query/include/matador/object/foreign_node_completer.hpp

#ifndef FOREIGN_NODE_COMPLETER_HPP
#define FOREIGN_NODE_COMPLETER_HPP

#include "matador/object/internal/shadow_repository.hpp"
#include "matador/object/many_to_many_relation.hpp"
#include "matador/object/repository_node.hpp"
#include "matador/object/join_columns_collector.hpp"
#include "matador/object/object_ptr.hpp"

#include "matador/utils/primary_key_attribute.hpp"

#include "matador/logger/log_manager.hpp"

#include <stack>

#include "repository.hpp"

namespace matador::object {
/**
 * Processes the given node and ensures
 * that all foreign nodes needed by the given node
 * relations are attached in schema.
 */
template<typename NodeType>
class foreign_node_completer final {
private:
  using node_ptr = std::shared_ptr<repository_node>;

public:
  template<class Type>
  static void complete(const std::shared_ptr<repository_node> &node) {
    internal::shadow_repository shadow(node->repo_);
    foreign_node_completer<Type> completer(shadow);

    completer.complete_node(node);
  }

  template<class PrimaryKeyType>
  static void on_primary_key(const char * /*id*/, PrimaryKeyType &/*pk*/, const utils::primary_key_attribute & /*attr*/ = utils::default_pk_attributes) {}
  static void on_revision(const char * /*id*/, uint64_t &/*rev*/) {}
  template<typename AttributeType>
  static void on_attribute(const char * /*id*/, AttributeType &/*val*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
  template<typename AttributeType>
  static void on_attribute(const char * /*id*/, std::optional<AttributeType> &/*val*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
  template<class ForeignPointerType>
  void on_belongs_to(const char *id, ForeignPointerType &/*obj*/, const utils::foreign_attributes &/*attr*/);
  template<class ForeignPointerType>
  void on_has_one(const char * /*id*/, ForeignPointerType &/*obj*/, const utils::foreign_attributes &/*attr*/);
  template<class CollectionType>
  void on_has_many(const char *id, CollectionType &,
                   const char *join_column,
                   const utils::foreign_attributes &attr,
                   std::enable_if_t<is_object_ptr<typename CollectionType::value_type>::value> * = nullptr);

  template<class CollectionType>
  void on_has_many(const char * /*id*/,
                   CollectionType &,
                   const char * /*join_column*/,
                   const utils::foreign_attributes & /*attr*/,
                   std::enable_if_t<!is_object_ptr<typename CollectionType::value_type>::value> * = nullptr) {
  }

  template<class CollectionType>
  void on_has_many_to_many(const char *id,
                           CollectionType &collection,
                           const char *join_column,
                           const char *inverse_join_column,
                           const utils::foreign_attributes &attr);
  template<class CollectionType>
  void on_has_many_to_many(const char *id, CollectionType &collection, const utils::foreign_attributes &attr);

private:
  explicit foreign_node_completer(internal::shadow_repository &shadow)
  : repo_(shadow)
  , log_(logger::create_logger("node_completer")) {}

  void complete_node(const std::shared_ptr<repository_node> &node) {
    nodes_.push(node);

    NodeType obj;
    access::process(*this, obj);
    nodes_.pop();
  }

  template<typename Type>
  void attach_node(const std::string &name = "") {
    if (repo_.contains(typeid(Type))) {
      return;
    }
    const auto node = repository_node::make_node<Type>(repo_.repo(), name);
    if (auto result = repo_.attach_node(node)) {
      complete<Type>(result.value());
    }
  }

  template<typename Type>
  void attach_relation_node(const std::string &name, const std::string &join_column, const std::string &inverse_join_column) {
    using relation_value_type = many_to_many_relation<Type, NodeType>;
    using value_type = Type;

    // Check if the object_ptr type is already inserted in the schema (by id)
    auto result = repo_.find_node(typeid(value_type));
    if (!result) {
      // Todo: throw internal error or attach node
      return;
    }

    const auto foreign_node = result.value();
    result = repo_.find_node(name);
    if (result) {
      return;
    }
    // Relation does not exist. Create it.
    auto creator = [join_column, inverse_join_column] {
      return std::make_unique<relation_value_type>(join_column, inverse_join_column);
    };

    result = repository_node::make_relation_node<relation_value_type>(repo_.repo(), name, std::move(creator));
    if (!result) {
      // Todo: throw internal error
      return;
    }

    auto& node = result.value();
    complete<relation_value_type>(result.value());

