// 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.

#pragma once

#include "core/column/column_string.h"

#include "util/simd/vstring_function.h"

namespace doris::string_hex {

static constexpr int MAX_STACK_CIPHER_LEN = 1024 * 64;

inline bool check_and_decode_one(char& c, const char src_c, bool flag) {

    int k = flag ? 16 : 1;

    int value = src_c - '0';

    // 9 = ('9'-'0')

    if (value >= 0 && value <= 9) {

        c += value * k;

        return true;

    }

    value = src_c - 'A';

    // 5 = ('F'-'A')

    if (value >= 0 && value <= 5) {

        c += (value + 10) * k;

        return true;

    }

    value = src_c - 'a';

    // 5 = ('f'-'a')

    if (value >= 0 && value <= 5) {

        c += (value + 10) * k;

        return true;

    }

    // not in ( ['0','9'], ['a','f'], ['A','F'] )

    return false;

}

inline int hex_decode(const char* src_str, ColumnString::Offset src_len, char* dst_str) {

    // if str length is odd or 0, return empty string like mysql dose.

    if ((src_len & 1) != 0 or src_len == 0) {

        return 0;

    }

    //check and decode one character at the same time

    // character in ( ['0','9'], ['a','f'], ['A','F'] ), return 'NULL' like mysql dose.

    for (auto i = 0, dst_index = 0; i < src_len; i += 2, dst_index++) {

        char c = 0;

        // combine two character into dst_str one character

        bool left_4bits_flag = check_and_decode_one(c, *(src_str + i), true);

        bool right_4bits_flag = check_and_decode_one(c, *(src_str + i + 1), false);

        if (!left_4bits_flag || !right_4bits_flag) {

            return 0;

        }

        *(dst_str + dst_index) = c;

    }

    return src_len / 2;

}

inline void hex_encode(const unsigned char* source, size_t srclen, unsigned char*& dst_data_ptr,

                       size_t& offset) {

    if (srclen != 0) {

        doris::simd::VStringFunctions::hex_encode(source, srclen,

                                                  reinterpret_cast<char*>(dst_data_ptr));

        dst_data_ptr += (srclen * 2);

        offset += (srclen * 2);

    }

}

} // namespace doris::string_hex