import json
import os
import time
import uuid
from dataclasses import dataclass
from typing import Any, Dict, Optional

import gevent
from locust import User, between, events, task

try:
	import websocket  # websocket-client
except Exception as exc:  # pragma: no cover
	websocket = None
	_websocket_import_error = exc
else:
	_websocket_import_error = None


@dataclass(frozen=True)
class NostrConfig:
	relay_url: str
	connect_timeout_s: float = 10.0
	recv_timeout_s: float = 10.0
	req_timeout_s: float = 10.0
	filter_obj: Dict[str, Any] = None  # type: ignore[assignment]


def _now_ms() -> float:
	return time.perf_counter() * 1000.0


def _fire_ws(name: str, start_ms: float, response_length: int = 0, exc: Optional[BaseException] = None) -> None:
	events.request.fire(
		request_type="WS",
		name=name,
		response_time=_now_ms() - start_ms,
		response_length=response_length,
		exception=exc,
	)


def _load_filter_from_env() -> Dict[str, Any]:
	raw = os.getenv("NOSTR_FILTER_JSON")
	if raw:
		try:
			parsed = json.loads(raw)
			if isinstance(parsed, dict):
				return parsed
		except Exception:
			pass
	# Default: keep it lightweight and likely to succeed on most relays
	return {"kinds": [1], "limit": 1}


def _load_config() -> NostrConfig:
	relay_url = os.getenv("NOSTR_RELAY_URL") or os.getenv("RELAY_URL") or "wss://relay.damus.io"
	return NostrConfig(
		relay_url=relay_url,
		connect_timeout_s=float(os.getenv("NOSTR_CONNECT_TIMEOUT", "10")),
		recv_timeout_s=float(os.getenv("NOSTR_RECV_TIMEOUT", "10")),
		req_timeout_s=float(os.getenv("NOSTR_REQ_TIMEOUT", "10")),
		filter_obj=_load_filter_from_env(),
	)


class NostrRelayUser(User):
	"""Locust user that load tests a Nostr relay via raw WebSockets.

	Each task:
	- opens/ensures a WS connection
	- sends a Nostr REQ with a unique subscription id
	- reads until EOSE (or timeout)
	- sends CLOSE for the subscription
	"""

	wait_time = between(0.5, 2.0)

	def __init__(self, environment):
		super().__init__(environment)
		self._cfg = _load_config()
		self._ws = None

	def on_start(self) -> None:
		if _websocket_import_error is not None:
			raise RuntimeError(
				"websocket-client is not available. Install dependencies via requirements.txt"
			) from _websocket_import_error
		self._connect()

	def on_stop(self) -> None:
		self._close_ws()

	def _connect(self) -> None:
		if self._ws is not None:
			return

		start = _now_ms()
		try:
			# websocket-client returns a WebSocket object
			ws = websocket.create_connection(
				self._cfg.relay_url,
				timeout=self._cfg.connect_timeout_s,
				enable_multithread=True,
			)
			ws.settimeout(self._cfg.recv_timeout_s)
			self._ws = ws
			_fire_ws("connect", start)
		except Exception as exc:
			_fire_ws("connect", start, exc=exc)
			self._ws = None
			raise

	def _close_ws(self) -> None:
		if self._ws is None:
			return
		start = _now_ms()
		try:
			self._ws.close()
			_fire_ws("close", start)
		except Exception as exc:
			_fire_ws("close", start, exc=exc)
		finally:
			self._ws = None

	def _send_json(self, name: str, msg: Any) -> None:
		payload = json.dumps(msg, separators=(",", ":"))
		start = _now_ms()
		try:
			assert self._ws is not None
			self._ws.send(payload)
			_fire_ws(name, start, response_length=len(payload))
		except Exception as exc:
			_fire_ws(name, start, exc=exc)
			self._close_ws()
			raise

	def _recv_text(self) -> str:
		assert self._ws is not None
		start = _now_ms()
		try:
			data = self._ws.recv()
			if data is None:
				raise TimeoutError("recv returned None")
			if isinstance(data, bytes):
				text = data.decode("utf-8", errors="replace")
			else:
				text = str(data)
			_fire_ws("recv", start, response_length=len(text))
			return text
		except Exception as exc:
			_fire_ws("recv", start, exc=exc)
			self._close_ws()
			raise

	def _req_until_eose(self, sub_id: str) -> int:
		"""Return number of EVENT messages seen for this sub_id."""
		deadline = time.monotonic() + self._cfg.req_timeout_s
		event_count = 0
		while time.monotonic() < deadline:
			raw = self._recv_text()
			try:
				msg = json.loads(raw)
			except Exception:
				continue

			if not isinstance(msg, list) or len(msg) < 2:
				continue

			msg_type = msg[0]
			msg_sub = msg[1]
			if msg_sub != sub_id:
				continue

			if msg_type == "EVENT":
				event_count += 1
			elif msg_type == "EOSE":
				return event_count
			elif msg_type == "NOTICE":
				return event_count
		raise TimeoutError("Timed out waiting for EOSE")

	@task
	def subscribe_once(self) -> None:
		self._connect()
		sub_id = uuid.uuid4().hex

		start = _now_ms()
		exc: Optional[BaseException] = None
		events_seen = 0
		try:
			self._send_json("REQ", ["REQ", sub_id, self._cfg.filter_obj])
			events_seen = self._req_until_eose(sub_id)
		except Exception as e:
			exc = e
		finally:
			try:
				# Always try to CLOSE; ignore failures
				if self._ws is not None:
					self._send_json("CLOSE", ["CLOSE", sub_id])
			except Exception:
				pass
			_fire_ws("REQ->EOSE", start, response_length=events_seen, exc=exc)
			if exc is not None:
				raise exc


# Usage:
#   locust -f loadtest.py
# Optional env:
#   NOSTR_RELAY_URL=wss://relay.example.com
#   NOSTR_FILTER_JSON='{"kinds":[1],"limit":5}'
#   NOSTR_REQ_TIMEOUT=10