content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF 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
   *
   *    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.apache.arrow.vector;
  
  import static java.util.Arrays.asList;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import org.apache.arrow.util.Preconditions;
  import org.apache.arrow.vector.BufferLayout.BufferType;
  import org.apache.arrow.vector.types.pojo.ArrowType;
  import org.apache.arrow.vector.types.pojo.ArrowType.ArrowTypeVisitor;
  import org.apache.arrow.vector.types.pojo.ArrowType.Binary;
  import org.apache.arrow.vector.types.pojo.ArrowType.BinaryView;
  import org.apache.arrow.vector.types.pojo.ArrowType.Bool;
  import org.apache.arrow.vector.types.pojo.ArrowType.Date;
  import org.apache.arrow.vector.types.pojo.ArrowType.Decimal;
  import org.apache.arrow.vector.types.pojo.ArrowType.Duration;
  import org.apache.arrow.vector.types.pojo.ArrowType.FixedSizeBinary;
  import org.apache.arrow.vector.types.pojo.ArrowType.FixedSizeList;
  import org.apache.arrow.vector.types.pojo.ArrowType.FloatingPoint;
  import org.apache.arrow.vector.types.pojo.ArrowType.Int;
  import org.apache.arrow.vector.types.pojo.ArrowType.Interval;
  import org.apache.arrow.vector.types.pojo.ArrowType.LargeBinary;
  import org.apache.arrow.vector.types.pojo.ArrowType.LargeUtf8;
  import org.apache.arrow.vector.types.pojo.ArrowType.Map;
  import org.apache.arrow.vector.types.pojo.ArrowType.Null;
  import org.apache.arrow.vector.types.pojo.ArrowType.RunEndEncoded;
  import org.apache.arrow.vector.types.pojo.ArrowType.Struct;
  import org.apache.arrow.vector.types.pojo.ArrowType.Time;
  import org.apache.arrow.vector.types.pojo.ArrowType.Timestamp;
  import org.apache.arrow.vector.types.pojo.ArrowType.Union;
  import org.apache.arrow.vector.types.pojo.ArrowType.Utf8;
  import org.apache.arrow.vector.types.pojo.ArrowType.Utf8View;
  
  /**
   * The buffer layout of vectors for a given type. It defines its own buffers followed by the buffers
   * for the children if it is a nested type (Struct_, List, Union)
   */
  public class TypeLayout {
  
    /** Constructs a new {@link TypeLayout} for the given <code>arrowType</code>. */
    public static TypeLayout getTypeLayout(final ArrowType arrowType) {
      TypeLayout layout =
          arrowType.accept(
              new ArrowTypeVisitor<TypeLayout>() {
  
                @Override
                public TypeLayout visit(Int type) {
                  return newFixedWidthTypeLayout(BufferLayout.dataBuffer(type.getBitWidth()));
                }
  
                @Override
                public TypeLayout visit(Union type) {
                  List<BufferLayout> vectors;
                  switch (type.getMode()) {
                    case Dense:
                      vectors =
                          asList(
                              BufferLayout.typeBuffer(),
                              BufferLayout.offsetBuffer() // offset to find the vector
                              );
                      break;
                    case Sparse:
                      vectors =
                          asList(
                              BufferLayout.typeBuffer() // type of the value at the index or 0 if null
                              );
                      break;
                    default:
                      throw new UnsupportedOperationException(
                          "Unsupported Union Mode: " + type.getMode());
                  }
                  return new TypeLayout(vectors);
                }
  
                @Override
                public TypeLayout visit(Struct type) {
                  List<BufferLayout> vectors = asList(BufferLayout.validityVector());
                  return new TypeLayout(vectors);
                }
  
                @Override
                public TypeLayout visit(Timestamp type) {
                  return newFixedWidthTypeLayout(BufferLayout.dataBuffer(64));
                }
  
                @Override
                public TypeLayout visit(ArrowType.List type) {
                  List<BufferLayout> vectors =
                      asList(BufferLayout.validityVector(), BufferLayout.offsetBuffer());
                  return new TypeLayout(vectors);
                }
  
                @Override
                public TypeLayout visit(ArrowType.ListView type) {
                  List<BufferLayout> vectors =
                      asList(
                          BufferLayout.validityVector(),
                          BufferLayout.offsetBuffer(),
                          BufferLayout.sizeBuffer());
                  return new TypeLayout(vectors);
                }
  
                @Override
                public TypeLayout visit(ArrowType.LargeListView type) {
                  List<BufferLayout> vectors =
                      asList(
                          BufferLayout.validityVector(),
                          BufferLayout.largeOffsetBuffer(),
                          BufferLayout.largeSizeBuffer());
                  return new TypeLayout(vectors);
                }
  
                @Override
                public TypeLayout visit(ArrowType.LargeList type) {
                  List<BufferLayout> vectors =
                      asList(BufferLayout.validityVector(), BufferLayout.largeOffsetBuffer());
                  return new TypeLayout(vectors);
                }
  
