JsonSerializer.hpp

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#pragma once
#include <nlohmann/json.hpp>
 
namespace Cori {
    namespace FileSystem {
        template<typename T>
        concept JsonSerializable = requires(T value, const nlohmann::json j) {
            { nlohmann::json(value) } -> std::same_as<nlohmann::json>;
            { j.get<T>() } -> std::same_as<T>;
        };

        class JsonSerializer {
        public:
            template<JsonSerializable T>
            static std::expected<void, Core::CoriError<>> Save(const T& data, const std::filesystem::path& filepath) {
                try {
 
                    const auto parent_dir = filepath.parent_path();
 
                    if (!parent_dir.empty()) {
                        std::filesystem::create_directories(parent_dir);
                    }
 
                    std::ofstream file(filepath);
                    if (!file.is_open()) {
                        return std::unexpected(Core::CoriError(std::format("Could not open file for writing: ", filepath.string())));
                    }
 
 
                    nlohmann::json j = data;
                    file << std::fixed << std::setprecision(4);
                    file << j.dump(4);
 
                    return {};
                }
                catch (const std::exception& e) {
                    return std::unexpected(Core::CoriError(std::format("An unexpected error occurred during save: ", e.what())));
                }
            }

            template<JsonSerializable T>
            static std::expected<T, Core::CoriError<>> Load(const std::filesystem::path& filepath) {
                if (!std::filesystem::exists(filepath)) {
                    return std::unexpected(Core::CoriError(std::format("File does not exist: ", filepath.string())));
                }
 
                try {
                    std::ifstream file(filepath);
                    if (!file.is_open()) {
                        return std::unexpected(Core::CoriError(std::format("Could not open file for reading: ", filepath.string())));
                    }
 
                    nlohmann::json j;
                    file >> j;
                    return j.get<T>();
                }
                catch (const nlohmann::json::exception& e) {
                    return std::unexpected(Core::CoriError(std::format("JSON processing error: ", e.what())));
                }
                catch (const std::exception& e) {
                    return std::unexpected(Core::CoriError(std::format("An unexpected error occurred during load: ", e.what())));
                }
            }
        };
    }
}