// Licensed to the Apache Software Foundation (ASF) under one

// 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 <fmt/format.h>

#include <glog/logging.h>

#include <stdint.h>

#include <time.h>

#include <algorithm>

#include <memory>

#include <ostream>

#include <random>

#include <string>

#include <utility>

#include "common/status.h"

#include "core/assert_cast.h"

#include "core/block/block.h"

#include "core/block/column_numbers.h"

#include "core/block/column_with_type_and_name.h"

#include "core/column/column.h"

#include "core/column/column_array.h"

#include "core/data_type/data_type.h"

#include "core/types.h"

#include "exprs/aggregate/aggregate_function.h"

#include "exprs/function/function.h"

#include "exprs/function/simple_function_factory.h"

namespace doris {

class FunctionContext;

} // namespace doris

namespace doris {

class FunctionArrayShuffle : public IFunction {

public:

    static constexpr auto name = "array_shuffle";

    static FunctionPtr create() { return std::make_shared<FunctionArrayShuffle>(); }

    /// Get function name.

    String get_name() const override { return name; }

    bool is_variadic() const override { return true; }

    size_t get_number_of_arguments() const override { return 1; }

    DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {

        DCHECK(arguments[0]->get_primitive_type() == TYPE_ARRAY)

                << "first argument for function: " << name << " should be DataTypeArray"

                << " and arguments[0] is " << arguments[0]->get_name();

        return arguments[0];

    }

    Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,

                        uint32_t result, size_t input_rows_count) const override {

        ColumnPtr src_column =

                block.get_by_position(arguments[0]).column->convert_to_full_column_if_const();

        const auto& src_column_array = assert_cast<const ColumnArray&>(*src_column);

        size_t seed = time(nullptr);

        if (arguments.size() == 2) {

            ColumnPtr seed_column =

                    block.get_by_position(arguments[1]).column->convert_to_full_column_if_const();

            seed = assert_cast<const ColumnInt64*>(seed_column.get())->get_element(0);

        }

        // time() and seed will not exceed the range of uint32.

        std::mt19937 g(cast_set<uint32_t>(seed));

        auto dest_column_ptr = _execute(src_column_array, g);

        if (!dest_column_ptr) {

            return Status::RuntimeError(

                    fmt::format("execute failed or unsupported types for function {}({})",

                                get_name(), block.get_by_position(arguments[0]).type->get_name()));

        }

        block.replace_by_position(result, std::move(dest_column_ptr));

        return Status::OK();

    }

private:

    ColumnPtr _execute(const ColumnArray& src_column_array, std::mt19937& g) const {

        const auto& src_offsets = src_column_array.get_offsets();

        const auto src_nested_column = src_column_array.get_data_ptr();

        ColumnArray::Offset64 src_offsets_size = src_offsets.size();

        IColumn::Permutation permutation(src_nested_column->size());

        for (size_t i = 0; i < src_nested_column->size(); ++i) {

            permutation[i] = i;

        }

        for (size_t i = 0; i < src_offsets_size; ++i) {

            auto last_offset = src_offsets[i - 1];

            auto src_offset = src_offsets[i];

            std::shuffle(&permutation[last_offset], &permutation[src_offset], g);

        }

        return ColumnArray::create(src_nested_column->permute(permutation, 0),

                                   src_column_array.get_offsets_ptr());

    }

};

void register_function_array_shuffle(SimpleFunctionFactory& factory) {

    factory.register_function<FunctionArrayShuffle>();

    factory.register_alias("array_shuffle", "shuffle");

}

} // namespace doris