package com.atlassian.vcache.internal.core;
   
   import com.atlassian.marshalling.api.MarshallingException;
   import com.atlassian.marshalling.api.MarshallingPair;
   import com.atlassian.vcache.ExternalCacheException;
   
   import javax.annotation.Nullable;
   import java.time.Duration;
   import java.util.Optional;
  import java.util.concurrent.CompletableFuture;
  import java.util.concurrent.CompletionStage;
  import java.util.function.LongConsumer;
  
  import static com.atlassian.vcache.ExternalCacheException.Reason.MARSHALLER_FAILURE;
  import static java.util.Objects.requireNonNull;
  
  /**
   * Contains common implementation methods.
   *
   * @since 1.0.0
   */
  public class VCacheCoreUtils {
      /**
       * Returns a successfully completed {@link CompletionStage} with the specified result.
       *
       * @param value the result for the future
       * @param <T>   the type of the result
       * @return a successfully completed {@link CompletionStage} with the specified result.
       */
      public static <T> CompletionStage<T> successful(T value) {
          final CompletableFuture<T> result = new CompletableFuture<>();
          result.complete(value);
          return result;
      }
  
      /**
       * Returns a failed {@link CompletionStage} with the specified cause.
       *
       * @param cause the cause of the failure
       * @param <T>   the type of the result
       * @param result A CompletionStage containing the result.
       *
       * @return a failed {@link CompletionStage} with the specified cause.
       */
      public static <T> CompletionStage<T> failed(CompletionStage<T> result, Throwable cause) {
          result.toCompletableFuture().completeExceptionally(cause);
          return result;
      }
  
      public static int roundUpToSeconds(Duration time) {
          if (time.isNegative()) {
              throw new IllegalArgumentException("duration cannot be negative: " + time);
          }
  
          final long result = (time.getNano() > 0) ? time.getSeconds() + 1 : time.getSeconds();
  
          if (result > Integer.MAX_VALUE) {
              throw new IllegalArgumentException("duration exceeds maximum number that can be held in an int");
          }
  
          return (int) result;
      }
  
      public static void whenPositive(long number, LongConsumer handler) {
          if (number > 0) {
              handler.accept(number);
          }
      }
  
      public static <V> byte[] marshall(V data, MarshallingPair<V> valueMarshalling) throws ExternalCacheException {
          try {
              return valueMarshalling.getMarshaller().marshallToBytes(requireNonNull(data));
          } catch (MarshallingException e) {
              throw new ExternalCacheException(MARSHALLER_FAILURE, e);
          }
      }
  
      public static <V> Optional<V> unmarshall(@Nullable byte[] data, MarshallingPair<V> valueMarshalling) throws ExternalCacheException {
          if (data == null) {
              return Optional.empty();
          }
  
          try {
              return Optional.of(valueMarshalling.getUnmarshaller().unmarshallFrom(data));
          } catch (MarshallingException ex) {
              throw new ExternalCacheException(MARSHALLER_FAILURE, ex);
          }
      }
  
      public static <K> boolean isEmpty(Iterable<K> iter) {
          return !iter.iterator().hasNext();
      }
  }