#pragma once

#include <cstring>
#include <string>
#include <vector>
#include <cstdint>

namespace FastNoise
{
    /** https://gist.github.com/tomykaira/f0fd86b6c73063283afe550bc5d77594
     * The MIT License (MIT)
     * Copyright (c) 2016 tomykaira
     *
     * Permission is hereby granted, free of charge, to any person obtaining
     * a copy of this software and associated documentation files (the
     * "Software"), to deal in the Software without restriction, including
     * without limitation the rights to use, copy, modify, merge, publish,
     * distribute, sublicense, and/or sell copies of the Software, and to
     * permit persons to whom the Software is furnished to do so, subject to
     * the following conditions:
     *
     * The above copyright notice and this permission notice shall be
     * included in all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
     * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
     * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
     * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     */
    namespace Base64
    {
        static std::string Encode( const std::vector<uint8_t>& data )
        {
            static constexpr char sEncodingTable[] = {
                'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
                'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
                'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
                'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
                'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
                'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
                'w', 'x', 'y', 'z', '0', '1', '2', '3',
                '4', '5', '6', '7', '8', '9', '+', '/'
            };

            size_t in_len = data.size();
            size_t out_len = 4 * ((in_len + 2) / 3);
            std::string ret( out_len, '\0' );
            size_t i;
            char* p = const_cast<char*>(ret.c_str());

            for( i = 0; i < in_len - 2; i += 3 )
            {
                *p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
                *p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int)(data[i + 1] & 0xF0) >> 4)];
                *p++ = sEncodingTable[((data[i + 1] & 0xF) << 2) | ((int)(data[i + 2] & 0xC0) >> 6)];
                *p++ = sEncodingTable[data[i + 2] & 0x3F];
            }
            if( i < in_len )
            {
                *p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
                if( i == (in_len - 1) )
                {
                    *p++ = sEncodingTable[((data[i] & 0x3) << 4)];
                    *p++ = '=';
                }
                else
                {
                    *p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int)(data[i + 1] & 0xF0) >> 4)];
                    *p++ = sEncodingTable[((data[i + 1] & 0xF) << 2)];
                }
                *p++ = '=';
            }

            return ret;
        }

        static std::vector<uint8_t> Decode( const char* input )
        {
            static constexpr unsigned char kDecodingTable[] = {
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
                52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
                64, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
                15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
                64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
                41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64
            };

            size_t in_len = std::strlen( input );
            if( in_len % 4 != 0 ) return {};

            size_t out_len = in_len / 4 * 3;
            if( input[in_len - 1] == '=' ) out_len--;
            if( input[in_len - 2] == '=' ) out_len--;

            std::vector<uint8_t> out( out_len );

            for( size_t i = 0, j = 0; i < in_len; )
            {
                uint32_t a = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
                uint32_t b = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
                uint32_t c = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
                uint32_t d = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];

                uint32_t triple = (a << 3 * 6) + (b << 2 * 6) + (c << 1 * 6) + (d << 0 * 6);

                if( j < out_len ) out[j++] = (triple >> 2 * 8) & 0xFF;
                if( j < out_len ) out[j++] = (triple >> 1 * 8) & 0xFF;
                if( j < out_len ) out[j++] = (triple >> 0 * 8) & 0xFF;
            }

            return out;
        }
    };
}