module;

#include <cmath>
#include <format>
#include <stdexcept>
#include <utility>

module mean_field;

import :model.structure.polytropic;

namespace mean_field::models::structure {
    PolytropicStructure::PolytropicStructure(
        eos::Polytrope equationOfState,
        const double targetMass
    )
        : m_equationOfState(std::move(equationOfState)),
          m_targetMass(targetMass) {
        validate();
    }

    const eos::Polytrope &PolytropicStructure::equationOfState() const noexcept {
        return m_equationOfState;
    }

    double PolytropicStructure::targetMass() const noexcept {
        return m_targetMass;
    }

    StructureSeed PolytropicStructure::makeInitialSeed(const StructureSeedRequest &request) const {
        const seed::RadialProfile profile = seed::generateLaneEmdenProfile(
            m_equationOfState, dimensions::DensityValue{request.centralDensity}, request.radialSampleCount
        );

        return {
            .radius          = profile.radius,
            .density         = profile.density,
            .enthalpy        = profile.specificEnthalpy,
            .stellarRadius   = profile.stellarRadius.value(),
            .centralDensity  = profile.centralDensity.value(),
            .centralEnthalpy = profile.centralSpecificEnthalpy.value()
        };
    }

    void PolytropicStructure::validate() const {
        const double polytropicIndex = m_equationOfState.polytropic_index();

        if (!std::isfinite(polytropicIndex) || polytropicIndex < 1.0 || polytropicIndex >= 5.0) {
            throw std::invalid_argument(
                std::format(
                    "PolytropicStructure requires a finite-radius polytrope with 1 <= n < 5. Instead n = {} was "
                    "provided.",
                    polytropicIndex
                )
            );
        }

        if (!std::isfinite(m_targetMass) || m_targetMass <= 0.0) {
            throw std::invalid_argument(
                std::format(
                    "The target stellar mass must be finite and positive. Instead a value of {} was provided.",
                    m_targetMass
                )
            );
        }
    }
} // namespace mean_field::models::structure