// The rules for a read-only link: it can expire, and it can need a passcode. Kept separate from the routes
// so they can be tested on their own.
import bcrypt from 'bcryptjs';

export const MAX_PASSCODE = 100;

// "never" (null/0) or a number of days, up to a year -> an expiry time in ms (or null)
export function expiryFromDays(days, now = Date.now()) {
  const n = Number(days);
  if (!days || !Number.isFinite(n) || n <= 0) return null;
  return now + Math.min(365, Math.round(n)) * 86_400_000;
}

export async function hashPasscode(passcode) {
  const p = String(passcode ?? '').slice(0, MAX_PASSCODE);
  return p.trim() ? bcrypt.hash(p.trim(), 10) : null;
}

// -> { ok: true } | { ok: false, status: 410, error } (expired) | { ok: false, status: 401, needsPasscode: true, error }
export async function checkShareAccess({ expiresAt, passHash, supplied }, now = Date.now()) {
  if (expiresAt && expiresAt <= now) return { ok: false, status: 410, error: 'This link has expired. Ask the person who shared it for a new one.' };
  if (!passHash) return { ok: true };
  const given = String(supplied ?? '').slice(0, MAX_PASSCODE).trim();
  if (!given) return { ok: false, status: 401, needsPasscode: true, error: 'This link needs a passcode.' };
  if (!(await bcrypt.compare(given, passHash))) return { ok: false, status: 401, needsPasscode: true, error: 'That passcode is not right.' };
  return { ok: true };
}

// "Hide my notes until…": before the reveal time a shared study shows only the passages and the discussion questions
// (no notes, outline, script, words or group notes), and says when the rest appears. The strip is done here, on the
// server, so the hidden text never reaches the browser. After the time (or with none set) the study is sent whole.
const OPEN_CHUNK_FIELDS = ['id', 'startVerse', 'endVerse', 'spilloverEndVerse', 'episodeNumber', 'episodeTitle', 'discussionQuestions'];

export function hideUntilReveal(project, revealAt, now = Date.now()) {
  if (!revealAt || revealAt <= now || !project || typeof project !== 'object') return project;
  return {
    id: project.id, title: project.title, translation: project.translation, series: project.series, outline: [],
    hiddenUntil: revealAt,
    chapters: (Array.isArray(project.chapters) ? project.chapters : []).map((ch) => ({
      book: ch.book, bookAbbrev: ch.bookAbbrev, chapter: ch.chapter, verses: ch.verses,
      chunks: (Array.isArray(ch.chunks) ? ch.chunks : []).map((chunk) => Object.fromEntries(OPEN_CHUNK_FIELDS.filter((f) => f in chunk).map((f) => [f, chunk[f]]))),
    })),
  };
}

// A reveal time from the browser -> ms in the future (up to a year), or null for "no hiding"
export function revealFromInput(value, now = Date.now()) {
  const n = Number(value);
  if (!value || !Number.isFinite(n) || n <= now) return null;
  return Math.min(n, now + 365 * 86_400_000);
}