query/include/matador/object/attribute_generator.hpp

#ifndef QUERY_COLUMN_DEFINITION_GENERATOR_HPP
#define QUERY_COLUMN_DEFINITION_GENERATOR_HPP

#include "matador/object/attribute.hpp"

#include "matador/utils/access.hpp"
#include "matador/utils/data_type_traits.hpp"
#include "matador/utils/error.hpp"
#include "matador/utils/field_attributes.hpp"
#include "matador/utils/primary_key_attribute.hpp"
#include "matador/utils/result.hpp"

#include <memory>
#include <typeindex>
#include <vector>

namespace matador::object {

class repository;

class fk_attribute_generator
{
public:
  fk_attribute_generator() = default;

  template<class Type>
  attribute generate(const char *id, Type &x, const std::shared_ptr<attribute> &ref_column) {
    access::process(*this, x);
    return attribute{id, type_, 0, ref_column, {utils::constraints::ForeignKey }, null_option_type::NOT_NULL};
  }

  template<typename ValueType>
  void on_primary_key(const char *, ValueType &/*pk*/, const utils::primary_key_attribute& attr = utils::default_pk_attributes) {
    type_ = utils::data_type_traits<ValueType>::type(attr.size());
  }
  static void on_revision(const char * /*id*/, uint64_t &/*rev*/) {}
  template < class Type >
  static void on_attribute(const char * /*id*/, Type &/*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
  static void on_attribute(const char * /*id*/, char * /*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
  template<class Pointer>
  static void on_belongs_to(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
  template<class Pointer>
  static void on_has_one(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
  template<class ContainerType>
  static void on_has_many(const char * /*id*/, ContainerType &, const char *, const utils::foreign_attributes &/*attr*/) {}
  template<class ContainerType>
  static void on_has_many_to_many(const char * /*id*/, ContainerType & /*cont*/, const char * /*join_column*/, const char * /*inverse_join_column*/, const utils::foreign_attributes &/*attr*/) {}
  template<class ContainerType>
  static void on_has_many_to_many(const char * /*id*/, ContainerType & /*cont*/, const utils::foreign_attributes &/*attr*/) {}

private:
  utils::basic_type type_{};
};

class attribute_generator final {
private:
  attribute_generator(std::vector<attribute> &columns, const repository &repo, object &obj);

public:
  ~attribute_generator() = default;

  template < class Type >
  static std::vector<attribute> generate(const repository &repo, object &obj) {
    std::vector<attribute> columns;
    attribute_generator gen(columns, repo, obj);
    Type t;
    access::process(gen, t);
    return columns;
  }

  template < class Type >
  static std::vector<attribute> generate(const Type& t, const repository &repo, object &obj) {
    std::vector<attribute> columns;
    attribute_generator gen(columns, repo, obj);
    access::process(gen, t);
    return columns;
  }

  template < class Type >
  void on_primary_key(const char *, Type &x, const utils::primary_key_attribute& attr = utils::default_pk_attributes);
  void on_revision(const char *id, uint64_t &rev);

  template<typename Type>
  void on_attribute(const char *id, Type &x, const utils::field_attributes &attr = utils::null_attributes);

  template<typename Type>
  void on_attribute(const char *id, std::optional<Type> &x, const utils::field_attributes &attr = utils::null_attributes);

  template<class Pointer>
  void on_belongs_to(const char *id, Pointer &x, const utils::foreign_attributes &/*attr*/) {
    on_foreign_key(id, x);
  }
  template<class Pointer>
  void on_has_one(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {
    // on_foreign_key(id, x);
  }

  template <class Pointer>
  void on_foreign_key(const char *id, Pointer &x) {
    std::shared_ptr<attribute> ref_column;
    std::type_index ti = typeid(typename Pointer::value_type);
    if (const auto result = determine_foreign_ref(std::type_index(ti))) {
        ref_column = *result;
    } else {
        ref_column = std::make_shared<attribute>();
        insert_missing_reference_column(ti, ref_column);
    }
    if (x.empty()) {
      typename Pointer::value_type temp_val;
      columns_.push_back(fk_column_generator_.generate(id, temp_val, ref_column));
    } else {
      columns_.push_back(fk_column_generator_.generate(id, *x, ref_column));
    }
  }
  template<class ContainerType>
  static void on_has_many(const char * /*id*/, ContainerType &, const char *, const utils::foreign_attributes &/*attr*/) {}
  template<class ContainerType>
  static void on_has_many_to_many(const char * /*id*/, ContainerType & /*cont*/, const char * /*join_column*/, const char * /*inverse_join_column*/, const utils::foreign_attributes &/*attr*/) {}
  template<class ContainerType>
  static void on_has_many_to_many(const char * /*id*/, ContainerType & /*cont*/, const utils::foreign_attributes &/*attr*/) {}

private:
  [[nodiscard]] utils::result<std::shared_ptr<attribute>, utils::error> determine_foreign_ref(const std::type_index &ti) const;
  void insert_missing_reference_column(const std::type_index &ti, const std::shared_ptr<attribute>& ref_column) const;

private:
  size_t index_ = 0;
  std::vector<attribute> &columns_;
  const repository &repo_;
  object &obj_;

  fk_attribute_generator fk_column_generator_;
};

template<typename ValueType>
void attribute_generator::on_primary_key(const char *id, ValueType &x, const utils::primary_key_attribute& attr) {
  on_attribute(id, x, { attr.size(), utils::constraints::PrimaryKey });
}

template<typename Type>
void attribute_generator::on_attribute(const char *id, Type &/*x*/, const utils::field_attributes &attr) {
  auto &ref = columns_.emplace_back(id, utils::data_type_traits<Type>::type(attr.size()), attr, null_option_type::NOT_NULL);
  ref.owner_ = &obj_;
}

template<typename Type>
void attribute_generator::on_attribute(const char *id, std::optional<Type> & /*x*/, const utils::field_attributes &attr) {
  auto &ref = columns_.emplace_back(id, utils::data_type_traits<Type>::type(attr.size()), attr, null_option_type::NULLABLE);
  ref.owner_ = &obj_;
}

}
#endif //QUERY_COLUMN_DEFINITION_GENERATOR_HPP