parry2d 0.26.1

use crate::bounding_volume::Aabb;
use crate::math::{Real, Vector};
use crate::partitioning::{Bvh, BvhBuildStrategy, BvhNode, BvhNodeIndex, TraversalAction};

fn make_test_aabb(i: usize) -> Aabb {
    Aabb::from_half_extents(Vector::splat(i as Real).into(), Vector::splat(1.0))
}

#[test]
fn test_leaves_iteration() {
    let leaves = [
        make_test_aabb(0), // mins at (0,0,0) - should pass
        make_test_aabb(5), // mins at (5,5,5) - should be filtered out
    ];
    let bvh = Bvh::from_leaves(BvhBuildStrategy::Binned, &leaves);

    // Only allow nodes with mins.x <= 3.0 (should only pass leaf 0)
    let check = |node: &BvhNode| -> bool { node.mins.x <= 3.0 };

    let mut found_invalid_leaf = false;
    for leaf_index in bvh.leaves(check) {
        if leaf_index == 1 {
            // This is the leaf that should be filtered out
            found_invalid_leaf = true;
            break;
        }
    }

    if found_invalid_leaf {
        panic!("Leaves iterator returned an invalid leaf");
    }
}

#[test]
fn test_traverse_indexed() {
    // Empty tree: callback must never fire, regardless of `subtree` being `None`.
    let empty = Bvh::new();
    empty.traverse_indexed(None, |_, _| {
        panic!("callback should not be called on an empty BVH");
    });

    // Single-leaf tree exercises the partial-root branch when starting from the root.
    let single = Bvh::from_leaves(BvhBuildStrategy::Binned, &[make_test_aabb(0)]);
    let mut single_visited = std::vec::Vec::new();
    single.traverse_indexed(None, |node, idx| {
        single_visited.push((idx, node.leaf_data()));
        TraversalAction::Continue
    });
    assert_eq!(single_visited.len(), 1);
    assert_eq!(single_visited[0].0, BvhNodeIndex::left(0));
    assert_eq!(single_visited[0].1, Some(0));

    // Multi-leaf tree: traversing from the root must visit every leaf, and the
    // index passed to the callback must round-trip through `bvh.nodes`.
    let leaves: std::vec::Vec<_> = (0..16).map(make_test_aabb).collect();
    let bvh = Bvh::from_leaves(BvhBuildStrategy::Binned, &leaves);

    let mut seen_leaves = std::vec::Vec::new();
    let mut traverse_indexed_calls = std::vec::Vec::new();
    bvh.traverse_indexed(None, |node, idx| {
        // Every reported index must point to the same node we just received.
        let by_idx: &BvhNode = &bvh.nodes[idx];
        assert!(core::ptr::eq(by_idx, node));

        traverse_indexed_calls.push(idx);
        if let Some(data) = node.leaf_data() {
            seen_leaves.push(data);
        }
        TraversalAction::Continue
    });
    seen_leaves.sort();
    assert_eq!(seen_leaves, (0..16).collect::<std::vec::Vec<_>>());

    // `traverse_indexed(None, ...)` must visit exactly the same nodes (in the same
    // order) as `traverse`.
    let mut traverse_nodes: std::vec::Vec<*const BvhNode> = std::vec::Vec::new();
    bvh.traverse(|node| {
        traverse_nodes.push(node as *const _);
        TraversalAction::Continue
    });
    let indexed_nodes: std::vec::Vec<*const BvhNode> = traverse_indexed_calls
        .iter()
        .map(|idx| &bvh.nodes[*idx] as *const _)
        .collect();
    assert_eq!(traverse_nodes, indexed_nodes);

    // Starting from a specific subtree must only visit that subtree (the start
    // node and its descendants), and every reported leaf must belong to it.
    let subtree_root_idx = BvhNodeIndex::left(0);
    let mut subtree_leaves = std::vec::Vec::new();
    let mut subtree_visited = std::vec::Vec::new();
    bvh.traverse_indexed(Some(subtree_root_idx), |node, idx| {
        subtree_visited.push(idx);
        if let Some(data) = node.leaf_data() {
            subtree_leaves.push(data);
        }
        TraversalAction::Continue
    });
    assert_eq!(subtree_visited[0], subtree_root_idx);
    // The subtree's leaves must be a non-empty strict subset of the full set.
    assert!(!subtree_leaves.is_empty());
    assert!(subtree_leaves.len() < 16);
    for leaf in &subtree_leaves {
        assert!(seen_leaves.contains(leaf));
    }
    // Leaf count reported by the subtree's root must match the visited leaves.
    assert_eq!(
        bvh.nodes[subtree_root_idx].leaf_count() as usize,
        subtree_leaves.len()
    );

