module;

#include <concepts>
#include <memory>
#include <type_traits>
#include <utility>

export module mean_field:model.stellar;

export import :eos.base;
export import :model.structure.base;
export import :surface.base;

export namespace mean_field::models {
    template <typename Candidate>
    concept StructurePrescription =
        std::derived_from<std::remove_cvref_t<Candidate>, mean_field::models::structure::StructureBase>;

    template <typename Candidate>
    concept SurfacePrescription = std::derived_from<std::remove_cvref_t<Candidate>, mean_field::surface::SurfaceBase>;

    /*
     * Public ownership facade for a physical structure prescription and its
     * stellar-surface prescription.
     *
     * The concrete prescriptions are allocated once at construction. Their
     * stable addresses allow future prepared operators and contexts to borrow
     * references without making ownership part of the user-facing API.
     */
    class StellarModel final {
    public:
        template <
            StructurePrescription StructureType,
            SurfacePrescription SurfaceType>
        explicit StellarModel(
            StructureType &&structurePrescription,
            SurfaceType &&surfacePrescription
        )
            : StellarModel(
                  std::make_unique<std::remove_cvref_t<StructureType>>(
                      std::forward<StructureType>(structurePrescription)
                  ),
                  std::make_unique<std::remove_cvref_t<SurfaceType>>(std::forward<SurfaceType>(surfacePrescription))
              ) {
        }

        ~StellarModel()                                   = default;

        StellarModel(const StellarModel &)                = delete;

        StellarModel &operator=(const StellarModel &)     = delete;

        StellarModel(StellarModel &&) noexcept            = default;

        StellarModel &operator=(StellarModel &&) noexcept = default;

        [[nodiscard]] const mean_field::models::structure::StructureBase &structurePrescription() const noexcept {
            return *m_structurePrescription;
        }

        [[nodiscard]] const mean_field::surface::SurfaceBase &surfacePrescription() const noexcept {
            return *m_surfacePrescription;
        }

        [[nodiscard]] const mean_field::eos::EquationOfState &equationOfState() const noexcept {
            return m_structurePrescription->equationOfState();
        }

        [[nodiscard]] double targetMass() const noexcept {
            return m_structurePrescription->targetMass();
        }

        [[nodiscard]] mean_field::models::structure::StructureSeed
        makeInitialSeed(const mean_field::models::structure::StructureSeedRequest &request) const {
            return m_structurePrescription->makeInitialSeed(request);
        }

        [[nodiscard]] const mean_field::surface::ResolvedSurfaceCondition &resolvedSurfaceCondition() const noexcept {
            return m_resolvedSurfaceCondition;
        }

    private:
        explicit StellarModel(
            std::unique_ptr<mean_field::models::structure::StructureBase> structurePrescription,
            std::unique_ptr<mean_field::surface::SurfaceBase> surfacePrescription
        )
            : m_structurePrescription(std::move(structurePrescription)),
              m_surfacePrescription(std::move(surfacePrescription)),
              m_resolvedSurfaceCondition(validateAndResolve(
                  *m_structurePrescription,
                  *m_surfacePrescription
              )) {
        }

        [[nodiscard]] static mean_field::surface::ResolvedSurfaceCondition validateAndResolve(
            const mean_field::models::structure::StructureBase &structurePrescription,
            const mean_field::surface::SurfaceBase &surfacePrescription
        ) {
            structurePrescription.validate();

            const mean_field::eos::EquationOfState &equationOfState = structurePrescription.equationOfState();

            surfacePrescription.validate(equationOfState);

            return surfacePrescription.resolve(equationOfState);
        }

        std::unique_ptr<mean_field::models::structure::StructureBase> m_structurePrescription;

        std::unique_ptr<mean_field::surface::SurfaceBase> m_surfacePrescription;

        mean_field::surface::ResolvedSurfaceCondition m_resolvedSurfaceCondition;
    };
} // namespace mean_field::models