#ifndef QUERY_BACKEND_PROVIDER_HPP
#define QUERY_BACKEND_PROVIDER_HPP

#include "matador/utils/library.hpp"

#include <memory>
#include <string>
#include <unordered_map>

namespace matador::sql {

class connection_impl;
struct connection_info;
class dialect;

class backend_provider
{
private:
  backend_provider();

public:
  static backend_provider& instance();

  connection_impl* create_connection(const std::string &connection_type, const connection_info &info);
  void destroy_connection(const std::string &connection_type, connection_impl *c);
  const dialect& connection_dialect(const std::string &connection_type);

private:
  struct backend_context {
    backend_context(const std::string &connection_type,
                    const std::string &backends_path);
    backend_context(const backend_context&) = delete;
    backend_context& operator=(const backend_context&) = delete;
    backend_context(backend_context&&) noexcept = default;
    backend_context& operator=(backend_context&&) noexcept = default;
    ~backend_context();

    typedef connection_impl*(*create_func)(const connection_info&);
    typedef void (*destroy_func)(connection_impl*);
    typedef const dialect*(*dialect_func)();

    create_func create_connection{};
    destroy_func destroy_connection{};
    dialect_func get_dialect{};
    utils::library lib;
  };
private:
  using backends_t = std::unordered_map<std::string, std::unique_ptr<backend_context>>;
  backends_t backends_;
  std::string backends_path_;
};
}
#endif //QUERY_BACKEND_PROVIDER_HPP