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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/table_function/vexplode_map.h"

#include <glog/logging.h>

#include <ostream>

#include "common/status.h"

#include "core/block/block.h"

#include "core/block/column_with_type_and_name.h"

#include "core/column/column.h"

#include "exprs/vexpr.h"

#include "exprs/vexpr_context.h"

namespace doris {

VExplodeMapTableFunction::VExplodeMapTableFunction() {

    _fn_name = "vexplode_map";

}

bool extract_column_map_info(const IColumn& src, ColumnMapExecutionData& data) {

    const IColumn* map_col = &src;

    // extract array nullable info

    if (src.is_nullable()) {

        const auto& null_col = reinterpret_cast<const ColumnNullable&>(src);

        // map column's nullmap

        data.map_nullmap_data = null_col.get_null_map_data().data();

        map_col = null_col.get_nested_column_ptr().get();

    }

    if (const auto map_col_guard = check_and_get_column<ColumnMap>(map_col); !map_col_guard) {

        return false;

    } else {

        data.map_col = map_col_guard.get();

    }

    data.offsets_ptr = &data.map_col->get_offsets();

    return true;

}

Status VExplodeMapTableFunction::process_init(Block* block, RuntimeState* state) {

    CHECK(_expr_context->root()->children().size() == 1)

            << "VExplodeMapTableFunction only support 1 child but has "

            << _expr_context->root()->children().size();

    ColumnPtr value_column;

    RETURN_IF_ERROR(_expr_context->root()->children()[0]->execute_column(

            _expr_context.get(), block, nullptr, block->rows(), value_column));

    _collection_column = value_column->convert_to_full_column_if_const();

    if (!extract_column_map_info(*_collection_column, _map_detail)) {

        return Status::NotSupported("column type {} not supported now, only support array or map",

                                    _collection_column->get_name());

    }

    return Status::OK();

}

void VExplodeMapTableFunction::process_row(size_t row_idx) {

    DCHECK(row_idx < _collection_column->size());

    TableFunction::process_row(row_idx);

    if (!_map_detail.map_nullmap_data || !_map_detail.map_nullmap_data[row_idx]) {

        _collection_offset = (*_map_detail.offsets_ptr)[row_idx - 1];

        _cur_size = (*_map_detail.offsets_ptr)[row_idx] - _collection_offset;

    }

}

void VExplodeMapTableFunction::process_close() {

    _collection_column = nullptr;

    _map_detail.reset();

    _collection_offset = 0;

}

void VExplodeMapTableFunction::get_same_many_values(MutableColumnPtr& column, int length) {

    // now we only support map column explode to struct column

    size_t pos = _collection_offset + _cur_offset;

    // if current is empty map row, also append a default value

    if (current_empty()) {

        column->insert_many_defaults(length);

        return;

    }

    ColumnStruct* ret = nullptr;

    // this _is_nullable is whole output column's nullable

    if (_is_nullable) {

        // make map kv value into struct

        ret = assert_cast<ColumnStruct*>(

                assert_cast<ColumnNullable*>(column.get())->get_nested_column_ptr().get());

        assert_cast<ColumnUInt8*>(

                assert_cast<ColumnNullable*>(column.get())->get_null_map_column_ptr().get())

                ->insert_many_defaults(length);

    } else if (is_column<ColumnStruct>(column.get())) {

        ret = assert_cast<ColumnStruct*>(column.get());

    } else {

        throw Exception(ErrorCode::INTERNAL_ERROR,

                        "only support map column explode to struct column");

    }

    if (!ret || ret->tuple_size() != 2) {

        throw Exception(

                ErrorCode::INTERNAL_ERROR,

                "only support map column explode to two column, but given:  ", ret->tuple_size());

    }

    ret->get_column(0).insert_many_from(_map_detail.map_col->get_keys(), pos, length);

    ret->get_column(1).insert_many_from(_map_detail.map_col->get_values(), pos, length);

}

int VExplodeMapTableFunction::get_value(MutableColumnPtr& column, int max_step) {

    max_step = std::min(max_step, (int)(_cur_size - _cur_offset));

    size_t pos = _collection_offset + _cur_offset;

    if (current_empty()) {

        column->insert_default();

        max_step = 1;

    } else {

        ColumnStruct* struct_column = nullptr;

        if (_is_nullable) {

            auto* nullable_column = assert_cast<ColumnNullable*>(column.get());

            struct_column =

                    assert_cast<ColumnStruct*>(nullable_column->get_nested_column_ptr().get());

            auto* nullmap_column =

                    assert_cast<ColumnUInt8*>(nullable_column->get_null_map_column_ptr().get());

            // here nullmap_column insert max_step many defaults as if MAP[row_idx] is NULL

            // will be not update value, _cur_size = 0, means current_empty;

            // so here could insert directly

            nullmap_column->insert_many_defaults(max_step);

        } else {

            struct_column = assert_cast<ColumnStruct*>(column.get());

        }

        if (!struct_column || struct_column->tuple_size() != 2) {

            throw Exception(ErrorCode::INTERNAL_ERROR,

                            "only support map column explode to two column, but given:  ",

                            struct_column->tuple_size());

        }

        struct_column->get_column(0).insert_range_from(_map_detail.map_col->get_keys(), pos,

                                                       max_step);

        struct_column->get_column(1).insert_range_from(_map_detail.map_col->get_values(), pos,

                                                       max_step);

    }

    forward(max_step);

    return max_step;

}

} // namespace doris