/*

Copyright (c) 2008-2009, 2013-2017, 2019-2020, Arvid Norberg

Copyright (c) 2016, 2018, Alden Torres

All rights reserved.

Redistribution and use in source and binary forms, with or without

modification, are permitted provided that the following conditions

are met:

    * Redistributions of source code must retain the above copyright

      notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright

      notice, this list of conditions and the following disclaimer in

      the documentation and/or other materials provided with the distribution.

    * Neither the name of the author nor the names of its

      contributors may be used to endorse or promote products derived

      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE.

*/

#include <algorithm>

#include "libtorrent/parse_url.hpp"

#include "libtorrent/string_util.hpp"

#include "libtorrent/string_view.hpp"

namespace libtorrent {

  // returns protocol, auth, hostname, port, path

  std::tuple<std::string, std::string, std::string, int, std::string>

    parse_url_components(std::string url, error_code& ec)

  {

    std::string hostname; // hostname only

    std::string auth; // user:pass

    std::string protocol; // http or https for instance

    int port = -1;

    std::string::iterator at;

    std::string::iterator colon;

    std::string::iterator port_pos;

    // PARSE URL

    auto start = url.begin();

    // remove white spaces in front of the url

    while (start != url.end() && is_space(*start))

      ++start;

    auto end = std::find(url.begin(), url.end(), ':');

    protocol.assign(start, end);

    if (end == url.end())

    {

      ec = errors::unsupported_url_protocol;

      goto exit;

    }

    ++end;

    if (end == url.end() || *end != '/')

    {

      ec = errors::unsupported_url_protocol;

      goto exit;

    }

    ++end;

    if (end == url.end() || *end != '/')

    {

      ec = errors::unsupported_url_protocol;

      goto exit;

    }

    ++end;

    start = end;

    at = std::find(start, url.end(), '@');

    colon = std::find(start, url.end(), ':');

    end = std::min({

      std::find(start, url.end(), '/')

      , std::find(start, url.end(), '?')

      , std::find(start, url.end(), '#')

      });

    if (at != url.end()

      && colon != url.end()

      && colon < at

      && at < end)

    {

      auth.assign(start, at);

      start = at;

      ++start;

    }

    // this is for IPv6 addresses

    if (start != url.end() && *start == '[')

    {

      port_pos = std::find(start, url.end(), ']');

      if (port_pos == url.end())

      {

        ec = errors::expected_close_bracket_in_address;

        goto exit;

      }

      // strip the brackets

      hostname.assign(start + 1, port_pos);

      port_pos = std::find(port_pos, url.end(), ':');

    }

    else

    {

      port_pos = std::find(start, url.end(), ':');

      if (port_pos < end) hostname.assign(start, port_pos);

      else hostname.assign(start, end);

    }

    if (port_pos < end)

    {

      ++port_pos;

      for (auto i = port_pos; i < end; ++i)

      {

        if (is_digit(*i)) continue;

        ec = errors::invalid_port;

        goto exit;

      }

      port = std::atoi(std::string(port_pos, end).c_str());

    }

    start = end;

exit:

    std::string path_component(start, url.end());

    if (path_component.empty()

      || path_component.front() == '?'

      || path_component.front() == '#')

    {

      path_component.insert(path_component.begin(), '/');

    }

    return std::make_tuple(std::move(protocol)

      , std::move(auth)

      , std::move(hostname)

      , port

      , path_component);

  }

  // splits a url into the base url and the path

  std::tuple<std::string, std::string>

    split_url(std::string url, error_code& ec)

  {

    std::string base;

    std::string path;

    // PARSE URL

    auto pos = std::find(url.begin(), url.end(), ':');

    if (pos == url.end() || url.end() - pos < 3

      || *(pos + 1) != '/' || *(pos + 2) != '/')

    {

      ec = errors::unsupported_url_protocol;

      return std::make_tuple(std::move(url), std::move(path));

    }

    pos += 3; // skip "://"

    pos = std::find(pos, url.end(), '/');

    if (pos == url.end())

    {

      return std::make_tuple(std::move(url), std::move(path));

    }

    base.assign(url.begin(), pos);

    path.assign(pos, url.end());

    return std::make_tuple(std::move(base), std::move(path));

  }

  TORRENT_EXTRA_EXPORT bool is_idna(string_view hostname)

  {

    for (;;)

    {

      auto dot = hostname.find('.');

      string_view const label = (dot == string_view::npos) ? hostname : hostname.substr(0, dot);

      if (label.size() >= 4

        && (label[0] == 'x' || label[0] == 'X')

        && (label[1] == 'n' || label[1] == 'N')

        && label.substr(2, 2) == "--"_sv)

        return true;

      if (dot == string_view::npos) return false;

      hostname = hostname.substr(dot + 1);

    }

  }

  bool has_tracker_query_string(string_view query_string)

  {

    static string_view const tracker_args[] = {

      "info_hash"_sv, "event"_sv, "port"_sv, "left"_sv, "key"_sv,

      "uploaded"_sv, "downloaded"_sv, "corrupt"_sv, "peer_id"_sv

    };

    while (!query_string.empty())

    {

      string_view arg;

      std::tie(arg, query_string) = split_string(query_string, '&');

      auto const name = split_string(arg, '=').first;

      for (auto const& tracker_arg : tracker_args)

      {

        if (string_equal_no_case(name, tracker_arg))

          return true;

      }

    }

    return false;

  }

}