// 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.
// This file is copied from
// https://github.com/ClickHouse/ClickHouse/blob/master/src/Functions/If.cpp
// and modified by Doris

#include "if.h"

#include <glog/logging.h>
#include <stddef.h>

#include <algorithm>
#include <boost/iterator/iterator_facade.hpp>
#include <memory>
#include <type_traits>
#include <utility>

#include "common/status.h"
#include "util/simd/bits.h"
#include "vec/aggregate_functions/aggregate_function.h"
#include "vec/columns/column.h"
#include "vec/columns/column_const.h"
#include "vec/columns/column_nullable.h"
#include "vec/columns/column_vector.h"
#include "vec/columns/columns_number.h"
#include "vec/common/assert_cast.h"
#include "vec/common/typeid_cast.h"
#include "vec/core/block.h"
#include "vec/core/column_numbers.h"
#include "vec/core/column_with_type_and_name.h"
#include "vec/core/types.h"
#include "vec/data_types/data_type.h"
#include "vec/data_types/data_type_nullable.h"
#include "vec/data_types/data_type_number.h"
#include "vec/functions/cast_type_to_either.h"
#include "vec/functions/function.h"
#include "vec/functions/function_helpers.h"
#include "vec/functions/simple_function_factory.h"
namespace doris {
class FunctionContext;

namespace vectorized {
namespace NumberTraits {
struct Error;
} // namespace NumberTraits
} // namespace vectorized
} // namespace doris

namespace doris::vectorized {

size_t count_true_with_notnull(const ColumnPtr& col) {
    if (col->only_null()) {
        return 0;
    }

    if (const auto* const_col = check_and_get_column_const<ColumnVector<UInt8>>(col.get())) {
        bool is_true = const_col->get_bool(0);
        return is_true ? col->size() : 0;
    }

    auto count = col->size();
    if (col->is_nullable()) {
        const auto* nullable = assert_cast<const ColumnNullable*>(col.get());
        const auto* __restrict null_data = nullable->get_null_map_data().data();
        const auto* __restrict bool_data =
                ((const ColumnVector<UInt8>&)(nullable->get_nested_column())).get_data().data();

        size_t null_count = count - simd::count_zero_num((const int8_t*)null_data, count);

        if (null_count == count) {
            return 0;
        } else if (null_count == 0) {
            size_t true_count = count - simd::count_zero_num((const int8_t*)bool_data, count);
            return true_count;
        } else {
            // In fact, the null_count maybe is different with true_count, but it's no impact
            return null_count;
        }
    } else {
        const auto* bool_col = assert_cast<const ColumnUInt8*>(col.get());
        const auto* __restrict bool_data = bool_col->get_data().data();
        return count - simd::count_zero_num((const int8_t*)bool_data, count);
    }
}
// todo(wb) support llvm codegen
class FunctionIf : public IFunction {
public:
    static constexpr auto name = "if";

    static FunctionPtr create() { return std::make_shared<FunctionIf>(); }
    String get_name() const override { return name; }

    size_t get_number_of_arguments() const override { return 3; }
    bool use_default_implementation_for_nulls() const override { return false; }
    DataTypePtr get_return_type_impl(const DataTypes& arguments) const override {
        // if return type is custom, one of nullable return type will be nullable
        bool nullable = arguments[1]->is_nullable() || arguments[2]->is_nullable();
        if (nullable) {
            return make_nullable(arguments[1]);
        } else {
            return arguments[1];
        }
    }

    static ColumnPtr materialize_column_if_const(const ColumnPtr& column) {
        return column->convert_to_full_column_if_const();
    }

    static ColumnPtr make_nullable_column_if_not(const ColumnPtr& column) {
        if (is_column_nullable(*column)) return column;

        return ColumnNullable::create(materialize_column_if_const(column),
                                      ColumnUInt8::create(column->size(), 0));
    }

    static ColumnPtr get_nested_column(const ColumnPtr& column) {
        if (auto* nullable = check_and_get_column<ColumnNullable>(*column))
            return nullable->get_nested_column_ptr();
        else if (const auto* column_const = check_and_get_column<ColumnConst>(*column))
            return ColumnConst::create(get_nested_column(column_const->get_data_column_ptr()),
                                       column->size());

