// Related-note scoring, shared by the Eleventy build and the browser. Keep it import-free.

const LINK_WEIGHT = 3;

/** @type {(a: string, b: string) => number} */
const desc = (a, b) => (a < b ? 1 : a > b ? -1 : 0);

/**
 * Rank notes connected to a set of notes: +3 per link (either direction) and
 * +1 per shared tag, summed over every note in the set.
 * @template {{slug: string, title: string, tended: string, tags: string[], links: string[]}} T
 * @param {T[]} entries
 * @param {string[]} setSlugs  notes already on the page
 * @param {number} [limit]
 * @returns {T[]}
 */
export function scoreCandidates(entries, setSlugs, limit = 5) {
  const inSet = new Set(setSlugs);
  const set = entries.filter((x) => inSet.has(x.slug));
  return entries
    .filter((c) => !inSet.has(c.slug))
    .map((c) => {
      let score = 0;
      for (const s of set) {
        if (c.links.includes(s.slug) || s.links.includes(c.slug)) score += LINK_WEIGHT;
        score += c.tags.filter((t) => s.tags.includes(t)).length;
      }
      return { c, score };
    })
    .filter((x) => x.score > 0)
    .sort((a, b) => b.score - a.score || desc(a.c.tended, b.c.tended) || -desc(a.c.title, b.c.title))
    .slice(0, limit)
    .map((x) => x.c);
}