import express from "express";
import cors from "cors";
import bcrypt from "bcryptjs";
import jwt from "jsonwebtoken";
import pg from "pg";
// import fetch from "node-fetch"; // YA NO ES NECESARIO EN NODE 20

const { Pool } = pg;
const app = express();

// =========================
// MIDDLEWARES (IMPORTANTE EL ORDEN)
// =========================
app.use(cors()); // <--- AÑADIDO: Habilita CORS para que tu web pueda conectarse
app.use(express.json());

// =========================
// ENV
// =========================
const {
  DATABASE_URL,
  JWT_SECRET,
  EVOLUTION_BASE_URL,
  EVOLUTION_API_KEY,
  EVOLUTION_INSTANCE,
} = process.env;

if (!DATABASE_URL || !JWT_SECRET) {
  console.error("❌ Faltan variables de entorno críticas (DATABASE_URL o JWT_SECRET)");
  process.exit(1);
}

// =========================
// DB CONNECTION
// =========================
const pool = new Pool({
  connectionString: DATABASE_URL,
  ssl: DATABASE_URL.includes("localhost") ? false : { rejectUnauthorized: false }
});

// =========================
// RUTA DE SALUD (Health Check)
// =========================
// Esta ruta arregla el mensaje "Cannot GET /" y te confirma que la API vive.
app.get("/", (req, res) => {
  res.send("🚀 IntegraRepara API v1.0 - Funcionando correctamente");
});

// =========================
// HELPERS
// =========================
function normalizePhone(phone) {
  let p = String(phone || "").trim().replace(/\s+/g, "").replace(/-/g, "");
  if (!p) return "";
  // Lógica simple para España
  if (!p.startsWith("+") && /^[6789]\d{8}$/.test(p)) {
    return "+34" + p;
  }
  return p;
}

function genCode6() {
  return String(Math.floor(100000 + Math.random() * 900000));
}

function signToken(user) {
  return jwt.sign(
    { sub: user.id, phone: user.phone, email: user.email },
    JWT_SECRET,
    { expiresIn: "30d" }
  );
}

// Middleware de autenticación
function authMiddleware(req, res, next) {
  const h = req.headers.authorization || "";
  const token = h.startsWith("Bearer ") ? h.slice(7) : "";
  if (!token) return res.status(401).json({ ok: false, error: "No token" });
  try {
    const payload = jwt.verify(token, JWT_SECRET);
    req.user = payload;
    next();
  } catch {
    return res.status(401).json({ ok: false, error: "Token inválido o expirado" });
  }
}

// =========================
// EVOLUTION API (WHATSAPP)
// =========================
async function sendWhatsAppCode(phone, code) {
  if (!EVOLUTION_BASE_URL || !EVOLUTION_API_KEY) {
    console.warn("⚠️ Evolution API no configurada. Código (Log):", code);
    return { ok: true, skipped: true }; 
  }
  try {
    const url = `${EVOLUTION_BASE_URL.replace(/\/$/, "")}/message/sendText/${EVOLUTION_INSTANCE}`;
    const body = {
      number: phone.replace("+", ""), 
      text: `🔐 Tu código de verificación IntegraRepara es: *${code}*\n\nNo lo compartas con nadie.`
    };
    
    // Fetch nativo de Node (sin librería extra)
    const res = await fetch(url, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "apikey": EVOLUTION_API_KEY
      },
      body: JSON.stringify(body)
    });
    
    const data = await res.json();
    if (!res.ok) {
      console.error("❌ Error Evolution:", data);
      return { ok: false };
    }
    return { ok: true };
  } catch (error) {
    console.error("❌ Error enviando WhatsApp:", error);
    return { ok: false };
  }
}

// =========================
// RUTAS DE AUTENTICACIÓN
// =========================

// 1. REGISTRO
app.post("/auth/register", async (req, res) => {
  const client = await pool.connect();
  try {
    const { fullName, phone, address, dni, email, password } = req.body;
    const p = normalizePhone(phone);
    if (!fullName || !p || !email || !password) {
      return res.status(400).json({ ok: false, error: "Faltan datos" });
    }
    const passwordHash = await bcrypt.hash(password, 10);
    
    await client.query('BEGIN');
    // Verificamos si existe
    const checkUser = await client.query("SELECT * FROM users WHERE email = $1 OR phone = $2", [email, p]);
    let userId;
    