        return column;
    }

    Status execute_generic(Block& block, const ColumnUInt8* cond_col,
                           const ColumnWithTypeAndName& then_col_type_name,
                           const ColumnWithTypeAndName& else_col_type_name, uint32_t result,
                           size_t input_row_count) const {
        MutableColumnPtr result_column = block.get_by_position(result).type->create_column();
        result_column->reserve(input_row_count);

        const IColumn& then_col = *then_col_type_name.column;
        const IColumn& else_col = *else_col_type_name.column;
        bool then_is_const = is_column_const(then_col);
        bool else_is_const = is_column_const(else_col);

        const auto& cond_array = cond_col->get_data();

        if (then_is_const && else_is_const) {
            const IColumn& then_nested_column =
                    assert_cast<const ColumnConst&>(then_col).get_data_column();
            const IColumn& else_nested_column =
                    assert_cast<const ColumnConst&>(else_col).get_data_column();
            for (size_t i = 0; i < input_row_count; i++) {
                if (cond_array[i])
                    result_column->insert_from(then_nested_column, 0);
                else
                    result_column->insert_from(else_nested_column, 0);
            }
        } else if (then_is_const) {
            const IColumn& then_nested_column =
                    assert_cast<const ColumnConst&>(then_col).get_data_column();

            for (size_t i = 0; i < input_row_count; i++) {
                if (cond_array[i])
                    result_column->insert_from(then_nested_column, 0);
                else
                    result_column->insert_from(else_col, i);
            }
        } else if (else_is_const) {
            const IColumn& else_nested_column =
                    assert_cast<const ColumnConst&>(else_col).get_data_column();

            for (size_t i = 0; i < input_row_count; i++) {
                if (cond_array[i])
                    result_column->insert_from(then_col, i);
                else
                    result_column->insert_from(else_nested_column, 0);
            }
        } else {
            for (size_t i = 0; i < input_row_count; i++) {
                result_column->insert_from(cond_array[i] ? then_col : else_col, i);
            }
        }
        block.replace_by_position(result, std::move(result_column));
        return Status::OK();
    }

    void execute_basic_type(Block& block, const ColumnUInt8* cond_col,
                            const ColumnWithTypeAndName& then_col,
                            const ColumnWithTypeAndName& else_col, uint32_t result,
                            Status& status) const {
        if (then_col.type->get_type_id() != else_col.type->get_type_id()) {
            status = Status::InternalError("then and else column type must be same");
            return;
        }
        DCHECK(WhichDataType {then_col.type}.is_int() || WhichDataType {then_col.type}.is_float());
        auto valid = cast_type_to_either<DataTypeInt8, DataTypeInt16, DataTypeInt32, DataTypeInt64,
                                         DataTypeInt128, DataTypeFloat32, DataTypeFloat64>(
                then_col.type.get(), [&](const auto& type) -> bool {
                    using DataType = std::decay_t<decltype(type)>;
                    using Type = typename DataType::FieldType;
                    auto res_column = NumIfImpl<Type>::execute_if(cond_col->get_data(),
                                                                  then_col.column, else_col.column);
                    if (!res_column) {
                        return false;
                    }
                    block.replace_by_position(result, std::move(res_column));
                    return true;
                });
        if (!valid) {
            status = Status::InternalError("unexpected args column type {} , {} , of function {}",
                                           then_col.type->get_name(), else_col.type->get_name(),
                                           get_name());
        }
    }

    Status execute_for_null_then_else(FunctionContext* context, Block& block,
                                      const ColumnWithTypeAndName& arg_cond,
                                      const ColumnWithTypeAndName& arg_then,
                                      const ColumnWithTypeAndName& arg_else, uint32_t result,
                                      size_t input_rows_count, bool& handled) const {
        bool then_is_null = arg_then.column->only_null();
        bool else_is_null = arg_else.column->only_null();

        handled = false;
        if (!then_is_null && !else_is_null) {
            return Status::OK();
        }

        if (then_is_null && else_is_null) {
            block.get_by_position(result).column =
                    block.get_by_position(result).type->create_column_const_with_default_value(
                            input_rows_count);
            handled = true;
            return Status::OK();
        }

        const auto* cond_col = typeid_cast<const ColumnUInt8*>(arg_cond.column.get());
        const ColumnConst* cond_const_col =
                check_and_get_column_const<ColumnVector<UInt8>>(arg_cond.column.get());

