// 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,
  username: a.username || null, memberId: a.memberId || 0, joinedVia: a.joinedVia || null,
  lineBannerUrl: a.lineBannerUrl || null, lineTargetUrl: a.lineTargetUrl || null, wallOffers: a.wallOffers || null,
  avatarUrl: a.avatarUrl || null, bio: a.bio || null, socials: a.socials || null,
  chatAvailable: a.chatAvailable === false ? false : true, lastSeen: a.lastSeen || 0,
  address: a.address || null, created: a.created } : null;
const USER_RE = /^[a-zA-Z0-9_]{3,20}$/;
const normUser = u => String(u || '').trim().toLowerCase();

// ---- 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, via) {
    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(), joinedVia: via || null };
      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 byUsername(u) {
    for (const a of Object.values(this.db.byEmail)) if (a.username === u) return pub(a);
    return null;
  },
  async setUsername(e, u) {
    const acct = this.db.byEmail[e];
    if (!acct) return { error: 'No such account.' };
    for (const a of Object.values(this.db.byEmail)) if (a.username === u && a.email !== e)
      return { error: 'That username is taken. Try another.' };
    acct.username = u;
    this.save();
    return { ok: true, account: pub(acct) };
  },
  async setLineBanner(e, bannerUrl, targetUrl) {
    const acct = this.db.byEmail[e];
    if (!acct) return { error: 'No such account.' };
    acct.lineBannerUrl = bannerUrl || null;
    acct.lineTargetUrl = targetUrl || null;
    this.save();
    return { ok: true, account: pub(acct) };
  },
  async setWallOffers(e, json) {
    const acct = this.db.byEmail[e];
    if (!acct) return { error: 'No such account.' };
    acct.wallOffers = json || null; this.save();
    return { ok: true, account: pub(acct) };
  },
  async setProfile(e, avatarUrl, bio, socials) {
    const acct = this.db.byEmail[e];
    if (!acct) return { error: 'No such account.' };
    if (avatarUrl !== undefined) acct.avatarUrl = avatarUrl || null;
    if (bio !== undefined) acct.bio = bio || null;
    if (socials !== undefined) acct.socials = socials || null;
    this.save();
    return { ok: true, account: pub(acct) };
  },
  async touchSeen(e) { const a = this.db.byEmail[e]; if (a) { a.lastSeen = Date.now(); this.save(); } },
  async setChatAvailable(e, v) { const a = this.db.byEmail[e]; if (!a) return { error: 'No such account.' }; a.chatAvailable = !!v; this.save(); return { ok: true, available: !!v }; },
  async getMutes(e) { const a = this.db.byEmail[e]; return (a && Array.isArray(a.chatMutes)) ? a.chatMutes : []; },
  async setMute(owner, target, muted) {
    const a = this.db.byEmail[owner]; if (!a) return { error: 'No such account.' };
    const set = new Set((a.chatMutes || []).map(x => String(x).toLowerCase())); const t = String(target).toLowerCase();
    if (muted) set.add(t); else set.delete(t);
    a.chatMutes = [...set].slice(0, 500); this.save(); return { ok: true, muted: !!muted };
  },
  async byMemberId(id) {
    const a = Object.values(this.db.byEmail).find(x => x.memberId === Number(id));
    return a ? pub(a) : null;
  },
  async setMemberId(e, id) {
    const acct = this.db.byEmail[e];
    if (acct && acct.memberId !== id) { acct.memberId = id; this.save(); }
  },
  async namesForMembers(ids) {
    const out = {};
    for (const a of Object.values(this.db.byEmail))
      if (a.username && a.memberId && ids.includes(a.memberId)) out[a.memberId] = a.username;
    return out;
  },
  async listByReferrer(refs) {
    const set = new Set(refs.filter(Boolean).map(String));
    return Object.values(this.db.byEmail)
      .filter(a => set.has(String(a.sponsorRef || '')))
      .sort((a, b) => b.created - a.created)
      .slice(0, 200).map(pub);
  },
  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 listAll(limit) { return Object.values(this.db.byEmail).sort((a, b) => (b.created || 0) - (a.created || 0)).slice(0, limit).map(pub); },
  async setSponsorRef(e, ref) {
    const acct = this.db.byEmail[e];
    if (!acct) return { error: 'No such account.' };
    acct.sponsorRef = ref; 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,
  username: r.username, memberId: r.member_id || 0, joinedVia: r.joined_via || null,
  lineBannerUrl: r.line_banner_url, lineTargetUrl: r.line_target_url, wallOffers: r.wall_offers || null,
  avatarUrl: r.avatar_url, bio: r.bio, socials: r.socials,
  chatAvailable: r.chat_available === 0 ? false : true, lastSeen: Number(r.last_seen || 0),
  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, via) {
    const code = newCode();
    let created = false;
    try {
      await db.q('INSERT INTO accounts (email,pass,sponsor_ref,code,address,created,joined_via) VALUES (?,NULL,?,?,NULL,?,?)',
        [e, ref, code, Date.now(), via || null]);
      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 byUsername(u) { const r = await db.q('SELECT * FROM accounts WHERE username=?', [u]); return rowPub(r[0]); },
