from __future__ import annotations

import json
import os
import socketserver
import tempfile
import threading
from collections.abc import Callable
from contextlib import suppress
from dataclasses import dataclass
from http import HTTPStatus
from http.server import BaseHTTPRequestHandler
from pathlib import Path
from typing import Any

import pytest

from buildbot_autoscale_ext.client import (
    DaemonClient,
    DaemonError,
    RetryPolicy,
    UnixSocketHTTPConnection,
)


@dataclass
class ServerState:
    post_count: int = 0
    get_count: int = 0


class _Handler(BaseHTTPRequestHandler):
    server: _UnixHTTPServer

    def do_GET(self) -> None:  # noqa: N802
        self.server.state.get_count += 1
        status, body = self.server.on_get(self.path, self.server.state.get_count)
        self._send(status, body)

    def do_POST(self) -> None:  # noqa: N802
        self.server.state.post_count += 1
        size = int(self.headers.get("Content-Length", "0"))
        raw = self.rfile.read(size) if size else b"{}"
        payload = json.loads(raw.decode("utf-8"))
        status, body = self.server.on_post(self.path, payload, self.server.state.post_count)
        self._send(status, body)

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

    def _send(self, status: int, body: dict[str, Any]) -> None:
        encoded = json.dumps(body).encode("utf-8")
        self.send_response(status)
        self.send_header("Content-Type", "application/json")
        self.send_header("Content-Length", str(len(encoded)))
        self.end_headers()
        self.wfile.write(encoded)


class _UnixHTTPServer(socketserver.UnixStreamServer):
    def __init__(
        self,
        socket_path: str,
        *,
        on_get: Callable[[str, int], tuple[int, dict[str, Any]]],
        on_post: Callable[[str, dict[str, Any], int], tuple[int, dict[str, Any]]],
    ) -> None:
        self.on_get = on_get
        self.on_post = on_post
        self.state = ServerState()
        super().__init__(socket_path, _Handler)


class FakeDaemon:
    def __init__(
        self,
        socket_path: str,
        *,
        on_get: Callable[[str, int], tuple[int, dict[str, Any]]],
        on_post: Callable[[str, dict[str, Any], int], tuple[int, dict[str, Any]]],
    ) -> None:
        self._socket_path = socket_path
        self._server = _UnixHTTPServer(socket_path, on_get=on_get, on_post=on_post)
        self._thread = threading.Thread(target=self._server.serve_forever, daemon=True)

    def __enter__(self) -> FakeDaemon:
        self._thread.start()
        return self

    def __exit__(self, exc_type: object, exc: object, tb: object) -> None:
        del exc_type, exc, tb
        self._server.shutdown()
        self._server.server_close()
        with suppress(FileNotFoundError):
            os.unlink(self._socket_path)


@pytest.fixture
def socket_path() -> str:
    with tempfile.TemporaryDirectory() as tmp:
        yield str(Path(tmp) / "daemon.sock")


def _client(socket_path: str, attempts: int = 3) -> DaemonClient:
    return DaemonClient(
        socket_path=socket_path,
        retry_policy=RetryPolicy(max_attempts=attempts, base_seconds=0.001, max_seconds=0.01),
    )


def test_post_json_success(socket_path: str) -> None:
    with FakeDaemon(
        socket_path,
        on_get=lambda _p, _a: (HTTPStatus.OK, {}),
        on_post=lambda _p, payload, _a: (HTTPStatus.OK, {"echo": payload["system"]}),
    ):
        response = _client(socket_path).post_json(
            "/v1/reservations",
            {"system": "x86_64-linux"},
            timeout_seconds=1.0,
            retryable_statuses={429, 500, 503},
        )

    assert response == {"echo": "x86_64-linux"}


def test_get_json_success(socket_path: str) -> None:
    with FakeDaemon(
        socket_path,
        on_get=lambda _p, _a: (HTTPStatus.OK, {"phase": "ready"}),
        on_post=lambda _p, _payload, _a: (HTTPStatus.OK, {}),
    ):
        response = _client(socket_path).get_json(
            "/v1/reservations/r1",
            timeout_seconds=1.0,
            retryable_statuses={429, 500, 503},
        )

    assert response == {"phase": "ready"}


def test_transient_503_retries_then_raises(socket_path: str) -> None:
    with (
        FakeDaemon(
            socket_path,
            on_get=lambda _p, _a: (HTTPStatus.SERVICE_UNAVAILABLE, {"error": "busy"}),
            on_post=lambda _p, _payload, _a: (HTTPStatus.OK, {}),
        ) as daemon,
        pytest.raises(DaemonError) as exc,
    ):
        _client(socket_path, attempts=3).get_json(
            "/v1/reservations/r1",
            timeout_seconds=1.0,
            retryable_statuses={429, 500, 502, 503, 504},
        )

    assert exc.value.status == HTTPStatus.SERVICE_UNAVAILABLE
    assert daemon._server.state.get_count == 3


def test_400_not_retried(socket_path: str) -> None:
    with (
        FakeDaemon(
            socket_path,
            on_get=lambda _p, _a: (HTTPStatus.BAD_REQUEST, {"error": "bad"}),
            on_post=lambda _p, _payload, _a: (HTTPStatus.OK, {}),
        ) as daemon,
        pytest.raises(DaemonError) as exc,
    ):
        _client(socket_path, attempts=5).get_json(
            "/v1/reservations/r1",
            timeout_seconds=1.0,
            retryable_statuses={429, 500, 502, 503, 504},
        )

    assert exc.value.status == HTTPStatus.BAD_REQUEST
    assert daemon._server.state.get_count == 1


def test_connection_refused_retries_then_raises(
    socket_path: str,
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    def _boom(self: UnixSocketHTTPConnection) -> None:
        raise ConnectionRefusedError("refused")

    monkeypatch.setattr(UnixSocketHTTPConnection, "connect", _boom)

    with pytest.raises(DaemonError):
        _client(socket_path, attempts=3).get_json(
            "/v1/reservations/r1",
            timeout_seconds=1.0,
            retryable_statuses={429, 500, 502, 503, 504},
        )


def test_backoff_attempts_at_least_two(socket_path: str) -> None:
    with (
        FakeDaemon(
            socket_path,
            on_get=lambda _p, _a: (HTTPStatus.SERVICE_UNAVAILABLE, {"error": "busy"}),
            on_post=lambda _p, _payload, _a: (HTTPStatus.OK, {}),
        ) as daemon,
        pytest.raises(DaemonError),
    ):
        _client(socket_path, attempts=2).get_json(
            "/v1/reservations/r1",
            timeout_seconds=1.0,
            retryable_statuses={429, 500, 502, 503, 504},
        )

    assert daemon._server.state.get_count >= 2