// 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 "common/exception.h"

#include "exprs/function/function.h"

#include "exprs/lambda_function/lambda_execution_context.h"

#include "exprs/vexpr.h"

#include "exprs/vexpr_context.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_impl(VExprContext* context, const Block* block, const Selector* selector,

                               size_t count, ColumnPtr& result_column) const override {

        DCHECK(_open_finished || block == nullptr);

        const int column_position = _get_column_position(context, block);

        if (column_position < 0 || column_position >= block->columns()) {

            return Status::InternalError(

                    "input block not contain column ref {}, column_id={}, gap={}, block={}",

                    _column_name, _column_id, _gap.load(), block->dump_structure());

        }

        auto origin_column = block->get_by_position(column_position).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);

        const int column_position = _get_column_position_without_context(block);

        if (column_position < 0 || column_position >= block->columns()) {

            throw doris::Exception(

                    ErrorCode::INTERNAL_ERROR,

                    "input block not contain column ref {}, column_id={}, gap={}, block={}",

                    _column_name, _column_id, _gap.load(), block->dump_structure());

        }

        return block->get_by_position(column_position).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) { _gap = gap; }

    int get_gap() const { return _gap.load(); }

    bool has_gap() const { return _gap.load() >= 0; }

    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 _get_column_position(VExprContext* context, const Block* block) const {

        if (context != nullptr) {

            const auto resolve_result =

                    context->lambda_execution_context().resolve_column_position(_column_name);

            if (resolve_result.found) {

                return resolve_result.column_position;

            }

            if (resolve_result.searched_named_scope) {

                return -1;

            }

        }

        return _get_column_position_without_context(block);

    }

    int _get_column_position_without_context(const Block* block) const {

        if (_gap.load() == -1) {

            return _find_column_position_by_name(block);

        }

        return _column_id + _gap.load();

    }

    int _find_column_position_by_name(const Block* block) const {

        if (block == nullptr) {

            return -1;

        }

        for (int position = block->columns() - 1; position >= 0; --position) {

            if (block->get_by_position(position).name == _column_name) {

                return position;

            }

        }

        return -1;

    }

    int _column_id;

    std::atomic<int> _gap = -1;

    std::string _column_name;

};

} // namespace doris