// DragonX Wallet - ImGui Edition
// Copyright 2024-2026 The Hush Developers
// Released under the GPLv3

#include "base64.h"
#include <cstring>

namespace dragonx {
namespace util {

static const char base64_chars[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/";

static inline bool is_base64(unsigned char c) {
    return (isalnum(c) || (c == '+') || (c == '/'));
}

std::string base64_encode(const unsigned char* data, size_t len)
{
    std::string ret;
    ret.reserve(((len + 2) / 3) * 4);

    int i = 0;
    unsigned char char_array_3[3];
    unsigned char char_array_4[4];

    while (len--) {
        char_array_3[i++] = *(data++);
        if (i == 3) {
            char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
            char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
            char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
            char_array_4[3] = char_array_3[2] & 0x3f;

            for (i = 0; i < 4; i++)
                ret += base64_chars[char_array_4[i]];
            i = 0;
        }
    }

    if (i) {
        for (int j = i; j < 3; j++)
            char_array_3[j] = '\0';

        char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);

        for (int j = 0; j < i + 1; j++)
            ret += base64_chars[char_array_4[j]];

        while (i++ < 3)
            ret += '=';
    }

    return ret;
}

std::vector<unsigned char> base64_decode(const std::string& encoded)
{
    size_t in_len = encoded.size();
    int i = 0;
    int in_ = 0;
    unsigned char char_array_4[4], char_array_3[3];
    std::vector<unsigned char> ret;

    while (in_len-- && (encoded[in_] != '=') && is_base64(encoded[in_])) {
        char_array_4[i++] = encoded[in_]; in_++;
        if (i == 4) {
            for (i = 0; i < 4; i++) {
                const char* p = strchr(base64_chars, char_array_4[i]);
                char_array_4[i] = p ? static_cast<unsigned char>(p - base64_chars) : 0;
            }

            char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
            char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
            char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

            for (i = 0; i < 3; i++)
                ret.push_back(char_array_3[i]);
            i = 0;
        }
    }

    if (i) {
        for (int j = 0; j < i; j++) {
            const char* p = strchr(base64_chars, char_array_4[j]);
            char_array_4[j] = p ? static_cast<unsigned char>(p - base64_chars) : 0;
        }

        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
        char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);

        for (int j = 0; j < i - 1; j++)
            ret.push_back(char_array_3[j]);
    }

    return ret;
}

} // namespace util
} // namespace dragonx
