import { createSignal, createEffect, onSettled } from "solid-js";
import { connectWs } from "./ws";
import type { RoomState, ChatMessage, ClientMessage } from "./types";

/** Auto-clear an error signal after `ms`, unless the `unless` predicate matches the error. */
export function useAutoDismiss(
  [error, setError]: [() => string | null, (v: string | null) => void],
  opts: { ms?: number; unless?: (err: string) => boolean } = {},
): void {
  createEffect(
    () => error(),
    (err) => {
      if (!err) return;
      if (opts.unless?.(err)) return;
      const timer = setTimeout(() => setError(null), opts.ms ?? 5000);
      return () => clearTimeout(timer);
    },
  );
}

/** Manage WebSocket connection lifecycle for a room. */
export function useRoomConnection(roomId: string, userName: string) {
  const [state, setState] = createSignal<RoomState | null>(null);
  const [chats, setChats] = createSignal<ChatMessage[]>([]);
  const [connected, setConnected] = createSignal(false);
  const [error, setError] = createSignal<string | null>(null);
  const [sendFn, setSendFn] = createSignal<((msg: ClientMessage) => void) | null>(null);
  const initialLoad = { current: true };

  const startConnecting = () => {
    if (sendFn()) return;

    const send = connectWs(roomId, userName, {
      onState: (s) => {
        initialLoad.current = false;
        setState(s);
      },
      onChat: (msg) =>
        setChats((prev) => {
          const next = [...prev, msg];
          return next.length > 200 ? next.slice(-200) : next;
        }),
      onDisconnect: () => {
        setConnected(false);
        setSendFn(null);
      },
      onError: (reason) => {
        setError(reason);
      },
    });
    setSendFn(() => send);
    setConnected(true);
    setError(null);
  };

  onSettled(() => {
    startConnecting();
    setTimeout(() => {
      if (initialLoad.current) {
        setError("Room not found or unavailable");
      }
    }, 8000);
  });

  // Reconnect on disconnect with backoff.
  createEffect(
    () => [connected(), sendFn()],
    ([isConnected, send]) => {
      if (!isConnected && !send) {
        const timer = setTimeout(startConnecting, 3000);
        return () => clearTimeout(timer);
      }
    },
  );

  // Auto-dismiss transient errors, but not "not found".
  useAutoDismiss([error, setError], { unless: (err) => err.includes("not found") });

  const send = (msg: ClientMessage) => sendFn()?.(msg);

  return { state, chats, connected, error, setError, send };
}