/*
    * Copyright 2014 Jin Kwon <jinahya_at_gmail.com>.
    *
    * 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 com.github.jinahya.simple.file.back;
  
  
  import com.github.jinahya.simple.file.back.FileBack.FileOperation;
  import java.nio.ByteBuffer;
  import java.nio.channels.ReadableByteChannel;
  import java.nio.channels.WritableByteChannel;
  import java.util.Optional;
  import static java.util.Optional.ofNullable;
  import java.util.function.Consumer;
  import java.util.function.Supplier;
  
  
  /**
   * A context between clients and file backs.
   *
   * @author Jin Kwon <jinahya_at_gmail.com>
   */
  public interface FileContext {
  
  
      /**
       * Properties can be configured within file contexts.
       */
      public static enum PropertyKey {
  
  
          /**
           * A constant for the key of a property whose value is an instance of
           * {@code Supplier<FileOperation>} which supplies the target operation.
           */
          FILE_OPERATION_SUPPLIER,
          /**
           * A constant for the key of a property whose value is an instance of
           * {@code Consumer<String>} which consumes the path name.
           */
          PATH_NAME_CONSUMER,
          /**
           * A constant for the key of a property whose values si an instance of
           * {@code Supplier<String>} which supplies the path name.
           */
          PATH_NAME_SUPPLIER,
          /**
           * A constant for the key of a property whose value is an instance of
           * {@code Consumer<ReadableByteChannel>} which consumes source file
           * channel.
           */
          SOURCE_CHANNEL_CONSUMER,
          /**
           * A constant for the key of a property whose value is an instance of
           * {@code Consumer<WritableByteChannel>} which consumes the target file
           * channel.
           */
          TARGET_CHANNEL_CONSUMER,
          /**
           * A constant for the key of a property whose value is an instance of
           * {@code Supplier<RedableByteChanel>} which supplies the source file
           * channel.
           */
          SOURCE_CHANNEL_SUPPLIER,
          /**
           * A constant for the key of a property whose value is an instance of
           * {@code Supplier<WritableByteChannel>} which supplies a target file
           * channel.
           */
          TARGET_CHANNEL_SUPPLIER,
          /**
           * A constants for the key of a property whose value is an instance of
           * {@code Consumer<Long>} which consumes the number of bytes copied from
           * the source file part.
           */
          SOURCE_COPIED_CONSUMER,
          /**
           * A constant for the key of a property whose value is an instance of
           * {@code Consumer<Long>} which consumes the number of bytes copied to
           * target file part.
           */
          TARGET_COPIED_CONSUMER,
          /**
           * A constant for the key of a property whose value is an instance of
           * {@code Supplier<ByteBuffer>} which supplies the key bytes for
           * locating the source file part.
          */
         SOURCE_KEY_SUPPLIER,
         /**
          * A constant for the key of a property whose value is an instance of
          * {@code Supplier<ByteBuffer>} which supplies the key bytes the
          * locating the target file part.
          */
         TARGET_KEY_SUPPLIER,
         /**
          * A constant for the key of a property whose value is an instance of
          * {@code Consumer<Object>} which consumes an implementation specific
          * type of source file reference.
          */
         SOURCE_OBJECT_CONSUMER,
         /**
          * A constant for the key of a property whose value is an instance of
          * {@code Consumer<Object>} which consumes an implementation specific
          * type of target file reference.
          */
         TARGET_OBJECT_CONSUMER
 
 
     }
 
 
     /**
      * Returns an optional property value mapped to specified
      * {@code propertyKey}.
      *
      * @param propertyKey the property key
      *
      * @return an optional value.
      */
     Optional<Object> property(PropertyKey propertyKey);
 
