/*  This file is part of libravatarserv.
 *  Copyright © 2022 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 "request.hpp"

#include "hash.hpp"
#include "types.hpp"

#include <algorithm>
#include <cstdint>
#include <iostream>
#include <stdexcept>
#include <string>
#include <string_view>

namespace libravatarserv::request {

request_t parse(const std::string_view uri) {
    constexpr std::uint8_t offset{8};
    if (uri.substr(0, offset) != "/avatar/"
        || uri.find("..", offset) != std::string_view::npos) {
        std::cout << "Status: 400 Bad Request\n\n";
        throw std::runtime_error{"Invalid URL"};
    }

    request_t req;
    req.size = 80;

    size_t pos{uri.find('?')};
    if (pos == std::string_view::npos) {
        pos = uri.size();
    }
    req.hash.resize(pos - offset);
    std::transform(uri.begin() + offset, uri.begin() + pos, req.hash.begin(),
                   ::tolower);

    if (req.hash.size() == 64 && hash::is_valid(req.hash)) {
        req.algo = algorithm_t::SHA256;
    } else if (req.hash.size() == 32 && hash::is_valid(req.hash)) {
        req.algo = algorithm_t::MD5;
    } else {
        std::cout << "Status: 400 Bad Request\n\n";
        throw std::runtime_error{"Invalid hash"};
    }

    if (pos != uri.size()) {
        std::string uri_rest;
        uri_rest.resize(uri.size() - pos);
        std::transform(uri.begin() + pos, uri.end(), uri_rest.begin(),
                       ::tolower);

        auto strsize{get_parameter(uri_rest, "s")};
        if (strsize.empty()) {
            strsize = get_parameter(uri_rest, "size");
        }
        if (!strsize.empty()) {
            try {
                req.size = static_cast<int16_t>(std::stoul(strsize.data()));
                if (req.size > 512) {
                    req.size = 512;
                } else if (req.size < 1) {
                    req.size = 80;
                }
            } catch (...) {}
        }

        req.fallback = get_parameter(uri_rest, "d");
        if (req.fallback.empty()) {
            req.fallback = get_parameter(uri_rest, "default");
        }
    }

    return req;
}

std::string_view get_parameter(const std::string_view uri,
                               const std::string &parameter) {
    size_t pos{uri.find("?" + parameter + "=")};
    if (pos == std::string_view::npos) {
        pos = uri.find("&" + parameter + "=");
    }
    if (pos != std::string_view::npos) {
        pos += (2 + parameter.length());
        return uri.substr(pos, uri.find('&', pos));
    }

    return {};
}

} // namespace libravatarserv::request