        /// If then is NULL, we create Nullable column with null mask OR-ed with condition.
        if (then_is_null) {
            if (cond_col) {
                if (is_column_nullable(*arg_else.column)) { // if(cond, null, nullable)
                    auto arg_else_column = arg_else.column;
                    auto result_column = (*std::move(arg_else_column)).mutate();
                    assert_cast<ColumnNullable&>(*result_column)
                            .apply_null_map(assert_cast<const ColumnUInt8&>(*arg_cond.column));
                    block.replace_by_position(result, std::move(result_column));
                } else { // if(cond, null, not_nullable)
                    block.replace_by_position(
                            result,
                            ColumnNullable::create(materialize_column_if_const(arg_else.column),
                                                   arg_cond.column));
                }
            } else if (cond_const_col) {
                if (cond_const_col->get_value<UInt8>()) { // if(true, null, else)
                    block.get_by_position(result).column =
                            block.get_by_position(result).type->create_column()->clone_resized(
                                    input_rows_count);
                } else { // if(false, null, else)
                    block.get_by_position(result).column =
                            make_nullable_column_if_not(arg_else.column);
                }
            } else {
                return Status::InternalError(
                        "Illegal column {} of first argument of function {}. Must be ColumnUInt8 "
                        "or ColumnConstUInt8.",
                        arg_cond.column->get_name(), get_name());
            }
        } else { /// If else is NULL, we create Nullable column with null mask OR-ed with negated condition.
            if (cond_col) {
                size_t size = input_rows_count;

                if (is_column_nullable(*arg_then.column)) { // if(cond, nullable, NULL)
                    auto arg_then_column = arg_then.column;
                    auto result_column = (*std::move(arg_then_column)).mutate();
                    assert_cast<ColumnNullable&>(*result_column)
                            .apply_negated_null_map(
                                    assert_cast<const ColumnUInt8&>(*arg_cond.column));
                    block.replace_by_position(result, std::move(result_column));
                } else { // if(cond, not_nullable, NULL)
                    const auto& null_map_data = cond_col->get_data();
                    auto negated_null_map = ColumnUInt8::create();
                    auto& negated_null_map_data = negated_null_map->get_data();
                    negated_null_map_data.resize(size);

                    for (size_t i = 0; i < size; ++i) {
                        negated_null_map_data[i] = !null_map_data[i];
                    }

                    block.replace_by_position(
                            result,
                            ColumnNullable::create(materialize_column_if_const(arg_then.column),
                                                   std::move(negated_null_map)));
                }
            } else if (cond_const_col) {
                if (cond_const_col->get_value<UInt8>()) { // if(true, then, NULL)
                    block.get_by_position(result).column =
                            make_nullable_column_if_not(arg_then.column);
                } else { // if(false, then, NULL)
                    block.get_by_position(result).column =
                            block.get_by_position(result).type->create_column()->clone_resized(
                                    input_rows_count);
                }
            } else {
                return Status::InternalError(
                        "Illegal column {} of first argument of function {}. Must be ColumnUInt8 "
                        "or ColumnConstUInt8.",
                        arg_cond.column->get_name(), get_name());
            }
        }
        handled = true;
        return Status::OK();
    }

    Status execute_for_nullable_then_else(FunctionContext* context, Block& block,
                                          const ColumnWithTypeAndName& arg_cond,
                                          const ColumnWithTypeAndName& arg_then,
                                          const ColumnWithTypeAndName& arg_else, uint32_t result,
                                          size_t input_rows_count, bool& handled) const {
        auto then_type_is_nullable = arg_then.type->is_nullable();
        auto else_type_is_nullable = arg_else.type->is_nullable();
        handled = false;
        if (!then_type_is_nullable && !else_type_is_nullable) {
            return Status::OK();
        }

