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// 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_v2.h"

#include <glog/logging.h>

#include <algorithm>

#include <cstdint>

#include <ostream>

#include <span>

#include "common/status.h"

#include "core/assert_cast.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_struct.h"

#include "core/column/column_variant.h"

#include "core/column/column_variant_v2.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 "core/data_type/data_type_nullable.h"

#include "core/data_type/data_type_variant.h"

#include "core/data_type/primitive_type.h"

#include "exprs/function/cast/cast_variant_v2_internal.h"

#include "exprs/function/function_helpers.h"

#include "exprs/vexpr.h"

#include "exprs/vexpr_context.h"

namespace doris {

VExplodeV2TableFunction::VExplodeV2TableFunction() {

    _fn_name = "vexplode";

}

Status VExplodeV2TableFunction::_process_init_variant(Block* block, int value_column_idx,

                                                      int children_column_idx) {

    // explode variant array

    auto materialized =

            block->get_by_position(value_column_idx).column->convert_to_full_column_if_const();

    std::span<const uint8_t> outer_nulls;

    const IColumn* nested = materialized.get();

    if (const auto* nullable = check_and_get_column<ColumnNullable>(nested)) {

        outer_nulls = nullable->get_null_map_data();

        nested = &nullable->get_nested_column();

    }

    if (const auto* variant_v2 = check_and_get_column<ColumnVariantV2>(nested)) {

        auto variant_type = std::make_shared<DataTypeVariant>();

        auto target_type = std::make_shared<DataTypeArray>(variant_type);

        ColumnPtr array_column;

        RETURN_IF_ERROR(CastWrapper::variant_v2_internal::cast_variant_to_array(

                nullptr, *variant_v2, target_type, variant_v2->size(), outer_nulls, &array_column));

        _array_columns[children_column_idx] = std::move(array_column);

        auto& detail = _multi_detail[children_column_idx];

        detail.output_as_variant = true;

        detail.nested_type = make_nullable(std::move(variant_type));

        _variant_v2_outputs[children_column_idx] = true;

        _has_variant_v2_output = true;

        return Status::OK();

    }

    auto column = remove_nullable(materialized);

    auto variant_column_ptr = IColumn::mutate(std::move(column));

    auto& variant_column = assert_cast<ColumnVariant&>(*variant_column_ptr);

    variant_column.finalize();

    _multi_detail[children_column_idx].output_as_variant = true;

    _multi_detail[children_column_idx].variant_enable_doc_mode = variant_column.enable_doc_mode();

    if (!variant_column.is_null_root()) {

        _array_columns[children_column_idx] = 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());

        }

        _multi_detail[children_column_idx].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_columns[children_column_idx] = std::move(array_column);

        _multi_detail[children_column_idx].nested_type = std::make_shared<DataTypeNothing>();

    }

    return Status::OK();

}

Status VExplodeV2TableFunction::process_init(Block* block, RuntimeState* state) {

    auto expr_size = _expr_context->root()->children().size();

    CHECK(expr_size >= 1) << "VExplodeV2TableFunction support one or more child but has "

                          << expr_size;

    int value_column_idx = -1;

    _multi_detail.resize(expr_size);

    _array_offsets.resize(expr_size);

    _array_columns.resize(expr_size);

    _variant_v2_outputs.assign(expr_size, false);

    for (int i = 0; i < expr_size; i++) {

        RETURN_IF_ERROR(_expr_context->root()->children()[i]->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, i));

        } else {

            _array_columns[i] = block->get_by_position(value_column_idx)

                                        .column->convert_to_full_column_if_const();

        }

        if (!extract_column_array_info(*_array_columns[i], _multi_detail[i])) {

            return Status::NotSupported(

                    "column type {} not supported now",

                    block->get_by_position(value_column_idx).column->get_name());

        }

        if (check_and_get_column<ColumnVariantV2>(_multi_detail[i].nested_col.get()) != nullptr) {

            _variant_v2_outputs[i] = true;

            _has_variant_v2_output = true;

