//! Resolving an integrated fighter position against the stage.

use crate::fighter::ecb::FighterPreviousECB;
use crate::fighter::{FighterECB, FighterPreviousTranslation, FighterTranslation};
use crate::math::segment::FGSegment2d;
use crate::math::vec::FGVec2;
use crate::stage::line::{StageCollision, StageLineID, StagePolyType};
/*
pub fn collide_fighter_with_scene(
    fighters: Query<(&FighterECB, &mut FighterVelocity, &mut FighterTranslation)>,
    stage_planes: Query<&StagePoly>,
    mut gizmos: Gizmos,
) {
    for (ecb, mut velocity, mut translation) in fighters {
        for plane in stage_planes {
            let ray_from = translation.0;
            let ray_to = translation.0 + Vec2::new(0.0, -ecb.vertical_half);

            let intersection_result = plane.intersect_ray(Segment2d::new(ray_from, ray_to));

            if let Some(result) = intersection_result {
                gizmos.sphere(
                    Isometry3d::from(Vec3::new(result.position.x, result.position.y, 0.0)),
                    0.1f32,
                    HOT_PINK,
                );
                velocity.0 = plane.project(velocity.0);
                translation.0 = result.position + Vec2::new(0.0, ecb.vertical_half);
            }
        }
    }
}
*/
#[derive(Clone)]
pub struct AirCollisionWithStageResult {
    pub line_id: StageLineID,
    pub hit_position: FGVec2,
    pub hit_normal: FGVec2,
}

pub fn air_collide_with_stage(
    prev_translation: &FighterPreviousTranslation,
    translation: &FighterTranslation,
    prev_ecb: &FighterPreviousECB,
    ecb: &FighterECB,
    stage_collision: &StageCollision,
    ignored_polys: &[usize],
    can_ignore_soft_platforms: bool,
) -> Option<AirCollisionWithStageResult> {
    let ray_segment = FGSegment2d::new(
        prev_translation.0 + prev_ecb.get_bottom_point(),
        translation.0 + ecb.get_bottom_point(),
    );

    stage_collision
        .stage_polys
        .iter()
        .enumerate()
        .filter(|(poly_idx, poly)| {
            !ignored_polys.contains(poly_idx)
                && !(can_ignore_soft_platforms && matches!(poly.poly_type, StagePolyType::Platform))
        })
        .filter_map(|(poly_idx, poly)| {
            poly.intersect_ray(ray_segment).map(|intersect_result| {
                (
                    AirCollisionWithStageResult {
                        line_id: {
                            StageLineID {
                                polygon: poly_idx,
                                segment: intersect_result.segment_idx,
                            }
                        },
                        hit_position: intersect_result.position,
                        hit_normal: intersect_result.normal,
                    },
                    intersect_result
                        .position
                        .distance_squared(ray_segment.point2()),
                )
            })
        })
        .max_by(|(_, a), (_, b)| a.cmp(b))
        .map(|(result, _)| result)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::fighter::ecb::{FighterECB, FighterPreviousECB};
    use crate::stage::line::{StagePoly, StagePolyLineSegmentType, StagePolyType};

    fn horizontal_platform(y: &str) -> StagePoly {
        StagePoly::build(
            StagePolyType::Platform,
            &[
                (FGVec2::lit("-2", y), StagePolyLineSegmentType::Floor),
                (FGVec2::lit("2", y), StagePolyLineSegmentType::Floor),
            ],
        )
    }

    fn solid_floor() -> StagePoly {
        StagePoly::build(
            StagePolyType::Closed,
            &[
                (FGVec2::lit("-2", "0"), StagePolyLineSegmentType::Floor),
                (FGVec2::lit("2", "0"), StagePolyLineSegmentType::Floor),
                (FGVec2::lit("2", "-2"), StagePolyLineSegmentType::Wall),
                (FGVec2::lit("-2", "-2"), StagePolyLineSegmentType::Wall),
            ],
        )
    }

    #[test]
    fn airborne_collision_skips_ignored_polygons() {
        let stage_collision = StageCollision {
            stage_polys: vec![horizontal_platform("0"), horizontal_platform("1")],
        };
        let previous_translation = FighterPreviousTranslation(FGVec2::lit("0", "2"));
        let translation = FighterTranslation(FGVec2::lit("0", "-1"));
        let previous_ecb = FighterPreviousECB {
            bottom: FGVec2::ZERO,
            top: FGVec2::ZERO,
            left: FGVec2::ZERO,
            right: FGVec2::ZERO,
        };
        let ecb = FighterECB {
            bottom: FGVec2::ZERO,
            top: FGVec2::ZERO,
            left: FGVec2::ZERO,
            right: FGVec2::ZERO,
        };

        let collision = air_collide_with_stage(
            &previous_translation,
            &translation,
            &previous_ecb,
            &ecb,
            &stage_collision,
            &[1],
            false,
        )
        .expect("the non-ignored platform should still be collidable");

        assert_eq!(collision.line_id.polygon, 0);
        assert_eq!(collision.hit_position, FGVec2::lit("0", "0"));
    }

    #[test]
    fn airborne_collision_skips_soft_platforms_while_passing_down() {
        let stage_collision = StageCollision {
            stage_polys: vec![horizontal_platform("0")],
        };
        let previous_translation = FighterPreviousTranslation(FGVec2::lit("0", "2"));
        let translation = FighterTranslation(FGVec2::lit("0", "-1"));
        let previous_ecb = FighterPreviousECB {
            bottom: FGVec2::ZERO,
            top: FGVec2::ZERO,
            left: FGVec2::ZERO,
            right: FGVec2::ZERO,
        };
        let ecb = FighterECB {
            bottom: FGVec2::ZERO,
            top: FGVec2::ZERO,
            left: FGVec2::ZERO,
            right: FGVec2::ZERO,
        };

        assert!(air_collide_with_stage(
            &previous_translation,
            &translation,
            &previous_ecb,
            &ecb,
            &stage_collision,
            &[],
            true,
        )
        .is_none());

        assert_eq!(
            air_collide_with_stage(
                &previous_translation,
                &translation,
                &previous_ecb,
                &ecb,
                &stage_collision,
                &[],
                false,
            )
            .expect("air dodges still collide with soft platforms")
            .hit_position,
            FGVec2::lit("0", "0")
        );
    }

    #[test]
    fn airborne_collision_still_hits_solid_floors_while_passing_down() {
        let stage_collision = StageCollision {
            stage_polys: vec![solid_floor()],
        };
        let previous_translation = FighterPreviousTranslation(FGVec2::lit("0", "2"));
        let translation = FighterTranslation(FGVec2::lit("0", "-1"));
        let previous_ecb = FighterPreviousECB {
            bottom: FGVec2::ZERO,
            top: FGVec2::ZERO,
            left: FGVec2::ZERO,
            right: FGVec2::ZERO,
        };
        let ecb = FighterECB {
            bottom: FGVec2::ZERO,
            top: FGVec2::ZERO,
            left: FGVec2::ZERO,
            right: FGVec2::ZERO,
        };

        let collision = air_collide_with_stage(
            &previous_translation,
            &translation,
            &previous_ecb,
            &ecb,
            &stage_collision,
            &[],
            true,
        )
        .expect("solid floors remain collidable while passing down");

        assert_eq!(collision.line_id.polygon, 0);
        assert_eq!(collision.hit_position, FGVec2::lit("0", "0"));
    }
}