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#pragma once

#include <concepts>
#include <cstdint>
#include <initializer_list>
#include <optional>
#include <string>
#include <string_view>
#include <type_traits>
#include <variant>
#include <vector>

#include <openvic-dataloader/detail/Constexprs.hpp>

#include <fmt/compile.h>
#include <fmt/core.h>
#include <fmt/format.h>

namespace ovdl::csv {
   template<typename T, typename Value>
   concept IsMap =
      requires(T t) {
         { t.begin() } -> std::same_as<typename T::const_iterator>;
         { t.end() } -> std::same_as<typename T::const_iterator>;
         { t.empty() } -> std::same_as<bool>;
         { t.size() } -> std::same_as<typename T::size_type>;
         { t.at("") } -> std::same_as<const Value&>;
         { t.find("") } -> std::same_as<typename T::const_iterator>;
         { t[""] } -> std::same_as<const Value&>;
      };

   class ValueNode {
   public:
      struct Placeholder {
         static constexpr char ESCAPE_CHAR = '$';
         static constexpr std::string_view ESCAPE_STR = std::string_view { &ESCAPE_CHAR, 1 };

         std::string value;
         inline std::string as_string(std::string_view prefix = ESCAPE_STR, std::optional<std::string_view> suffix = std::nullopt) const {
            return fmt::format(FMT_COMPILE("{}{}{}"), prefix, value, suffix.value_or(prefix));
         }
      };

      using internal_value_type = std::variant<std::string, Placeholder>;
      using position_type = std::uint32_t;

      ValueNode();
      ValueNode(std::string_view string, position_type position = 0);
      ValueNode(std::vector<internal_value_type> value_list, position_type position = 0);
      ValueNode(std::initializer_list<internal_value_type> value_list, position_type position = 0);

      void set_position(position_type position);
      position_type get_position() const;

      void set_as_list(internal_value_type value);
      void add_to_list(internal_value_type value);
      bool list_is_empty() const;

      OVDL_STRING_CONSTEXPR std::string make_from_map(const IsMap<std::string> auto& map) const {
         std::vector<std::string_view> pre_joined(_value_list.size());

         for (auto&& value : _value_list) {
            pre_joined.push_back(std::visit([&](auto&& arg) -> std::string_view {
               using T = std::decay_t<decltype(arg)>;
               if constexpr (std::is_same_v<T, std::string>) {
                  return arg;
               } else if constexpr (std::is_same_v<T, Placeholder>) {
                  return map[arg.value];
               }
            },
               value));
         }

         return fmt::format(FMT_COMPILE("{}"), fmt::join(pre_joined, ""));
      }

      std::string make(std::string_view prefix = Placeholder::ESCAPE_STR, std::optional<std::string_view> suffix = std::nullopt) const;

   private:
      position_type _position;
      std::vector<internal_value_type> _value_list;
   };
}