                @Override
                public TypeLayout visit(FixedSizeList type) {
                  List<BufferLayout> vectors = asList(BufferLayout.validityVector());
                  return new TypeLayout(vectors);
                }
  
                @Override
                public TypeLayout visit(Map type) {
                  List<BufferLayout> vectors =
                      asList(BufferLayout.validityVector(), BufferLayout.offsetBuffer());
                  return new TypeLayout(vectors);
                }
  
                @Override
                public TypeLayout visit(FloatingPoint type) {
                  int bitWidth;
                  switch (type.getPrecision()) {
                    case HALF:
                      bitWidth = 16;
                      break;
                    case SINGLE:
                      bitWidth = 32;
                      break;
                    case DOUBLE:
                      bitWidth = 64;
                      break;
                    default:
                      throw new UnsupportedOperationException(
                          "Unsupported Precision: " + type.getPrecision());
                  }
                  return newFixedWidthTypeLayout(BufferLayout.dataBuffer(bitWidth));
                }
  
                @Override
                public TypeLayout visit(Decimal type) {
                  return newFixedWidthTypeLayout(BufferLayout.dataBuffer(type.getBitWidth()));
                }
  
                @Override
                public TypeLayout visit(FixedSizeBinary type) {
                  return newFixedWidthTypeLayout(
                      new BufferLayout(BufferType.DATA, type.getByteWidth() * 8));
                }
  
                @Override
                public TypeLayout visit(Bool type) {
                  return newFixedWidthTypeLayout(BufferLayout.booleanVector());
                }
  
                @Override
                public TypeLayout visit(Binary type) {
                  return newVariableWidthTypeLayout();
                }
  
                @Override
                public TypeLayout visit(ArrowType.BinaryView type) {
                  return newVariableWidthViewTypeLayout();
                }
  
                @Override
                public TypeLayout visit(Utf8 type) {
                  return newVariableWidthTypeLayout();
                }
  
                @Override
                public TypeLayout visit(Utf8View type) {
                  return newVariableWidthViewTypeLayout();
                }
  
                @Override
                public TypeLayout visit(LargeUtf8 type) {
                  return newLargeVariableWidthTypeLayout();
                }
  
                @Override
                public TypeLayout visit(LargeBinary type) {
                  return newLargeVariableWidthTypeLayout();
                }
  
                private TypeLayout newVariableWidthTypeLayout() {
                  return newPrimitiveTypeLayout(
                      BufferLayout.validityVector(),
                      BufferLayout.offsetBuffer(),
                      BufferLayout.byteVector());
                }
  
                private TypeLayout newVariableWidthViewTypeLayout() {
                  return new TypeLayout(
                      false, BufferLayout.validityVector(), BufferLayout.viewVector());
                }
  
                private TypeLayout newLargeVariableWidthTypeLayout() {
                  // NOTE: only considers the non variadic buffers
                  return newPrimitiveTypeLayout(
                      BufferLayout.validityVector(),
                      BufferLayout.largeOffsetBuffer(),
                      BufferLayout.byteVector());
                }
  
                private TypeLayout newPrimitiveTypeLayout(BufferLayout... vectors) {
                  return new TypeLayout(asList(vectors));
                }
  
                public TypeLayout newFixedWidthTypeLayout(BufferLayout dataVector) {
                  return newPrimitiveTypeLayout(BufferLayout.validityVector(), dataVector);
                }
  
                @Override
                public TypeLayout visit(Null type) {
                  return new TypeLayout(Collections.emptyList());
                }
  
                @Override
                public TypeLayout visit(Date type) {
                  switch (type.getUnit()) {
                    case DAY:
                      return newFixedWidthTypeLayout(BufferLayout.dataBuffer(32));
                    case MILLISECOND:
                      return newFixedWidthTypeLayout(BufferLayout.dataBuffer(64));
                    default:
                      throw new UnsupportedOperationException("Unknown unit " + type.getUnit());
                  }
                }
  
                @Override
                public TypeLayout visit(Time type) {
                  return newFixedWidthTypeLayout(BufferLayout.dataBuffer(type.getBitWidth()));
                }
  
                @Override
                public TypeLayout visit(Interval type) {
                  switch (type.getUnit()) {
                    case DAY_TIME:
                      return newFixedWidthTypeLayout(BufferLayout.dataBuffer(64));
                    case YEAR_MONTH:
                      return newFixedWidthTypeLayout(BufferLayout.dataBuffer(32));
                    case MONTH_DAY_NANO:
                      return newFixedWidthTypeLayout(BufferLayout.dataBuffer(128));
                    default:
                      throw new UnsupportedOperationException("Unknown unit " + type.getUnit());
                  }
                }
  
                @Override
                public TypeLayout visit(Duration type) {
                  return newFixedWidthTypeLayout(BufferLayout.dataBuffer(64));
                }
  
                @Override
                public TypeLayout visit(RunEndEncoded type) {
                  return new TypeLayout(Collections.<BufferLayout>emptyList());
                }
              });
      return layout;
    }
  
