import { Request, Response } from 'express';
import { getAllMetrics, resetMetrics } from '../utils/metrics.js';
import { getLogger } from '../utils/logging.js';

const logger = getLogger();

/**
 * Get metrics endpoint handler
 */
export function getMetricsHandler(req: Request, res: Response): void {
  try {
    const metrics = getAllMetrics();
    
    // Respond with metrics in requested format
    const format = req.query.format as string;
    if (format === 'text') {
      // Simple text format for metrics
      let text = '';
      
      // Counters
      for (const [key, value] of Object.entries(metrics.counters)) {
        text += `# COUNTER\n${key} ${value}\n`;
      }
      
      // Gauges
      for (const [key, value] of Object.entries(metrics.gauges)) {
        text += `# GAUGE\n${key} ${value}\n`;
      }
      
      // Histograms
      for (const [key, data] of Object.entries(metrics.histograms)) {
        text += '# HISTOGRAM\n';
        // Check if data is an object before using Object.entries
        if (data && typeof data === 'object') {
          for (const [stat, value] of Object.entries(data as Record<string, unknown>)) {
            text += `${key}.${stat} ${value}\n`;
          }
        }
      }
      
      res.setHeader('Content-Type', 'text/plain');
      res.send(text);
    } else {
      // Default to JSON format
      res.json(metrics);
    }
    
    logger.debug('Metrics endpoint called', { 
      clientIp: req.ip, 
      userAgent: req.headers['user-agent'] 
    });
  } catch (error) {
    logger.error('Error in metrics endpoint', { error });
    res.status(500).json({ error: 'Failed to retrieve metrics' });
  }
}

/**
 * Reset metrics endpoint handler
 */
export function resetMetricsHandler(req: Request, res: Response): void {
  try {
    resetMetrics();
    logger.info('Metrics reset', { clientIp: req.ip });
    res.json({ success: true, message: 'Metrics reset successful' });
  } catch (error) {
    logger.error('Error resetting metrics', { error });
    res.status(500).json({ error: 'Failed to reset metrics' });
  }
}