// ============================================================
//  Saeedalo — Client-Side App Engine
//  User management, bank account generation, session handling
// ============================================================

const DB_KEY   = 'saeedalo_users';
const SESS_KEY = 'saeedalo_session';

// ── User Storage ─────────────────────────────────────────────
function getUsers() { try { return JSON.parse(localStorage.getItem(DB_KEY) || '[]'); } catch { return []; } }
function saveUsers(users) { localStorage.setItem(DB_KEY, JSON.stringify(users)); }
function getUser(id) { return getUsers().find(u => u.id === id) || null; }
function updateUser(id, patch) {
  const users = getUsers();
  const idx = users.findIndex(u => u.id === id);
  if (idx >= 0) { users[idx] = { ...users[idx], ...patch }; saveUsers(users); return users[idx]; }
  return null;
}

// ── Session ───────────────────────────────────────────────────
function getSession() { try { return JSON.parse(sessionStorage.getItem(SESS_KEY) || localStorage.getItem(SESS_KEY) || 'null'); } catch { return null; } }
function setSession(user, remember = false) {
  const s = JSON.stringify({ id: user.id, email: user.email, ts: Date.now() });
  sessionStorage.setItem(SESS_KEY, s);
  if (remember) localStorage.setItem(SESS_KEY, s);
}
function clearSession() { sessionStorage.removeItem(SESS_KEY); localStorage.removeItem(SESS_KEY); }
function requireAuth() {
  const s = getSession();
  if (!s) { window.location.href = '/login.html'; return null; }
  const user = getUser(s.id);
  if (!user) { clearSession(); window.location.href = '/login.html'; return null; }
  return user;
}

// ── Bank Account Generator ────────────────────────────────────
function randDigits(n) { return Array.from({ length: n }, () => Math.floor(Math.random() * 10)).join(''); }
function generateIBAN(country) {
  const map = { DE: '1301', GB: '2000', FR: '3000', AE: '9999' };
  const bban = randDigits(18);
  return `${country}${map[country] || '00'}${bban}`;
}
function generateBankAccounts() {
  return {
    USD: { accountNumber: randDigits(10), routingNumber: '026073150', bankName: 'Saeedalo Bank (US)', swift: 'SAEDUS33' },
    EUR: { iban: generateIBAN('DE'), bic: 'SAEDDE1XXXX', bankName: 'Saeedalo Bank (EU)' },
    GBP: { accountNumber: randDigits(8), sortCode: '20-00-00', bankName: 'Saeedalo Bank (UK)', swift: 'SAEDGB2L' },
    AED: { iban: generateIBAN('AE'), bic: 'SAEDAEADXXX', bankName: 'Saeedalo Bank (UAE)' },
    SAR: { iban: 'SA' + randDigits(22), bankName: 'Saeedalo Bank (KSA)' },
    PKR: { accountNumber: randDigits(16), bankName: 'Saeedalo Bank (PK)' },
    INR: { accountNumber: randDigits(12), ifsc: 'SAED0001234', bankName: 'Saeedalo Bank (India)' },
  };
}

// ── User Registration ─────────────────────────────────────────
function registerUser(data) {
  const users = getUsers();
  if (users.find(u => u.email.toLowerCase() === data.email.toLowerCase())) {
    throw new Error('An account with this email already exists. Please sign in.');
  }
  const id = 'USR-' + Date.now() + '-' + randDigits(4);
  const bankAccounts = generateBankAccounts();
  const wallets = Object.keys(bankAccounts).map((cur, i) => ({
    id: 'WAL-' + randDigits(8), currency: cur, balance: 0,
    reserved: 0, status: 'ACTIVE', isPrimary: i === 0, ...bankAccounts[cur],
    createdAt: new Date().toISOString()
  }));
  const user = {
    id, email: data.email.toLowerCase(),
    passwordHash: btoa(data.password), // simple encoding for demo
    firstName: data.firstName, lastName: data.lastName,
    phone: data.phone || '', country: data.country || '',
    accountType: data.accountType || 'personal',
    kycStatus: 'NOT_STARTED', kycTier: 'TIER_0',
    businessProfile: data.businessProfile || null,
    wallets, transactions: [], cards: [],
    referralCode: 'SAE' + randDigits(6),
    createdAt: new Date().toISOString(),
    lastLoginAt: new Date().toISOString(),
    notifications: [
      { id:'N1', type:'WELCOME', title:'Welcome to Saeedalo!', message:'Your account is ready. Complete verification to unlock higher limits.', read:false, createdAt:new Date().toISOString() },
      { id:'N2', type:'KYC', title:'Verify your identity', message:'Complete Tier 1 verification to increase your limits to $10,000/day.', read:false, createdAt:new Date().toISOString() }
    ]
  };
  users.push(user);
  saveUsers(users);
  return user;
}

