package com.guinetik.hexafun.examples.sysmon;
   
   import java.io.File;
   import java.lang.management.ManagementFactory;
   import java.lang.management.MemoryMXBean;
   import java.lang.management.OperatingSystemMXBean;
   
   /**
    * Real implementation of MetricsProvider using JVM/OS metrics.
   *
   * <p>Uses Java's management beans to read actual system metrics.
   * Note: CPU load may return -1 if not available on the platform.</p>
   */
  public class RealMetricsProvider implements MetricsProvider {
  
      private final OperatingSystemMXBean osBean;
      private final MemoryMXBean memoryBean;
  
      public RealMetricsProvider() {
          this.osBean = ManagementFactory.getOperatingSystemMXBean();
          this.memoryBean = ManagementFactory.getMemoryMXBean();
      }
  
      @Override
      public double getCpuUsage() {
          if (
              osBean instanceof com.sun.management.OperatingSystemMXBean sunBean
          ) {
              double load = sunBean.getCpuLoad();
  
              // First call returns -1, need to wait and retry
              if (load < 0) {
                  try {
                      Thread.sleep(100); // Let it collect data
                      load = sunBean.getCpuLoad();
                  } catch (InterruptedException ignored) {}
              }
  
              if (load >= 0) {
                  return load * 100.0;
              }
          }
          return -1;
      }
  
      @Override
      public double getMemoryUsage() {
          if (
              osBean instanceof com.sun.management.OperatingSystemMXBean sunBean
          ) {
              long total = sunBean.getTotalMemorySize();
              long free = sunBean.getFreeMemorySize();
              if (total > 0) {
                  return ((double) (total - free) / total) * 100.0;
              }
          }
  
          // Fallback: JVM heap usage (not system memory, but better than nothing)
          var heap = memoryBean.getHeapMemoryUsage();
          return ((double) heap.getUsed() / heap.getMax()) * 100.0;
      }
  
      @Override
      public double getDiskUsage() {
          // Get all roots and pick the main one
          File[] roots = File.listRoots();
          if (roots.length == 0) return -1;
  
          // Use first root (C:\ on Windows, / on Unix)
          File root = roots[0];
          long total = root.getTotalSpace();
          long free = root.getUsableSpace(); // usableSpace is more accurate than freeSpace
  
          if (total > 0) {
              return ((double) (total - free) / total) * 100.0;
          }
          return -1;
      }
  }