const express = require('express');
const { spawn } = require('child_process');
const fs = require('fs');
const path = require('path');
const app = express();
const port = 3005; // Port for the GTM Architect service

app.use(express.json({ limit: '50mb' }));

// Determine Environment and Paths
const distPath = path.join(__dirname, 'dist');
const isProduction = fs.existsSync(distPath);
const staticDir = isProduction ? distPath : __dirname;

console.log(`[Init] Serving static files from: ${staticDir}`);
app.use(express.static(staticDir));

// Determine Python Script Path
// In Docker (optimized), script is in same dir. Locally, it might be one level up.
let pythonScriptPath = path.join(__dirname, 'gtm_architect_orchestrator.py');
if (!fs.existsSync(pythonScriptPath)) {
    pythonScriptPath = path.join(__dirname, '../gtm_architect_orchestrator.py');
}
console.log(`[Init] Using Python script at: ${pythonScriptPath}`);


function callPythonScript(mode, data, res) {
    const pythonProcess = spawn('python3', [pythonScriptPath, '--mode', mode]);

    let pythonData = '';
    let errorData = '';

    pythonProcess.stdout.on('data', (data) => {
        pythonData += data.toString();
    });

    pythonProcess.stderr.on('data', (data) => {
        errorData += data.toString();
    });

    pythonProcess.on('close', (code) => {
        if (code !== 0) {
            console.error(`Python script exited with code ${code}`);
            console.error('Stderr:', errorData);
            return res.status(500).json({ error: 'Python script execution failed.', details: errorData });
        }
        try {
            const result = JSON.parse(pythonData);
            res.json(result);
        } catch (e) {
            console.error('Failed to parse Python script output:', e);
            console.error('Raw output:', pythonData);
            res.status(500).json({ error: 'Failed to parse Python script output.', details: pythonData });
        }
    });

    pythonProcess.stdin.write(JSON.stringify(data));
    pythonProcess.stdin.end();
}

// API endpoint to handle requests from the frontend
app.post('/api/gtm', (req, res) => {
    const { mode, data } = req.body;
    if (!mode || !data) {
        return res.status(400).json({ error: 'Missing mode or data in request body' });
    }
    callPythonScript(mode, data, res);
});

// Serve the main index.html for any other requests to support client-side routing
app.get('*', (req, res) => {
  res.sendFile(path.join(staticDir, 'index.html'));
});


const server = app.listen(port, () => {
    console.log(`GTM Architect server listening at http://localhost:${port} (Timeout: 600s)`);
});

// Prevent 502 Bad Gateway by increasing Node.js server timeouts to match Nginx
server.setTimeout(600000);
server.keepAliveTimeout = 610000;
server.headersTimeout = 620000;