#include <random>
#include <bitcoin/bitcoin.hpp>

// The string we are searching for
const std::string search = "1kid";

// Generate a random secret key. A random 32 bytes.
bc::ec_secret random_secret(std::default_random_engine& engine);
// Extract the Bitcoin address from an EC secret.
std::string bitcoin_address(const bc::ec_secret& secret);
// Case insensitive comparison with the search string.
bool match_found(const std::string& address);

int main()
{
    // random_device on Linux uses "/dev/urandom"
    // CAUTION: Depending on implementation this RNG may not be secure enough!
    // Do not use vanity keys generated by this example in production
    std::random_device random;
    std::default_random_engine engine(random());
    
    // Loop continuously...
    while (true)
    {
        // Generate a random secret.
        bc::ec_secret secret = random_secret(engine);
        // Get the address.
        std::string address = bitcoin_address(secret);
        // Does it match our search string? (1kid)
        if (match_found(address))
        {
            // Success!
            std::cout << "Found vanity address! " << address << std::endl;
            std::cout << "Secret: " << bc::encode_base16(secret) << std::endl;
            return 0;
        }
    }
    // Should never reach here!
    return 0;
}

bc::ec_secret random_secret(std::default_random_engine& engine)
{
    // Create new secret...
    bc::ec_secret secret;
    // Iterate through every byte setting a random value...
    for (uint8_t& byte: secret)
        byte = engine() & 255;
    // Return result.
    return secret;
}

std::string bitcoin_address(const bc::ec_secret& secret)
{
    // Convert secret to payment address
    bc::wallet::ec_private private_key(secret);
    bc::wallet::payment_address payaddr(private_key);
    // Return encoded form.
    return payaddr.encoded();
}

bool match_found(const std::string& address)
{
    auto addr_it = address.begin();
    // Loop through the search string comparing it to the lower case
    // character of the supplied address.
    for (auto it = search.begin(); it != search.end(); ++it, ++addr_it)
        if (*it != std::tolower(*addr_it))
            return false;
    // Reached end of search string, so address matches.
    return true;
}