// 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 <atomic>

#include "exprs/function/function.h"

#include "exprs/vexpr.h"

#include "runtime/descriptors.h"

#include "runtime/runtime_state.h"

namespace doris {

class VColumnRef final : public VExpr {

    ENABLE_FACTORY_CREATOR(VColumnRef);

public:

    //this is different of slotref is using slot_id find a column_id

    //slotref: need to find the equal id in tuple, then return column_id, the plan of FE is very important

    //columnref: is columnid = slotid, not used to find, so you should know this column placed in block

    VColumnRef(const TExprNode& node)

            : VExpr(node),

              _column_id(node.column_ref.column_id),

              _column_name(node.column_ref.column_name) {}

    Status prepare(RuntimeState* state, const RowDescriptor& desc, VExprContext* context) override {

        RETURN_IF_ERROR_OR_PREPARED(VExpr::prepare(state, desc, context));

        DCHECK_EQ(_children.size(), 0);

        if (_column_id < 0) {

            return Status::InternalError(

                    "VColumnRef have invalid slot id: {}, _column_name: {}, desc: {}", _column_id,

                    _column_name, desc.debug_string());

        }

        _prepare_finished = true;

        return Status::OK();

    }

    Status open(RuntimeState* state, VExprContext* context,

                FunctionContext::FunctionStateScope scope) override {

        DCHECK(_prepare_finished);

        RETURN_IF_ERROR(VExpr::open(state, context, scope));

        _open_finished = true;

        return Status::OK();

    }

    Status execute_column(VExprContext* context, const Block* block, Selector* selector,

                          size_t count, ColumnPtr& result_column) const override {

        DCHECK(_open_finished || block == nullptr);

        auto origin_column = block->get_by_position(_column_id + _gap).column;

        result_column = filter_column_with_selector(origin_column, selector, count);

        return Status::OK();

    }

    DataTypePtr execute_type(const Block* block) const override {

        DCHECK(_open_finished || block == nullptr);

        return block->get_by_position(_column_id + _gap).type;

    }

    bool is_constant() const override { return false; }

    int column_id() const { return _column_id; }

    const std::string& expr_name() const override { return _column_name; }

    void set_gap(int gap) {

        if (_gap == 0) {

            _gap = gap;

        }

    }

    std::string debug_string() const override {

        std::stringstream out;

        out << "VColumnRef(slot_id: " << _column_id << ",column_name: " << _column_name

            << VExpr::debug_string() << ")";

        return out.str();

    }

    double execute_cost() const override { return 0.0; }

private:

    int _column_id;

    std::atomic<int> _gap = 0;

    std::string _column_name;

};

} // namespace doris