    /** Gets the number of {@link BufferLayout}s for the given <code>arrowType</code>. */
    public static int getTypeBufferCount(final ArrowType arrowType) {
      return arrowType.accept(
          new ArrowTypeVisitor<Integer>() {
  
            /**
             * All fixed width vectors have a common number of buffers 2: one validity buffer, plus a
             * data buffer.
             */
            static final int FIXED_WIDTH_BUFFER_COUNT = 2;
  
            /**
             * All variable width vectors have a common number of buffers 3: a validity buffer, an
             * offset buffer, and a data buffer.
             */
            static final int VARIABLE_WIDTH_BUFFER_COUNT = 3;
  
            @Override
            public Integer visit(Int type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Union type) {
              switch (type.getMode()) {
                case Dense:
                  // TODO: validate this
                  return 2;
                case Sparse:
                  // type buffer
                  return 1;
                default:
                  throw new UnsupportedOperationException(
                      "Unsupported Union Mode: " + type.getMode());
              }
            }
  
            @Override
            public Integer visit(Struct type) {
              // validity buffer
              return 1;
            }
  
            @Override
            public Integer visit(Timestamp type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(ArrowType.List type) {
              // validity buffer + offset buffer
              return 2;
            }
  
            @Override
            public Integer visit(ArrowType.ListView type) {
              // validity buffer + offset buffer + size buffer
              return 3;
            }
  
            @Override
            public Integer visit(ArrowType.LargeList type) {
              // validity buffer + offset buffer
              return 2;
            }
  
            @Override
            public Integer visit(ArrowType.LargeListView type) {
              // validity buffer + offset buffer + size buffer
              return 3;
            }
  
            @Override
            public Integer visit(FixedSizeList type) {
              // validity buffer
              return 1;
            }
  
            @Override
            public Integer visit(Map type) {
              // validity buffer + offset buffer
              return 2;
            }
  
            @Override
            public Integer visit(FloatingPoint type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Decimal type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(FixedSizeBinary type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Bool type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Binary type) {
              return VARIABLE_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(BinaryView type) {
              // NOTE: only consider the validity and view buffers
              return 2;
            }
  
            @Override
            public Integer visit(Utf8 type) {
              return VARIABLE_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Utf8View type) {
              // NOTE: only consider the validity and view buffers
              return 2;
            }
  
            @Override
            public Integer visit(LargeUtf8 type) {
              return VARIABLE_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(LargeBinary type) {
              return VARIABLE_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Null type) {
              return 0;
            }
  
            @Override
            public Integer visit(Date type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Time type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Interval type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(Duration type) {
              return FIXED_WIDTH_BUFFER_COUNT;
            }
  
            @Override
            public Integer visit(RunEndEncoded type) {
              return 0;
            }
          });
    }
  
    private final List<BufferLayout> bufferLayouts;
  
    private final boolean isFixedBufferCount;
  
    /**
     * Constructs a new {@link TypeLayout}.
     *
     * @param bufferLayouts the individual {@linkplain BufferLayout}s for the given type
     * @param isFixedBufferCount whether the number of buffers is fixed
     */
    public TypeLayout(List<BufferLayout> bufferLayouts, boolean isFixedBufferCount) {
      super();
      this.bufferLayouts = Preconditions.checkNotNull(bufferLayouts);
      this.isFixedBufferCount = isFixedBufferCount;
    }
  
    public TypeLayout(List<BufferLayout> bufferLayouts) {
      this(bufferLayouts, true);
    }
  
    public TypeLayout(BufferLayout... bufferLayouts) {
      this(asList(bufferLayouts), true);
    }
  
    public TypeLayout(boolean isFixedBufferCount, BufferLayout... bufferLayouts) {
      this(asList(bufferLayouts), isFixedBufferCount);
    }
  
    /** Returns the individual {@linkplain BufferLayout}s for the given type. */
    public List<BufferLayout> getBufferLayouts() {
      return bufferLayouts;
    }
  
    /**
     * Returns the types of each buffer for this layout. A layout can consist of multiple buffers for
     * example a validity bitmap buffer, a value buffer or an offset buffer.
     */
    public List<BufferType> getBufferTypes() {
      List<BufferType> types = new ArrayList<>(bufferLayouts.size());
      for (BufferLayout vector : bufferLayouts) {
        types.add(vector.getType());
      }
      return types;
    }
  
    /**
     * Determines whether the buffer count is fixed for the given type.
     *
     * @return true if the buffer count is fixed, false otherwise
     */
    public boolean isFixedBufferCount() {
      return isFixedBufferCount;
    }
  
    @Override
    public String toString() {
      return bufferLayouts.toString();
    }
  
    @Override
    public int hashCode() {
      return bufferLayouts.hashCode();
    }
  
    @Override
    public boolean equals(Object obj) {
      if (this == obj) {
        return true;
      }
      if (obj == null) {
        return false;
      }
      if (!(obj instanceof TypeLayout)) {
        return false;
      }
      TypeLayout other = (TypeLayout) obj;
      return bufferLayouts.equals(other.bufferLayouts);
    }
  }
  