use geo::algorithm::bounding_rect::BoundingRect;
use geo::algorithm::translate::Translate;
use geo::Polygon;
use geo_types::{Coordinate, LineString, MultiPolygon};

pub trait MultiPolygonExt {
    fn scale_to_width(&self, size: f64) -> Self;
    fn scale(&self, factor: f64) -> Self;
}

impl MultiPolygonExt for MultiPolygon<f64> {
    fn scale_to_width(&self, size: f64) -> Self {
        let option = self.bounding_rect().unwrap();
        let diff = f64::abs(option.min().x - option.max().x);
        let scale = size / diff;
        self.scale(scale)
    }

    fn scale(&self, factor: f64) -> Self {
        let bounding_rectangle = self.bounding_rect().unwrap();
        let zeroed_multi_polygons =
            self.translate(-bounding_rectangle.min().x, -bounding_rectangle.min().y);
        let mut new_polygons: Vec<Polygon<f64>> = Vec::new();
        for polygon in zeroed_multi_polygons.iter() {
            // map interiors
            let mut interiors: Vec<LineString<f64>> = Vec::new();
            for interior_line_string in polygon.interiors().to_vec() {
                let mut new_line_string: Vec<Coordinate<f64>> = Vec::new();
                for point in interior_line_string.into_points() {
                    new_line_string.push(Coordinate {
                        x: point.x() * factor,
                        y: point.y() * factor,
                    });
                }
                interiors.push(LineString::from(new_line_string));
            }
            // map exterior
            let mut new_line_string: Vec<Coordinate<f64>> = Vec::new();
            for point in polygon.exterior().clone().into_points() {
                new_line_string.push(Coordinate {
                    x: point.x() * factor,
                    y: point.y() * factor,
                });
            }
            let exterior = LineString::from(new_line_string);
            new_polygons.push(Polygon::new(exterior, interiors));
        }
        MultiPolygon::from(new_polygons)
            .translate(bounding_rectangle.min().x, bounding_rectangle.min().y)
    }
}