        auto* then_is_nullable = check_and_get_column<ColumnNullable>(*arg_then.column);
        auto* else_is_nullable = check_and_get_column<ColumnNullable>(*arg_else.column);
        bool then_column_is_const_nullable = false;
        bool else_column_is_const_nullable = false;
        if (then_type_is_nullable && then_is_nullable == nullptr) {
            //this case is a const(nullable column)
            auto& const_column = assert_cast<const ColumnConst&>(*arg_then.column);
            then_is_nullable =
                    assert_cast<const ColumnNullable*>(const_column.get_data_column_ptr().get());
            then_column_is_const_nullable = true;
        }

        if (else_type_is_nullable && else_is_nullable == nullptr) {
            //this case is a const(nullable column)
            auto& const_column = assert_cast<const ColumnConst&>(*arg_else.column);
            else_is_nullable =
                    assert_cast<const ColumnNullable*>(const_column.get_data_column_ptr().get());
            else_column_is_const_nullable = true;
        }

        /** Calculate null mask of result and nested column separately.
          */
        ColumnPtr result_null_mask;
        {
            // get null map from column:
            // a. get_null_map_column_ptr() : it's a real nullable column, so could get it from nullable column
            // b. create a const_nullmap_column: it's a not nullable column or a const nullable column, contain a const value
            Block temporary_block;
            temporary_block.insert(arg_cond);
            auto then_nested_null_map =
                    (then_type_is_nullable && !then_column_is_const_nullable)
                            ? then_is_nullable->get_null_map_column_ptr()
                            : DataTypeUInt8().create_column_const_with_default_value(
                                      input_rows_count);
            temporary_block.insert({then_nested_null_map, std::make_shared<DataTypeUInt8>(),
                                    "then_column_null_map"});

            auto else_nested_null_map =
                    (else_type_is_nullable && !else_column_is_const_nullable)
                            ? else_is_nullable->get_null_map_column_ptr()
                            : DataTypeUInt8().create_column_const_with_default_value(
                                      input_rows_count);
            temporary_block.insert({else_nested_null_map, std::make_shared<DataTypeUInt8>(),
                                    "else_column_null_map"});
            temporary_block.insert(
                    {nullptr, std::make_shared<DataTypeUInt8>(), "result_column_null_map"});

            RETURN_IF_ERROR(_execute_impl_internal(context, temporary_block, {0, 1, 2}, 3,
                                                   temporary_block.rows()));

            result_null_mask = temporary_block.get_by_position(3).column;
        }

        ColumnPtr result_nested_column;

        {
            Block temporary_block(
                    {arg_cond,
                     {get_nested_column(arg_then.column), remove_nullable(arg_then.type), ""},
                     {get_nested_column(arg_else.column), remove_nullable(arg_else.type), ""},
                     {nullptr, remove_nullable(block.get_by_position(result).type), ""}});

            RETURN_IF_ERROR(_execute_impl_internal(context, temporary_block, {0, 1, 2}, 3,
                                                   temporary_block.rows()));

            result_nested_column = temporary_block.get_by_position(3).column;
        }

        auto column = ColumnNullable::create(materialize_column_if_const(result_nested_column),
                                             materialize_column_if_const(result_null_mask));
        block.replace_by_position(result, std::move(column));
        handled = true;
        return Status::OK();
    }

    Status execute_for_null_condition(FunctionContext* context, Block& block,
                                      const ColumnNumbers& arguments,
                                      const ColumnWithTypeAndName& arg_cond,
                                      const ColumnWithTypeAndName& arg_then,
                                      const ColumnWithTypeAndName& arg_else, uint32_t result,
                                      bool& handled) const {
        bool cond_is_null = arg_cond.column->only_null();
        handled = false;

        if (cond_is_null) {
            block.replace_by_position(result,
                                      arg_else.column->clone_resized(arg_cond.column->size()));
            handled = true;
            return Status::OK();
        }

        if (const auto* nullable = check_and_get_column<ColumnNullable>(*arg_cond.column)) {
            DCHECK(remove_nullable(arg_cond.type)->get_type_id() == TypeIndex::UInt8);

