/*
    * Copyright 2012-2025 CodeLibs Project and the Others.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied. See the License for the specific language
   * governing permissions and limitations under the License.
   */
  package org.codelibs.fess.util;
  
  import static org.apache.commons.io.FileUtils.ONE_EB_BI;
  import static org.apache.commons.io.FileUtils.ONE_GB_BI;
  import static org.apache.commons.io.FileUtils.ONE_KB_BI;
  import static org.apache.commons.io.FileUtils.ONE_MB_BI;
  import static org.apache.commons.io.FileUtils.ONE_PB_BI;
  import static org.apache.commons.io.FileUtils.ONE_TB_BI;
  
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.time.LocalDateTime;
  import java.time.ZonedDateTime;
  import java.util.Collection;
  import java.util.Date;
  import java.util.Map;
  import java.util.Objects;
  
  /**
   * Utility class for memory operations and size calculations.
   */
  public final class MemoryUtil {
      private MemoryUtil() {
      }
  
      /**
       * Gets a formatted memory usage log string.
       *
       * @return formatted memory usage information
       */
      public static String getMemoryUsageLog() {
          final Runtime runtime = Runtime.getRuntime();
          final long freeBytes = runtime.freeMemory();
          final long maxBytes = runtime.maxMemory();
          final long totalBytes = runtime.totalMemory();
          final long usedBytes = totalBytes - freeBytes;
          return "Mem:{used " + byteCountToDisplaySize(usedBytes) + ", heap " + byteCountToDisplaySize(totalBytes) + ", max "
                  + byteCountToDisplaySize(maxBytes) + "}";
      }
  
      /**
       * Converts byte count to human-readable size format.
       *
       * @param size the size in bytes
       * @return formatted size string
       */
      public static String byteCountToDisplaySize(final long size) {
          return byteCountToDisplaySize(BigInteger.valueOf(size));
      }
  
      private static String byteCountToDisplaySize(final BigInteger size) {
          Objects.requireNonNull(size, "size");
          final String displaySize;
  
          if (size.divide(ONE_EB_BI).compareTo(BigInteger.ZERO) > 0) {
              displaySize = new BigDecimal(size.divide(ONE_PB_BI)).divide(BigDecimal.valueOf(1000)) + "EB";
          } else if (size.divide(ONE_PB_BI).compareTo(BigInteger.ZERO) > 0) {
              displaySize = new BigDecimal(size.divide(ONE_TB_BI)).divide(BigDecimal.valueOf(1000)) + "PB";
          } else if (size.divide(ONE_TB_BI).compareTo(BigInteger.ZERO) > 0) {
              displaySize = new BigDecimal(size.divide(ONE_GB_BI)).divide(BigDecimal.valueOf(1000)) + "TB";
          } else if (size.divide(ONE_GB_BI).compareTo(BigInteger.ZERO) > 0) {
              displaySize = new BigDecimal(size.divide(ONE_MB_BI)).divide(BigDecimal.valueOf(1000)) + "GB";
          } else if (size.divide(ONE_MB_BI).compareTo(BigInteger.ZERO) > 0) {
              displaySize = new BigDecimal(size.divide(ONE_KB_BI)).divide(BigDecimal.valueOf(1000)) + "MB";
          } else if (size.divide(ONE_KB_BI).compareTo(BigInteger.ZERO) > 0) {
              displaySize = new BigDecimal(size).divide(BigDecimal.valueOf(1000)) + "KB";
          } else {
              displaySize = size + "bytes";
          }
          return displaySize;
      }
  
      /**
       * Gets the currently used memory in bytes.
       *
       * @return used memory in bytes
       */
      public static long getUsedMemory() {
          final Runtime runtime = Runtime.getRuntime();
          final long freeBytes = runtime.freeMemory();
          final long totalBytes = runtime.totalMemory();
          return totalBytes - freeBytes;
      }
  
     /**
      * Estimates the size of an object in bytes.
      *
      * @param obj the object to calculate size for
      * @return estimated size in bytes
      */
     public static long sizeOf(final Object obj) {
         if (obj == null) {
             return 0L;
         }
         if (obj instanceof String) {
             return ((String) obj).length() + 56L;
         }
         if (obj instanceof Number) {
             return 24L;
         }
         if (obj instanceof Date) {
             return 32L;
         }
         if (obj instanceof LocalDateTime) {
             return 80L;
         }
         if (obj instanceof ZonedDateTime) {
             return 2128L;
         }
         if (obj instanceof Object[]) {
             long size = 0;
             for (final Object value : (Object[]) obj) {
                 size += sizeOf(value);
             }
             return size;
         }
         if (obj instanceof Collection<?>) {
             long size = 0;
             for (final Object value : (Collection<?>) obj) {
                 size += sizeOf(value);
             }
             return size;
         }
         if (obj instanceof Map<?, ?>) {
             long size = 0;
             for (final Map.Entry<?, ?> entry : ((Map<?, ?>) obj).entrySet()) {
                 size += sizeOf(entry.getKey());
                 size += sizeOf(entry.getValue());
             }
             return size;
         }
         return 16L;
     }
 }