// 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 "core/column/column.h"

#include "core/column/subcolumn_tree.h"

#include "core/data_type/data_type.h"

namespace doris::segment_v2 {

// This file Defined ColumnIterator and ColumnReader for reading variant subcolumns. The types from read schema and from storage are

// different, so we need to wrap the ColumnIterator from execution phase and storage column reading phase.And we also

// maintain the tree structure to get the full JSON structure for variants.

// Wrapped ColumnIterator from execution phase, the type is from read schema

class ColumnIterator;

class ColumnReader;

struct SubstreamIterator {

    MutableColumnPtr column;

    std::unique_ptr<ColumnIterator> iterator;

    std::shared_ptr<const IDataType> type;

    std::shared_ptr<DataTypeSerDe> serde;

    bool inited = false;

    size_t rows_read = 0;

    SubstreamIterator() = default;

    SubstreamIterator(MutableColumnPtr&& col, std::unique_ptr<ColumnIterator>&& it,

                      std::shared_ptr<const IDataType> t);

};

// path -> SubstreamIterator

using SubstreamReaderTree = SubcolumnsTree<SubstreamIterator, false>;

// Meta for the storage layer, the file_column_type indicates the read type of the column in segment file

struct SubcolumnMeta {

    std::shared_ptr<const IDataType> file_column_type;

    int32_t footer_ordinal = -1;

};

using SubcolumnColumnMetaInfo = SubcolumnsTree<SubcolumnMeta, true>;

} // namespace doris::segment_v2