// Exbyte Depot — waitlist collector + secure admin panel.
//
// Public:  serves the landing page and accepts POST /api/waitlist (dedup).
// Admin:   password-gated (scrypt), rate-limited, signed-cookie session.
//          view signups + export CSV. No plaintext secrets in the codebase.

import express from "express";
import rateLimit from "express-rate-limit";
import path from "node:path";
import fs from "node:fs";
import { fileURLToPath } from "node:url";

import { addEmail, countEmails, listEmails } from "./lib/db.js";
import {
  verifyPassword,
  safeEqual,
  issueToken,
  requireAuth,
  setSessionCookie,
  clearSessionCookie,
} from "./lib/auth.js";

// --- load .env (built into Node, no dotenv dependency) ----------------------
const __dirname = path.dirname(fileURLToPath(import.meta.url));
try {
  process.loadEnvFile(path.join(__dirname, ".env"));
} catch {
  /* no .env file — rely on real environment variables */
}

const {
  PORT = 8787,
  NODE_ENV = "development",
  ADMIN_USER,
  ADMIN_PASS_HASH,
  SESSION_SECRET,
  TRUST_PROXY = "0",
  LANDING_DIR = path.join(__dirname, "..", "landing"),
} = process.env;

const IS_PROD = NODE_ENV === "production";
const SESSION_TTL_MS = 8 * 60 * 60 * 1000; // 8 hours

// --- refuse to boot without the security-critical config --------------------
const missing = [];
if (!ADMIN_USER) missing.push("ADMIN_USER");
if (!ADMIN_PASS_HASH) missing.push("ADMIN_PASS_HASH");
if (!SESSION_SECRET || SESSION_SECRET.length < 24) missing.push("SESSION_SECRET (>=24 chars)");
if (missing.length) {
  console.error(
    `\n[waitlist] Refusing to start — missing/weak config: ${missing.join(", ")}\n` +
      `  1) cp .env.example .env\n` +
      `  2) npm run gen-secret        # paste into SESSION_SECRET\n` +
      `  3) npm run set-password      # paste into ADMIN_PASS_HASH\n`
  );
  process.exit(1);
}

const app = express();
app.disable("x-powered-by");
if (TRUST_PROXY !== "0") app.set("trust proxy", Number(TRUST_PROXY) || 1);
app.use(express.json({ limit: "16kb" }));
app.use(express.urlencoded({ extended: false, limit: "16kb" }));

// --- security headers (self-contained; no external origins) -----------------
app.use((req, res, next) => {
  res.setHeader("X-Content-Type-Options", "nosniff");
  res.setHeader("X-Frame-Options", "DENY");
  res.setHeader("Referrer-Policy", "no-referrer");
  res.setHeader("Cross-Origin-Opener-Policy", "same-origin");
  res.setHeader("Permissions-Policy", "geolocation=(), microphone=(), camera=()");
  res.setHeader(
    "Content-Security-Policy",
    [
      "default-src 'self'",
      "style-src 'self' 'unsafe-inline'",
      "script-src 'self' 'unsafe-inline'",
      "img-src 'self' data:",
      "base-uri 'self'",
      "form-action 'self'",
      "frame-ancestors 'none'",
    ].join("; ")
  );
  next();
});

// --- rate limiters ----------------------------------------------------------
const loginLimiter = rateLimit({
  windowMs: 15 * 60 * 1000,
  max: 8, // per IP per window
  standardHeaders: true,
  legacyHeaders: false,
  message: { error: "Too many attempts. Try again later." },
});
const waitlistLimiter = rateLimit({
  windowMs: 10 * 60 * 1000,
  max: 20,
  standardHeaders: true,
  legacyHeaders: false,
  message: { error: "Too many requests. Slow down." },
});

