from __future__ import annotations

import threading
from collections.abc import Callable, Iterator, Mapping
from contextlib import contextmanager
from dataclasses import dataclass
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from queue import SimpleQueue
from typing import Final


@dataclass(frozen=True, slots=True)
class Request:
    method: str
    target: str
    headers: Mapping[str, str]
    body: bytes


@dataclass(frozen=True, slots=True)
class Reply:
    status: int = 200
    body: bytes = b"{}"
    content_type: str = "application/json"
    chunks: tuple[bytes, ...] | None = None
    abort_after: int | None = None
    gate_after_first: threading.Event | None = None


@dataclass(frozen=True, slots=True)
class Wire:
    url: str
    received: SimpleQueue[Request]
    disconnected: SimpleQueue[str]

    def drain(self) -> tuple[Request, ...]:
        return tuple(self.received.get_nowait() for _ in range(self.received.qsize()))


@contextmanager
def wire_server(respond: Callable[[Request], Reply]) -> Iterator[Wire]:
    """Owned TCP peer; requests traverse the real HTTP client and serialization."""
    received: Final[SimpleQueue[Request]] = SimpleQueue()
    errors: Final[SimpleQueue[Exception]] = SimpleQueue()
    disconnected: Final[SimpleQueue[str]] = SimpleQueue()

    class Handler(BaseHTTPRequestHandler):
        protocol_version = "HTTP/1.1"
        timeout = 5

        def respond(self) -> None:
            request: Final = Request(
                self.command, self.path,
                {name.lower(): value for name, value in self.headers.items()},
                self.rfile.read(int(self.headers.get("content-length", "0"))),
            )
            received.put(request)
            try:
                reply = respond(request)
            except Exception as error:
                errors.put(error)
                reply = Reply(status=500)
            self.send_response(reply.status)
            self.send_header("content-type", reply.content_type)
            if reply.chunks is None:
                self.send_header("content-length", str(len(reply.body)))
            else:
                self.send_header("transfer-encoding", "chunked")
            self.send_header("connection", "close")
            self.end_headers()
            try:
                if reply.chunks is None:
                    self.wfile.write(reply.body)
                else:
                    for index, chunk in enumerate(reply.chunks):
                        if reply.abort_after == index:
                            break
                        self.wfile.write(b"%x\r\n%s\r\n" % (len(chunk), chunk))
                        self.wfile.flush()
                        if index == 0 and reply.gate_after_first is not None:
                            assert reply.gate_after_first.wait(timeout=5), "Stream barrier was never released"
                    else:
                        self.wfile.write(b"0\r\n\r\n")
                        self.wfile.flush()
            except (BrokenPipeError, ConnectionResetError):
                disconnected.put(request.target)
            except Exception as error:
                errors.put(error)
            self.close_connection = True

        do_POST = respond
        do_PUT = respond
        do_GET = respond
        do_DELETE = respond

        def log_message(self, format: str, *args: object) -> None:
            pass

    class OwnedHTTPServer(ThreadingHTTPServer):
        daemon_threads = False

    with OwnedHTTPServer(("127.0.0.1", 0), Handler) as server:
        thread: Final = threading.Thread(target=server.serve_forever, kwargs={"poll_interval": 0.05})
        thread.start()
        try:
            yield Wire(f"http://127.0.0.1:{server.server_port}", received, disconnected)
        finally:
            server.shutdown()
            thread.join(timeout=6)
            assert not thread.is_alive(), "Owned HTTP server survived cleanup"
            server.server_close()
            failure: Final = None if errors.empty() else errors.get_nowait()
            assert failure is None, f"Owned HTTP peer failed: {failure!r}"