        }

    }

    return Status::OK();

}

bool VExplodeV2TableFunction::support_block_fast_path() const {

    return _multi_detail.size() == 1 && !_has_variant_v2_output;

}

Status VExplodeV2TableFunction::prepare_block_fast_path(Block* /*block*/, RuntimeState* /*state*/,

                                                        BlockFastPathContext* ctx) {

    DCHECK(support_block_fast_path());

    const auto& detail = _multi_detail[0];

    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;

    ctx->generate_row_index = _generate_row_index;

    return Status::OK();

}

void VExplodeV2TableFunction::process_row(size_t row_idx) {

    TableFunction::process_row(row_idx);

    for (int i = 0; i < _multi_detail.size(); i++) {

        auto& detail = _multi_detail[i];

        if (!detail.array_nullmap_data || !detail.array_nullmap_data[row_idx]) {

            _array_offsets[i] = (*detail.offsets_ptr)[row_idx - 1];

            // find max size in array

            auto cur_size = (*detail.offsets_ptr)[row_idx] - _array_offsets[i];

            _cur_size = std::max<unsigned long>(_cur_size, cur_size);

        }

    }

    _row_idx = row_idx;

}

void VExplodeV2TableFunction::process_close() {

    _multi_detail.clear();

    _array_offsets.clear();

    _array_columns.clear();

    _variant_v2_outputs.clear();

    _row_idx = 0;

    _has_variant_v2_output = false;

}

void VExplodeV2TableFunction::_ensure_variant_v2_output(MutableColumnPtr& column) const {

    if (!_has_variant_v2_output) {

        return;

    }

    const bool struct_output = _multi_detail.size() > 1 || _generate_row_index;

    if (!struct_output) {

        auto* nullable = check_and_get_column<ColumnNullable>(column.get());

        DORIS_CHECK(nullable != nullptr);

        if (check_and_get_column<ColumnVariantV2>(&nullable->get_nested_column()) != nullptr) {

            return;

        }

        DORIS_CHECK_EQ(column->size(), 0);

        column = ColumnNullable::create(ColumnVariantV2::create(), ColumnUInt8::create());

        return;

    }

    IColumn* nested_output = column.get();

    if (auto* nullable = check_and_get_column<ColumnNullable>(nested_output)) {

        nested_output = nullable->get_nested_column_ptr().get();

    }

    auto* struct_column = check_and_get_column<ColumnStruct>(nested_output);

    DORIS_CHECK(struct_column != nullptr);

    for (size_t i = 0; i < _variant_v2_outputs.size(); ++i) {

        if (!_variant_v2_outputs[i]) {

            continue;

        }

        const size_t field_index = i + (_generate_row_index ? 1 : 0);

        ColumnPtr& field = struct_column->get_column_ptr(field_index);

        const auto* nullable = check_and_get_column<ColumnNullable>(field.get());

        DORIS_CHECK(nullable != nullptr);

        if (check_and_get_column<ColumnVariantV2>(&nullable->get_nested_column()) != nullptr) {

            continue;

        }

        DORIS_CHECK(field->empty());

        field = ColumnNullable::create(ColumnVariantV2::create(), ColumnUInt8::create());

    }

}

void VExplodeV2TableFunction::get_same_many_values(MutableColumnPtr& column, int length) {

    _ensure_variant_v2_output(column);

    if (current_empty()) {

        column->insert_many_defaults(length);

        return;

    }

    ColumnStruct* struct_column = nullptr;

    std::vector<IColumn*> columns;

    const bool multi_sub_columns = _multi_detail.size() > 1 || _generate_row_index;

    if (multi_sub_columns) {

        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();

            nullmap_column->insert_many_defaults(length);

        } else {

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

        }

        for (size_t i = 0; i != _multi_detail.size(); ++i) {

            columns.emplace_back(&struct_column->get_column(i + (_generate_row_index ? 1 : 0)));

        }

    } else {

        columns.push_back(column.get());