// --- helpers ----------------------------------------------------------------
const EMAIL_RE = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
function normalizeEmail(v) {
  return String(v || "").trim().toLowerCase();
}
function clientIp(req) {
  return (req.ip || "").replace(/^::ffff:/, "") || null;
}
function sendView(res, file, replacements = {}) {
  let html = fs.readFileSync(path.join(__dirname, "views", file), "utf8");
  for (const [k, v] of Object.entries(replacements)) {
    html = html.replaceAll(`{{${k}}}`, v);
  }
  res.type("html").send(html);
}

// ============================================================================
//  PUBLIC — waitlist signup
// ============================================================================
app.post("/api/waitlist", waitlistLimiter, (req, res) => {
  // honeypot: bots fill hidden fields; humans leave them blank
  if (req.body && typeof req.body.website === "string" && req.body.website.trim() !== "") {
    return res.json({ ok: true, deduped: true }); // silently accept, store nothing
  }
  const email = normalizeEmail(req.body?.email);
  if (!email || email.length > 254 || !EMAIL_RE.test(email)) {
    return res.status(400).json({ ok: false, error: "Enter a valid email." });
  }
  try {
    const { added } = addEmail({
      email,
      source: (req.body?.source || "landing").toString().slice(0, 64),
      ip: clientIp(req),
      userAgent: (req.headers["user-agent"] || "").slice(0, 300),
    });
    return res.json({ ok: true, added, deduped: !added });
  } catch (e) {
    console.error("[waitlist] insert failed:", e.message);
    return res.status(500).json({ ok: false, error: "Server error." });
  }
});

// ============================================================================
//  ADMIN — auth
// ============================================================================
app.get("/admin/login", (req, res) => sendView(res, "login.html"));

app.post("/admin/login", loginLimiter, (req, res) => {
  const user = String(req.body?.username || "");
  const pass = String(req.body?.password || "");
  const ok = safeEqual(user, ADMIN_USER) && verifyPassword(pass, ADMIN_PASS_HASH);
  if (!ok) {
    return res.status(401).redirect("/admin/login?error=1");
  }
  const token = issueToken(ADMIN_USER, SESSION_SECRET, SESSION_TTL_MS);
  setSessionCookie(res, token, { secure: IS_PROD, ttlMs: SESSION_TTL_MS });
  res.redirect("/admin");
});

app.post("/admin/logout", (req, res) => {
  clearSessionCookie(res, { secure: IS_PROD });
  res.redirect("/admin/login");
});

// everything below requires a valid session
app.use("/admin", requireAuth(SESSION_SECRET));

app.get("/admin", (req, res) => sendView(res, "admin.html", { USER: req.admin.u }));

app.get("/admin/api/emails", (req, res) => {
  res.json({ count: countEmails(), emails: listEmails() });
});

// CSV export
app.get("/admin/export.csv", (req, res) => {
  const rows = listEmails();
  const esc = (v) => {
    const s = v == null ? "" : String(v);
    return /[",\n\r]/.test(s) ? `"${s.replaceAll('"', '""')}"` : s;
  };
  const header = ["email", "source", "ip", "created_at"];
  const lines = [header.join(",")];
  for (const r of rows) {
    lines.push([r.email, r.source, r.ip, r.created_at].map(esc).join(","));
  }
  const csv = "" + lines.join("\r\n"); // BOM so Excel reads UTF-8
  const stamp = new Date().toISOString().slice(0, 10);
  res.setHeader("Content-Type", "text/csv; charset=utf-8");
  res.setHeader("Content-Disposition", `attachment; filename="waitlist-${stamp}.csv"`);
  res.send(csv);
});

// ============================================================================
//  LANDING (static) — served last so /api and /admin win
// ============================================================================
app.use(
  express.static(LANDING_DIR, {
    extensions: ["html"],
    setHeaders: (res) => res.setHeader("Cache-Control", "no-cache"),
  })
);

app.listen(PORT, () => {
  console.log(`[waitlist] listening on http://localhost:${PORT}`);
  console.log(`[waitlist] landing:  ${LANDING_DIR}`);
  console.log(`[waitlist] admin:    http://localhost:${PORT}/admin  (${IS_PROD ? "prod" : "dev"})`);
});