  async setUsername(e, u) {
    try { await db.q('UPDATE accounts SET username=? WHERE email=?', [u, e]); }
    catch (err) {
      if (err.code === 'ER_DUP_ENTRY') return { error: 'That username is taken. Try another.' };
      throw err;
    }
    return { ok: true, account: await this.byEmail(e) };
  },
  async setLineBanner(e, bannerUrl, targetUrl) {
    await db.q('UPDATE accounts SET line_banner_url=?, line_target_url=? WHERE email=?', [bannerUrl || null, targetUrl || null, e]);
    return { ok: true, account: await this.byEmail(e) };
  },
  async setWallOffers(e, json) {
    await db.q('UPDATE accounts SET wall_offers=? WHERE email=?', [json || null, e]);
    return { ok: true, account: await this.byEmail(e) };
  },
  async setProfile(e, avatarUrl, bio, socials) {
    if (avatarUrl !== undefined) await db.q('UPDATE accounts SET avatar_url=? WHERE email=?', [avatarUrl || null, e]);
    if (bio !== undefined) await db.q('UPDATE accounts SET bio=? WHERE email=?', [bio || null, e]);
    if (socials !== undefined) await db.q('UPDATE accounts SET socials=? WHERE email=?', [socials || null, e]);
    return { ok: true, account: await this.byEmail(e) };
  },
  async touchSeen(e) { await db.q('UPDATE accounts SET last_seen=? WHERE email=?', [Date.now(), e]); },
  async setChatAvailable(e, v) { await db.q('UPDATE accounts SET chat_available=? WHERE email=?', [v ? 1 : 0, e]); return { ok: true, available: !!v }; },
  async getMutes(e) {
    const r = await db.q('SELECT chat_mutes FROM accounts WHERE email=?', [e]);
    try { const arr = JSON.parse((r[0] && r[0].chat_mutes) || '[]'); return Array.isArray(arr) ? arr : []; } catch (x) { return []; }
  },
  async setMute(owner, target, muted) {
    const cur = await this.getMutes(owner);
    const set = new Set(cur.map(x => String(x).toLowerCase())); const t = String(target).toLowerCase();
    if (muted) set.add(t); else set.delete(t);
    await db.q('UPDATE accounts SET chat_mutes=? WHERE email=?', [JSON.stringify([...set].slice(0, 500)), owner]);
    return { ok: true, muted: !!muted };
  },
  async byMemberId(id) {
    const r = await db.q('SELECT * FROM accounts WHERE member_id=?', [Number(id)]);
    return rowPub(r[0]);
  },
  async setMemberId(e, id) { await db.q('UPDATE accounts SET member_id=? WHERE email=? AND (member_id IS NULL OR member_id<>?)', [id, e, id]); },
  async namesForMembers(ids) {
    if (!ids.length) return {};
    const rows = await db.q('SELECT member_id, username FROM accounts WHERE username IS NOT NULL AND member_id IN ('
      + ids.map(() => '?').join(',') + ')', ids);
    const out = {};
    for (const r of rows) out[r.member_id] = r.username;
    return out;
  },
  async listByReferrer(refs) {
    const clean = refs.filter(Boolean).map(String);
    if (!clean.length) return [];
    const rows = await db.q('SELECT * FROM accounts WHERE sponsor_ref IN (' + clean.map(() => '?').join(',')
      + ') ORDER BY created DESC LIMIT 200', clean);
    return rows.map(rowPub);
  },
  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 listAll(limit) { const rows = await db.q('SELECT * FROM accounts ORDER BY created DESC LIMIT ?', [Number(limit) || 500]); return rows.map(rowPub); },
  async setSponsorRef(e, ref) {
    const r = await db.q('UPDATE accounts SET sponsor_ref=? WHERE email=?', [ref, e]);
    if (!r.affectedRows) return { error: 'No such account.' };
    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, via) {
  const e = normEmail(email);
  if (!EMAIL_RE.test(e)) return { error: 'That email address does not look right.' };
  return impl().ensure(e, String(sponsorRef || ''), String(via || '').toLowerCase().slice(0, 20) || null);
}
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 byUsername(u) {
  const n = normUser(u);
  return USER_RE.test(n) ? impl().byUsername(n) : null;
}
async function setUsername(email, username) {
  const n = normUser(username);
  if (!USER_RE.test(n)) return { error: 'Usernames are 3 to 20 letters, numbers, or underscores.' };
  if (/^\d+$/.test(n)) return { error: 'Usernames need at least one letter.' }; // keep /join/<number> unambiguous
  return impl().setUsername(normEmail(email), n);
}
async function setMemberId(email, id) { return impl().setMemberId(normEmail(email), Number(id) || 0); }
async function namesForMembers(ids) { return impl().namesForMembers([...new Set(ids)].filter(n => n > 0)); }
async function listByReferrer(refs) { return impl().listByReferrer(refs || []); }
// the tokens a member could have been joined under (code, username, or numeric id)
function refTokens(a) {
  return [a.code, a.username, a.memberId ? String(a.memberId) : null].filter(Boolean).map(String);
}
// walk the downline breadth-first to `depth` levels. Returns
// [{ level, members:[pub...] }]; emails are included on pub but the CALLER
// decides who may see them (directs only, per product rule).
