server.js

import { randomBytes } from "node:crypto";
import cors from "cors";
import express from "express";

const app = express();

// Environment configuration
const PORT = process.env.PORT || 3001;

// Middleware
app.use(cors());
app.use(express.json());

// ==================== In-memory DB ====================
// sessionId -> { createdAt, updatedAt, userId, messages: [{ role, content, timestamp }] }
const sessions = new Map();

function nowMs() {
  return Date.now();
}

function createSessionId() {
  return `session-${nowMs()}-${randomBytes(6).toString("hex")}`;
}

function getOrCreateSession(sessionId, userId) {
  if (sessionId && sessions.has(sessionId)) {
    return sessions.get(sessionId);
  }
  const id = sessionId || createSessionId();
  const session = {
    id,
    userId: userId || "demo-user",
    createdAt: nowMs(),
    updatedAt: nowMs(),
    messages: [],
  };
  sessions.set(id, session);
  return session;
}

function buildReply(message, session) {
  const trimmed = String(message || "").trim();
  if (!trimmed) {
    return {
      message: "I didn't catch that — can you rephrase?",
      confidence: 0.6,
      suggestions: [],
    };
  }

  const lower = trimmed.toLowerCase();
  if (lower.includes("help")) {
    return {
      message:
        "Try: “Summarize my last message”, “Give me 3 next steps”, or “Ask me clarifying questions.”",
      confidence: 0.9,
      suggestions: [
        "Summarize my last message",
        "Give me 3 next steps",
        "Ask me clarifying questions",
      ],
    };
  }

  return {
    message: `You said: "${trimmed}". (Session messages: ${session.messages.length})`,
    confidence: 0.9,
    suggestions: [],
  };
}

// ==================== API ROUTES ====================

// Health check
app.get("/health", (_req, res) => {
  res.json({ status: "ok", timestamp: new Date().toISOString() });
});

// Chat with Eliza (in-memory demo)
app.post("/api/chat/eliza", async (req, res) => {
  try {
    const { message, sessionId, userId } = req.body ?? {};
    const session = getOrCreateSession(sessionId, userId);

    session.messages.push({
      role: "user",
      content: String(message ?? ""),
      timestamp: nowMs(),
    });
    session.updatedAt = nowMs();

    const reply = buildReply(message, session);
    session.messages.push({
      role: "assistant",
      content: reply.message,
      timestamp: nowMs(),
    });
    session.updatedAt = nowMs();

    res.json({ ...reply, sessionId: session.id });
  } catch (error) {
    console.error("Error chatting with Eliza:", error);
    res.status(500).json({ error: error.message });
  }
});

// Start server
app.listen(PORT, () => {
  console.log(`🤖 Eliza Classic Chat API running on port ${PORT}`);
});