// 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 <gen_cpp/PlanNodes_types.h>

#include "common/status.h"

#include "exprs/vexpr_fwd.h"

#include "runtime/descriptors.h"

#include "storage/predicate/block_column_predicate.h"

#include "util/profile_collector.h"

namespace doris {

class ColumnPredicate;

} // namespace doris

namespace doris {

#include "common/compile_check_begin.h"

class Block;

class VSlotRef;

// This a reader interface for all file readers.

// A GenericReader is responsible for reading a file and return

// a set of blocks with specified schema,

class GenericReader : public ProfileCollector {

public:

    GenericReader() : _push_down_agg_type(TPushAggOp::type::NONE) {}

    void set_push_down_agg_type(TPushAggOp::type push_down_agg_type) {

        _push_down_agg_type = push_down_agg_type;

    }

    virtual Status get_next_block(Block* block, size_t* read_rows, bool* eof) = 0;

    // Type is always nullable to process illegal values.

    virtual Status get_columns(std::unordered_map<std::string, DataTypePtr>* name_to_type,

                               std::unordered_set<std::string>* missing_cols) {

        return Status::NotSupported("get_columns is not implemented");

    }

    // This method is responsible for initializing the resource for parsing schema.

    // It will be called before `get_parsed_schema`.

    virtual Status init_schema_reader() {

        return Status::NotSupported("init_schema_reader is not implemented for this reader.");

    }

    // `col_types` is always nullable to process illegal values.

    virtual Status get_parsed_schema(std::vector<std::string>* col_names,

                                     std::vector<DataTypePtr>* col_types) {

        return Status::NotSupported("get_parsed_schema is not implemented for this reader.");

    }

    ~GenericReader() override = default;

    /// If the underlying FileReader has filled the partition&missing columns,

    /// The FileScanner does not need to fill

    virtual bool fill_all_columns() const { return _fill_all_columns; }

    /// Tell the underlying FileReader the partition&missing columns,

    /// and the FileReader determine to fill columns or not.

    /// Should set _fill_all_columns = true, if fill the columns.

    virtual Status set_fill_columns(

            const std::unordered_map<std::string, std::tuple<std::string, const SlotDescriptor*>>&

                    partition_columns,

            const std::unordered_map<std::string, VExprContextSPtr>& missing_columns) {

        return Status::OK();

    }

    virtual Status close() { return Status::OK(); }

    Status read_by_rows(const std::list<int64_t>& row_ids) {

        _read_by_rows = true;

        _row_ids = row_ids;

        return _set_read_one_line_impl();

    }

    /// The reader is responsible for counting the number of rows read,

    /// because some readers, such as parquet/orc,

    /// can skip some pages/rowgroups through indexes.

    virtual bool count_read_rows() { return false; }

protected:

    virtual Status _set_read_one_line_impl() {

        return Status::NotSupported("read_by_rows is not implemented for this reader.");

    }

    const size_t _MIN_BATCH_SIZE = 4064; // 4094 - 32(padding)

    /// Whether the underlying FileReader has filled the partition&missing columns

    bool _fill_all_columns = false;

    TPushAggOp::type _push_down_agg_type {};

    // For TopN queries, rows will be read according to row ids produced by TopN result.

    bool _read_by_rows = false;

    std::list<int64_t> _row_ids;

    // Cache to save some common part such as file footer.

    // Maybe null if not used

    FileMetaCache* _meta_cache = nullptr;

};

#include "common/compile_check_end.h"

} // namespace doris