use crate::{CoordNum, Geometry};
use std::iter::FromIterator;
use std::ops::{Index, IndexMut};

/// A collection of [`Geometry`](enum.Geometry.html) types.
///
/// It can be created from a `Vec` of Geometries, or from an Iterator which yields Geometries.
///
/// Looping over this object yields its component **Geometry
/// enum members** (_not_ the underlying geometry
/// primitives), and it supports iteration and indexing as
/// well as the various
/// [`MapCoords`](algorithm/map_coords/index.html)
/// functions, which _are_ directly applied to the
/// underlying geometry primitives.
///
/// # Examples
/// ## Looping
///
/// ```
/// use std::convert::TryFrom;
/// use geo_types::{Point, point, Geometry, GeometryCollection};
/// let p = point!(x: 1.0, y: 1.0);
/// let pe = Geometry::Point(p);
/// let gc = GeometryCollection(vec![pe]);
/// for geom in gc {
///     println!("{:?}", Point::try_from(geom).unwrap().x());
/// }
/// ```
/// ## Implements `iter()`
///
/// ```
/// use std::convert::TryFrom;
/// use geo_types::{Point, point, Geometry, GeometryCollection};
/// let p = point!(x: 1.0, y: 1.0);
/// let pe = Geometry::Point(p);
/// let gc = GeometryCollection(vec![pe]);
/// gc.iter().for_each(|geom| println!("{:?}", geom));
/// ```
///
/// ## Mutable Iteration
///
/// ```
/// use std::convert::TryFrom;
/// use geo_types::{Point, point, Geometry, GeometryCollection};
/// let p = point!(x: 1.0, y: 1.0);
/// let pe = Geometry::Point(p);
/// let mut gc = GeometryCollection(vec![pe]);
/// gc.iter_mut().for_each(|geom| {
///    if let Geometry::Point(p) = geom {
///        p.set_x(0.2);
///    }
/// });
/// let updated = gc[0].clone();
/// assert_eq!(Point::try_from(updated).unwrap().x(), 0.2);
/// ```
///
/// ## Indexing
///
/// ```
/// use std::convert::TryFrom;
/// use geo_types::{Point, point, Geometry, GeometryCollection};
/// let p = point!(x: 1.0, y: 1.0);
/// let pe = Geometry::Point(p);
/// let gc = GeometryCollection(vec![pe]);
/// println!("{:?}", gc[0]);
/// ```
///
#[derive(Eq, PartialEq, Clone, Debug, Hash)]
pub struct GeometryCollection<T>(pub Vec<Geometry<T>>)
where
    T: CoordNum;

impl<T: CoordNum> Default for GeometryCollection<T> {
    fn default() -> Self {
        Self::new()
    }
}

impl<T: CoordNum> GeometryCollection<T> {
    /// Return an empty GeometryCollection
    pub fn new() -> GeometryCollection<T> {
        GeometryCollection(Vec::new())
    }

    /// Number of geometries in this GeometryCollection
    pub fn len(&self) -> usize {
        self.0.len()
    }

    /// Is this GeometryCollection empty
    pub fn is_empty(&self) -> bool {
        self.0.is_empty()
    }
}

/// Convert any Geometry (or anything that can be converted to a Geometry) into a
/// GeometryCollection
impl<T: CoordNum, IG: Into<Geometry<T>>> From<IG> for GeometryCollection<T> {
    fn from(x: IG) -> Self {
        GeometryCollection(vec![x.into()])
    }
}

/// Collect Geometries (or what can be converted to a Geometry) into a GeometryCollection
impl<T: CoordNum, IG: Into<Geometry<T>>> FromIterator<IG> for GeometryCollection<T> {
    fn from_iter<I: IntoIterator<Item = IG>>(iter: I) -> Self {
        GeometryCollection(iter.into_iter().map(|g| g.into()).collect())
    }
}

impl<T: CoordNum> Index<usize> for GeometryCollection<T> {
    type Output = Geometry<T>;

    fn index(&self, index: usize) -> &Geometry<T> {
        self.0.index(index)
    }
}

impl<T: CoordNum> IndexMut<usize> for GeometryCollection<T> {
    fn index_mut(&mut self, index: usize) -> &mut Geometry<T> {
        self.0.index_mut(index)
    }
}

// structure helper for consuming iterator
#[derive(Debug)]
pub struct IntoIteratorHelper<T: CoordNum> {
    iter: ::std::vec::IntoIter<Geometry<T>>,
}

// implement the IntoIterator trait for a consuming iterator. Iteration will
// consume the GeometryCollection
impl<T: CoordNum> IntoIterator for GeometryCollection<T> {
    type Item = Geometry<T>;
    type IntoIter = IntoIteratorHelper<T>;

    // note that into_iter() is consuming self
    fn into_iter(self) -> Self::IntoIter {
        IntoIteratorHelper {
            iter: self.0.into_iter(),
        }
    }
}

// implement Iterator trait for the helper struct, to be used by adapters
impl<T: CoordNum> Iterator for IntoIteratorHelper<T> {
    type Item = Geometry<T>;

    // just return the reference
    fn next(&mut self) -> Option<Self::Item> {
        self.iter.next()
    }
}

// structure helper for non-consuming iterator
#[derive(Debug)]
pub struct IterHelper<'a, T: CoordNum> {
    iter: ::std::slice::Iter<'a, Geometry<T>>,
}

// implement the IntoIterator trait for a non-consuming iterator. Iteration will
// borrow the GeometryCollection
impl<'a, T: CoordNum> IntoIterator for &'a GeometryCollection<T> {
    type Item = &'a Geometry<T>;
    type IntoIter = IterHelper<'a, T>;

    // note that into_iter() is consuming self
    fn into_iter(self) -> Self::IntoIter {
        IterHelper {
            iter: self.0.iter(),
        }
    }
}

// implement the Iterator trait for the helper struct, to be used by adapters
impl<'a, T: CoordNum> Iterator for IterHelper<'a, T> {
    type Item = &'a Geometry<T>;

    // just return the str reference
    fn next(&mut self) -> Option<Self::Item> {
        self.iter.next()
    }
}

// structure helper for mutable non-consuming iterator
#[derive(Debug)]
pub struct IterMutHelper<'a, T: CoordNum> {
    iter: ::std::slice::IterMut<'a, Geometry<T>>,
}

// implement the IntoIterator trait for a mutable non-consuming iterator. Iteration will
// mutably borrow the GeometryCollection
impl<'a, T: CoordNum> IntoIterator for &'a mut GeometryCollection<T> {
    type Item = &'a mut Geometry<T>;
    type IntoIter = IterMutHelper<'a, T>;

    // note that into_iter() is consuming self
    fn into_iter(self) -> Self::IntoIter {
        IterMutHelper {
            iter: self.0.iter_mut(),
        }
    }
}

// implement the Iterator trait for the helper struct, to be used by adapters
impl<'a, T: CoordNum> Iterator for IterMutHelper<'a, T> {
    type Item = &'a mut Geometry<T>;

    // just return the str reference
    fn next(&mut self) -> Option<Self::Item> {
        self.iter.next()
    }
}

impl<'a, T: CoordNum> GeometryCollection<T> {
    pub fn iter(&'a self) -> IterHelper<'a, T> {
        self.into_iter()
    }

    pub fn iter_mut(&'a mut self) -> IterMutHelper<'a, T> {
        self.into_iter()
    }
}