package com.atlassian.vcache;
   
   import java.time.Duration;
   import java.util.Optional;
   import javax.annotation.Nonnull;
   
   import com.atlassian.annotations.PublicApi;
   
   import static com.atlassian.vcache.SettingsUtils.ifPresent;
  import static java.util.Objects.requireNonNull;
  
  /**
   * An immutable representation of settings for an {@link JvmCache}.
   *
   * @since 1.0
   */
  @PublicApi
  public class JvmCacheSettings
  {
      private final Optional<Integer> maxEntries;
      private final Optional<Duration> defaultTtl;
  
      JvmCacheSettings(Optional<Integer> maxEntries, Optional<Duration> defaultTtl)
      {
          this.maxEntries = requireNonNull(maxEntries);
          this.defaultTtl = requireNonNull(defaultTtl);
      }
  
      /**
       * Returns a new {@link JvmCacheSettings} instance where the current settings
       * are overridden with settings specified in <tt>overrides</tt>. Only properties
       * in <tt>overrides</tt> that are present will be applied.
       * @param overrides contains the settings to override
       * @return a new {@link JvmCacheSettings} instance with the <tt>overrides</tt> settings applied.
       */
      @Nonnull
      public JvmCacheSettings override(JvmCacheSettings overrides)
      {
          return new JvmCacheSettings(
                  ifPresent(overrides.getMaxEntries(), getMaxEntries()),
                  ifPresent(overrides.getDefaultTtl(), getDefaultTtl()));
      }
  
      /**
       * Returns the maximum number of entries allowed.
       * @return the maximum number of entries allowed.
       */
      @Nonnull
      public Optional<Integer> getMaxEntries()
      {
          return maxEntries;
      }
  
      /**
       * Returns the default time-to-live for entries when added.
       * @return the default time-to-live for entries when added.
       */
      @Nonnull
      public Optional<Duration> getDefaultTtl()
      {
          return defaultTtl;
      }
  }