#include "yaml-cpp/binary.h"
#include "yaml-cpp/ostream.h"

namespace YAML
{
    static const char encoding[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    void WriteBase64(ostream& out, const unsigned char *data, std::size_t size)
    {
        const char PAD = '=';
        
        out << "\"";
        std::size_t chunks = size / 3;
        std::size_t remainder = size % 3;
        
        for(std::size_t i=0;i<chunks;i++, data += 3) {
            out << encoding[data[0] >> 2];
            out << encoding[((data[0] & 0x3) << 4) | (data[1] >> 4)];
            out << encoding[((data[1] & 0xf) << 2) | (data[2] >> 6)];
            out << encoding[data[2] & 0x3f];
        }
        
        switch(remainder) {
            case 0:
                break;
            case 1:
                out << encoding[data[0] >> 2];
                out << encoding[((data[0] & 0x3) << 4)];
                out << PAD;
                out << PAD;
                break;
            case 2:
                out << encoding[data[0] >> 2];
                out << encoding[((data[0] & 0x3) << 4) | (data[1] >> 4)];
                out << encoding[((data[1] & 0xf) << 2)];
                out << PAD;
                break;
        }
        
        out << "\"";
    }
    
    static const unsigned char decoding[] = {
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255, 62,255,255,255, 63,
         52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255,  0,255,255,
        255,  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, 25,255,255,255,255,255,
        255, 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, 51,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
        255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
    };

    std::vector<unsigned char> ReadBase64(const std::string& input)
    {
        typedef std::vector<unsigned char> ret_type;
        if(input.empty())
            return ret_type();
        
        ret_type ret(3 * input.size() / 4 + 1);
        unsigned char *out = &ret[0];
        
        unsigned value = 0;
        for(std::size_t i=0;i<input.size();i++) {
            unsigned char d = decoding[static_cast<unsigned>(input[i])];
            if(d == 255)
                return ret_type();

            value = (value << 6) | d;
            if(i % 4 == 3) {
                *out++ = value >> 16;
                if(i > 0 && input[i - 1] != '=')
                    *out++ = value >> 8;
                if(input[i] != '=')
                    *out++ = value;
            }
        }
        
        ret.resize(out - &ret[0]);
        return ret;
    }
}