 
     /**
      * Returns an optional property value mapped to specified
      * {@code propertyKey}.
      *
      * @param <T> value type parameter
      * @param proprtyKey property key
      * @param valueType value type.
      *
      * @return an optional value of property.
      */
     default <T> Optional<T> property(final PropertyKey proprtyKey,
                                      final Class<T> valueType) {
 
         if (valueType == null) {
             throw new NullPointerException("null type");
         }
 
         return ofNullable(valueType.cast(property(proprtyKey).orElse(null)));
     }
 
 
     /**
      * Sets a new property value mapped to specified {@code propertyKey}. Note
      * that providing {@code null} for {@code propertyValue} will remove
      * previous mapping.
      *
      * @param propertyKey the property key
      * @param propertyValue the property value; {@code null} for removal of
      * mapping.
      *
      * @return an optional property value previously mapped to specified
      * {@code propertyKey}.
      */
     Optional<Object> property(PropertyKey propertyKey, Object propertyValue);
 
 
     /**
      * Sets a new property value mapped to specified {@code propertyKey}.
      *
      * @param <T> value type parameter
      * @param propertyKey property key
      * @param propertyValue the new property value.
      * @param valueType value type.
      *
      * @return an optional property value previously mapped to specified
      * {@code propertyKey}.
      */
     default <T> Optional<T> property(final PropertyKey propertyKey,
                                      final T propertyValue,
                                      final Class<T> valueType) {
 
         if (valueType == null) {
             throw new NullPointerException("null type");
         }
 
         return ofNullable(valueType.cast(property(propertyKey, propertyValue)
             .orElse(null)));
     }
 
 
     /**
      * Return the current property value mapped to
      * {@link PropertyKey#FILE_OPERATION_SUPPLIER}.
      *
      * @return the current value mapped to
      * {@link PropertyKey#FILE_OPERATION_SUPPLIER} or {@code null} if no
      * mappings found.
      */
     @SuppressWarnings("unchecked")
     default Supplier<FileOperation> fileOperationSupplier() {
 
         return (Supplier<FileOperation>) property(
             PropertyKey.FILE_OPERATION_SUPPLIER)
             .orElse(null);
     }
 
 
     /**
      * Sets a new property value mapped to
      * {@link PropertyKey#FILE_OPERATION_SUPPLIER}.
      *
      * @param fileOperationSupplier the new value.
      *
      * @return the previous value mapped to
      * {@link PropertyKey#FILE_OPERATION_SUPPLIER} or {@code null} if there is
      * no mappings.
      */
     @SuppressWarnings("unchecked")
     default Supplier<FileOperation> fileOperationSupplier(
         final Supplier<FileOperation> fileOperationSupplier) {
 
         return (Supplier<FileOperation>) property(
             PropertyKey.FILE_OPERATION_SUPPLIER, fileOperationSupplier)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<String> pathNameConsumer() {
 
         return (Consumer<String>) property(PropertyKey.PATH_NAME_CONSUMER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<String> pathNameConsumer(
         final Consumer<String> pathNameConsumer) {
 
         return (Consumer<String>) property(PropertyKey.PATH_NAME_CONSUMER,
                                            pathNameConsumer)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<String> pathNameSupplier() {
 
         return (Supplier<String>) property(PropertyKey.PATH_NAME_SUPPLIER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<String> pathNameSupplier(
         final Supplier<String> pathNameSupplier) {
 
         return (Supplier<String>) property(PropertyKey.PATH_NAME_SUPPLIER,
                                            pathNameSupplier)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<ReadableByteChannel> sourceChannelConsumer() {
 
         return (Consumer<ReadableByteChannel>) property(
             PropertyKey.SOURCE_CHANNEL_CONSUMER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<ReadableByteChannel> sourceChannelConsumer(
         final Consumer<ReadableByteChannel> sourceChannelConsumer) {
 
         return (Consumer<ReadableByteChannel>) property(
             PropertyKey.SOURCE_CHANNEL_CONSUMER, sourceChannelConsumer)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<ReadableByteChannel> sourceChannelSupplier() {
 
         return (Supplier<ReadableByteChannel>) property(
             PropertyKey.SOURCE_CHANNEL_SUPPLIER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<ReadableByteChannel> sourceChannelSupplier(
         final Supplier<ReadableByteChannel> sourceChannelSuppleir) {
 
         return (Supplier<ReadableByteChannel>) property(
             PropertyKey.SOURCE_CHANNEL_SUPPLIER, sourceChannelSuppleir)
             .orElse(null);
     }
 
