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// Copyright (c) 2018-2020 Thomas Kramer.
// SPDX-FileCopyrightText: 2018-2022 Thomas Kramer
//
// SPDX-License-Identifier: AGPL-3.0-or-later

//! Multi-polygons are a set of multiple polygons.

use crate::CoordinateType;

use crate::point::Point;
use crate::polygon::Polygon;

pub use crate::traits::{BoundingBox, DoubledOrientedArea, MapPointwise, WindingNumber};

use crate::edge::Edge;
use crate::prelude::Rect;
use crate::traits::{TryBoundingBox, TryIntoBoundingBox};
use std::iter::FromIterator;

/// A `MultiPolygon` is a list of polygons. There is no restrictions on the polygons (they can be
/// intersecting, empty, etc.).
#[derive(Default, Clone, Debug, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct MultiPolygon<T> {
    /// The list of polygons which defines the content of this multi polygon.
    pub polygons: Vec<Polygon<T>>,
}

impl<T> MultiPolygon<T> {
    /// Create an empty set of polygons.
    pub fn new() -> Self {
        Self { polygons: vec![] }
    }

    /// Create a `MultiPolygon` from a vector of `Polygon`s.
    pub fn from_polygons(polygons: Vec<Polygon<T>>) -> Self {
        MultiPolygon { polygons }
    }

    /// Return the number of polygons.
    pub fn len(&self) -> usize {
        self.polygons.len()
    }

    /// Check if polygon is empty.
    pub fn is_empty(&self) -> bool {
        self.polygons.is_empty()
    }

    /// Insert a polygon into the region.
    pub fn insert(&mut self, polygon: Polygon<T>) {
        self.polygons.push(polygon)
    }
}

impl<T: Copy> MultiPolygon<T> {
    /// Iterate over all edges of the polygons including holes.
    pub fn all_edges_iter(&self) -> impl Iterator<Item = Edge<T>> + '_ {
        self.polygons.iter().flat_map(|p| p.all_edges_iter())
    }
}

impl<T> WindingNumber<T> for MultiPolygon<T>
where
    T: CoordinateType,
{
    fn winding_number(&self, point: Point<T>) -> isize {
        self.polygons.iter().map(|p| p.winding_number(point)).sum()
    }
}

impl<T> MapPointwise<T> for MultiPolygon<T>
where
    T: CoordinateType,
{
    fn transform<F: Fn(Point<T>) -> Point<T>>(&self, tf: F) -> Self {
        MultiPolygon::from_polygons(self.polygons.iter().map(|p| p.transform(&tf)).collect())
    }
}

impl<T, IP: Into<Polygon<T>>> From<IP> for MultiPolygon<T> {
    fn from(x: IP) -> Self {
        MultiPolygon::from_polygons(vec![x.into()])
    }
}

impl<T> From<Vec<Polygon<T>>> for MultiPolygon<T> {
    fn from(polygons: Vec<Polygon<T>>) -> Self {
        MultiPolygon { polygons }
    }
}

impl<T, IP: Into<Polygon<T>>> FromIterator<IP> for MultiPolygon<T> {
    fn from_iter<I: IntoIterator<Item = IP>>(iter: I) -> Self {
        MultiPolygon::from_polygons(iter.into_iter().map(|p| p.into()).collect())
    }
}

impl<T> IntoIterator for MultiPolygon<T> {
    type Item = Polygon<T>;
    type IntoIter = ::std::vec::IntoIter<Polygon<T>>;

    fn into_iter(self) -> Self::IntoIter {
        self.polygons.into_iter()
    }
}

impl<T: CoordinateType> TryBoundingBox<T> for MultiPolygon<T> {
    fn try_bounding_box(&self) -> Option<Rect<T>> {
        self.polygons.iter().try_into_bounding_box()
    }
}

//impl<'a, T: CoordinateType> IntoIterator for &'a MultiPolygon<T> {
//    type Item = &'a Polygon<T>;
//    type IntoIter = ::std::vec::IntoIter<&'a Polygon<T>>;
//
//    fn into_iter(self) -> Self::IntoIter {
//        let p = &self.polygons;
//        p.into_iter()
//    }
//}