from threading import Thread, Event
from http.client import HTTPConnection
from http.client import OK
import errno
from platform import platform
from socket import socket
from time import sleep

def main():
    print("Platform:", platform())
    
    with socket() as server_socket:
        server_socket.bind(("localhost", 0))
        server_socket.listen(1)
        allow_close = Event()
        close_done = Event()
        args = (server_socket, allow_close, close_done)
        thread = Thread(target=run_server, args=args)
        thread.start()
        
        address = server_socket.getsockname()
        allow_close.set()
        demo_request("short-request", address, "GET", "/",
            close_done=close_done)
        demo_request("2mb-request", address,
            "POST", "/", body=bytes(int(2e6)), close_done=close_done)
        allow_close.clear()
        demo_request("close-while-sending", address, "POST", "/",
            headers={"Content-Length": "10"},
            body=close_in_body(allow_close, close_done))
        thread.join()

def close_in_body(allow_close, close_done):
    # HTTPConnection has already sent header data
    sleep(0.1)  # Attempt to allow data to be buffered at TCP level
    allow_close.set()
    close_done.wait()
    yield b"123456789\n"

def demo_request(desc, address, *pos, close_done=None, **kw):
    client = HTTPConnection(*address)
    try:
        client.request("GET", "/" + desc)
        response = client.getresponse()
        assert response.status == OK
        assert response.read() == b""
        
        sleep(0.3)  # Emulate period in which server might drop connection
        if close_done:
            close_done.wait()
        
        try:
            stage = "request()"
            client.request(*pos, **kw)
            stage = "getresponse()"
            response = client.getresponse()
        except Exception as exception:
            code = ""
            if isinstance(exception, EnvironmentError):
                code = "; errno=" + errno.errorcode[exception.errno]
            msg = "{}: {} raised {!r}{}"
            print(msg.format(desc, stage, exception, code))
        else:
            msg = "{}: Got response: {} {}"
            print(msg.format(desc, response.status, response.reason))
            response.read()
    finally:
        client.close()

def run_server(server, allow_close, close_done):
    for _ in range(3):
        [client, _] = server.accept()
        close_done.clear()
        with client, client.makefile("rb") as reader:
            assert reader.readline().startswith(b"GET ")
            while reader.readline().rstrip(b"\r\n"):
                pass
            client.sendall(
                b"HTTP/1.1 200 OK\r\n"
                b"Content-Length: 0\r\n"
                b"\r\n"
            )
            
            sleep(0.1)  # Emulate server timing out the connection
            allow_close.wait()
        close_done.set()

if __name__ == "__main__":
    main()