const { Pool } = require('pg');
const logger = require('./logger');

/**
 * Health Monitoring Module
 * Tracks application health metrics including uptime and database connectivity
 */

const startTime = Date.now();

/**
 * Get application health status
 * @returns {Object} Health status object with status, uptime, and timestamp
 */
async function getHealthStatus(pool) {
  try {
    // Check database connectivity
    const dbHealthStart = Date.now();
    const dbResult = await pool.query('SELECT NOW()');
    const dbHealthDuration = Date.now() - dbHealthStart;
    
    const dbHealthy = dbResult.rows.length > 0;

    return {
      status: dbHealthy ? 'healthy' : 'degraded',
      uptime: Math.floor((Date.now() - startTime) / 1000), // uptime in seconds
      timestamp: new Date().toISOString(),
      database: {
        connected: dbHealthy,
        responseTime: `${dbHealthDuration}ms`
      }
    };
  } catch (err) {
    logger.error('Health check failed', { error: err.message });
    return {
      status: 'unhealthy',
      uptime: Math.floor((Date.now() - startTime) / 1000),
      timestamp: new Date().toISOString(),
      database: {
        connected: false,
        error: err.message
      }
    };
  }
}

/**
 * Get uptime in seconds since application start
 * @returns {number} Uptime in seconds
 */
function getUptime() {
  return Math.floor((Date.now() - startTime) / 1000);
}

module.exports = {
  getHealthStatus,
  getUptime
};