    jinja_env = aiohttp_jinja2.setup(
        app, loader=jinja2.FileSystemLoader(template_path))
    # jinja_env.filters['datetimeformat'] = format_datetime

    # setup routes
    app.add_routes([web.get('/', index)])
    if args.static:
        for name, path in args.static:
            print ("Adding static route {0} -> {1}".format(name, path))
            app.router.add_static(name, path)

    app.on_startup.append(start_background_tasks)
    app.on_cleanup.append(cleanup_background_tasks)
    web.run_app(app, host=args.host, port=args.port)

if __name__ == "__main__":
    main()