//! Data structure to describe a constraint between two rigid bodies.

use std::rc::Rc;
use std::cell::RefCell;

use alga::general::Real;
use ncollide::query::Contact;
use object::RigidBody;
use detection::joint::{Fixed, BallInSocket};
use math::Point;

/// A constraint between two rigid bodies.
pub enum Constraint<N: Real> {
    /// A contact.
    RBRB(Rc<RefCell<RigidBody<N>>>, Rc<RefCell<RigidBody<N>>>, Contact<Point<N>>),
    /// A ball-in-socket joint.
    BallInSocket(Rc<RefCell<BallInSocket<N>>>),
    /// A fixed joint.
    Fixed(Rc<RefCell<Fixed<N>>>),
}

impl<N: Real> Clone for Constraint<N> {
    fn clone(&self) -> Constraint<N> {
        match *self {
            Constraint::RBRB(ref a, ref b, ref c) => Constraint::RBRB(a.clone(), b.clone(), c.clone()),
            Constraint::BallInSocket(ref bis)     => Constraint::BallInSocket(bis.clone()),
            Constraint::Fixed(ref f)              => Constraint::Fixed(f.clone()),
        }
    }
}