async function downline(email, depth = 3) {
  const root = await byEmail(email);
  if (!root) return [];
  const seen = new Set([String(root.email)]);
  const levels = [];
  let frontier = [root];
  for (let lvl = 1; lvl <= depth; lvl++) {
    const toks = [...new Set(frontier.flatMap(refTokens))];
    if (!toks.length) break;
    const kids = (await listByReferrer(toks)).filter(k => !seen.has(String(k.email)));
    if (!kids.length) break;
    kids.forEach(k => seen.add(String(k.email)));
    levels.push({ level: lvl, members: kids });
    frontier = kids;
  }
  return levels;
}
async function linkWallet(email, address) {
  const a = normAddr(address);
  if (!/^0x[0-9a-f]{40}$/.test(a)) return { error: 'Bad wallet address.' };
  return impl().linkWallet(normEmail(email), a);
}
async function count() { return impl().count(); }
// admin: newest-first account list, and re-pointing a member's sponsor (a
// username, share code, or numeric member id: the same tokens join links use)
async function listAll(limit = 500) { return impl().listAll(limit); }
async function setSponsorRef(email, ref) { return impl().setSponsorRef(normEmail(email), String(ref || '').trim().toLowerCase().slice(0, 40)); }

// resolve a member's DIRECT sponsor account (the token they joined under)
async function sponsorOf(email) {
  const root = await byEmail(email);
  if (!root || !root.sponsorRef) return null;
  const ref = String(root.sponsorRef);
  let s = null;
  try { s = await byCode(ref); } catch (e) {}
  if (!s) { try { s = await byUsername(ref); } catch (e) {} }
  if (!s && /^\d+$/.test(ref)) { try { s = await byMemberId(Number(ref)); } catch (e) {} }
  return s || null;
}
// is `memberEmail` anywhere in `sponsorEmail`'s downline (to `depth` levels)?
async function isDownlineOf(sponsorEmail, memberEmail, depth = 3) {
  const target = String(memberEmail || '').toLowerCase();
  const levels = await downline(sponsorEmail, depth);
  return levels.some(L => L.members.some(m => String(m.email || '').toLowerCase() === target));
}
async function getChatSettings(email) {
  const a = await byEmail(email);
  return { available: a ? a.chatAvailable !== false : true, mutes: await impl().getMutes(String(email || '').toLowerCase()) };
}

module.exports = { init, signup, login, ensure, byEmail, byAddress, byCode, byUsername, listAll, setSponsorRef,
  setUsername, setMemberId, namesForMembers, listByReferrer, downline, linkWallet, count,
  setLineBanner: (e, b, t) => impl().setLineBanner(String(e || '').toLowerCase(), b, t),
  setWallOffers: (e, j) => impl().setWallOffers(String(e || '').toLowerCase(), j),
  setProfile: (e, a, bio, socials) => impl().setProfile(String(e || '').toLowerCase(), a, bio, socials),
  touchSeen: e => impl().touchSeen(String(e || '').toLowerCase()),
  setChatAvailable: (e, v) => impl().setChatAvailable(String(e || '').toLowerCase(), v),
  getMutes: e => impl().getMutes(String(e || '').toLowerCase()),
  setMute: (o, t, m) => impl().setMute(String(o || '').toLowerCase(), String(t || '').toLowerCase(), m),
  sponsorOf, isDownlineOf, getChatSettings,
  byMemberId: id => impl().byMemberId(id) };