#ifndef NTX_MAPINDEX_H
#define NTX_MAPINDEX_H

#include <string>
#include <unordered_map>
#include <optional>
#include <functional>
#include <memory>

namespace ntx
{

  /**
   * @brief Bidirektionaler Index: String-Key → size_t Position.
   * 
   * Verwendet Komposition statt Vererbung.
   * Key → Index: O(1) via unordered_map.
   */
  class NtxMapIndex
  {

  public:

    NtxMapIndex() = default;

    // --- Lookup ---
    std::optional<size_t> indexOf(const std::string& key) const noexcept;
    bool containsKey(const std::string& key) const noexcept;

    // --- Iteration ---

    /// Iteriert über alle Key→Index Paare.
    /// Template muss im Header bleiben.
    template <typename Fn>
    void forEachKey(Fn&& fn) const
    {
      for (const auto& [key, idx] : m_keyToIndex)
        fn(key, idx);
    }

    // --- Modification ---
    void addKey(const std::string& key, size_t index);
    void removeAt(size_t index);
    bool removeKey(const std::string& key);
    bool replaceKey(const std::string& oldKey, const std::string& newKey);
    bool addAlias(const std::string& existingKey, const std::string& alias);

    size_t size() const noexcept;
    bool empty() const noexcept;
    void clear() noexcept;

  private:

    std::unordered_map<std::string, size_t> m_keyToIndex;
  };

  using NtxMapIndexPtr = std::shared_ptr<NtxMapIndex>;

} // namespace ntx

#endif // NTX_MAPINDEX_H