/*
    * Copyright 2020-2023 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.software.os.linux;
   
   import java.util.Locale;
   import java.util.Map;
   
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.driver.linux.proc.ProcessStat;
  import oshi.software.common.AbstractOSThread;
  import oshi.software.os.OSProcess.State;
  import oshi.util.FileUtil;
  import oshi.util.ParseUtil;
  import oshi.util.platform.linux.ProcPath;
  
  /**
   * OSThread implementation
   */
  @ThreadSafe
  public class LinuxOSThread extends AbstractOSThread {
  
      private static final int[] PROC_TASK_STAT_ORDERS = new int[LinuxOSThread.ThreadPidStat.values().length];
      static {
          for (LinuxOSThread.ThreadPidStat stat : LinuxOSThread.ThreadPidStat.values()) {
              // The PROC_PID_STAT enum indices are 1-indexed.
              // Subtract one to get a zero-based index
              PROC_TASK_STAT_ORDERS[stat.ordinal()] = stat.getOrder() - 1;
          }
      }
  
      private final int threadId;
      private String name;
      private State state = State.INVALID;
      private long minorFaults;
      private long majorFaults;
      private long startMemoryAddress;
      private long contextSwitches;
      private long kernelTime;
      private long userTime;
      private long startTime;
      private long upTime;
      private int priority;
  
      public LinuxOSThread(int processId, int tid) {
          super(processId);
          this.threadId = tid;
          updateAttributes();
      }
  
      @Override
      public int getThreadId() {
          return this.threadId;
      }
  
      @Override
      public String getName() {
          return this.name;
      }
  
      @Override
      public State getState() {
          return this.state;
      }
  
      @Override
      public long getStartTime() {
          return this.startTime;
      }
  
      @Override
      public long getStartMemoryAddress() {
          return this.startMemoryAddress;
      }
  
      @Override
      public long getContextSwitches() {
          return this.contextSwitches;
      }
  
      @Override
      public long getMinorFaults() {
          return this.minorFaults;
      }
  
      @Override
      public long getMajorFaults() {
          return this.majorFaults;
      }
  
      @Override
      public long getKernelTime() {
          return this.kernelTime;
      }
  
      @Override
      public long getUserTime() {
          return this.userTime;
     }
 
     @Override
     public long getUpTime() {
         return this.upTime;
     }
 
     @Override
     public int getPriority() {
         return this.priority;
     }
 
     @Override
     public boolean updateAttributes() {
         this.name = FileUtil.getStringFromFile(
                 String.format(Locale.ROOT, ProcPath.TASK_COMM, this.getOwningProcessId(), this.threadId));
         Map<String, String> status = FileUtil.getKeyValueMapFromFile(
                 String.format(Locale.ROOT, ProcPath.TASK_STATUS, this.getOwningProcessId(), this.threadId), ":");
         String stat = FileUtil.getStringFromFile(
                 String.format(Locale.ROOT, ProcPath.TASK_STAT, this.getOwningProcessId(), this.threadId));
         if (stat.isEmpty()) {
             this.state = State.INVALID;
             return false;
         }
         long now = System.currentTimeMillis();
         long[] statArray = ParseUtil.parseStringToLongArray(stat, PROC_TASK_STAT_ORDERS,
                 ProcessStat.PROC_PID_STAT_LENGTH, ' ');
 
         // BOOTTIME is in seconds and start time from proc/pid/stat is in jiffies.
         // Combine units to jiffies and convert to millijiffies before hz division to
         // avoid precision loss without having to cast
         this.startTime = (LinuxOperatingSystem.BOOTTIME * LinuxOperatingSystem.getHz()
                 + statArray[LinuxOSThread.ThreadPidStat.START_TIME.ordinal()]) * 1000L / LinuxOperatingSystem.getHz();
         // BOOT_TIME could be up to 500ms off and start time up to 5ms off. A process
         // that has started within last 505ms could produce a future start time/negative
         // up time, so insert a sanity check.
         if (this.startTime >= now) {
             this.startTime = now - 1;
         }
         this.minorFaults = statArray[ThreadPidStat.MINOR_FAULTS.ordinal()];
         this.majorFaults = statArray[ThreadPidStat.MAJOR_FAULT.ordinal()];
         this.startMemoryAddress = statArray[ThreadPidStat.START_CODE.ordinal()];
         long voluntaryContextSwitches = ParseUtil.parseLongOrDefault(status.get("voluntary_ctxt_switches"), 0L);
         long nonVoluntaryContextSwitches = ParseUtil.parseLongOrDefault(status.get("nonvoluntary_ctxt_switches"), 0L);
         this.contextSwitches = voluntaryContextSwitches + nonVoluntaryContextSwitches;
         this.state = ProcessStat.getState(status.getOrDefault("State", "U").charAt(0));
         this.kernelTime = statArray[ThreadPidStat.KERNEL_TIME.ordinal()] * 1000L / LinuxOperatingSystem.getHz();
         this.userTime = statArray[ThreadPidStat.USER_TIME.ordinal()] * 1000L / LinuxOperatingSystem.getHz();
         this.upTime = now - startTime;
         this.priority = (int) statArray[ThreadPidStat.PRIORITY.ordinal()];
         return true;
     }
 
     /**
      * Enum used to update attributes. The order field represents the 1-indexed numeric order of the stat in
      * /proc/pid/task/tid/stat per the man file.
      */
     private enum ThreadPidStat {
         // The parsing implementation in ParseUtil requires these to be declared
         // in increasing order
         PPID(4), MINOR_FAULTS(10), MAJOR_FAULT(12), USER_TIME(14), KERNEL_TIME(15), PRIORITY(18), THREAD_COUNT(20),
         START_TIME(22), VSZ(23), RSS(24), START_CODE(26);
 
         private final int order;
 
         ThreadPidStat(int order) {
             this.order = order;
         }
 
         public int getOrder() {
             return this.order;
         }
     }
 }