    // auto& node = result.value();
    const auto local_endpoint = std::make_shared<relation_endpoint>(name, relation_type::HasMany, node);
    const auto join_endpoint = std::make_shared<relation_endpoint>(join_column, relation_type::BelongsTo, nodes_.top());
    const auto inverse_join_endpoint = std::make_shared<relation_endpoint>(inverse_join_column, relation_type::BelongsTo, foreign_node);
    const auto foreign_endpoint = std::make_shared<relation_endpoint>(name, relation_type::HasMany, node);
    // register relation endpoint in local node
    nodes_.top()->info_->register_relation_endpoint(typeid(value_type), local_endpoint);
    // register relation endpoint in foreign node
    foreign_node->info_->register_relation_endpoint(nodes_.top()->type_index(), foreign_endpoint);
    // register endpoints in relation node
    node->info_->register_relation_endpoint(nodes_.top()->type_index(), join_endpoint);
    node->info_->register_relation_endpoint(typeid(value_type), inverse_join_endpoint);
    // link endpoints
    link_relation_endpoints(local_endpoint, join_endpoint);
    link_relation_endpoints(foreign_endpoint, inverse_join_endpoint);
  }

private:
  using endpoint_ptr = std::shared_ptr<relation_endpoint>;
  static void register_relation_endpoints(const endpoint_ptr &endpoint,
                                          const endpoint_ptr &other_endpoint);
  static void link_relation_endpoints(const endpoint_ptr &endpoint,
                                      const endpoint_ptr &other_endpoint);

private:
  template<typename Type>
  friend class foreign_node_completer;

private:
  std::stack<node_ptr> nodes_;
  internal::shadow_repository &repo_;
  logger::logger log_;
  join_columns_collector join_columns_collector_{};
};


template<typename NodeType>
template<class ForeignPointerType>
void foreign_node_completer<NodeType>::on_belongs_to(const char * /*id*/, ForeignPointerType &, const utils::foreign_attributes &) {
  attach_node<typename ForeignPointerType::value_type>();
}

template<typename NodeType>
template<class ForeignPointerType>
void foreign_node_completer<NodeType>::on_has_one(const char *, ForeignPointerType &, const utils::foreign_attributes &) {
  attach_node<typename ForeignPointerType::value_type>();
}

template<typename NodeType>
template<class CollectionType>
void foreign_node_completer<NodeType>::on_has_many(const char * /*id*/,
                                                   CollectionType &, const char * /*join_column*/,
                                                   const utils::foreign_attributes & /*attr*/,
                                                   std::enable_if_t<is_object_ptr<typename CollectionType::value_type>::value> *) {
  attach_node<typename CollectionType::value_type::value_type>();
}

template<typename NodeType>
template<class CollectionType>
void foreign_node_completer<NodeType>::on_has_many_to_many(const char *id, CollectionType & /*collection*/,
                                                           const char *join_column,
                                                           const char *inverse_join_column,
                                                           const utils::foreign_attributes & /*attr*/) {
  if (!repo_.expecting_relation_node(id)) {
    repo_.expect_relation_node(id, typeid(typename CollectionType::value_type::value_type));
  } else {
    attach_relation_node<typename CollectionType::value_type::value_type>(id, join_column, inverse_join_column);
    repo_.remove_expected_relation_node(id);
  }
}

template<typename NodeType>
template<class CollectionType>
void foreign_node_completer<NodeType>::on_has_many_to_many(const char *id,
                                                           CollectionType & /*collection*/,
                                                           const utils::foreign_attributes & /*attr*/) {
  if (!repo_.expecting_relation_node(id)) {
    repo_.expect_relation_node(id, typeid(typename CollectionType::value_type::value_type));
  } else {
    const auto join_columns = join_columns_collector_.collect<typename CollectionType::value_type::value_type>();
    attach_relation_node<typename CollectionType::value_type::value_type>(id, join_columns.join_column, join_columns.inverse_join_column);
    repo_.remove_expected_relation_node(id);
  }
}

template<typename NodeType>
void foreign_node_completer<NodeType>::register_relation_endpoints(const endpoint_ptr &endpoint,
                                                                   const endpoint_ptr &other_endpoint) {
  endpoint->node_->info_->register_relation_endpoint(other_endpoint->node_->type_index(), endpoint);
  other_endpoint->node_->info_->register_relation_endpoint(endpoint->node_->type_index(), other_endpoint);
  link_relation_endpoints(endpoint, other_endpoint);
}

template<typename NodeType>
void foreign_node_completer<NodeType>::link_relation_endpoints(const endpoint_ptr &endpoint, const endpoint_ptr &other_endpoint) {
  endpoint->link_foreign_endpoint(other_endpoint);
  other_endpoint->link_foreign_endpoint(endpoint);
}
}
#endif //FOREIGN_NODE_COMPLETER_HPP