use serde::{Deserialize, Serialize};

use aabb_quadtree::geom::{Point, Rect};

use crate::{Distance, LonLat, Polygon, Pt2D, Ring};

/// Represents a rectangular boundary of `Pt2D` points.
#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
pub struct Bounds {
    pub min_x: f64,
    pub min_y: f64,
    pub max_x: f64,
    pub max_y: f64,
}

impl Bounds {
    /// A boundary including no points.
    pub fn new() -> Bounds {
        Bounds {
            min_x: f64::MAX,
            min_y: f64::MAX,
            max_x: f64::MIN,
            max_y: f64::MIN,
        }
    }

    pub fn zero() -> Self {
        Bounds {
            min_x: 0.0,
            min_y: 0.0,
            max_x: 0.0,
            max_y: 0.0,
        }
    }

    /// Create a boundary covering some points.
    pub fn from(pts: &[Pt2D]) -> Bounds {
        let mut b = Bounds::new();
        for pt in pts {
            b.update(*pt);
        }
        b
    }

    /// Update the boundary to include this point.
    pub fn update(&mut self, pt: Pt2D) {
        self.min_x = self.min_x.min(pt.x());
        self.max_x = self.max_x.max(pt.x());
        self.min_y = self.min_y.min(pt.y());
        self.max_y = self.max_y.max(pt.y());
    }

    /// Unions two boundaries.
    pub fn union(&mut self, other: Bounds) {
        self.update(Pt2D::new(other.min_x, other.min_y));
        self.update(Pt2D::new(other.max_x, other.max_y));
    }

    /// Expand the existing boundary by some distance evenly on all sides.
    pub fn add_buffer(&mut self, sides: Distance) {
        self.min_x -= sides.inner_meters();
        self.max_x += sides.inner_meters();
        self.min_y -= sides.inner_meters();
        self.max_y += sides.inner_meters();
    }

    /// Transform the boundary by scaling its corners.
    pub fn scale(mut self, factor: f64) -> Self {
        self.min_x *= factor;
        self.min_y *= factor;
        self.max_x *= factor;
        self.max_y *= factor;
        self
    }

    /// True if the point is within the boundary.
    pub fn contains(&self, pt: Pt2D) -> bool {
        pt.x() >= self.min_x && pt.x() <= self.max_x && pt.y() >= self.min_y && pt.y() <= self.max_y
    }

    /// Converts the boundary to the format used by `aabb_quadtree`.
    pub fn as_bbox(&self) -> Rect {
        Rect {
            top_left: Point {
                x: self.min_x as f32,
                y: self.min_y as f32,
            },
            bottom_right: Point {
                x: self.max_x as f32,
                y: self.max_y as f32,
            },
        }
    }

    /// Creates a rectangle covering this boundary.
    pub fn get_rectangle(&self) -> Polygon {
        Ring::must_new(vec![
            Pt2D::new(self.min_x, self.min_y),
            Pt2D::new(self.max_x, self.min_y),
            Pt2D::new(self.max_x, self.max_y),
            Pt2D::new(self.min_x, self.max_y),
            Pt2D::new(self.min_x, self.min_y),
        ])
        .into_polygon()
    }

    /// The width of this boundary.
    // TODO Really should be Distance
    pub fn width(&self) -> f64 {
        self.max_x - self.min_x
    }

    /// The height of this boundary.
    pub fn height(&self) -> f64 {
        self.max_y - self.min_y
    }

    /// The center point of this boundary.
    pub fn center(&self) -> Pt2D {
        Pt2D::new(
            self.min_x + self.width() / 2.0,
            self.min_y + self.height() / 2.0,
        )
    }
}

/// Represents a rectangular boundary of `LonLat` points. After building one of these, `LonLat`s
/// can be transformed into `Pt2D`s, treating the top-left of the boundary as (0, 0), and growing
/// to the right and down (screen-drawing order, not Cartesian) in meters.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct GPSBounds {
    pub min_lon: f64,
    pub min_lat: f64,
    pub max_lon: f64,
    pub max_lat: f64,
}

impl GPSBounds {
    /// A boundary including no points.
    pub fn new() -> GPSBounds {
        GPSBounds {
            min_lon: f64::MAX,
            min_lat: f64::MAX,
            max_lon: f64::MIN,
            max_lat: f64::MIN,
        }
    }

    /// Create a boundary covering some points.
    pub fn from(pts: Vec<LonLat>) -> GPSBounds {
        let mut b = GPSBounds::new();
        for pt in pts {
            b.update(pt);
        }
        b
    }

    /// Update the boundary to include this point.
    pub fn update(&mut self, pt: LonLat) {
        self.min_lon = self.min_lon.min(pt.x());
        self.max_lon = self.max_lon.max(pt.x());
        self.min_lat = self.min_lat.min(pt.y());
        self.max_lat = self.max_lat.max(pt.y());
    }

    /// True if the point is within the boundary.
    pub fn contains(&self, pt: LonLat) -> bool {
        pt.x() >= self.min_lon
            && pt.x() <= self.max_lon
            && pt.y() >= self.min_lat
            && pt.y() <= self.max_lat
    }

    /// The bottom-right corner of the boundary, in map-space.
    // TODO cache this
    pub fn get_max_world_pt(&self) -> Pt2D {
        let width = LonLat::new(self.min_lon, self.min_lat)
            .gps_dist(LonLat::new(self.max_lon, self.min_lat));
        let height = LonLat::new(self.min_lon, self.min_lat)
            .gps_dist(LonLat::new(self.min_lon, self.max_lat));
        Pt2D::new(width.inner_meters(), height.inner_meters())
    }

    /// Converts the boundary to map-space.
    pub fn to_bounds(&self) -> Bounds {
        let mut b = Bounds::new();
        b.update(Pt2D::new(0.0, 0.0));
        b.update(self.get_max_world_pt());
        b
    }

    /// Convert all points to map-space, failing if any points are outside this boundary.
    pub fn try_convert(&self, pts: &[LonLat]) -> Option<Vec<Pt2D>> {
        let mut result = Vec::new();
        for gps in pts {
            if !self.contains(*gps) {
                return None;
            }
            result.push(gps.to_pt(self));
        }
        Some(result)
    }

    /// Convert all points to map-space. The points may be outside this boundary.
    pub fn convert(&self, pts: &[LonLat]) -> Vec<Pt2D> {
        pts.iter().map(|gps| gps.to_pt(self)).collect()
    }

    /// Convert map-space points back to `LonLat`s. This is only valid if the `GPSBounds` used
    /// is the same as the one used to originally produce the `Pt2D`s.
    pub fn convert_back(&self, pts: &[Pt2D]) -> Vec<LonLat> {
        pts.iter().map(|pt| pt.to_gps(self)).collect()
    }

    /// Returns points in order covering this boundary.
    pub fn get_rectangle(&self) -> Vec<LonLat> {
        vec![
            LonLat::new(self.min_lon, self.min_lat),
            LonLat::new(self.max_lon, self.min_lat),
            LonLat::new(self.max_lon, self.max_lat),
            LonLat::new(self.min_lon, self.max_lat),
            LonLat::new(self.min_lon, self.min_lat),
        ]
    }
}