/*
    * Copyright 2020-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.hardware.platform.unix.aix;
   
   import java.util.ArrayList;
   import java.util.Comparator;
   import java.util.List;
  import java.util.Map;
  import java.util.function.Supplier;
  import java.util.stream.Collectors;
  
  import com.sun.jna.Native;
  import com.sun.jna.platform.unix.aix.Perfstat.perfstat_disk_t;
  
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.driver.unix.aix.Ls;
  import oshi.driver.unix.aix.Lscfg;
  import oshi.driver.unix.aix.Lspv;
  import oshi.hardware.HWDiskStore;
  import oshi.hardware.HWPartition;
  import oshi.hardware.common.AbstractHWDiskStore;
  import oshi.util.Constants;
  import oshi.util.tuples.Pair;
  
  /**
   * AIX hard disk implementation.
   */
  @ThreadSafe
  public final class AixHWDiskStore extends AbstractHWDiskStore {
  
      private final Supplier<perfstat_disk_t[]> diskStats;
  
      private long reads = 0L;
      private long readBytes = 0L;
      private long writes = 0L;
      private long writeBytes = 0L;
      private long currentQueueLength = 0L;
      private long transferTime = 0L;
      private long timeStamp = 0L;
      private List<HWPartition> partitionList;
  
      private AixHWDiskStore(String name, String model, String serial, long size, Supplier<perfstat_disk_t[]> diskStats) {
          super(name, model, serial, size);
          this.diskStats = diskStats;
      }
  
      @Override
      public synchronized long getReads() {
          return reads;
      }
  
      @Override
      public synchronized long getReadBytes() {
          return readBytes;
      }
  
      @Override
      public synchronized long getWrites() {
          return writes;
      }
  
      @Override
      public synchronized long getWriteBytes() {
          return writeBytes;
      }
  
      @Override
      public synchronized long getCurrentQueueLength() {
          return currentQueueLength;
      }
  
      @Override
      public synchronized long getTransferTime() {
          return transferTime;
      }
  
      @Override
      public synchronized long getTimeStamp() {
          return timeStamp;
      }
  
      @Override
      public List<HWPartition> getPartitions() {
          return this.partitionList;
      }
  
      @Override
      public synchronized boolean updateAttributes() {
          long now = System.currentTimeMillis();
          for (perfstat_disk_t stat : diskStats.get()) {
              String name = Native.toString(stat.name);
              if (name.equals(this.getName())) {
                  // we only have total transfers so estimate read/write ratio from blocks
                  long blks = stat.rblks + stat.wblks;
                  if (blks == 0L) {
                      this.reads = stat.xfers;
                      this.writes = 0L;
                 } else {
                     long approximateReads = Math.round(stat.xfers * stat.rblks / (double) blks);
                     long approximateWrites = stat.xfers - approximateReads;
                     // Enforce monotonic increase
                     if (approximateReads > this.reads) {
                         this.reads = approximateReads;
                     }
                     if (approximateWrites > this.writes) {
                         this.writes = approximateWrites;
                     }
                 }
                 this.readBytes = stat.rblks * stat.bsize;
                 this.writeBytes = stat.wblks * stat.bsize;
                 this.currentQueueLength = stat.qdepth;
                 this.transferTime = stat.time;
                 this.timeStamp = now;
                 return true;
             }
         }
         return false;
     }
 
     /**
      * Gets the disks on this machine
      *
      * @param diskStats Memoized supplier of disk statistics
      *
      * @return a list of {@link HWDiskStore} objects representing the disks
      */
     public static List<HWDiskStore> getDisks(Supplier<perfstat_disk_t[]> diskStats) {
         Map<String, Pair<Integer, Integer>> majMinMap = Ls.queryDeviceMajorMinor();
         List<AixHWDiskStore> storeList = new ArrayList<>();
         for (perfstat_disk_t disk : diskStats.get()) {
             String storeName = Native.toString(disk.name);
             Pair<String, String> ms = Lscfg.queryModelSerial(storeName);
             String model = ms.getA() == null ? Native.toString(disk.description) : ms.getA();
             String serial = ms.getB() == null ? Constants.UNKNOWN : ms.getB();
             storeList.add(createStore(storeName, model, serial, disk.size << 20, diskStats, majMinMap));
         }
         return storeList.stream()
                 .sorted(Comparator.comparingInt(
                         s -> s.getPartitions().isEmpty() ? Integer.MAX_VALUE : s.getPartitions().get(0).getMajor()))
                 .collect(Collectors.toList());
     }
 
     private static AixHWDiskStore createStore(String diskName, String model, String serial, long size,
             Supplier<perfstat_disk_t[]> diskStats, Map<String, Pair<Integer, Integer>> majMinMap) {
         AixHWDiskStore store = new AixHWDiskStore(diskName, model.isEmpty() ? Constants.UNKNOWN : model, serial, size,
                 diskStats);
         store.partitionList = Lspv.queryLogicalVolumes(diskName, majMinMap);
         store.updateAttributes();
         return store;
     }
 }