// Copyright 2023 PingCAP, Inc.
//
// Licensed 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 <Core/TypeListNumber.h>
#include <Functions/GatherUtils/GatherUtils.h>
#include <Functions/GatherUtils/Sinks.h>
#include <Functions/GatherUtils/Sources.h>

namespace DB::GatherUtils
{
/// Creates IArraySink from ColumnArray

template <typename... Types>
struct ArraySinkCreator;

template <typename Type, typename... Types>
struct ArraySinkCreator<Type, Types...>
{
    static std::unique_ptr<IArraySink> create(ColumnArray & col, NullMap * null_map, size_t column_size)
    {
        if (typeid_cast<ColumnVector<Type> *>(&col.getData()))
        {
            if (null_map)
                return std::make_unique<NullableArraySink<NumericArraySink<Type>>>(col, *null_map, column_size);
            return std::make_unique<NumericArraySink<Type>>(col, column_size);
        }

        return ArraySinkCreator<Types...>::create(col, null_map, column_size);
    }
};

template <>
struct ArraySinkCreator<>
{
    static std::unique_ptr<IArraySink> create(ColumnArray & col, NullMap * null_map, size_t column_size)
    {
        if (null_map)
            return std::make_unique<NullableArraySink<GenericArraySink>>(col, *null_map, column_size);
        return std::make_unique<GenericArraySink>(col, column_size);
    }
};

std::unique_ptr<IArraySink> createArraySink(ColumnArray & col, size_t column_size)
{
    using Creator = ApplyTypeListForClass<ArraySinkCreator, TypeListNumbers>::Type;
    if (auto * column_nullable = typeid_cast<ColumnNullable *>(&col.getData()))
    {
        auto column = ColumnArray::create(
            column_nullable->getNestedColumnPtr()->assumeMutable(),
            col.getOffsetsPtr()->assumeMutable());
        return Creator::create(*column, &column_nullable->getNullMapData(), column_size);
    }
    return Creator::create(col, nullptr, column_size);
}
} // namespace DB::GatherUtils