#ifndef RAPIDBASE64_HPP_INCLUDED_20201031_GAOZILAI
#define RAPIDBASE64_HPP_INCLUDED_20201031_GAOZILAI

// Copyright (C) 2020 Gao Zilai
// Version 1.0
//! \file RapidBase64.hpp This file contains Encoding and Decoding
namespace RapidBase64
{
    int Encoding(const unsigned char* in_data, int in_count, char* out_base64)
    {
        static const char* base64_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789""+/"; // -_
        int cnt = in_count / 3 * 3;
        for (int i = 0; i < cnt; i += 3, out_base64 += 4) {
            unsigned char a0 = in_data[i];
            unsigned char a1 = in_data[i + 1];
            unsigned char a2 = in_data[i + 2];
            out_base64[0] = base64_chars[a0 >> 2];
            out_base64[1] = base64_chars[((a0 & 0x03) << 4) + (a1 >> 4)];
            out_base64[2] = base64_chars[((a1 & 0x0f) << 2) + (a2 >> 6)];
            out_base64[3] = base64_chars[a2 & 0x3f];
        }

        if (cnt + 1 == in_count) {
            unsigned char a0 = in_data[cnt];
            out_base64[0] = base64_chars[a0 >> 2];
            out_base64[1] = base64_chars[(a0 & 0x03) << 4];
            out_base64[2] = '=';
            out_base64[3] = '=';
        } else if (cnt + 2 == in_count) {
            unsigned char a0 = in_data[cnt];
            unsigned char a1 = in_data[cnt + 1];
            out_base64[0] = base64_chars[a0 >> 2];
            out_base64[1] = base64_chars[((a0 & 0x03) << 4) + (a1 >> 4)];
            out_base64[2] = base64_chars[(a1 & 0x0f) << 2];
            out_base64[3] = '=';
        }
        return (in_count + 2) / 3 * 4;
    }

    int Decoding(const char* in_base64, int in_charcount, unsigned char* out_data)
    {
        static const unsigned char pm[] = {
             0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0 
             0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 10 
             0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20 
             0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 30 
             0, 0, 0,62, 0,62, 0,63,52,53, // 40 
            54,55,56,57,58,59,60,61, 0, 0, // 50 
             0, 0, 0, 0, 0, 0, 1, 2, 3, 4, // 60 
             5, 6, 7, 8, 9,10,11,12,13,14, // 70 
            15,16,17,18,19,20,21,22,23,24, // 80 
            25, 0, 0, 0, 0,63, 0,26,27,28, // 90 
            29,30,31,32,33,34,35,36,37,38, // 100 
            39,40,41,42,43,44,45,46,47,48, // 110 
            49,50,51, 0, 0, 0, 0, 0        // 120 
        };

        int cnt = in_charcount - 4;
        for (int i = 0; i < cnt; i += 4, out_data += 3) {
            unsigned char a0 = pm[in_base64[i]];
            unsigned char a1 = pm[in_base64[i + 1]];
            unsigned char a2 = pm[in_base64[i + 2]];
            unsigned char a3 = pm[in_base64[i + 3]];
            out_data[0] = (a0 << 2) + (a1 >> 4);
            out_data[1] = (a1 << 4) + (a2 >> 2);
            out_data[2] = (a2 << 6) + a3;
        }

        int out_cnt = cnt / 4 * 3;
        if (in_base64[cnt + 2] == '=') {
            unsigned char a0 = pm[in_base64[cnt]];
            unsigned char a1 = pm[in_base64[cnt + 1]];
            out_data[0] = (a0 << 2) + (a1 >> 4);
            out_cnt += 1;
        } else if (in_base64[cnt + 3] == '=') {
            unsigned char a0 = pm[in_base64[cnt]];
            unsigned char a1 = pm[in_base64[cnt + 1]];
            unsigned char a2 = pm[in_base64[cnt + 2]];
            out_data[0] = (a0 << 2) + (a1 >> 4);
            out_data[1] = (a1 << 4) + (a2 >> 2);
            out_cnt += 2;
        } else {
            unsigned char a0 = pm[in_base64[cnt]];
            unsigned char a1 = pm[in_base64[cnt + 1]];
            unsigned char a2 = pm[in_base64[cnt + 2]];
            unsigned char a3 = pm[in_base64[cnt + 3]];
            out_data[0] = (a0 << 2) + (a1 >> 4);
            out_data[1] = (a1 << 4) + (a2 >> 2);
            out_data[2] = (a2 << 6) + a3;
            out_cnt += 3;
        }
        return out_cnt;
    }
}
#endif