// ── Login ─────────────────────────────────────────────────────
function loginUser(email, password, remember) {
  const users = getUsers();
  const user = users.find(u => u.email.toLowerCase() === email.toLowerCase());
  if (!user) throw new Error('No account found with this email address.');
  if (user.passwordHash !== btoa(password)) throw new Error('Incorrect password. Please try again.');
  updateUser(user.id, { lastLoginAt: new Date().toISOString() });
  setSession(user, remember);
  return user;
}

// ── KYC ──────────────────────────────────────────────────────
function submitKYC(userId, data) {
  return updateUser(userId, {
    kycData: data, kycStatus: 'UNDER_REVIEW',
    kycSubmittedAt: new Date().toISOString()
  });
}
function approveKYC(userId, tier) {
  return updateUser(userId, { kycStatus: 'APPROVED', kycTier: tier, kycApprovedAt: new Date().toISOString() });
}

// ── Transactions ──────────────────────────────────────────────
function addTransaction(userId, tx) {
  const user = getUser(userId);
  if (!user) return;
  const newTx = { id: 'TXN-' + randDigits(10), ...tx, createdAt: new Date().toISOString(), status: 'COMPLETED' };
  const txs = [...(user.transactions || []), newTx];
  updateUser(userId, { transactions: txs.slice(-200) }); // keep last 200
  return newTx;
}

// ── Wallet Credit/Debit ───────────────────────────────────────
function creditWallet(userId, currency, amount, description) {
  const user = getUser(userId);
  if (!user) return;
  const wallets = user.wallets.map(w =>
    w.currency === currency ? { ...w, balance: (Number(w.balance) + amount) } : w
  );
  updateUser(userId, { wallets });
  addTransaction(userId, { type:'DEPOSIT', currency, amount, description, walletId: user.wallets.find(w=>w.currency===currency)?.id });
}
function debitWallet(userId, currency, amount, description) {
  const user = getUser(userId);
  if (!user) return false;
  const wallet = user.wallets.find(w => w.currency === currency);
  if (!wallet || Number(wallet.balance) < amount) return false;
  const wallets = user.wallets.map(w =>
    w.currency === currency ? { ...w, balance: Math.max(0, Number(w.balance) - amount) } : w
  );
  updateUser(userId, { wallets });
  addTransaction(userId, { type:'WITHDRAWAL', currency, amount: -amount, description, walletId: wallet.id });
  return true;
}

// ── FX Rates (approximate) ────────────────────────────────────
const FX = { USD:1,EUR:0.921,GBP:0.786,AED:3.672,SAR:3.751,PKR:278.5,INR:83.47,CAD:1.364,AUD:1.512,SGD:1.342,JPY:157.4,CHF:0.897,CNY:7.25 };
function convert(amount, from, to) {
  const rate = FX[to] / FX[from];
  const fee = amount * 0.006;
  return { received: ((amount - fee) * rate).toFixed(2), rate: rate.toFixed(4), fee: fee.toFixed(2) };
}

// ── KYC Tier Limits ───────────────────────────────────────────
const LIMITS = {
  TIER_0: { single:500,   daily:500,    monthly:1000   },
  TIER_1: { single:5000,  daily:10000,  monthly:25000  },
  TIER_2: { single:50000, daily:100000, monthly:500000 },
  TIER_3: { single:1e6,   daily:5e6,    monthly:50e6   },
};
function getLimits(tier) { return LIMITS[tier] || LIMITS.TIER_0; }

// ── Helpers ───────────────────────────────────────────────────
function formatCurrency(amount, currency) {
  return new Intl.NumberFormat('en-US', { style:'currency', currency, minimumFractionDigits:2 }).format(amount);
}
function formatDate(iso) {
  return new Intl.DateTimeFormat('en-US', { month:'short', day:'numeric', hour:'2-digit', minute:'2-digit' }).format(new Date(iso));
}
function maskAccount(num) { if (!num) return ''; return '····' + num.slice(-4); }
function totalBalanceUSD(wallets) {
  return wallets.reduce((s,w) => s + (Number(w.balance) / (FX[w.currency] || 1)), 0);
}
function getInitials(user) { return ((user.firstName||'')[0]+(user.lastName||'')[0]).toUpperCase() || 'U'; }