/**
 * Lazy detail fetches. Only detail pages call these; the list, search and
 * game switching all run off the bundled snapshot.
 *
 * In-flight requests are de-duplicated in memory. Durable caching (across
 * reloads and offline) is the service worker's job — see src/sw.js, which
 * runs stale-while-revalidate over this origin.
 */
const BASE = 'https://pokeapi.co/api/v2';
const inflight = new Map();

export function getJSON(path) {
  if (inflight.has(path)) return inflight.get(path);
  const promise = fetch(`${BASE}/${path}`)
    .then((res) => {
      if (!res.ok) throw new Error(`${path} → ${res.status}`);
      return res.json();
    })
    .finally(() => inflight.delete(path));
  inflight.set(path, promise);
  return promise;
}

export const getPokemon = (idOrName) => getJSON(`pokemon/${idOrName}`);
export const getSpecies = (idOrName) => getJSON(`pokemon-species/${idOrName}`);
export const getEvolutionChain = (id) => getJSON(`evolution-chain/${id}`);
export const getMove = (idOrName) => getJSON(`move/${idOrName}`);
export const getItem = (idOrName) => getJSON(`item/${idOrName}`);
export const getEncounters = (id) => getJSON(`pokemon/${id}/encounters`);

// Full name indexes for the lookup tabs — one request each, then the
// service worker keeps them (stale-while-revalidate).
export const getMoveIndex = () => getJSON('move?limit=2000');
export const getItemIndex = () => getJSON('item?limit=3000');

/** Run async `fn` over `items` with a bounded number of parallel workers. */
export async function mapLimit(items, limit, fn) {
  const out = new Array(items.length);
  let i = 0;
  await Promise.all(
    Array.from({ length: Math.min(limit, items.length) }, async () => {
      while (i < items.length) {
        const idx = i++;
        out[idx] = await fn(items[idx], idx);
      }
    }),
  );
  return out;
}