/*  This file is part of libravatarserv.
 *  Copyright © 2018,2019 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 <iostream>
#include <algorithm>
#include <cstdlib>
#include "libravatarserv.hpp"

using std::cout;
using std::cerr;
using std::endl;
using namespace http;

const Request http::parse_request(const string &request)
{
    if (request.substr(0, 8) == "/favicon")
    {
        cout << "Status: 404 Not Found\n\n";
        std::exit(1);
    }
    if (request.substr(0, 8) != "/avatar/" ||
        request.find("..", 8) != std::string::npos)
    {
        cout << "Status: 400 Bad Request\n\n";
        cerr << "Error: Invalid URL.\n";
        std::exit(1);
    }

    int16_t size = 80;
    string fallback;
    string digest = request.substr(8);
    std::transform(digest.begin(), digest.end(), digest.begin(), ::tolower);
    std::size_t pos_digest = digest.find('?');

    if (pos_digest != std::string::npos)
    {
        string answer;
        {
            answer = get_parameter(request, "s");
            if (!answer.empty())
            {
                try
                {
                    size = static_cast<int16_t>(std::stoul(answer));
                } catch (const std::exception &) {}
            }
            else
            {
                answer = get_parameter(request, "size");
                if (!answer.empty())
                {
                    try
                    {
                        size = static_cast<int16_t>(std::stoul(answer));
                    } catch (const std::exception &) {}
                }
            }
            if (size > 512)
            {
                size = 512;
            }
            else if (size <= 0)
            {
                size = 80;
            }
        }
        {
            answer = get_parameter(request, "d");
            if (!answer.empty())
            {
                fallback = answer;
            }
            else
            {
                answer = get_parameter(request, "default");
                if (!answer.empty())
                {
                    fallback = answer;
                }
            }
        }
    }

    digest = digest.substr(0, pos_digest);
    pos_digest = digest.find('.');
    if (pos_digest != std::string::npos)
    {
        digest = digest.substr(0, pos_digest);
    }

    return { digest, size, fallback };
}

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

    return "";
}

void http::send_redirect(const Request &request)
{
    const char *env = std::getenv("HTTPS");
    string baseurl;
    if (env != nullptr && env[1] == 'n')
    {   // "on"
        baseurl = "https://seccdn.libravatar.org";
    }
    else
    {
        baseurl = "http://cdn.libravatar.org";
    }
    cout << "Status: 307 Temporary Redirect\n";
    cout << "Location: " << baseurl << "/avatar/"
         << request.digest << "?s=" << request.size
         << "&d=" << request.fallback << endl << endl;
}