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use crate::{CoordNum, Polygon};
use std::iter::FromIterator;

/// A collection of [`Polygon`s](struct.Polygon.html). Can
/// be created from a `Vec` of `Polygon`s, or from an
/// Iterator which yields `Polygon`s. Iterating over this
/// object yields the component `Polygon`s.
///
/// # Semantics
///
/// The _interior_ and the _boundary_ are the union of the
/// interior and the boundary of the constituent polygons.
///
/// # Validity
///
/// - The interiors of no two constituent polygons may intersect.
///
/// - The boundaries of two (distinct) constituent polygons
/// may only intersect at finitely many points.
///
/// Refer to section 6.1.14 of the OGC-SFA for a formal
/// definition of validity. Note that the validity is not
/// enforced, but expected by the operations and
/// predicates that operate on it.
#[derive(Eq, PartialEq, Clone, Debug, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct MultiPolygon<T>(pub Vec<Polygon<T>>)
where
    T: CoordNum;

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

impl<T: CoordNum, IP: Into<Polygon<T>>> From<Vec<IP>> for MultiPolygon<T> {
    fn from(x: Vec<IP>) -> Self {
        MultiPolygon(x.into_iter().map(|p| p.into()).collect())
    }
}

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

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

    fn into_iter(self) -> Self::IntoIter {
        self.0.into_iter()
    }
}

impl<'a, T: CoordNum> IntoIterator for &'a MultiPolygon<T> {
    type Item = &'a Polygon<T>;
    type IntoIter = ::std::slice::Iter<'a, Polygon<T>>;

    fn into_iter(self) -> Self::IntoIter {
        (&self.0).iter()
    }
}

impl<'a, T: CoordNum> IntoIterator for &'a mut MultiPolygon<T> {
    type Item = &'a mut Polygon<T>;
    type IntoIter = ::std::slice::IterMut<'a, Polygon<T>>;

    fn into_iter(self) -> Self::IntoIter {
        (&mut self.0).iter_mut()
    }
}

impl<T: CoordNum> MultiPolygon<T> {
    pub fn iter(&self) -> impl Iterator<Item = &Polygon<T>> {
        self.0.iter()
    }

    pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut Polygon<T>> {
        self.0.iter_mut()
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::polygon;

    #[test]
    fn test_iter() {
        let multi = MultiPolygon(vec![
            polygon![(x: 0, y: 0), (x: 2, y: 0), (x: 1, y: 2), (x:0, y:0)],
            polygon![(x: 10, y: 10), (x: 12, y: 10), (x: 11, y: 12), (x:10, y:10)],
        ]);

        let mut first = true;
        for p in &multi {
            if first {
                assert_eq!(
                    p,
                    &polygon![(x: 0, y: 0), (x: 2, y: 0), (x: 1, y: 2), (x:0, y:0)]
                );
                first = false;
            } else {
                assert_eq!(
                    p,
                    &polygon![(x: 10, y: 10), (x: 12, y: 10), (x: 11, y: 12), (x:10, y:10)]
                );
            }
        }

        // Do it again to prove that `multi` wasn't `moved`.
        first = true;
        for p in &multi {
            if first {
                assert_eq!(
                    p,
                    &polygon![(x: 0, y: 0), (x: 2, y: 0), (x: 1, y: 2), (x:0, y:0)]
                );
                first = false;
            } else {
                assert_eq!(
                    p,
                    &polygon![(x: 10, y: 10), (x: 12, y: 10), (x: 11, y: 12), (x:10, y:10)]
                );
            }
        }
    }

    #[test]
    fn test_iter_mut() {
        let mut multi = MultiPolygon(vec![
            polygon![(x: 0, y: 0), (x: 2, y: 0), (x: 1, y: 2), (x:0, y:0)],
            polygon![(x: 10, y: 10), (x: 12, y: 10), (x: 11, y: 12), (x:10, y:10)],
        ]);

        for poly in &mut multi {
            poly.exterior_mut(|exterior| {
                for coord in exterior {
                    coord.x += 1;
                    coord.y += 1;
                }
            });
        }

        for poly in multi.iter_mut() {
            poly.exterior_mut(|exterior| {
                for coord in exterior {
                    coord.x += 1;
                    coord.y += 1;
                }
            });
        }

        let mut first = true;
        for p in &multi {
            if first {
                assert_eq!(
                    p,
                    &polygon![(x: 2, y: 2), (x: 4, y: 2), (x: 3, y: 4), (x:2, y:2)]
                );
                first = false;
            } else {
                assert_eq!(
                    p,
                    &polygon![(x: 12, y: 12), (x: 14, y: 12), (x: 13, y: 14), (x:12, y:12)]
                );
            }
        }
    }
}