const express = require('express');
const cors = require('cors');
const path = require('path');
const { scrapePBTechCPUs } = require('./scrapers/pbtech');
const { fetchBenchmarkData, findBenchmarkScore } = require('./scrapers/cpubenchmark');

const app = express();
const PORT = process.env.PORT || 3000;

app.use(cors());
app.use(express.static('public'));

// Server-Sent Events endpoint for real-time progress
app.get('/api/scrape', async (req, res) => {
  // Set headers for SSE
  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');

  // Helper function to send progress updates
  const sendProgress = (message) => {
    res.write(`data: ${JSON.stringify({ type: 'progress', message })}\n\n`);
  };

  try {
    sendProgress('Starting CPU comparison...');

    // Fetch CPUs from PB Tech
    sendProgress('Step 1/3: Fetching CPUs from PB Tech...');
    const cpus = await scrapePBTechCPUs(sendProgress);

    if (cpus.length === 0) {
      sendProgress('No CPUs found on PB Tech. Please check the website.');
      res.write(`data: ${JSON.stringify({ type: 'error', message: 'No CPUs found' })}\n\n`);
      res.end();
      return;
    }

    // Fetch benchmark data
    sendProgress('Step 2/3: Fetching CPU benchmarks...');
    const benchmarkData = await fetchBenchmarkData(sendProgress);

    // Match CPUs with benchmarks and calculate performance per dollar
    sendProgress('Step 3/3: Calculating performance per dollar...');

    const results = [];
    for (let i = 0; i < cpus.length; i++) {
      const cpu = cpus[i];
      const benchmark = findBenchmarkScore(cpu.name, benchmarkData);

      if (benchmark) {
        const performancePerDollar = benchmark / cpu.price;
        results.push({
          name: cpu.name,
          price: cpu.price,
          benchmark: benchmark,
          performancePerDollar: performancePerDollar,
          inStock: cpu.inStock
        });
      }

      if ((i + 1) % 5 === 0) {
        sendProgress(`Processed ${i + 1}/${cpus.length} CPUs...`);
      }
    }

    // Sort by performance per dollar (descending)
    results.sort((a, b) => b.performancePerDollar - a.performancePerDollar);

    sendProgress(`Found ${results.length} CPUs with benchmark data!`);
    sendProgress('Analysis complete!');

    // Send final results
    res.write(`data: ${JSON.stringify({ type: 'complete', data: results })}\n\n`);
    res.end();

  } catch (error) {
    console.error('Scraping error:', error);
    sendProgress(`Error: ${error.message}`);
    res.write(`data: ${JSON.stringify({ type: 'error', message: error.message })}\n\n`);
    res.end();
  }
});

app.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}`);
});