    }

    if (_generate_row_index) {

        auto& pos_column = assert_cast<ColumnInt32&>(struct_column->get_column(0));

        pos_column.insert_many_vals(static_cast<int32_t>(_cur_offset), length);

    }

    for (int i = 0; i < _multi_detail.size(); i++) {

        auto& detail = _multi_detail[i];

        size_t pos = _array_offsets[i] + _cur_offset;

        size_t element_size = _multi_detail[i].array_col->size_at(_row_idx);

        auto& struct_field = *columns.at(i);

        if ((detail.array_nullmap_data && detail.array_nullmap_data[_row_idx])) {

            struct_field.insert_many_defaults(length);

        } else {

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

            auto* nullmap_column = nullable_column->get_null_map_column_ptr().get();

            // only need to check if the value at position pos is null

            if (element_size < _cur_offset ||

                (detail.nested_nullmap_data && detail.nested_nullmap_data[pos])) {

                nullable_column->insert_many_defaults(length);

            } else {

                nullable_column->get_nested_column_ptr()->insert_many_from(*detail.nested_col, pos,

                                                                           length);

                nullmap_column->insert_many_defaults(length);

            }

        }

    }

}

int VExplodeV2TableFunction::get_value(MutableColumnPtr& column, int max_step) {

    _ensure_variant_v2_output(column);

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

    const bool multi_sub_columns = _multi_detail.size() > 1 || _generate_row_index;

    ColumnStruct* struct_column = nullptr;

    std::vector<IColumn*> columns;

    if (current_empty()) {

        column->insert_default();

        max_step = 1;

    } else {

        if (multi_sub_columns) {

            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();

                nullmap_column->insert_many_defaults(max_step);

            } else {

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

            }

            for (size_t i = 0; i != _multi_detail.size(); ++i) {

                columns.emplace_back(&struct_column->get_column(i + (_generate_row_index ? 1 : 0)));

            }

        } else {

            columns.emplace_back(column.get());

        }

        if (_generate_row_index) {

            auto& pos_column = assert_cast<ColumnInt32&>(struct_column->get_column(0));

            pos_column.insert_range_of_integer(static_cast<int32_t>(_cur_offset),

                                               static_cast<int32_t>(_cur_offset + max_step));

        }

        for (int i = 0; i < _multi_detail.size(); i++) {

            auto& detail = _multi_detail[i];

            size_t pos = _array_offsets[i] + _cur_offset;

            size_t element_size = _multi_detail[i].array_col->size_at(_row_idx);

            auto& struct_field = *columns.at(i);

            if (detail.array_nullmap_data && detail.array_nullmap_data[_row_idx]) {

                struct_field.insert_many_defaults(max_step);

            } else {

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

                auto* nullmap_column = nullable_column->get_null_map_column_ptr().get();

                if (element_size >= _cur_offset + max_step) {

                    nullable_column->get_nested_column_ptr()->insert_range_from(*detail.nested_col,

                                                                                pos, max_step);

                    if (detail.nested_nullmap_data) {

                        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, max_step * sizeof(UInt8));

                    } else {

                        nullmap_column->insert_many_defaults(max_step);

                    }

                } else if (element_size > _cur_offset) {

                    auto current_insert_num = element_size - _cur_offset;

                    nullable_column->get_nested_column_ptr()->insert_range_from(

                            *detail.nested_col, pos, current_insert_num);

                    if (detail.nested_nullmap_data) {

                        size_t old_size = nullmap_column->size();

                        nullmap_column->resize(old_size + current_insert_num);

                        memcpy(nullmap_column->get_data().data() + old_size,

                               detail.nested_nullmap_data + pos,

                               current_insert_num * sizeof(UInt8));

                    } else {

                        nullmap_column->insert_many_defaults(current_insert_num);

                    }

                    nullable_column->insert_many_defaults(max_step - current_insert_num);

                } else {

                    nullable_column->insert_many_defaults(max_step);

                }

            }

        }

    }

    forward(max_step);

    return max_step;

}

} // namespace doris