import { createContext, useContext } from "solid-js";
import type { Accessor } from "solid-js";
import type { Me, PersonState } from "./api";

/**
 * What the routed pages need from the shell.
 *
 * A context rather than props because route components are constructed by the
 * router and cannot be handed anything. It holds the *live* store, so both pages
 * share one polling loop rather than starting one each.
 */
export interface SessionValue {
  me: Me;
  people: Record<number, PersonState>;
  order: Accessor<number[]>;
  serverTime: Accessor<number>;
  selected: Accessor<number | null>;
  select: (id: number) => void;
  trail: Accessor<[number, number][] | null>;
}

export const SessionContext = createContext<SessionValue>();

export function useSession(): SessionValue {
  const value = useContext(SessionContext);
  if (!value) throw new Error("useSession outside the shell");
  return value;
}