use crate::geometry::ParticlesContacts;
use crate::math::Real;
use crate::object::{Boundary, Fluid};
use crate::TimestepManager;

/// Trait implemented by non-pressure forces.
///
/// This includes all non-pressure forces internal to a same fluid, or acting
/// between a fluid and a boundary.
pub trait NonPressureForce: Send + Sync {
    /// Compute and applies the non-pressure forces to the given fluid.
    ///
    /// The force application should result in adding accelerations to the
    /// `fluid.accelerations` field.
    fn solve(
        &mut self,
        timestep: &TimestepManager,
        kernel_radius: Real,
        fluid_fluid_contacts: &ParticlesContacts,
        fluid_boundaries_contacts: &ParticlesContacts,
        fluid: &mut Fluid,
        boundaries: &[Boundary],
        densities: &[Real],
    );

    /// Apply the given permutation to all relevant field of this non-pressure force.
    ///
    /// This is currently not used so it can be left empty.
    fn apply_permutation(&mut self, _permutation: &[usize]) {}
}