json_builder.hpp

#pragma once

#include "teqp/models/vdW.hpp"
#include "teqp/models/cubics.hpp"
#include "teqp/models/CPA.hpp"
#include "teqp/models/pcsaft.hpp"

#include "nlohmann/json.hpp"

namespace teqp {

    using vad = std::valarray<double>;

    // Define the EOS types by interrogating the types returned by the respective factory function
    using cub = decltype(canonical_PR(vad{}, vad{}, vad{}));
    using cpatype = decltype(CPA::CPAfactory(nlohmann::json{}));
    using pcsafttype = decltype(PCSAFT::PCSAFTfactory(nlohmann::json{}));

    using AllowedModels = std::variant<vdWEOS1, cub, cpatype, pcsafttype>;

    AllowedModels build_model(const nlohmann::json& json) {

        // Extract the name of the model and the model parameters
        std::string kind = json.at("kind");
        auto spec = json.at("model");

        if (kind == "vdW1") {
            return vdWEOS1(spec.at("a"), spec.at("b"));
        }
        else if (kind == "PR") {
            std::valarray<double> Tc_K = spec.at("Tcrit / K"), pc_Pa = spec.at("pcrit / Pa"), acentric = spec.at("acentric");
            return canonical_PR(Tc_K, pc_Pa, acentric);
        }
        else if (kind == "SRK") {
            std::valarray<double> Tc_K = spec.at("Tcrit / K"), pc_Pa = spec.at("pcrit / Pa"), acentric = spec.at("acentric");
            return canonical_SRK(Tc_K, pc_Pa, acentric);
        }
        else if (kind == "CPA") {
            return CPA::CPAfactory(spec);
        }
        else if (kind == "PCSAFT") {
            return PCSAFT::PCSAFTfactory(spec);
        }
        else {
            throw teqpcException(30, "Unknown kind:" + kind);
        }
    }

};