#include "cpp/htmlparser/atomutil.h"

#include "cpp/htmlparser/hash.h"

namespace htmlparser {

Atom AtomUtil::ToAtom(const std::string& s) {

  if (s.empty() || s.size() > kMaxAtomLength) {

    return Atom::UNKNOWN;

  }

  uint32_t hash = Hash::FNVHash(s, kInitialHashValue);

  uint32_t table_index = hash & (kNamesHashTable.size() - 1);

  uint32_t atom_value = kNamesHashTable[table_index];

  int atom_len = atom_value & 0xff;

  if (atom_len == s.size() && ToString(atom_value) == s) {

    return CastToAtom(atom_value);

  }

  table_index = (hash >> 16) & (kNamesHashTable.size() - 1);

  atom_value = kNamesHashTable[table_index];

  atom_len = atom_value & 0xff;

  if (atom_len == s.size() && ToString(atom_value).compare(s) == 0) {

    return CastToAtom(atom_value);

  }

  return Atom::UNKNOWN;

}

std::string AtomUtil::ToString(Atom a, std::string_view unknown_tag_name) {

  if (a == Atom::UNKNOWN) return std::string(unknown_tag_name);

  uint32_t start = static_cast<uint32_t>(a) >> 8;

  uint32_t n = static_cast<uint32_t>(a) & 0xff;

  if ((start + n) > kAtomText.size()) {

    return std::string(unknown_tag_name);

  }

  return std::string(kAtomText.substr(start, n));

}

}  // namespace htmlparser