            // update nested column by null map
            const auto* __restrict null_map = nullable->get_null_map_data().data();
            auto* __restrict nested_bool_data =
                    ((ColumnVector<UInt8>&)(nullable->get_nested_column())).get_data().data();
            auto rows = nullable->size();
            for (size_t i = 0; i < rows; i++) {
                nested_bool_data[i] &= !null_map[i];
            }
            auto column_size = block.columns();
            block.insert({nullable->get_nested_column_ptr(), remove_nullable(arg_cond.type),
                          arg_cond.name});

            handled = true;
            return _execute_impl_internal(context, block, {column_size, arguments[1], arguments[2]},
                                          result, rows);
        }
        return Status::OK();
    }

    Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,
                        uint32_t result, size_t input_rows_count) const override {
        const ColumnWithTypeAndName& arg_then = block.get_by_position(arguments[1]);
        const ColumnWithTypeAndName& arg_else = block.get_by_position(arguments[2]);

        /// A case for identical then and else (pointers are the same).
        if (arg_then.column.get() == arg_else.column.get()) {
            /// Just point result to them.
            block.replace_by_position(result, arg_then.column);
            return Status::OK();
        }

        ColumnWithTypeAndName& cond_column = block.get_by_position(arguments[0]);
        cond_column.column = materialize_column_if_const(cond_column.column);
        const ColumnWithTypeAndName& arg_cond = block.get_by_position(arguments[0]);

        auto true_count = count_true_with_notnull(arg_cond.column);
        auto item_count = arg_cond.column->size();
        if (true_count == item_count || true_count == 0) {
            bool result_nullable = block.get_by_position(result).type->is_nullable();
            if (true_count == item_count) {
                block.replace_by_position(
                        result,
                        result_nullable
                                ? make_nullable(arg_then.column->clone_resized(input_rows_count))
                                : arg_then.column->clone_resized(input_rows_count));
            } else {
                block.replace_by_position(
                        result,
                        result_nullable
                                ? make_nullable(arg_else.column->clone_resized(input_rows_count))
                                : arg_else.column->clone_resized(input_rows_count));
            }
            return Status::OK();
        }

        return _execute_impl_internal(context, block, arguments, result, input_rows_count);
    }

    Status _execute_impl_internal(FunctionContext* context, Block& block,
                                  const ColumnNumbers& arguments, uint32_t result,
                                  size_t input_rows_count) const {
        const ColumnWithTypeAndName& arg_then = block.get_by_position(arguments[1]);
        const ColumnWithTypeAndName& arg_else = block.get_by_position(arguments[2]);
        ColumnWithTypeAndName& cond_column = block.get_by_position(arguments[0]);
        cond_column.column = materialize_column_if_const(cond_column.column);
        const ColumnWithTypeAndName& arg_cond = block.get_by_position(arguments[0]);

        Status ret = Status::OK();
        bool handled = false;
        RETURN_IF_ERROR(execute_for_null_condition(context, block, arguments, arg_cond, arg_then,
                                                   arg_else, result, handled));

        if (!handled) {
            RETURN_IF_ERROR(execute_for_null_then_else(context, block, arg_cond, arg_then, arg_else,
                                                       result, input_rows_count, handled));
        }

        if (!handled) {
            RETURN_IF_ERROR(execute_for_nullable_then_else(context, block, arg_cond, arg_then,
                                                           arg_else, result, input_rows_count,
                                                           handled));
        }

        if (handled) {
            return Status::OK();
        }

        const auto* cond_col = assert_cast<const ColumnUInt8*>(arg_cond.column.get());
        const ColumnConst* cond_const_col =
                check_and_get_column_const<ColumnVector<UInt8>>(arg_cond.column.get());

        if (cond_const_col) {
            block.get_by_position(result).column =
                    cond_const_col->get_value<UInt8>() ? arg_then.column : arg_else.column;
            return Status::OK();
        }

        WhichDataType which_type(arg_then.type);
        if (which_type.is_int() || which_type.is_float()) {
            Status status;
            execute_basic_type(block, cond_col, arg_then, arg_else, result, status);
            return status;
        } else {
            return execute_generic(block, cond_col, arg_then, arg_else, result, input_rows_count);
        }
    }
};

void register_function_if(SimpleFunctionFactory& factory) {
    factory.register_function<FunctionIf>();
}

} // namespace doris::vectorized