/**
 * Journal completions — client-side loader for /__COMPLETIONS.json
 *
 * Fetches once on first call, caches the result. Call `invalidateCompletions()`
 * to force a re-fetch (e.g., when the content source changes).
 */

import { createSignal } from "solid-js";

// ------------------- Types (mirrors CLI) -------------------

export interface DiceCompletion {
  label: string;
  notation: string;
  source: string;
}

export interface LinkCompletion {
  path: string;
  label: string;
  section: string | null;
}

export interface JournalCompletions {
  dice: DiceCompletion[];
  links: LinkCompletion[];
}

// ------------------- Cache -------------------

let _cache: JournalCompletions = { dice: [], links: [] };
let _loaded = false;

/** Thawed value signal; invalidate resets it. */
const [completions, setCompletions] = createSignal<JournalCompletions>(_cache);

// ------------------- Fetch -------------------

async function load(): Promise<void> {
  try {
    const resp = await fetch("/__COMPLETIONS.json");
    if (resp.ok) {
      const data = await resp.json();
      _cache = {
        dice: Array.isArray(data.dice) ? data.dice : [],
        links: Array.isArray(data.links) ? data.links : [],
      };
    } else {
      _cache = { dice: [], links: [] };
    }
  } catch {
    _cache = { dice: [], links: [] };
  }
  _loaded = true;
  setCompletions(_cache);
}

/** Ensure data is loaded (lazy, idempotent). */
let _promise: Promise<void> | null = null;
export function ensureCompletions(): Promise<void> {
  if (!_promise) _promise = load();
  return _promise;
}

/** Force a re-fetch on next use. */
export function invalidateCompletions(): void {
  _loaded = false;
  _promise = null;
}

// ------------------- Hook -------------------

/**
 * Reactive completions data for the journal input.
 * Triggers a lazy fetch on first access; returns empty arrays while loading.
 */
export function useJournalCompletions(): JournalCompletions {
  if (!_loaded) {
    void ensureCompletions();
  }
  return completions();
}