 
     /**
      * Returns the current property value mapped to
      * {@link PropertyKey#SOURCE_COPIED_CONSUMER}.
      *
      * @return the current property value mapped to
      * {@link PropertyKey#SOURCE_COPIED_CONSUMER} or {@code null} if no mappings
      * found.
      */
     @SuppressWarnings("unchecked")
     default Consumer<Long> sourceCopiedConsumer() {
 
         return (Consumer<Long>) property(PropertyKey.SOURCE_COPIED_CONSUMER)
             .orElse(null);
     }
 
 
     /**
      * Sets the new value for {@link PropertyKey#SOURCE_COPIED_CONSUMER}.
      *
      * @param sourceCopiedConsumer the new value; {@code null} for removal of
      * entry.
      *
      * @return previous value mapped; possibly {@code null}.
      */
     @SuppressWarnings("unchecked")
     default Consumer<Long> sourceCopiedConsumer(
         final Consumer<Long> sourceCopiedConsumer) {
 
         return (Consumer<Long>) property(PropertyKey.SOURCE_COPIED_CONSUMER,
                                          sourceCopiedConsumer)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<ByteBuffer> sourceKeySupplier() {
 
         return (Supplier<ByteBuffer>) property(PropertyKey.SOURCE_KEY_SUPPLIER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<ByteBuffer> sourceKeySupplier(
         final Supplier<ByteBuffer> sourceKeySupplier) {
 
         return (Supplier<ByteBuffer>) property(PropertyKey.SOURCE_KEY_SUPPLIER,
                                                sourceKeySupplier)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<Object> sourceObjectConsumer() {
 
         return (Consumer<Object>) property(PropertyKey.SOURCE_OBJECT_CONSUMER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<Object> sourceObjectConsumer(
         final Consumer<Object> sourceObjectConsumer) {
 
         return (Consumer<Object>) property(PropertyKey.SOURCE_OBJECT_CONSUMER,
                                            sourceObjectConsumer)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<Long> targetCopiedConsumer() {
 
         return (Consumer<Long>) property(PropertyKey.TARGET_COPIED_CONSUMER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<Long> targetCopiedConsumer(
         final Consumer<Long> targetCopiedConsumer) {
 
         return (Consumer<Long>) property(PropertyKey.TARGET_COPIED_CONSUMER,
                                          targetCopiedConsumer)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<ByteBuffer> targetKeySupplier() {
 
         return (Supplier<ByteBuffer>) property(PropertyKey.TARGET_KEY_SUPPLIER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<ByteBuffer> targetKeySupplier(
         final Supplier<ByteBuffer> targetKeySupplier) {
 
         return (Supplier<ByteBuffer>) property(PropertyKey.TARGET_KEY_SUPPLIER,
                                                targetKeySupplier)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<WritableByteChannel> targetChannelConsumer() {
 
         return (Consumer<WritableByteChannel>) property(
             PropertyKey.TARGET_CHANNEL_CONSUMER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<WritableByteChannel> targetChannelConsumer(
         final Consumer<WritableByteChannel> targetChannelConsumer) {
 
         return (Consumer<WritableByteChannel>) property(
             PropertyKey.TARGET_CHANNEL_CONSUMER, targetChannelConsumer)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<WritableByteChannel> targetChannelSupplier() {
 
         return (Supplier<WritableByteChannel>) property(
             PropertyKey.TARGET_CHANNEL_SUPPLIER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Supplier<WritableByteChannel> targetChannelSupplier(
         final Supplier<WritableByteChannel> targetChannelSupplier) {
 
         return (Supplier<WritableByteChannel>) property(
             PropertyKey.TARGET_CHANNEL_SUPPLIER, targetChannelSupplier)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<Object> targetObjectConsumer() {
 
         return (Consumer<Object>) property(PropertyKey.TARGET_OBJECT_CONSUMER)
             .orElse(null);
     }
 
 
     @SuppressWarnings("unchecked")
     default Consumer<Object> targetObjectConsumer(
         final Consumer<Object> targetObjectConsumer) {
 
         return (Consumer<Object>) property(PropertyKey.TARGET_OBJECT_CONSUMER,
                                            targetObjectConsumer)
             .orElse(null);
     }
 
 
 }