    if (checkUser.rowCount > 0) {
      const existing = checkUser.rows[0];
      if (existing.is_verified) {
        await client.query('ROLLBACK');
        return res.status(409).json({ ok: false, error: "El usuario ya existe y está verificado. Por favor inicia sesión." });
      } else {
        // Existe pero NO verificado: Actualizamos datos
        await client.query(
          `UPDATE users SET full_name=$1, address=$2, dni=$3, password_hash=$4 WHERE id=$5`,
          [fullName, address, dni, passwordHash, existing.id]
        );
        userId = existing.id;
      }
    } else {
      // Nuevo usuario
      const insert = await client.query(
        `INSERT INTO users (full_name, phone, address, dni, email, password_hash) 
         VALUES ($1, $2, $3, $4, $5, $6) RETURNING id`,
        [fullName, p, address, dni, email, passwordHash]
      );
      userId = insert.rows[0].id;
    }
    // Generar código
    const code = genCode6();
    const codeHash = await bcrypt.hash(code, 10);
    const expiresAt = new Date(Date.now() + 10 * 60 * 1000); // 10 min
    
    // Invalidar códigos anteriores e insertar nuevo
    await client.query("DELETE FROM login_codes WHERE user_id = $1", [userId]);
    await client.query(
      `INSERT INTO login_codes (user_id, phone, code_hash, expires_at) VALUES ($1, $2, $3, $4)`,
      [userId, p, codeHash, expiresAt]
    );
    
    // Enviar WhatsApp
    await sendWhatsAppCode(p, code);
    await client.query('COMMIT');
    res.json({ ok: true, phone: p, msg: "Código enviado" });
  } catch (e) {
    await client.query('ROLLBACK');
    console.error(e);
    res.status(500).json({ ok: false, error: "Error interno del servidor" });
  } finally {
    client.release();
  }
});

// 2. VERIFICACIÓN
app.post("/auth/verify", async (req, res) => {
  try {
    const { phone, code } = req.body;
    const p = normalizePhone(phone);
    // Buscar código válido
    const codeQuery = await pool.query(
      `SELECT lc.*, u.id as user_id, u.email, u.full_name, u.phone 
       FROM login_codes lc
       JOIN users u ON lc.user_id = u.id
       WHERE lc.phone = $1 AND lc.consumed_at IS NULL AND lc.expires_at > NOW()
       ORDER BY lc.created_at DESC LIMIT 1`,
      [p]
    );
    if (codeQuery.rowCount === 0) {
      return res.status(400).json({ ok: false, error: "Código inválido o expirado" });
    }
    const row = codeQuery.rows[0];
    const valid = await bcrypt.compare(String(code), row.code_hash);
    if (!valid) {
      return res.status(400).json({ ok: false, error: "Código incorrecto" });
    }
    // Consumir código y verificar usuario
    await pool.query("UPDATE login_codes SET consumed_at = NOW() WHERE id = $1", [row.id]);
    await pool.query("UPDATE users SET is_verified = TRUE WHERE id = $1", [row.user_id]);
    const user = { id: row.user_id, email: row.email, phone: row.phone };
    const token = signToken(user);
    res.json({ ok: true, token });
  } catch (e) {
    console.error(e);
    res.status(500).json({ ok: false, error: "Error verificando código" });
  }
});

// 3. LOGIN
app.post("/auth/login", async (req, res) => {
  try {
    const { email, password } = req.body;
    const u = await pool.query("SELECT * FROM users WHERE email = $1", [email]);
    if (u.rowCount === 0) return res.status(401).json({ ok: false, error: "Credenciales inválidas" });
    const user = u.rows[0];
    const match = await bcrypt.compare(password, user.password_hash);
    if (!match) return res.status(401).json({ ok: false, error: "Credenciales inválidas" });
    if (!user.is_verified) {
      return res.status(403).json({ ok: false, error: "Cuenta no verificada." });
    }
    const token = signToken(user);
    res.json({ ok: true, token });
  } catch (e) {
    res.status(500).json({ ok: false, error: "Error en login" });
  }
});

// 4. DATOS PROTEGIDOS
app.get("/services", authMiddleware, async (req, res) => {
    const q = await pool.query("SELECT * FROM services WHERE user_id = $1 ORDER BY created_at DESC", [req.user.sub]);
    res.json({ ok: true, services: q.rows });
});

const port = process.env.PORT || 3000;
app.listen(port, () => console.log(`🚀 Server en puerto ${port}`));