/*

Copyright (c) 2014-2019, Arvid Norberg

Copyright (c) 2016-2017, 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 <cstring>

#include "libtorrent/xml_parse.hpp"

#include "libtorrent/string_util.hpp"

namespace libtorrent {

  void xml_parse(string_view input

    , std::function<void(int, string_view, string_view)> callback)

  {

    char const* p = input.data();

    char const* end = input.data() + input.size();

    for (;p != end; ++p)

    {

      char const* start = p;

      // look for tag start

      for (; p != end && *p != '<'; ++p);

      if (p != start)

      {

        callback(xml_string, {start, std::size_t(p - start)}, {});

      }

      if (p == end) break;

      // skip '<'

      ++p;

      if (p != end && p + 8 < end && string_begins_no_case("![CDATA[", p))

      {

        // CDATA. match '![CDATA['

        p += 8;

        start = p;

        while (p != end && !string_begins_no_case("]]>", p - 2)) ++p;

        // parse error

        if (p == end)

        {

          callback(xml_parse_error, "unexpected end of file", {});

          break;

        }

        callback(xml_string, {start, std::size_t(p - start - 2)}, {});

        continue;

      }

      // parse the name of the tag.

      for (start = p; p != end && *p != '>' && !is_space(*p); ++p);

      char const* tag_name_end = p;

      // skip the attributes for now

      for (; p != end && *p != '>'; ++p);

      // parse error

      if (p == end)

      {

        callback(xml_parse_error, "unexpected end of file", {});

        break;

      }

      TORRENT_ASSERT(*p == '>');

      char const* tag_end = p;

      if (*start == '/')

      {

        ++start;

        callback(xml_end_tag, {start, std::size_t(tag_name_end - start)}, {});

      }

      else if (*(p - 1) == '/')

      {

        callback(xml_empty_tag, {start, std::size_t(std::min(tag_name_end - start, p - start - 1))}, {});

        tag_end = p - 1;

      }

      else if (*start == '?' && *(p - 1) == '?')

      {

        ++start;

        callback(xml_declaration_tag, {start, std::size_t(std::min(tag_name_end - start, p - start - 1))}, {});

        tag_end = p - 1;

      }

      else if (start + 5 < p && std::memcmp(start, "!--", 3) == 0 && std::memcmp(p - 2, "--", 2) == 0)

      {

        start += 3;

        callback(xml_comment, {start, std::size_t(tag_name_end - start - 2)}, {});

        continue;

      }

      else

      {

        callback(xml_start_tag, {start, std::size_t(tag_name_end - start)}, {});

      }

      // parse attributes

      for (char const* i = tag_name_end; i < tag_end; ++i)

      {

        char const* val_start = nullptr;

        // find start of attribute name

        while (i != tag_end && is_space(*i)) ++i;

        if (i == tag_end) break;

        start = i;

        // find end of attribute name

        while (i != tag_end && *i != '=' && !is_space(*i)) ++i;

        auto const name_len = static_cast<std::size_t>(i - start);

        // look for equality sign

        for (; i != tag_end && *i != '='; ++i);

        // no equality sign found. Report this as xml_tag_content

        // instead of a series of key value pairs

        if (i == tag_end)

        {

          callback(xml_tag_content, {start, std::size_t(i - start)}, {});

          break;

        }

        ++i;

        while (i != tag_end && is_space(*i)) ++i;

        // check for parse error (values must be quoted)

        if (i == tag_end || (*i != '\'' && *i != '\"'))

        {

          callback(xml_parse_error, "unquoted attribute value", {});

          break;

        }

        char quote = *i;

        ++i;

        val_start = i;

        for (; i != tag_end && *i != quote; ++i);

        // parse error (missing end quote)

        if (i == tag_end)

        {

          callback(xml_parse_error, "missing end quote on attribute", {});

          break;

        }

        callback(xml_attribute, {start, name_len}, {val_start, std::size_t(i - val_start)});

      }

    }

  }

}