// main.js
// Express server for: Ops UI (static) + SSE stream + Local WhatsApp Simulator + simple in-memory stores
// Run: npm i express cors  &&  node main.js
// Open: http://localhost:3000

import express from "express";
import cors from "cors";
import crypto from "crypto";
import path from "path";
import { fileURLToPath } from "url";

const app = express();
app.use(cors());
app.use(express.json({ limit: "1mb" }));

// Serve /public as static (UI + webcomponents)
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const publicDir = path.join(__dirname, "public");
app.use(express.static(publicDir));

/**
 * In-memory store (MVP). Replace with Postgres later.
 */
const conversations = new Map(); // chat_id -> conversation snapshot
const runs = new Map(); // run_id -> run object

/**
 * SSE clients (Server-Sent Events)
 */
const sseClients = new Set();

function sseSend(event, data) {
  const payload = `event: ${event}\ndata: ${JSON.stringify(data)}\n\n`;
  for (const res of sseClients) res.write(payload);
}

function nowIso() {
  return new Date().toISOString();
}

function newId(prefix = "run") {
  return `${prefix}_${crypto.randomUUID()}`;
}

function upsertConversation(chat_id, patch) {
  const prev = conversations.get(chat_id) || {
    chat_id,
    from: patch.from || chat_id,
    state: "IDLE",
    intent: "other",
    last_activity: nowIso(),
    status: "ok",
    last_run_id: null,
  };

  const next = {
    ...prev,
    ...patch,
    last_activity: nowIso(),
  };

  conversations.set(chat_id, next);
  return next;
}

/**
 * TODO: Replace this with your real pipeline later:
 * - loadState from Postgres
 * - call LLM (structured output)
 * - product search (LIMITED) + resolve ids
 * - create/update Woo order
 * - create MercadoPago link
 * - save state
 */
async function processMessage({ chat_id, from, text }) {
  const prevConv = conversations.get(chat_id) || null;

  const run_id = newId("run");
  const started_at = Date.now();

  // Minimal simulated LLM output (replace later)
  const plan = {
    reply: `Recibido: "${text}". ¿Querés retiro o envío?`,
    next_state: "BUILDING_ORDER",
    intent: "create_order",
    missing_fields: ["delivery_or_pickup"],
    order_action: "none",
    basket_resolved: { items: [] },
  };

  const invariants = {
    ok: true,
    checks: [
      { name: "required_keys_present", ok: true },
      { name: "no_checkout_without_payment_link", ok: true },
      { name: "no_order_action_without_items", ok: true },
    ],
  };

  const run = {
    run_id,
    ts: nowIso(),
    chat_id,
    from,
    status: "ok", // ok|warn|error
    prev_state: prevConv?.state || "IDLE",
    input: { text },
    llm_output: plan,
    tools: [], // later: [{name, ok, ms, input_summary, output_summary}]
    invariants,
    final_reply: plan.reply,
    order_id: null,
    payment_link: null,
    latency_ms: Date.now() - started_at,
  };

  runs.set(run_id, run);

  const conv = upsertConversation(chat_id, {
    from,
    state: plan.next_state,
    intent: plan.intent,
    status: run.status,
    last_run_id: run_id,
  });

  // Push realtime events to UI
  sseSend("conversation.upsert", conv);
  sseSend("run.created", run);

  return run;
}

/**
 * SSE endpoint (UI connects here)
 */
app.get("/stream", (req, res) => {
  res.setHeader("Content-Type", "text/event-stream");
  res.setHeader("Cache-Control", "no-cache");
  res.setHeader("Connection", "keep-alive");

  // If compression middleware ever added, you'd need res.flushHeaders()
  res.flushHeaders?.();

  // hello event
  res.write(`event: hello\ndata: ${JSON.stringify({ ts: nowIso() })}\n\n`);

  sseClients.add(res);

  req.on("close", () => {
    sseClients.delete(res);
    res.end();
  });
});

/**
 * Local WhatsApp Simulator:
 * POST /sim/send  { chat_id, from_phone, text }
 */
app.post("/sim/send", async (req, res) => {
  const { chat_id, from_phone, text } = req.body || {};
  if (!chat_id || !from_phone || !text) {
    return res.status(400).json({ ok: false, error: "chat_id, from_phone, text are required" });
  }
  try {
    const run = await processMessage({ chat_id, from: from_phone, text });
    res.json({ ok: true, run_id: run.run_id, reply: run.final_reply });
  } catch (err) {
    res.status(500).json({ ok: false, error: "internal_error", detail: String(err?.message || err) });
  }
});

/**
 * List conversations
 * GET /conversations?q=&status=&state=
 */
app.get("/conversations", (req, res) => {
  const { q = "", status = "", state = "" } = req.query;

  const items = [...conversations.values()]
    .filter(c => (q ? (String(c.chat_id).includes(q) || String(c.from).includes(q)) : true))
    .filter(c => (status ? c.status === status : true))
    .filter(c => (state ? c.state === state : true))
    .sort((a, b) => (a.last_activity < b.last_activity ? 1 : -1));

  res.json({ items });
});

/**
 * List runs (optionally by chat_id)
 * GET /runs?chat_id=&limit=50
 */
app.get("/runs", (req, res) => {
  const { chat_id, limit = "50" } = req.query;
  const lim = Math.max(1, Math.min(200, parseInt(limit, 10) || 50));

  let items = [...runs.values()].sort((a, b) => (a.ts < b.ts ? 1 : -1));
  if (chat_id) items = items.filter(r => r.chat_id === chat_id);

  res.json({ items: items.slice(0, lim) });
});

/**
 * Run detail
 * GET /runs/:run_id
 */
app.get("/runs/:run_id", (req, res) => {
  const run = runs.get(req.params.run_id);
  if (!run) return res.status(404).json({ ok: false, error: "not_found" });
  res.json(run);
});

/**
 * Root: serve UI
 */
app.get("/", (req, res) => {
  res.sendFile(path.join(publicDir, "index.html"));
});

const port = process.env.PORT || 3000;
app.listen(port, () => {
  console.log(`UI: http://localhost:${port}`);
});