    // Starting from a leaf node visits exactly that leaf.
    let leaf_idx = *traverse_indexed_calls
        .iter()
        .find(|idx| bvh.nodes[**idx].is_leaf())
        .expect("the tree must contain at least one leaf");
    let mut leaf_only = std::vec::Vec::new();
    bvh.traverse_indexed(Some(leaf_idx), |node, idx| {
        leaf_only.push((idx, node.leaf_data()));
        TraversalAction::Continue
    });
    assert_eq!(leaf_only.len(), 1);
    assert_eq!(leaf_only[0].0, leaf_idx);
    assert!(leaf_only[0].1.is_some());

    // `Prune` at the start node must visit it once and stop.
    let mut prune_visits = 0;
    bvh.traverse_indexed(Some(BvhNodeIndex::left(0)), |_, _| {
        prune_visits += 1;
        TraversalAction::Prune
    });
    assert_eq!(prune_visits, 1);

    // `EarlyExit` at the start node must visit it once and stop.
    let mut exit_visits = 0;
    bvh.traverse_indexed(Some(BvhNodeIndex::left(0)), |_, _| {
        exit_visits += 1;
        TraversalAction::EarlyExit
    });
    assert_eq!(exit_visits, 1);

    // `EarlyExit` partway through must short-circuit the full traversal.
    let mut early = 0;
    bvh.traverse_indexed(None, |_, _| {
        early += 1;
        if early >= 3 {
            TraversalAction::EarlyExit
        } else {
            TraversalAction::Continue
        }
    });
    assert_eq!(early, 3);
}

#[test]
fn bvh_build_and_removal() {
    // Check various combination of building pattern and removal pattern.
    // The tree validity is asserted at every step.
    #[derive(Copy, Clone, Debug)]
    enum BuildPattern {
        Ploc,
        Binned,
        Insert,
    }

    #[derive(Copy, Clone, Debug)]
    enum RemovalPattern {
        InOrder,
        RevOrder,
        EvenOdd,
    }

    for build_pattern in [
        BuildPattern::Ploc,
        BuildPattern::Binned,
        BuildPattern::Insert,
    ] {
        for removal_pattern in [
            RemovalPattern::InOrder,
            RemovalPattern::RevOrder,
            RemovalPattern::EvenOdd,
        ] {
            for len in 1..=100 {
                std::println!(
                    "Testing build: {:?}, removal: {:?}, len: {}",
                    build_pattern,
                    removal_pattern,
                    len
                );
                let leaves: std::vec::Vec<_> = (0..len).map(make_test_aabb).collect();

                let mut bvh = match build_pattern {
                    BuildPattern::Binned => Bvh::from_leaves(BvhBuildStrategy::Binned, &leaves),
                    BuildPattern::Ploc => Bvh::from_leaves(BvhBuildStrategy::Ploc, &leaves),
                    BuildPattern::Insert => {
                        let mut bvh = Bvh::new();
                        for i in 0..len {
                            bvh.insert(make_test_aabb(i), i as u32);
                            bvh.assert_well_formed();
                        }
                        bvh
                    }
                };

                for _ in 0..3 {
                    bvh.assert_well_formed();

                    match removal_pattern {
                        RemovalPattern::InOrder => {
                            // Remove in insertion order.
                            for i in 0..len {
                                bvh.remove(i as u32);
                                bvh.assert_well_formed();
                            }
                        }
                        RemovalPattern::RevOrder => {
                            // Remove in reverse insertion order.
                            for i in (0..len).rev() {
                                bvh.remove(i as u32);
                                bvh.assert_well_formed();
                            }
                        }
                        RemovalPattern::EvenOdd => {
                            // Remove even indices first, then odd.
                            for i in (0..len).filter(|i| i % 2 == 0) {
                                bvh.remove(i as u32);
                                bvh.assert_well_formed();
                            }
                            for i in (0..len).filter(|i| i % 2 != 0) {
                                bvh.remove(i as u32);
                                bvh.assert_well_formed();
                            }
                        }
                    }

                    // Re-insert everything.
                    for (i, leaf) in leaves.iter().enumerate() {
                        bvh.insert(*leaf, i as u32);
                    }
                }
            }
        }
    }
}