import { SPECIALIZATIONS } from '../data/specializations';

const FALLBACK_RANK = SPECIALIZATIONS.length - 1;
const MAX_RANK_WEIGHT = SPECIALIZATIONS.length;

export function priorityScore(specs: string[], ranking: string[]): number {
  const rankIndex = new Map(ranking.map((id, i) => [id, i]));
  return specs.reduce(
    (sum, id) => sum + (MAX_RANK_WEIGHT - (rankIndex.get(id) ?? FALLBACK_RANK)),
    0,
  );
}

export function makePriorityScorer(ranking: string[]): (specs: string[]) => number {
  const rankIndex = new Map(ranking.map((id, i) => [id, i]));
  return (specs) =>
    specs.reduce(
      (sum, id) => sum + (MAX_RANK_WEIGHT - (rankIndex.get(id) ?? FALLBACK_RANK)),
      0,
    );
}

/**
 * Lexicographic comparison weight: each spec encoded as a bit, top-ranked
 * spec = highest bit. Higher rankWeight means a strictly preferred plan
 * under priority order (a single top-ranked spec outweighs any combination
 * of lower-ranked specs). Used by comparators; not for display.
 */
export function priorityRankWeight(specs: string[], ranking: string[]): number {
  const rankIndex = new Map(ranking.map((id, i) => [id, i]));
  const N = ranking.length;
  let w = 0;
  for (const id of specs) {
    const r = rankIndex.get(id);
    if (r === undefined) continue;
    w += 1 << (N - 1 - r);
  }
  return w;
}

export function makePriorityRankWeight(ranking: string[]): (specs: string[]) => number {
  const rankIndex = new Map(ranking.map((id, i) => [id, i]));
  const N = ranking.length;
  return (specs) => {
    let w = 0;
    for (const id of specs) {
      const r = rankIndex.get(id);
      if (r === undefined) continue;
      w += 1 << (N - 1 - r);
    }
    return w;
  };
}