// Site-side member accounts. Dual-mode:
//   MySQL (db.enabled) for real concurrency in production,
//   JSON volume file as the no-DATABASE_URL fallback (local dev).
// All exported functions are async; both modes return identical shapes.
// The chain remains the source of truth for money/credits/qualification.
const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const db = require('./db');

let DATA_DIR = null;

// ---- shared helpers ----
function hashPassword(password) {
  const salt = crypto.randomBytes(16);
  const hash = crypto.scryptSync(String(password), salt, 32);
  return salt.toString('hex') + ':' + hash.toString('hex');
}
function checkPassword(password, stored) {
  try {
    const [saltHex, hashHex] = String(stored).split(':');
    const hash = crypto.scryptSync(String(password), Buffer.from(saltHex, 'hex'), 32);
    return crypto.timingSafeEqual(hash, Buffer.from(hashHex, 'hex'));
  } catch (e) { return false; }
}
const EMAIL_RE = /^[^\s@]+@[^\s@]+\.[^\s@]{2,}$/;
const normEmail = e => String(e || '').trim().toLowerCase();
const normAddr = a => String(a || '').trim().toLowerCase();
function newCode(taken) {
  let c;
  do { c = crypto.randomBytes(5).toString('base64url').replace(/[-_]/g, '').slice(0, 7).toLowerCase(); }
  while (!c || c.length < 6 || /^\d+$/.test(c) || (taken && taken(c)));
  return c;
}
const pub = a => a ? { email: a.email, sponsorRef: a.sponsorRef || '', code: a.code || null,
  address: a.address || null, created: a.created } : null;

// ---- JSON fallback ----
const J = {
  db: { v: 2, byEmail: {}, byAddress: {}, byCode: {}, joins: 0 },
  FILE: () => path.join(DATA_DIR, 'accounts.json'),
  load() {
    try { this.db = JSON.parse(fs.readFileSync(this.FILE(), 'utf8')); } catch (e) {}
    if (!this.db || !this.db.v) this.db = { v: 2, byEmail: {}, byAddress: {}, byCode: {}, joins: 0 };
    if (!this.db.byCode) this.db.byCode = {};
    for (const a of Object.values(this.db.byEmail)) {
      if (!a.code) { a.code = newCode(c => this.db.byCode[c]); this.db.byCode[a.code] = a.email; }
      else if (!this.db.byCode[a.code]) this.db.byCode[a.code] = a.email;
    }
  },
  save() {
    try {
      const tmp = this.FILE() + '.tmp';
      fs.writeFileSync(tmp, JSON.stringify(this.db), { mode: 0o600 });
      fs.renameSync(tmp, this.FILE());
    } catch (e) { console.error('accounts save failed', e.message); }
  },
  async signup(e, password, ref) {
    if (this.db.byEmail[e]) return { error: 'That email already has an account. Log in instead.' };
    const code = newCode(c => this.db.byCode[c]);
    this.db.byEmail[e] = { email: e, pass: hashPassword(password), sponsorRef: ref, code, address: null, created: Date.now() };
    this.db.byCode[code] = e;
    this.save();
    return { ok: true, created: true, account: pub(this.db.byEmail[e]) };
  },
  async login(e, password) {
    const a = this.db.byEmail[e];
    if (!a || !a.pass || !checkPassword(password, a.pass)) return { error: 'Wrong email or password.' };
    return { ok: true, account: pub(a) };
  },
  async ensure(e, ref) {
    let created = false;
    if (!this.db.byEmail[e]) {
      const code = newCode(c => this.db.byCode[c]);
      this.db.byEmail[e] = { email: e, pass: null, sponsorRef: ref, code, address: null, created: Date.now() };
      this.db.byCode[code] = e;
      created = true;
      this.save();
    }
    return { ok: true, created, account: pub(this.db.byEmail[e]) };
  },
  async byEmail(e) { return pub(this.db.byEmail[e]); },
  async byAddress(a) { const e = this.db.byAddress[a]; return e ? pub(this.db.byEmail[e]) : null; },
  async byCode(c) { const e = this.db.byCode[c]; return e ? pub(this.db.byEmail[e]) : null; },
  async linkWallet(e, a) {
    const acct = this.db.byEmail[e];
    if (!acct) return { error: 'No such account.' };
    if (acct.address && acct.address !== a) return { error: 'This account is already linked to wallet '
      + acct.address.slice(0, 6) + '…' + acct.address.slice(-4) + '. Connect that wallet instead.' };
    if (this.db.byAddress[a] && this.db.byAddress[a] !== e) return { error: 'That wallet is already linked to a different account.' };
    acct.address = a;
    this.db.byAddress[a] = e;
    this.save();
    return { ok: true, account: pub(acct) };
  },
  async count() { return Object.keys(this.db.byEmail).length; }
};

