"use client";

/**
 * Presence caret store (TASK-0093) — the single caret of the page currently
 * in view.
 *
 * One page is mounted per tab (route `[id]`), and exactly one Tiptap
 * editor is focused at a time, so a single optional caret is the whole
 * client-side state. The focused editor writes it (on focus + every
 * selection update), every blur clears it, and the per-page
 * `usePresence` hook (hooks/use-presence.ts) forwards it to the
 * `PresenceEmitter`, which throttles it into `presence` frames.
 *
 * A store (instead of context/props) matches the existing cross-component
 * state here (editor-store, auth-store, block-patch-store) and keeps the
 * recursive BlockRenderer untouched.
 */
import { create } from "zustand";
import type { PresenceSelection } from "@/lib/types";

/** The caret inside one block (offset within the block's text). */
export interface PresenceCaret {
  blockId: string;
  offset: number;
  /** A non-collapsed selection (MVP: inside this one block's doc). */
  selection?: PresenceSelection;
}

interface PresenceCaretState {
  /** The focused editor's caret, or null (nothing focused / no page). */
  caret: PresenceCaret | null;
  setCaret: (caret: PresenceCaret | null) => void;
}

export const usePresenceCaretStore = create<PresenceCaretState>()((set) => ({
  caret: null,
  setCaret: (caret) => set({ caret }),
}));