app.py

import asyncio
import poll_loop

from proxy import exports
from proxy.types import Ok
from proxy.imports import types, incoming_handler
from proxy.imports.types import Method_Get, IncomingRequest, ResponseOutparam, OutgoingResponse, Fields, OutgoingBody
from poll_loop import Stream, Sink, PollLoop


class IncomingHandler(exports.IncomingHandler):
    def handle(self, request: IncomingRequest, response_out: ResponseOutparam):
        # Dispatch the request using `asyncio`, backed by a custom event loop
        # based on `wasi:io/poll#poll-list`.
        loop = PollLoop()
        asyncio.set_event_loop(loop)
        loop.run_until_complete(handle_async(request, response_out))


async def handle_async(request: IncomingRequest, response_out: ResponseOutparam):
    method = request.method()
    path = request.path_with_query()

    if isinstance(method, Method_Get) and path == "/hello":
        response = OutgoingResponse(200, Fields(
            [("content-type", b"text/plain")]))
        response_body = response.write()

        ResponseOutparam.set(response_out, Ok(response))

        sink = Sink(response_body)
        await sink.send(b"Hello, world!")
        sink.close()

    elif isinstance(method, Method_Get):
        # Delegate to spin-fileserver component.
        incoming_handler.handle(request, response_out)

    else:
        response = OutgoingResponse(400, Fields([]))
        ResponseOutparam.set(response_out, Ok(response))
        OutgoingBody.finish(response.write(), None)