draconisplusplus/include/rfl/xml/Writer.hpp

#ifndef RFL_XML_WRITER_HPP_
#define RFL_XML_WRITER_HPP_

#include <exception>
#include <map>
#include <pugixml.hpp>
#include <sstream>
#include <stdexcept>
#include <string>
#include <string_view>
#include <type_traits>
#include <vector>

#include "../Ref.hpp"
#include "../Result.hpp"
#include "../always_false.hpp"

namespace rfl {
  namespace xml {

    struct Writer {
      static constexpr const char* XML_CONTENT = "xml_content";

      struct XMLOutputArray {
        XMLOutputArray(const std::string_view& _name,
                       const Ref<pugi::xml_node>& _node)
            : name_(_name), node_(_node) {}
        std::string_view name_;
        Ref<pugi::xml_node> node_;
      };

      struct XMLOutputObject {
        XMLOutputObject(const Ref<pugi::xml_node>& _node) : node_(_node) {}
        Ref<pugi::xml_node> node_;
      };

      struct XMLOutputVar {
        XMLOutputVar(const Ref<pugi::xml_node>& _node) : node_(_node) {}
        Ref<pugi::xml_node> node_;
      };

      using OutputArrayType  = XMLOutputArray;
      using OutputObjectType = XMLOutputObject;
      using OutputVarType    = XMLOutputVar;

      Writer(const Ref<pugi::xml_node>& _root, const std::string& _root_name)
          : root_(_root), root_name_(_root_name) {}

      ~Writer() = default;

      OutputArrayType array_as_root(const size_t _size) const noexcept {
        auto node_child =
            Ref<pugi::xml_node>::make(root_->append_child(root_name_.c_str()));
        return OutputArrayType(root_name_, node_child);
      }

      OutputObjectType object_as_root(const size_t _size) const noexcept {
        auto node_child =
            Ref<pugi::xml_node>::make(root_->append_child(root_name_.c_str()));
        return OutputObjectType(node_child);
      }

      OutputVarType null_as_root() const noexcept {
        auto node_child =
            Ref<pugi::xml_node>::make(root_->append_child(root_name_.c_str()));
        return OutputVarType(node_child);
      }

      template <class T>
      OutputVarType value_as_root(const T& _var) const noexcept {
        const auto str = to_string(_var);
        auto node_child =
            Ref<pugi::xml_node>::make(root_->append_child(root_name_.c_str()));
        node_child->append_child(pugi::node_pcdata).set_value(str.c_str());
        return OutputVarType(node_child);
      }

      OutputArrayType add_array_to_array(
          const size_t _size,
          OutputArrayType* _parent) const noexcept {
        return *_parent;
      }

      OutputArrayType add_array_to_object(
          const std::string_view& _name,
          const size_t _size,
          OutputObjectType* _parent) const noexcept {
        return OutputArrayType(_name, _parent->node_);
      }

      OutputObjectType add_object_to_array(
          const size_t _size,
          OutputArrayType* _parent) const noexcept {
        auto node_child = Ref<pugi::xml_node>::make(
            _parent->node_->append_child(_parent->name_.data()));
        return OutputObjectType(node_child);
      }

      OutputObjectType add_object_to_object(
          const std::string_view& _name,
          const size_t _size,
          OutputObjectType* _parent) const noexcept {
        auto node_child = Ref<pugi::xml_node>::make(
            _parent->node_->append_child(_name.data()));
        return OutputObjectType(node_child);
      }

      template <class T>
      OutputVarType add_value_to_array(const T& _var, OutputArrayType* _parent)
          const noexcept {
        const auto str  = to_string(_var);
        auto node_child = Ref<pugi::xml_node>::make(
            _parent->node_->append_child(_parent->name_.data()));
        node_child->append_child(pugi::node_pcdata).set_value(str.c_str());
        return OutputVarType(node_child);
      }

      template <class T>
      OutputVarType add_value_to_object(
          const std::string_view& _name,
          const T& _var,
          OutputObjectType* _parent,
          const bool _is_attribute = false) const noexcept {
        const auto str = to_string(_var);
        if (_is_attribute) {
          _parent->node_->append_attribute(_name.data()) = str.c_str();
          return OutputVarType(_parent->node_);
        } else if (_name == XML_CONTENT) {
          _parent->node_->append_child(pugi::node_pcdata)
              .set_value(str.c_str());
          return OutputVarType(_parent->node_);
        } else {
          auto node_child = Ref<pugi::xml_node>::make(
              _parent->node_->append_child(_name.data()));
          node_child->append_child(pugi::node_pcdata).set_value(str.c_str());
          return OutputVarType(node_child);
        }
      }

      OutputVarType add_null_to_array(OutputArrayType* _parent) const noexcept {
        auto node_child = Ref<pugi::xml_node>::make(
            _parent->node_->append_child(_parent->name_.data()));
        return OutputVarType(node_child);
      }

      OutputVarType add_null_to_object(
          const std::string_view& _name,
          OutputObjectType* _parent,
          const bool _is_attribute = false) const noexcept {
        if (_is_attribute) {
          return OutputVarType(_parent->node_);
        } else if (_name == XML_CONTENT) {
          return OutputVarType(_parent->node_);
        } else {
          auto node_child = Ref<pugi::xml_node>::make(
              _parent->node_->append_child(_name.data()));
          return OutputVarType(node_child);
        }
      }

      void end_array(OutputArrayType* _arr) const noexcept {}

      void end_object(OutputObjectType* _obj) const noexcept {}

     private:
      template <class T>
      std::string to_string(const T& _val) const noexcept {
        if constexpr (std::is_same<std::remove_cvref_t<T>, std::string>()) {
          return _val;
        } else if constexpr (std::is_same<std::remove_cvref_t<T>, bool>()) {
          return _val ? "true" : "false";
        } else if constexpr (std::is_floating_point<std::remove_cvref_t<T>>() ||
                             std::is_integral<std::remove_cvref_t<T>>()) {
          return std::to_string(_val);
        } else {
          static_assert(always_false_v<T>, "Unsupported type");
        }
      }

     public:
      Ref<pugi::xml_node> root_;

      std::string root_name_;
    };

  } // namespace xml
} // namespace rfl

#endif // XML_PARSER_HPP_