/*
    * Copyright 2016-2022 The OSHI Project Contributors
    * SPDX-License-Identifier: MIT
    */
   package oshi.util.platform.unix.freebsd;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
  import com.sun.jna.Memory;
  import com.sun.jna.Native;
  import com.sun.jna.Structure;
  import com.sun.jna.platform.unix.LibCAPI.size_t;
  
  import oshi.annotation.concurrent.ThreadSafe;
  import oshi.jna.ByRef.CloseableSizeTByReference;
  import oshi.jna.platform.unix.FreeBsdLibc;
  
  /**
   * Provides access to sysctl calls on FreeBSD
   */
  @ThreadSafe
  public final class BsdSysctlUtil {
  
      private static final Logger LOG = LoggerFactory.getLogger(BsdSysctlUtil.class);
  
      private static final String SYSCTL_FAIL = "Failed sysctl call: {}, Error code: {}";
  
      private BsdSysctlUtil() {
      }
  
      /**
       * Executes a sysctl call with an int result
       *
       * @param name name of the sysctl
       * @param def  default int value
       * @return The int result of the call if successful; the default otherwise
       */
      public static int sysctl(String name, int def) {
          int intSize = FreeBsdLibc.INT_SIZE;
          try (Memory p = new Memory(intSize); CloseableSizeTByReference size = new CloseableSizeTByReference(intSize)) {
              if (0 != FreeBsdLibc.INSTANCE.sysctlbyname(name, p, size, null, size_t.ZERO)) {
                  LOG.warn(SYSCTL_FAIL, name, Native.getLastError());
                  return def;
              }
              return p.getInt(0);
          }
      }
  
      /**
       * Executes a sysctl call with a long result
       *
       * @param name name of the sysctl
       * @param def  default long value
       * @return The long result of the call if successful; the default otherwise
       */
      public static long sysctl(String name, long def) {
          int uint64Size = FreeBsdLibc.UINT64_SIZE;
          try (Memory p = new Memory(uint64Size);
                  CloseableSizeTByReference size = new CloseableSizeTByReference(uint64Size)) {
              if (0 != FreeBsdLibc.INSTANCE.sysctlbyname(name, p, size, null, size_t.ZERO)) {
                  LOG.warn(SYSCTL_FAIL, name, Native.getLastError());
                  return def;
              }
              return p.getLong(0);
          }
      }
  
      /**
       * Executes a sysctl call with a String result
       *
       * @param name name of the sysctl
       * @param def  default String value
       * @return The String result of the call if successful; the default otherwise
       */
      public static String sysctl(String name, String def) {
          // Call first time with null pointer to get value of size
          try (CloseableSizeTByReference size = new CloseableSizeTByReference()) {
              if (0 != FreeBsdLibc.INSTANCE.sysctlbyname(name, null, size, null, size_t.ZERO)) {
                  LOG.warn(SYSCTL_FAIL, name, Native.getLastError());
                  return def;
              }
              // Add 1 to size for null terminated string
              try (Memory p = new Memory(size.longValue() + 1L)) {
                  if (0 != FreeBsdLibc.INSTANCE.sysctlbyname(name, p, size, null, size_t.ZERO)) {
                      LOG.warn(SYSCTL_FAIL, name, Native.getLastError());
                      return def;
                  }
                  return p.getString(0);
              }
          }
      }
  
      /**
       * Executes a sysctl call with a Structure result
       *
       * @param name   name of the sysctl
       * @param struct structure for the result
       * @return True if structure is successfuly populated, false otherwise
      */
     public static boolean sysctl(String name, Structure struct) {
         try (CloseableSizeTByReference size = new CloseableSizeTByReference(struct.size())) {
             if (0 != FreeBsdLibc.INSTANCE.sysctlbyname(name, struct.getPointer(), size, null, size_t.ZERO)) {
                 LOG.error(SYSCTL_FAIL, name, Native.getLastError());
                 return false;
             }
         }
         struct.read();
         return true;
     }
 
     /**
      * Executes a sysctl call with a Pointer result
      *
      * @param name name of the sysctl
      * @return An allocated memory buffer containing the result on success, null otherwise. Its value on failure is
      *         undefined.
      */
     public static Memory sysctl(String name) {
         try (CloseableSizeTByReference size = new CloseableSizeTByReference()) {
             if (0 != FreeBsdLibc.INSTANCE.sysctlbyname(name, null, size, null, size_t.ZERO)) {
                 LOG.error(SYSCTL_FAIL, name, Native.getLastError());
                 return null;
             }
             Memory m = new Memory(size.longValue());
             if (0 != FreeBsdLibc.INSTANCE.sysctlbyname(name, m, size, null, size_t.ZERO)) {
                 LOG.error(SYSCTL_FAIL, name, Native.getLastError());
                 m.close();
                 return null;
             }
             return m;
         }
     }
 }