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use geo_types::{LineString, Polygon, Rect};
use num_traits::Float;
use std::collections::BinaryHeap;
use std::rc::{Rc, Weak};

use super::sweep_event::SweepEvent;
use super::Operation;

pub fn fill_queue<F>(
    subject: &[Polygon<F>],
    clipping: &[Polygon<F>],
    sbbox: &mut Rect<F>,
    cbbox: &mut Rect<F>,
    operation: Operation,
) -> BinaryHeap<Rc<SweepEvent<F>>>
where
    F: Float,
{
    let mut event_queue: BinaryHeap<Rc<SweepEvent<F>>> = BinaryHeap::new();
    let mut contour_id = 0u32;

    for polygon in subject {
        contour_id += 1;
        process_polygon(&polygon.exterior(), true, contour_id, &mut event_queue, sbbox, true);
        for interior in polygon.interiors() {
            process_polygon(interior, true, contour_id, &mut event_queue, sbbox, false);
        }
    }

    for polygon in clipping {
        let exterior = operation != Operation::Difference;
        if exterior {
            contour_id += 1;
        }
        process_polygon(&polygon.exterior(), false, contour_id, &mut event_queue, cbbox, exterior);
        for interior in polygon.interiors() {
            process_polygon(interior, false, contour_id, &mut event_queue, cbbox, false);
        }
    }

    event_queue
}

fn process_polygon<F>(
    contour_or_hole: &LineString<F>,
    is_subject: bool,
    contour_id: u32,
    event_queue: &mut BinaryHeap<Rc<SweepEvent<F>>>,
    bbox: &mut Rect<F>,
    is_exterior_ring: bool,
) where
    F: Float,
{
    for line in contour_or_hole.lines() {
        if line.start == line.end {
            continue; // skip collapsed edges
        }

        let e1 = SweepEvent::new_rc(contour_id, line.start, false, Weak::new(), is_subject, is_exterior_ring);
        let e2 = SweepEvent::new_rc(
            contour_id,
            line.end,
            false,
            Rc::downgrade(&e1),
            is_subject,
            is_exterior_ring,
        );
        e1.set_other_event(&e2);

        if e1 < e2 {
            e2.set_left(true)
        } else {
            e1.set_left(true)
        }

        bbox.min.x = bbox.min.x.min(line.start.x);
        bbox.min.y = bbox.min.y.min(line.start.y);
        bbox.max.x = bbox.max.x.max(line.start.x);
        bbox.max.y = bbox.max.y.max(line.start.y);

        event_queue.push(e1);
        event_queue.push(e2);
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use geo_types::Coordinate;
    use std::cmp::Ordering;
    use std::collections::BinaryHeap;
    use std::rc::{Rc, Weak};

    fn make_simple(x: f64, y: f64, is_subject: bool) -> Rc<SweepEvent<f64>> {
        SweepEvent::new_rc(0, Coordinate { x, y }, false, Weak::new(), is_subject, true)
    }

    fn check_order_in_queue(first: Rc<SweepEvent<f64>>, second: Rc<SweepEvent<f64>>) {
        let mut queue: BinaryHeap<Rc<SweepEvent<f64>>> = BinaryHeap::new();

        assert_eq!(first.cmp(&second), Ordering::Greater);
        assert_eq!(second.cmp(&first), Ordering::Less);
        {
            queue.push(first.clone());
            queue.push(second.clone());

            let p1 = queue.pop().unwrap();
            let p2 = queue.pop().unwrap();

            assert!(Rc::ptr_eq(&first, &p1));
            assert!(Rc::ptr_eq(&second, &p2));
        }
        {
            queue.push(second.clone());
            queue.push(first.clone());

            let p1 = queue.pop().unwrap();
            let p2 = queue.pop().unwrap();

            assert!(Rc::ptr_eq(&first, &p1));
            assert!(Rc::ptr_eq(&second, &p2));
        }
    }

    #[test]
    fn test_least_by_x() {
        check_order_in_queue(make_simple(0.0, 0.0, false), make_simple(0.5, 0.5, false))
    }

    #[test]
    fn test_least_by_y() {
        check_order_in_queue(make_simple(0.0, 0.0, false), make_simple(0.0, 0.5, false))
    }

    #[test]
    fn test_least_left() {
        let e1 = make_simple(0.0, 0.0, false);
        e1.set_left(true);
        let e2 = make_simple(0.0, 0.0, false);
        e2.set_left(false);

        check_order_in_queue(e2, e1)
    }

    #[test]
    fn test_shared_edge_not_colinear() {
        let other_e1 = make_simple(1.0, 1.0, false);
        let e1 = make_simple(0.0, 0.0, false);
        e1.set_other_event(&other_e1);
        e1.set_left(true);
        let other_e2 = make_simple(2.0, 3.0, false);
        let e2 = make_simple(0.0, 0.0, false);
        e2.set_other_event(&other_e2);
        e2.set_left(true);

        check_order_in_queue(e1, e2)
    }

    #[test]
    fn test_collinear_edges() {
        let other_e1 = make_simple(1.0, 1.0, true);
        let e1 = make_simple(0.0, 0.0, true);
        e1.set_other_event(&other_e1);
        e1.set_left(true);
        let other_e2 = make_simple(2.0, 2.0, false);
        let e2 = make_simple(0.0, 0.0, false);
        e2.set_other_event(&other_e2);
        e2.set_left(true);

        check_order_in_queue(e1, e2)
    }
}