/*
    * Copyright 2021 The Netty Project
    *
    * The Netty Project licenses this file to you 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:
    *
    *   https://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 io.netty5.buffer.api;
  
  import io.netty5.buffer.api.internal.Statics;
  import io.netty5.buffer.api.internal.WrappingAllocation;
  
  import java.nio.charset.Charset;
  import java.util.function.Supplier;
  
  import static io.netty5.buffer.api.internal.Statics.allocatorClosedException;
  import static io.netty5.buffer.api.internal.Statics.standardDrop;
  
  class ManagedBufferAllocator implements BufferAllocator, AllocatorControl {
      private final MemoryManager manager;
      private final AllocationType allocationType;
      private volatile boolean closed;
  
      ManagedBufferAllocator(MemoryManager manager, boolean direct) {
          this.manager = manager;
          allocationType = direct? StandardAllocationTypes.OFF_HEAP : StandardAllocationTypes.ON_HEAP;
      }
  
      @Override
      public boolean isPooling() {
          return false;
      }
  
      @Override
      public AllocationType getAllocationType() {
          return allocationType;
      }
  
      @Override
      public Buffer allocate(int size) {
          if (closed) {
              throw allocatorClosedException();
          }
          Statics.assertValidBufferSize(size);
          return manager.allocateShared(this, size, standardDrop(manager), allocationType);
      }
  
      @Override
      public Supplier<Buffer> constBufferSupplier(byte[] bytes) {
          if (closed) {
              throw allocatorClosedException();
          }
          Buffer constantBuffer = manager.allocateShared(
                  this, bytes.length, standardDrop(manager), allocationType);
          constantBuffer.writeBytes(bytes).makeReadOnly();
          return () -> manager.allocateConstChild(constantBuffer);
      }
  
      @Override
      public Buffer copyOf(String str, Charset charset) {
          if (!allocationType.isDirect()) {
              // For on-heap buffers we can optimise a bit, and allocate with just one copy operation.
              byte[] bytes = str.getBytes(charset);
              // We use a wrapping allocation type, because the byte array is guaranteed by String to be un-aliased.
              WrappingAllocation allocation = new WrappingAllocation(bytes);
              Buffer buffer = manager.allocateShared(this, bytes.length, standardDrop(manager), allocation);
              return buffer.writerOffset(bytes.length);
          }
          return BufferAllocator.super.copyOf(str, charset);
      }
  
      @Override
      public void close() {
          closed = true;
      }
  
      @Override
      public BufferAllocator getAllocator() {
          return this;
      }
  }