import express from "express";
import cors from "cors";
import { listTools, executeTool } from "./agent.js";

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

// Health + welcome
app.get("/", (_req, res) => {
  res.status(200).json({
    status: "ok",
    service: "hf-ubuntu-agent-sse",
    tools: listTools().tools.map((t) => t.name)
  });
});

/**
 * SSE helper
 */
function openSSE(res) {
  res.setHeader("Content-Type", "text/event-stream");
  res.setHeader("Cache-Control", "no-cache, no-transform");
  res.setHeader("Connection", "keep-alive");
  res.flushHeaders?.();

  const send = (event, data) => {
    res.write(`event: ${event}\n`);
    res.write(`data: ${JSON.stringify(data)}\n\n`);
  };

  const keepAlive = setInterval(() => {
    res.write(`event: ping\ndata: "ok"\n\n`);
  }, 15000);

  const close = () => clearInterval(keepAlive);

  return { send, close };
}

/**
 * List available tools (simple JSON)
 */
app.get("/tools", (_req, res) => {
  res.json(listTools());
});

/**
 * MCP-like SSE execution endpoint:
 * GET /exec?tool=shell&command=ls%20-la
 * GET /exec?tool=python&code=print('hi')
 *
 * Body POST alternative also supported: { tool, args }
 */
app.get("/exec", (req, res) => {
  const { send, close } = openSSE(res);
  const tool = String(req.query.tool || "");
  let args = {};

  if (tool === "shell") {
    args = { command: String(req.query.command || "") };
  } else if (tool === "python") {
    args = { code: String(req.query.code || "") };
  }

  send("tools", listTools());

  executeTool(tool, args, send);

  req.on("close", () => {
    close();
  });
});

/**
 * JSON -> SSE execution (POST), useful for programmatic clients.
 * Body: { tool: "shell", args: { command: "ls -la" } }
 */
app.post("/run", (req, res) => {
  const { tool, args } = req.body || {};
  const { send, close } = openSSE(res);

  send("tools", listTools());

  executeTool(tool, args, send);

  req.on("close", () => {
    close();
  });
});

// IMPORTANT: honor HF Spaces $PORT
const PORT = process.env.PORT || 7860;
app.listen(PORT, "0.0.0.0", () => {
  console.log(`Ubuntu agent running on http://0.0.0.0:${PORT}`);
});