src/paimon/testing/utils/dict_array_converter.h

/*
 * 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.
 */

#pragma once

#include <memory>

#include "arrow/api.h"
#include "paimon/common/utils/arrow/status_utils.h"
#include "paimon/common/utils/checked_cast.h"
#include "paimon/core/casting/casting_utils.h"
#include "paimon/result.h"

namespace paimon::test {
class DictArrayConverter {
 public:
    DictArrayConverter() = delete;
    ~DictArrayConverter() = delete;

    // Decode dictionaries recursively, preserving binary values and normalizing string offsets
    // so test comparisons are stable across readers.
    static Result<std::shared_ptr<arrow::Array>> ConvertDictArray(
        const std::shared_ptr<arrow::Array>& array, arrow::MemoryPool* pool) {
        arrow::Type::type kind = array->type_id();
        switch (kind) {
            case arrow::Type::type::STRUCT: {
                // convert array
                auto struct_array = checked_pointer_cast<arrow::StructArray>(array);
                arrow::ArrayVector new_children;
                std::size_t size = struct_array->fields().size();
                for (size_t i = 0; i < size; i++) {
                    std::shared_ptr<arrow::Array> child = struct_array->field(static_cast<int>(i));
                    PAIMON_ASSIGN_OR_RAISE(std::shared_ptr<arrow::Array> new_child,
                                           ConvertDictArray(child, pool));
                    new_children.push_back(new_child);
                }

                // convert type
                arrow::FieldVector fields;
                fields.reserve(new_children.size());
                for (size_t i = 0; i < new_children.size(); i++) {
                    // Note: For test consistency, intentionally left nullable unspecified, as ORC
                    // discard nullable information, making it impossible to align.
                    // Moreover, this detail is currently not important for users.
                    fields.push_back(arrow::field(struct_array->type()->field(i)->name(),
                                                  new_children[i]->type()));
                }

                return std::make_shared<arrow::StructArray>(arrow::struct_(fields),
                                                            struct_array->length(), new_children,
                                                            struct_array->null_bitmap());
            }
            case arrow::Type::type::LIST: {
                auto list_array = checked_pointer_cast<arrow::ListArray>(array);
                PAIMON_ASSIGN_OR_RAISE(std::shared_ptr<arrow::Array> value_array,
                                       ConvertDictArray(list_array->values(), pool));
                return std::make_shared<arrow::ListArray>(
                    arrow::list(value_array->type()), list_array->length(),
                    list_array->value_offsets(), value_array, list_array->null_bitmap(),
                    list_array->null_count(), list_array->offset());
            }
            case arrow::Type::type::MAP: {
                auto map_array = checked_pointer_cast<arrow::MapArray>(array);
                PAIMON_ASSIGN_OR_RAISE(std::shared_ptr<arrow::Array> key_array,
                                       ConvertDictArray(map_array->keys(), pool));
                PAIMON_ASSIGN_OR_RAISE(std::shared_ptr<arrow::Array> item_array,
                                       ConvertDictArray(map_array->items(), pool));
                auto map_type = checked_pointer_cast<arrow::MapType>(map_array->type());
                auto new_map_type = std::make_shared<arrow::MapType>(
                    key_array->type(), item_array->type(), map_type->keys_sorted());
                return std::make_shared<arrow::MapArray>(
                    new_map_type, map_array->length(), map_array->value_offsets(), key_array,
                    item_array, map_array->null_bitmap(), map_array->null_count(),
                    map_array->offset());
            }
            case arrow::Type::type::DICTIONARY:
                return CastingUtils::DecodeDictionary(array, pool);
            default: {
                return array;
            }
        }
    }
};
}  // namespace paimon::test