// Switching the Sia account an s3d is connected to. s3d has no "log out":
// its connection (the app key), users, keys, buckets and upload buffer all
// live in its data folder. A switch moves that folder's contents into
// previous-account-<stamp>/ beside it (never deleted), so s3d starts fresh
// and can be connected to another account; a restore swaps one back.
//
// s3d.yml stays where it is: it holds addresses and the admin password, not
// the account. pithos.json (the user's label for the account) moves with the
// data, because the label belongs to that account.

import fs from 'node:fs';
import path from 'node:path';

const ARCHIVE_PREFIX = 'previous-account-';
const META = 'pithos-archive.json';
const LABEL_FILE = 'pithos.json';

const keep = (name) => name === 's3d.yml' || name.startsWith(ARCHIVE_PREFIX);

function stamp(d = new Date()) {
  const p = (n) => String(n).padStart(2, '0');
  return `${d.getFullYear()}${p(d.getMonth() + 1)}${p(d.getDate())}-${p(d.getHours())}${p(d.getMinutes())}${p(d.getSeconds())}`;
}

export function readLabel(dataDir) {
  try { return String(JSON.parse(fs.readFileSync(path.join(dataDir, LABEL_FILE), 'utf8')).accountLabel || ''); } catch { return ''; }
}

export function writeLabel(dataDir, label) {
  const clean = String(label || '').trim().slice(0, 120);
  fs.mkdirSync(dataDir, { recursive: true });
  let cur = {};
  try { cur = JSON.parse(fs.readFileSync(path.join(dataDir, LABEL_FILE), 'utf8')); } catch {}
  fs.writeFileSync(path.join(dataDir, LABEL_FILE), JSON.stringify({ ...cur, accountLabel: clean }, null, 2));
  return clean;
}

export function listArchives(dataDir) {
  let names = [];
  try { names = fs.readdirSync(dataDir).filter((n) => n.startsWith(ARCHIVE_PREFIX)); } catch { return []; }
  return names.sort().reverse().map((name) => {
    const dir = path.join(dataDir, name);
    let meta = {};
    try { meta = JSON.parse(fs.readFileSync(path.join(dir, META), 'utf8')); } catch {}
    return {
      name,
      archivedAt: meta.archivedAt || null,
      indexerUrl: meta.indexerUrl || null,
      label: meta.label || readLabel(dir),
      users: meta.users || [],
      hasData: fs.existsSync(path.join(dir, 's3d.db')),
    };
  });
}

// Moves the current account's data aside. `meta` is stored with it for the
// restore list: { indexerUrl, users }.
export function archiveCurrent(dataDir, meta = {}) {
  if (!fs.existsSync(path.join(dataDir, 's3d.db'))) throw new Error('there is no s3d data to move aside');
  let name = ARCHIVE_PREFIX + stamp();
  while (fs.existsSync(path.join(dataDir, name))) name += '-1';
  const dest = path.join(dataDir, name);
  fs.mkdirSync(dest);
  const label = readLabel(dataDir);
  for (const entry of fs.readdirSync(dataDir)) {
    if (keep(entry) || entry === name) continue;
    fs.renameSync(path.join(dataDir, entry), path.join(dest, entry));
  }
  fs.writeFileSync(path.join(dest, META), JSON.stringify({ archivedAt: new Date().toISOString(), label, ...meta }, null, 2));
  return { name, path: dest };
}

// Swaps an archived account back in. Whatever is current is archived first
// (when there is anything), so a restore never loses data either.
export function restoreArchive(dataDir, name, metaForCurrent = {}) {
  if (!name.startsWith(ARCHIVE_PREFIX) || name.includes('/') || name.includes('\\') || name.includes('..')) throw new Error('not an account archive');
  const src = path.join(dataDir, name);
  if (!fs.existsSync(path.join(src, 's3d.db'))) throw new Error('that archive has no s3d data');
  const archivedCurrent = fs.existsSync(path.join(dataDir, 's3d.db')) ? archiveCurrent(dataDir, metaForCurrent).name : null;
  // Anything left (tmp folders from a fresh, unconnected s3d) is clutter.
  for (const entry of fs.readdirSync(dataDir)) {
    if (keep(entry)) continue;
    fs.rmSync(path.join(dataDir, entry), { recursive: true, force: true });
  }
  for (const entry of fs.readdirSync(src)) {
    if (entry === META) continue;
    fs.renameSync(path.join(src, entry), path.join(dataDir, entry));
  }
  fs.rmSync(src, { recursive: true, force: true });
  return { restored: name, archivedCurrent };
}