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// 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.

#include "exprs/vcase_expr.h"

#include <gen_cpp/Exprs_types.h>

#include <gen_cpp/Types_types.h>

#include <ostream>

#include "common/status.h"

#include "core/block/block.h"

#include "core/block/column_with_type_and_name.h"

#include "core/block/columns_with_type_and_name.h"

#include "core/column/column.h"

#include "exec/common/util.hpp"

#include "exprs/aggregate/aggregate_function.h"

#include "exprs/vexpr_context.h"

#include "runtime/runtime_state.h"

namespace doris {

class RowDescriptor;

class RuntimeState;

} // namespace doris

namespace doris {

VCaseExpr::VCaseExpr(const TExprNode& node)

        : VExpr(node), _has_else_expr(node.case_expr.has_else_expr) {}

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

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

    ColumnsWithTypeAndName argument_template;

    DataTypes arguments;

    for (auto child : _children) {

        argument_template.emplace_back(nullptr, child->data_type(), child->expr_name());

        arguments.emplace_back(child->data_type());

    }

    VExpr::register_function_context(state, context);

    _prepare_finished = true;

    return Status::OK();

}

Status VCaseExpr::open(RuntimeState* state, VExprContext* context,

                       FunctionContext::FunctionStateScope scope) {

    DCHECK(_prepare_finished);

    for (auto& i : _children) {

        RETURN_IF_ERROR(i->open(state, context, scope));

    }

    if (scope == FunctionContext::FRAGMENT_LOCAL) {

        RETURN_IF_ERROR(VExpr::get_const_col(context, nullptr));

    }

    _open_finished = true;

    return Status::OK();

}

void VCaseExpr::close(VExprContext* context, FunctionContext::FunctionStateScope scope) {

    DCHECK(_prepare_finished);

    VExpr::close(context, scope);

}

Status VCaseExpr::execute_column_impl(VExprContext* context, const Block* block,

                                      const Selector* selector, size_t count,

                                      ColumnPtr& result_column) const {

    if (is_const_and_have_executed()) { // const have execute in open function

        result_column = get_result_from_const(count);

        return Status::OK();

    }

    DCHECK(_open_finished || block == nullptr);

    size_t rows_count = count;

    std::vector<ColumnPtr> when_columns;

    std::vector<ColumnPtr> then_columns;

    if (_has_else_expr) {

        ColumnPtr else_column_ptr;

        RETURN_IF_ERROR(

                _children.back()->execute_column(context, block, selector, count, else_column_ptr));

        then_columns.emplace_back(else_column_ptr);

    } else {

        then_columns.emplace_back(nullptr);

    }

    for (int i = 0; i < _children.size() - _has_else_expr; i += 2) {

        ColumnPtr when_column_ptr;

        RETURN_IF_ERROR(

                _children[i]->execute_column(context, block, selector, count, when_column_ptr));

        if (calculate_false_number(when_column_ptr) == rows_count) {

            continue;

        }

        when_columns.emplace_back(when_column_ptr);

        ColumnPtr then_column_ptr;

        RETURN_IF_ERROR(

                _children[i + 1]->execute_column(context, block, selector, count, then_column_ptr));

        then_columns.emplace_back(then_column_ptr);

    }

    if (then_columns.size() > UINT16_MAX) {

        return Status::NotSupported(

                "case when do not support more than UINT16_MAX then conditions");

    } else if (then_columns.size() > UINT8_MAX) {

        result_column = _execute_impl<uint16_t>(when_columns, then_columns, rows_count);

    } else {

        result_column = _execute_impl<uint8_t>(when_columns, then_columns, rows_count);

    }

    if (result_column->size() != count) {

        return Status::InternalError("case when result column size {} not equal input count {}",

                                     result_column->size(), count);

    }

    return Status::OK();

}

const std::string& VCaseExpr::expr_name() const {

    return EXPR_NAME;

}

std::string VCaseExpr::debug_string() const {

    std::stringstream out;

    out << "CaseExpr(has_else_expr=" << _has_else_expr << " function=" << FUNCTION_NAME << "){";

    bool first = true;

    for (const auto& input_expr : children()) {

        if (first) {

            first = false;

        } else {

            out << ",";

        }

        out << input_expr->debug_string();

    }

    out << "}";

    return out.str();

}

} // namespace doris