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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.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 "core/column/column_array.h"
#include "core/column/column_nothing.h"
#include "core/column/column_variant.h"
#include "core/data_type/data_type.h"
#include "core/data_type/data_type_array.h"
#include "core/data_type/data_type_nothing.h"
#include "exprs/function/function_helpers.h"
#include "exprs/vexpr.h"
#include "exprs/vexpr_context.h"

namespace doris {

VExplodeTableFunction::VExplodeTableFunction() {
    _fn_name = "vexplode";
}

Status VExplodeTableFunction::_process_init_variant(Block* block, int value_column_idx) {
    // explode variant array
    auto column_without_nullable = remove_nullable(block->get_by_position(value_column_idx).column);
    auto column = column_without_nullable->convert_to_full_column_if_const();
    auto variant_column_ptr = IColumn::mutate(std::move(column));
    auto& variant_column = assert_cast<ColumnVariant&>(*variant_column_ptr);
    variant_column.finalize();
    _detail.output_as_variant = true;
    _detail.variant_enable_doc_mode = variant_column.enable_doc_mode();
    if (!variant_column.is_null_root()) {
        _array_column = variant_column.get_root();
        // We need to wrap the output nested column within a variant column.
        // Otherwise the type is missmatched
        const auto* array_type = check_and_get_data_type<DataTypeArray>(
                remove_nullable(variant_column.get_root_type()).get());
        if (array_type == nullptr) {
            return Status::NotSupported("explode not support none array type {}",
                                        variant_column.get_root_type()->get_name());
        }
        _detail.nested_type = array_type->get_nested_type();
    } else {
        // null root, use nothing type
        auto array_column = ColumnNullable::create(ColumnArray::create(ColumnNothing::create(0)),
                                                   ColumnUInt8::create(0));
        array_column->insert_many_defaults(variant_column.size());
        _array_column = std::move(array_column);
        _detail.nested_type = std::make_shared<DataTypeNothing>();
    }
    return Status::OK();
}

Status VExplodeTableFunction::process_init(Block* block, RuntimeState* state) {
    CHECK(_expr_context->root()->children().size() == 1)
            << "VExplodeTableFunction only support 1 child but has "
            << _expr_context->root()->children().size();

    int value_column_idx = -1;
    RETURN_IF_ERROR(_expr_context->root()->children()[0]->execute(_expr_context.get(), block,
                                                                  &value_column_idx));
    if (block->get_by_position(value_column_idx).type->get_primitive_type() == TYPE_VARIANT) {
        RETURN_IF_ERROR(_process_init_variant(block, value_column_idx));
    } else {
        _array_column =
                block->get_by_position(value_column_idx).column->convert_to_full_column_if_const();
    }
    if (!extract_column_array_info(*_array_column, _detail)) {
        return Status::NotSupported("column type {} not supported now",
                                    block->get_by_position(value_column_idx).column->get_name());
    }

    return Status::OK();
}

bool VExplodeTableFunction::support_block_fast_path() const {
    return true;
}

Status VExplodeTableFunction::prepare_block_fast_path(Block* /*block*/, RuntimeState* /*state*/,
                                                      BlockFastPathContext* ctx) {
    if (!support_block_fast_path()) {
        return Status::NotSupported("vexplode doesn't support block fast path in current mode");
    }
    if (_detail.offsets_ptr == nullptr || _detail.nested_col.get() == nullptr) {
        return Status::InternalError("vexplode block fast path not initialized");
    }
    ctx->array_nullmap_data = _detail.array_nullmap_data;
    ctx->offsets_ptr = _detail.offsets_ptr;
    ctx->nested_col = _detail.nested_col;
    ctx->nested_nullmap_data = _detail.nested_nullmap_data;
    return Status::OK();
}

void VExplodeTableFunction::process_row(size_t row_idx) {
    DCHECK(row_idx < _array_column->size());
    TableFunction::process_row(row_idx);

    if (!_detail.array_nullmap_data || !_detail.array_nullmap_data[row_idx]) {
        _array_offset = (*_detail.offsets_ptr)[row_idx - 1];
        _cur_size = (*_detail.offsets_ptr)[row_idx] - _array_offset;
    }
}

void VExplodeTableFunction::process_close() {
    _array_column = nullptr;
    _detail.reset();
    _array_offset = 0;
}

void VExplodeTableFunction::get_same_many_values(MutableColumnPtr& column, int length) {
    size_t pos = _array_offset + _cur_offset;
    if (current_empty() || (_detail.nested_nullmap_data && _detail.nested_nullmap_data[pos])) {
        column->insert_many_defaults(length);
    } else {
        if (_is_nullable) {
            assert_cast<ColumnNullable*>(column.get())
                    ->get_nested_column_ptr()
                    ->insert_many_from(*_detail.nested_col, pos, length);
            assert_cast<ColumnNullable*>(column.get())
                    ->get_null_map_column_ptr()
                    ->insert_many_defaults(length);
        } else {
            column->insert_many_from(*_detail.nested_col, pos, length);
        }
    }
}

int VExplodeTableFunction::get_value(MutableColumnPtr& column, int max_step) {
    max_step = std::min(max_step, (int)(_cur_size - _cur_offset));
    size_t pos = _array_offset + _cur_offset;
    if (current_empty()) {
        column->insert_default();
        max_step = 1;
    } else {
        if (_is_nullable) {
            auto* nullable_column = assert_cast<ColumnNullable*>(column.get());
            auto nested_column = nullable_column->get_nested_column_ptr();
            auto* nullmap_column = nullable_column->get_null_map_column_ptr().get();
            nested_column->insert_range_from(*_detail.nested_col, pos, max_step);
            size_t old_size = nullmap_column->size();
            nullmap_column->resize(old_size + max_step);
            memcpy(nullmap_column->get_data().data() + old_size,
                   _detail.nested_nullmap_data + pos * sizeof(UInt8), max_step * sizeof(UInt8));
        } else {
            column->insert_range_from(*_detail.nested_col, pos, max_step);
        }
    }
    forward(max_step);
    return max_step;
}

} // namespace doris