/*
 *  asbots
 *  Copyright (C) 2021  niansa
 *
 *  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, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  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 <https://www.gnu.org/licenses/>.
 */
#include "nickserv.hpp"
#include "../instance.hpp"

#include <async/result.hpp>
#include <fmt/format.h>
#include <cryptopp/hex.h>
#include <cryptopp/sha.h>
#include <cryptopp/pwdbased.h>
#include <string>
#include <string_view>
#include <vector>
#include <memory>

using fmt::operator""_format;



async::result<void> NickServ::intitialize() {
    co_await i->netInfo.wait_ready();
    user = {
        .server = i->config.server.uid,
        .nick = std::string(getConfig("NickServ", "nickname").value_or("NickServ")),
        .realhost = i->config.server.name,
        .uid = uuid,
        .realname = i->netInfo.name
    };
    co_await mark_ready(user);

    using namespace sqlite_orm;
    storage = std::make_unique<Storage>(make_storage(
                                            std::string(getConfig("NickServ", "database").value_or("nickserv.sqlite")),
                                            make_table("users",
                                                       make_column("id", &Account::id, autoincrement(), primary_key()),
                                                       make_column("name", &Account::name),
                                                       make_column("email", &Account::email),
                                                       make_column("password_hash", &Account::password_hash))
                                            ));
    storage->sync_schema();

    commands = {
        {"identify", {[this] (u_User& sender, const std::vector<std::string_view>& args) -> async::result<void> {
                          // Check that user is not already identified
                          if (sender->loginName.has_value()) {
                              co_await i->send_event(user.get_notice("Error: You've already been identified!", sender->uid));
                              co_return;
                          }
                          // Get account name and password to use
                          std::string_view accountName, accountPwd;
                          if (args.size() > 1) {
                              accountName = args[0];
                              accountPwd = args[1];
                          } else {
                              accountName = sender->nick;
                              accountPwd = args[0];
                          }
                          // Get account from storage
                          auto accounts_found = storage->get_all<Account>(where(c(&Account::name) == std::string(accountName)));
                          if (accounts_found.empty()) {
                              co_await i->send_event(user.get_notice("Error: {} is not registered!"_format(accountName), sender->uid));
                              co_return;
                          }
                          auto& account = accounts_found[0];
                          // Check password
                          if (account.password_hash != pwdHash(accountPwd)) {
                              co_await i->send_event(user.get_notice("Error: Invalid password!", sender->uid));
                              co_return;
                          }
                          // Login
                          co_await i->send_event(sender->get_encap_su(account.name, i->config.server.uid));
                          // Report success
                          co_await i->send_event(user.get_notice("You have been identified!", sender->uid));
                      }, "[username] <password>", 1, false}
        },
        {"deidentify", {[this] (u_User& sender, const std::vector<std::string_view>& args) -> async::result<void> {
                            co_await i->send_event(sender->get_encap_su("", i->config.server.uid));
                            co_await i->send_event(user.get_notice("You have been deidentified!", sender->uid));
                        }, "", 0, true}
        },
        {"register", {[this] (u_User& sender, std::vector<std::string_view> args) -> async::result<void> {
                          // Check args
                          if (args.size() != 2) {
                              co_await i->send_event(user.get_notice("Error: Passwords may not contain spaces!", sender->uid));
                              co_return;
                          }
                          // Check that account does not exist already
                          {
                              auto accounts_found = storage->get_all<Account>(where(c(&Account::name) == sender->nick));
                              if (!accounts_found.empty()) {
                                  co_await i->send_event(user.get_notice("Error: {} has already been registered!"_format(sender->nick), sender->uid));
                                  co_return;
                              }
                          }
                          // Insert new account into database
                          storage->insert(Account{
                              .name = sender->nick,
                              .email = std::string(args[1]),
                              .password_hash = pwdHash(args[0])
                          });
                          // Report success
                          co_await i->send_event(user.get_notice("{} has been registered!"_format(sender->nick), sender->uid));
                      }, "<password> <email>", 2, false}
        },
    };
}

std::string NickServ::pwdHash(std::string_view pwd) {
    using namespace CryptoPP;

    auto salt = getConfig("NickServ", "salt").value_or("defaultsalt");

    static_assert(sizeof(pwd[0]) == 1, "std::string_view character width must be 1 for this to work... You might have a bad STL implementation.");

    int c = 1;
    byte derived[20];

    PKCS5_PBKDF2_HMAC<SHA1> pbkdf2;
    pbkdf2.DeriveKey(derived, sizeof(derived), 0, reinterpret_cast<const byte*>(pwd.data()), pwd.size(), reinterpret_cast<const byte*>(salt.data()), salt.size(), c);

    std::string fres;
    HexEncoder encoder(new StringSink(fres));

    encoder.Put(derived, sizeof(derived));
    encoder.MessageEnd();

    return fres;
}