query/include/matador/sql/internal/query_result_impl.hpp

#ifndef QUERY_QUERY_RESULT_IMPL_HPP
#define QUERY_QUERY_RESULT_IMPL_HPP

#include "matador/utils/access.hpp"
#include "matador/utils/field_attributes.hpp"
#include "matador/utils/foreign_attributes.hpp"
#include "matador/utils/default_type_traits.hpp"
#include "matador/utils/identifier.hpp"
#include "matador/utils/primary_key_attribute.hpp"

#include "matador/sql/interface/query_result_reader.hpp"
#include "matador/sql/internal/query_result_pk_resolver.hpp"
#include "matador/sql/record.hpp"

#include "matador/object/attribute.hpp"

#include <iostream>
#include <memory>
#include <stack>
#include <string>
#include <typeindex>
#include <unordered_set>

namespace matador::utils {
class value;
}

namespace matador::sql {
namespace detail {
class pk_reader {
public:
  explicit pk_reader(query_result_reader &reader);

  template<class Type>
  void read(Type &obj, const size_t column_index) {
    column_index_ = column_index;
    access::process(*this, obj);
  }

  template<typename ValueType>
  void on_primary_key(const char *id, ValueType &value, const utils::primary_key_attribute& attr = utils::default_pk_attributes);
  void on_revision(const char * /*id*/, uint64_t &/*rev*/) {
      ++column_index_;
  }

  template<class Type>
  void on_attribute(const char * /*id*/, Type &/*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {
      ++column_index_;
  }

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

  template<class ContainerType>
  static void on_has_many(const char * /*id*/, ContainerType &, const char * /*join_column*/, const utils::foreign_attributes &/*attr*/) {}
  template<class ContainerType>
  static void on_has_many_to_many(const char *id, ContainerType &c, 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 &c, const utils::foreign_attributes &/*attr*/) {}

private:
  size_t column_index_{};
  query_result_reader &reader_;
};
}

class query_result_impl {
public:
  query_result_impl(std::unique_ptr<query_result_reader> &&reader,
                    std::vector<object::attribute> &&prototype, size_t column_index = 0);
  query_result_impl(std::unique_ptr<query_result_reader> &&reader,
                    const std::vector<object::attribute> &prototype, size_t column_index = 0);

  template<typename ValueType>
  void on_primary_key(const char *id, ValueType &value, const utils::primary_key_attribute& attr = utils::default_pk_attributes) {
    utils::data_type_traits<ValueType>::read_value(*reader_, id, column_index_++, value, attr.size());
    if (type_stack_.size() == 1) {
      last_pk_ = current_pk_;
      current_pk_ = value;
    }
  }

  void on_revision(const char *id, uint64_t &rev);

  template<class Type>
  void on_attribute(const char *id, Type &x, const utils::field_attributes &/*attr*/ = utils::null_attributes) {
    utils::data_type_traits<Type>::read_value(*reader_, id, column_index_++, x);
  }

  void on_attribute(const char *id, char *value, const utils::field_attributes &attr = utils::null_attributes);
  void on_attribute(const char *id, std::string &value, const utils::field_attributes &attr = utils::null_attributes);
  void on_attribute(const char *id, utils::value &val, 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(x, attr);
  }

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

  template<class ContainerType>
  void on_has_many_to_many(const char *, ContainerType &, const char * /*join_column*/, const char * /*inverse_join_column*/, const utils::foreign_attributes &attr) {
    if (attr.fetch() == utils::fetch_type::LAZY) {

    } else {}
  }

  template<class ContainerType>
  void on_has_many_to_many(const char *, ContainerType &, const utils::foreign_attributes &attr) {
    if (attr.fetch() == utils::fetch_type::LAZY) {

    } else {}
  }

  template<class ContainerType>
  void on_has_many(const char * /*id*/, ContainerType &cont, const char * /*join_column*/,
                   const utils::foreign_attributes &attr) {
    if (attr.fetch() == utils::fetch_type::LAZY) {
      // pk_reader_.read(*id, column_index_++);
    } else {
      const auto ti = std::type_index(typeid(typename ContainerType::value_type::value_type));
      auto obj = std::make_unique<typename ContainerType::value_type::value_type>();
      type_stack_.push(ti);
      access::process(*this, *obj);
      type_stack_.pop();
      auto ptr = typename ContainerType::value_type(obj.release());
      const auto pk = ptr.primary_key();
      if (ptr.primary_key().is_valid()) {
        cont.push_back(ptr);
      }
    }
  }

  template<class Type>
  void bind(const Type &obj) {
    reader_->bind(obj);
  }

  [[nodiscard]] bool pk_has_changed() const {
    return !last_pk_.is_null() && last_pk_ != current_pk_;
  }

  template<class Type>
  bool fetch(Type &obj) {
    bool first = true;
    do {
      if (auto fetched = reader_->fetch(); !fetched.is_ok() || !*fetched) {
        return !first;
      }
      last_pk_ = current_pk_;
      current_pk_ = discover_current_primary_key(obj);
      if (pk_has_changed()) {
        reader_->unshift();
        last_pk_.clear();
        current_pk_.clear();
        break;
      }
      first = false;
      type_stack_.emplace(typeid(Type));
      column_index_ = reader_->start_column_index();
      access::process(*this, obj);
      type_stack_.pop();
    } while (last_pk_ == current_pk_);
    return true;
  }

  bool fetch(record &rec) {
    if (auto fetched = reader_->fetch(); !fetched.is_ok() || !*fetched) {
      return false;
    }

    column_index_ = reader_->start_column_index();
    access::process(*this, rec);
    return true;
  }

  [[nodiscard]] const std::vector<object::attribute> &prototype() const;

private:
  template<class Type>
  utils::identifier discover_current_primary_key(const Type &obj) {
    internal::query_result_pk_resolver resolver(*reader_);
    return resolver.discover(obj);
  }

  template<class Pointer>
  void on_foreign_key(Pointer &x, const utils::foreign_attributes &attr) {
    if (x.empty()) {
      x.reset(new typename Pointer::value_type);
    }
    if (attr.fetch() == utils::fetch_type::LAZY) {
      pk_reader_.read(*x, column_index_++);
    } else {
      const auto ti = std::type_index(typeid(*x));
      type_stack_.push(ti);
      access::process(*this, *x);
      type_stack_.pop();
    }
  }

protected:
  size_t column_index_ = 0;
  std::vector<object::attribute> prototype_;
  std::unique_ptr<query_result_reader> reader_;
  detail::pk_reader pk_reader_;
  std::stack<std::type_index> type_stack_;
  utils::identifier current_pk_{};
  utils::identifier last_pk_{};
};

namespace detail {
template<typename ValueType>
void pk_reader::on_primary_key(const char *id, ValueType &value, const utils::primary_key_attribute& attr) {
  utils::data_type_traits<ValueType>::read_value(reader_, id, column_index_++, value, attr.size());
}
}
}

#endif //QUERY_QUERY_RESULT_IMPL_HPP