/*
    * Copyright 2021-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.hardware.platform.unix.openbsd;
   
   import static oshi.jna.platform.unix.OpenBsdLibc.CTL_VFS;
   import static oshi.jna.platform.unix.OpenBsdLibc.VFS_BCACHESTAT;
   import static oshi.jna.platform.unix.OpenBsdLibc.VFS_GENERIC;
  import static oshi.util.Memoizer.defaultExpiration;
  import static oshi.util.Memoizer.memoize;
  
  import java.util.function.Supplier;
  
  import com.sun.jna.Memory;
  
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.hardware.VirtualMemory;
  import oshi.hardware.common.AbstractGlobalMemory;
  import oshi.jna.platform.unix.OpenBsdLibc.Bcachestats;
  import oshi.util.ExecutingCommand;
  import oshi.util.ParseUtil;
  import oshi.util.platform.unix.openbsd.OpenBsdSysctlUtil;
  
  /**
   * Memory obtained by sysctl vm.stats
   */
  @ThreadSafe
  final class OpenBsdGlobalMemory extends AbstractGlobalMemory {
  
      private final Supplier<Long> available = memoize(OpenBsdGlobalMemory::queryAvailable, defaultExpiration());
  
      private final Supplier<Long> total = memoize(OpenBsdGlobalMemory::queryPhysMem);
  
      private final Supplier<Long> pageSize = memoize(OpenBsdGlobalMemory::queryPageSize);
  
      private final Supplier<VirtualMemory> vm = memoize(this::createVirtualMemory);
  
      @Override
      public long getAvailable() {
          return available.get() * getPageSize();
      }
  
      @Override
      public long getTotal() {
          return total.get();
      }
  
      @Override
      public long getPageSize() {
          return pageSize.get();
      }
  
      @Override
      public VirtualMemory getVirtualMemory() {
          return vm.get();
      }
  
      private static long queryAvailable() {
          long free = 0L;
          long inactive = 0L;
          for (String line : ExecutingCommand.runNative("vmstat -s")) {
              if (line.endsWith("pages free")) {
                  free = ParseUtil.getFirstIntValue(line);
              } else if (line.endsWith("pages inactive")) {
                  inactive = ParseUtil.getFirstIntValue(line);
              }
          }
          int[] mib = new int[3];
          mib[0] = CTL_VFS;
          mib[1] = VFS_GENERIC;
          mib[2] = VFS_BCACHESTAT;
          try (Memory m = OpenBsdSysctlUtil.sysctl(mib)) {
              Bcachestats cache = new Bcachestats(m);
              return (cache.numbufpages + free + inactive);
          }
      }
  
      private static long queryPhysMem() {
          return OpenBsdSysctlUtil.sysctl("hw.physmem", 0L);
      }
  
      private static long queryPageSize() {
          return OpenBsdSysctlUtil.sysctl("hw.pagesize", 4096L);
      }
  
      private VirtualMemory createVirtualMemory() {
          return new OpenBsdVirtualMemory(this);
      }
  }