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// 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 (is_column_nullable(src)) {
        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 (data.map_col = check_and_get_column<ColumnMap>(map_col); !data.map_col) {
        return false;
    }

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