// ---- MySQL mode ----
const rowPub = r => r ? pub({ email: r.email, sponsorRef: r.sponsor_ref, code: r.code, address: r.address, created: Number(r.created) }) : null;
const D = {
  async signup(e, password, ref) {
    const code = newCode();
    try {
      await db.q('INSERT INTO accounts (email,pass,sponsor_ref,code,address,created) VALUES (?,?,?,?,NULL,?)',
        [e, hashPassword(password), ref, code, Date.now()]);
    } catch (err) {
      if (err.code === 'ER_DUP_ENTRY') return String(err.message).includes('code')
        ? this.signup(e, password, ref) // code collision: retry with a new code
        : { error: 'That email already has an account. Log in instead.' };
      throw err;
    }
    return { ok: true, created: true, account: await this.byEmail(e) };
  },
  async login(e, password) {
    const rows = await db.q('SELECT * FROM accounts WHERE email=?', [e]);
    if (!rows.length || !rows[0].pass || !checkPassword(password, rows[0].pass)) return { error: 'Wrong email or password.' };
    return { ok: true, account: rowPub(rows[0]) };
  },
  async ensure(e, ref) {
    const code = newCode();
    let created = false;
    try {
      await db.q('INSERT INTO accounts (email,pass,sponsor_ref,code,address,created) VALUES (?,NULL,?,?,NULL,?)',
        [e, ref, code, Date.now()]);
      created = true;
    } catch (err) {
      if (err.code !== 'ER_DUP_ENTRY') throw err;
      if (String(err.message).includes('code')) return this.ensure(e, ref);
    }
    return { ok: true, created, account: await this.byEmail(e) };
  },
  async byEmail(e) { const r = await db.q('SELECT * FROM accounts WHERE email=?', [e]); return rowPub(r[0]); },
  async byAddress(a) { const r = await db.q('SELECT * FROM accounts WHERE address=?', [a]); return rowPub(r[0]); },
  async byCode(c) { const r = await db.q('SELECT * FROM accounts WHERE code=?', [c]); return rowPub(r[0]); },
  async linkWallet(e, a) {
    const cur = await this.byEmail(e);
    if (!cur) return { error: 'No such account.' };
    if (cur.address && cur.address !== a) return { error: 'This account is already linked to wallet '
      + cur.address.slice(0, 6) + '…' + cur.address.slice(-4) + '. Connect that wallet instead.' };
    try { await db.q('UPDATE accounts SET address=? WHERE email=?', [a, e]); }
    catch (err) {
      if (err.code === 'ER_DUP_ENTRY') return { error: 'That wallet is already linked to a different account.' };
      throw err;
    }
    return { ok: true, account: await this.byEmail(e) };
  },
  async count() { const r = await db.q('SELECT COUNT(*) n FROM accounts'); return Number(r[0].n); }
};

const impl = () => db.enabled() ? D : J;
function init(opts) { DATA_DIR = opts.dataDir; J.load(); }

async function signup(email, password, sponsorRef) {
  const e = normEmail(email);
  if (!EMAIL_RE.test(e)) return { error: 'That email address does not look right.' };
  if (String(password || '').length < 8) return { error: 'Password needs at least 8 characters.' };
  return impl().signup(e, String(password), String(sponsorRef || ''));
}
async function login(email, password) { return impl().login(normEmail(email), String(password || '')); }
async function ensure(email, sponsorRef) {
  const e = normEmail(email);
  if (!EMAIL_RE.test(e)) return { error: 'That email address does not look right.' };
  return impl().ensure(e, String(sponsorRef || ''));
}
async function byEmail(email) { return impl().byEmail(normEmail(email)); }
async function byAddress(address) { return impl().byAddress(normAddr(address)); }
async function byCode(code) { return impl().byCode(String(code || '').toLowerCase()); }
async function linkWallet(email, address) {
  const a = normAddr(address);
  if (!/^0x[0-9a-f]{40}$/.test(a)) return { error: 'Bad wallet address.' };
  return impl().linkWallet(normEmail(email), a);
}
async function count() { return impl().count(); }

module.exports = { init, signup, login, ensure, byEmail, byAddress, byCode, linkWallet, count };