// How outline points are numbered. Kept free of imports so both the page and the exporters can use it.

const ROMAN = [[10, 'X'], [9, 'IX'], [5, 'V'], [4, 'IV'], [1, 'I']];
export function toRoman(n) {
  let out = '';
  let rest = n;
  for (const [value, symbol] of ROMAN) while (rest >= value) { out += symbol; rest -= value; }
  return out;
}
const letter = (n, upper) => {
  let out = '';
  let rest = n;
  while (rest > 0) { rest -= 1; out = String.fromCharCode((upper ? 65 : 97) + (rest % 26)) + out; rest = Math.floor(rest / 26); }
  return out;
};

// I. / A. / 1. / a. / (1) / (a), by level
export function labelFor(depth, index) {
  const n = index + 1;
  switch (depth) {
    case 0: return `${toRoman(n)}.`;
    case 1: return `${letter(n, true)}.`;
    case 2: return `${n}.`;
    case 3: return `${letter(n, false)}.`;
    case 4: return `(${n})`;
    default: return `(${letter(n, false)})`;
  }
}

export const KINDS = [
  ['', 'Point'], ['illustration', 'Illustration'], ['application', 'Application'],
  ['quote', 'Quote'], ['question', 'Question'], ['transition', 'Transition'],
];
export const kindLabel = (kind) => KINDS.find(([id]) => id === kind)?.[1] ?? '';