use num::{Zero, One};
use std::hash;
use std::fmt;
use approx::ApproxEq;

#[cfg(feature = "serde-serialize")]
use serde;

#[cfg(feature = "abomonation-serialize")]
use abomonation::Abomonation;

use alga::general::{Real, ClosedNeg};

use core::{DefaultAllocator, Scalar, MatrixN, VectorN};
use core::dimension::{DimName, DimNameSum, DimNameAdd, U1};
use core::storage::Owned;
use core::allocator::Allocator;

/// A translation.
#[repr(C)]
#[derive(Debug)]
pub struct Translation<N: Scalar, D: DimName>
    where DefaultAllocator: Allocator<N, D> {
    /// The translation coordinates, i.e., how much is added to a point's coordinates when it is
    /// translated.
    pub vector: VectorN<N, D>
}

impl<N: Scalar + hash::Hash, D: DimName + hash::Hash> hash::Hash for Translation<N, D>
    where DefaultAllocator: Allocator<N, D>,
          Owned<N, D>: hash::Hash {
    fn hash<H: hash::Hasher>(&self, state: &mut H) {
        self.vector.hash(state)
    }
}

impl<N: Scalar, D: DimName> Copy for Translation<N, D>
    where DefaultAllocator: Allocator<N, D>,
          Owned<N, D>: Copy { }

impl<N: Scalar, D: DimName> Clone for Translation<N, D>
    where DefaultAllocator: Allocator<N, D>,
          Owned<N, D>: Clone {
    #[inline]
    fn clone(&self) -> Self {
        Translation::from_vector(self.vector.clone())
    }
}

#[cfg(feature = "abomonation-serialize")]
impl<N, D> Abomonation for Translation<N, D>
    where N: Scalar,
          D: DimName,
          VectorN<N, D>: Abomonation,
          DefaultAllocator: Allocator<N, D>
{
    unsafe fn entomb(&self, writer: &mut Vec<u8>) {
        self.vector.entomb(writer)
    }

    unsafe fn embalm(&mut self) {
        self.vector.embalm()
    }

    unsafe fn exhume<'a, 'b>(&'a mut self, bytes: &'b mut [u8]) -> Option<&'b mut [u8]> {
        self.vector.exhume(bytes)
    }
}

#[cfg(feature = "serde-serialize")]
impl<N: Scalar, D: DimName> serde::Serialize for Translation<N, D>
where DefaultAllocator: Allocator<N, D>,
      Owned<N, D>: serde::Serialize {

    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
        where S: serde::Serializer {
            self.vector.serialize(serializer)
        }
}

#[cfg(feature = "serde-serialize")]
impl<'a, N: Scalar, D: DimName> serde::Deserialize<'a> for Translation<N, D>
where DefaultAllocator: Allocator<N, D>,
      Owned<N, D>: serde::Deserialize<'a> {

    fn deserialize<Des>(deserializer: Des) -> Result<Self, Des::Error>
        where Des: serde::Deserializer<'a> {
            let matrix = VectorN::<N, D>::deserialize(deserializer)?;

            Ok(Translation::from_vector(matrix))
        }
}

impl<N: Scalar, D: DimName> Translation<N, D>
    where DefaultAllocator: Allocator<N, D> {
    /// Creates a new translation from the given vector.
    #[inline]
    pub fn from_vector(vector: VectorN<N, D>) -> Translation<N, D> {
        Translation {
            vector: vector
        }
    }

    /// Inverts `self`.
    #[inline]
    pub fn inverse(&self) -> Translation<N, D>
        where N: ClosedNeg {
        Translation::from_vector(-&self.vector)
    }

    /// Converts this translation into its equivalent homogeneous transformation matrix.
    #[inline]
    pub fn to_homogeneous(&self) -> MatrixN<N, DimNameSum<D, U1>>
        where N: Zero + One,
              D: DimNameAdd<U1>,
              DefaultAllocator: Allocator<N, DimNameSum<D, U1>, DimNameSum<D, U1>> {
        let mut res = MatrixN::<N, DimNameSum<D, U1>>::identity();
        res.fixed_slice_mut::<D, U1>(0, D::dim()).copy_from(&self.vector);

        res
    }

    /// Inverts `self` in-place.
    #[inline]
    pub fn inverse_mut(&mut self)
        where N: ClosedNeg {
        self.vector.neg_mut()
    }
}

impl<N: Scalar + Eq, D: DimName> Eq for Translation<N, D>
    where DefaultAllocator: Allocator<N, D> {
}

impl<N: Scalar + PartialEq, D: DimName> PartialEq for Translation<N, D>
    where DefaultAllocator: Allocator<N, D> {
    #[inline]
    fn eq(&self, right: &Translation<N, D>) -> bool {
        self.vector == right.vector
    }
}

impl<N: Scalar + ApproxEq, D: DimName> ApproxEq for Translation<N, D>
    where DefaultAllocator: Allocator<N, D>,
          N::Epsilon: Copy {
    type Epsilon = N::Epsilon;

    #[inline]
    fn default_epsilon() -> Self::Epsilon {
        N::default_epsilon()
    }

    #[inline]
    fn default_max_relative() -> Self::Epsilon {
        N::default_max_relative()
    }

    #[inline]
    fn default_max_ulps() -> u32 {
        N::default_max_ulps()
    }

    #[inline]
    fn relative_eq(&self, other: &Self, epsilon: Self::Epsilon, max_relative: Self::Epsilon) -> bool {
        self.vector.relative_eq(&other.vector, epsilon, max_relative)
    }

    #[inline]
    fn ulps_eq(&self, other: &Self, epsilon: Self::Epsilon, max_ulps: u32) -> bool {
        self.vector.ulps_eq(&other.vector, epsilon, max_ulps)
    }
}

/*
 *
 * Display
 *
 */
impl<N: Real + fmt::Display, D: DimName> fmt::Display for Translation<N, D>
    where DefaultAllocator: Allocator<N, D> +
                            Allocator<usize, D> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let precision = f.precision().unwrap_or(3);

        try!(writeln!(f, "Translation {{"));
        try!(write!(f, "{:.*}", precision, self.vector));
        writeln!(f, "}}")
    }
}