// Loads imdb2movie.json / imdb2tv.json into memory and reloads on mtime change.

import { readFile, stat } from 'node:fs/promises';
import { join } from 'node:path';
import { TMDBINTEGRAL_DIR } from '../config.js';

const cache = { movie: null, tv: null };
const mtimes = { movie: 0, tv: 0 };

async function loadOne(type) {
  const file = join(TMDBINTEGRAL_DIR, `imdb2${type}.json`);
  const st = await stat(file);
  if (cache[type] && st.mtimeMs === mtimes[type]) return cache[type];
  const obj = JSON.parse(await readFile(file, 'utf8'));
  cache[type] = new Map(Object.entries(obj).map(([k, v]) => [k, Number(v)]));
  mtimes[type] = st.mtimeMs;
  return cache[type];
}

export async function lookupImdb(imdbId) {
  // Try movie first, then tv (matches PHP behaviour of exhaustive lookup).
  try {
    const movieMap = await loadOne('movie');
    if (movieMap.has(imdbId)) return { type: 'movie', tmdb: movieMap.get(imdbId) };
  } catch {
    /* file may be missing on a fresh install */
  }
  try {
    const tvMap = await loadOne('tv');
    if (tvMap.has(imdbId)) return { type: 'tv', tmdb: tvMap.get(imdbId) };
  } catch {
    /* same */
  }
  return null;
}

// Eager-load both mappings — used at server startup to remove the first-request
// 1s latency. Returns the number of entries loaded per type.
export async function preloadMappings() {
  const out = { movie: 0, tv: 0 };
  try {
    out.movie = (await loadOne('movie')).size;
  } catch {
    /* missing */
  }
  try {
    out.tv = (await loadOne('tv')).size;
  } catch {
    /* missing */
  }
  return out;
}