/*  This file is part of libravatarserv.
 *  Copyright © 2018 tastytea <tastytea@tastytea.de>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, version 3.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <algorithm>
#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1
#include <cryptopp/md5.h>
#include <cryptopp/sha.h>
#include <cryptopp/filters.h>
#include <cryptopp/hex.h>
#include "libravatarserv.hpp"

using namespace hash;

const string hash::md5(const string &text)
{
    using namespace CryptoPP;
    Weak::MD5 hash;
    string digest;

    StringSource s(text, true,
                   new HashFilter(hash,
                                  new HexEncoder(new StringSink(digest))));
    std::transform(digest.begin(), digest.end(), digest.begin(), ::tolower);
    return digest;
}

const string hash::sha256(const string &text)
{
    using namespace CryptoPP;
    SHA256 hash;
    string digest;

    StringSource s(text, true,
                   new HashFilter(hash,
                                  new HexEncoder(new StringSink(digest))));

    std::transform(digest.begin(), digest.end(), digest.begin(), ::tolower);
    return digest;
}

bool hash::fill_table()
{
    for (const fs::path &path :
         fs::recursive_directory_iterator(settings::avatar_dir))
    {
        if (fs::is_regular_file(path))
        {
            string email = path.filename();
            std::transform(email.begin(), email.end(), email.begin(), ::tolower);
            table.insert({ md5(email), email });
            table.insert({ sha256(email), email });
        }
    }
    return true;
}

bool hash::is_valid(const string &digest)
{
    if (digest.length() != 64 && digest.length() != 32)
    {
        return false;
    }
    if (std::any_of(digest.begin(), digest.end(), not_hex))
    {
        return false;
    }

    return true;
}

bool hash::not_hex(const char &c)
{
    if (c >= 0x61 && c <= 0x66)
    {   // a-f
        return false;
    }
    if (c >= 0x30 && c <= 0x39)
    {   // 0-9
        return false;
    }

    return true;
}