// 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.

#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