#[cfg(feature = "arbitrary")]
use crate::base::storage::Owned;
#[cfg(feature = "arbitrary")]
use quickcheck::{Arbitrary, Gen};

use num::One;
use rand::distributions::{Distribution, Standard};
use rand::Rng;

use simba::scalar::RealField;
use simba::simd::SimdRealField;

use crate::base::allocator::Allocator;
use crate::base::dimension::{DimName, U2};
use crate::base::{DefaultAllocator, Vector2, Vector3};

use crate::geometry::{
    AbstractRotation, Isometry, Isometry2, Isometry3, IsometryMatrix2, IsometryMatrix3, Point,
    Point3, Rotation, Rotation3, Translation, Translation2, Translation3, UnitComplex,
    UnitQuaternion,
};

impl<N: SimdRealField, D: DimName, R: AbstractRotation<N, D>> Isometry<N, D, R>
where
    N::Element: SimdRealField,
    DefaultAllocator: Allocator<N, D>,
{
    /// Creates a new identity isometry.
    ///
    /// # Example
    ///
    /// ```
    /// # use nalgebra::{Isometry2, Point2, Isometry3, Point3};
    ///
    /// let iso = Isometry2::identity();
    /// let pt = Point2::new(1.0, 2.0);
    /// assert_eq!(iso * pt, pt);
    ///
    /// let iso = Isometry3::identity();
    /// let pt = Point3::new(1.0, 2.0, 3.0);
    /// assert_eq!(iso * pt, pt);
    /// ```
    #[inline]
    pub fn identity() -> Self {
        Self::from_parts(Translation::identity(), R::identity())
    }

    /// The isometry that applies the rotation `r` with its axis passing through the point `p`.
    /// This effectively lets `p` invariant.
    ///
    /// # Example
    ///
    /// ```
    /// # #[macro_use] extern crate approx;
    /// # use std::f32;
    /// # use nalgebra::{Isometry2, Point2, UnitComplex};
    /// let rot = UnitComplex::new(f32::consts::PI);
    /// let pt = Point2::new(1.0, 0.0);
    /// let iso = Isometry2::rotation_wrt_point(rot, pt);
    ///
    /// assert_eq!(iso * pt, pt); // The rotation center is not affected.
    /// assert_relative_eq!(iso * Point2::new(1.0, 2.0), Point2::new(1.0, -2.0), epsilon = 1.0e-6);
    /// ```
    #[inline]
    pub fn rotation_wrt_point(r: R, p: Point<N, D>) -> Self {
        let shift = r.transform_vector(&-&p.coords);
        Self::from_parts(Translation::from(shift + p.coords), r)
    }
}

impl<N: SimdRealField, D: DimName, R: AbstractRotation<N, D>> One for Isometry<N, D, R>
where
    N::Element: SimdRealField,
    DefaultAllocator: Allocator<N, D>,
{
    /// Creates a new identity isometry.
    #[inline]
    fn one() -> Self {
        Self::identity()
    }
}

impl<N: RealField, D: DimName, R> Distribution<Isometry<N, D, R>> for Standard
where
    R: AbstractRotation<N, D>,
    Standard: Distribution<N> + Distribution<R>,
    DefaultAllocator: Allocator<N, D>,
{
    #[inline]
    fn sample<'a, G: Rng + ?Sized>(&self, rng: &'a mut G) -> Isometry<N, D, R> {
        Isometry::from_parts(rng.gen(), rng.gen())
    }
}

#[cfg(feature = "arbitrary")]
impl<N, D: DimName, R> Arbitrary for Isometry<N, D, R>
where
    N: SimdRealField + Arbitrary + Send,
    N::Element: SimdRealField,
    R: AbstractRotation<N, D> + Arbitrary + Send,
    Owned<N, D>: Send,
    DefaultAllocator: Allocator<N, D>,
{
    #[inline]
    fn arbitrary<G: Gen>(rng: &mut G) -> Self {
        Self::from_parts(Arbitrary::arbitrary(rng), Arbitrary::arbitrary(rng))
    }
}

/*
 *
 * Constructors for various static dimensions.
 *
 */

/// # Construction from a 2D vector and/or a rotation angle
impl<N: SimdRealField> IsometryMatrix2<N>
where
    N::Element: SimdRealField,
{
    /// Creates a new 2D isometry from a translation and a rotation angle.
    ///
    /// Its rotational part is represented as a 2x2 rotation matrix.
    ///
    /// # Example
    ///
    /// ```
    /// # use std::f32;
    /// # use nalgebra::{Isometry2, Vector2, Point2};
    /// let iso = Isometry2::new(Vector2::new(1.0, 2.0), f32::consts::FRAC_PI_2);
    ///
    /// assert_eq!(iso * Point2::new(3.0, 4.0), Point2::new(-3.0, 5.0));
    /// ```
    #[inline]
    pub fn new(translation: Vector2<N>, angle: N) -> Self {
        Self::from_parts(
            Translation::from(translation),
            Rotation::<N, U2>::new(angle),
        )
    }

    /// Creates a new isometry from the given translation coordinates.
    #[inline]
    pub fn translation(x: N, y: N) -> Self {
        Self::new(Vector2::new(x, y), N::zero())
    }

    /// Creates a new isometry from the given rotation angle.
    #[inline]
    pub fn rotation(angle: N) -> Self {
        Self::new(Vector2::zeros(), angle)
    }
}

impl<N: SimdRealField> Isometry2<N>
where
    N::Element: SimdRealField,
{
    /// Creates a new 2D isometry from a translation and a rotation angle.
    ///
    /// Its rotational part is represented as an unit complex number.
    ///
    /// # Example
    ///
    /// ```
    /// # use std::f32;
    /// # use nalgebra::{IsometryMatrix2, Point2, Vector2};
    /// let iso = IsometryMatrix2::new(Vector2::new(1.0, 2.0), f32::consts::FRAC_PI_2);
    ///
    /// assert_eq!(iso * Point2::new(3.0, 4.0), Point2::new(-3.0, 5.0));
    /// ```
    #[inline]
    pub fn new(translation: Vector2<N>, angle: N) -> Self {
        Self::from_parts(
            Translation::from(translation),
            UnitComplex::from_angle(angle),
        )
    }

    /// Creates a new isometry from the given translation coordinates.
    #[inline]
    pub fn translation(x: N, y: N) -> Self {
        Self::from_parts(Translation2::new(x, y), UnitComplex::identity())
    }

    /// Creates a new isometry from the given rotation angle.
    #[inline]
    pub fn rotation(angle: N) -> Self {
        Self::new(Vector2::zeros(), angle)
    }
}

// 3D rotation.
macro_rules! basic_isometry_construction_impl(
    ($RotId: ident < $($RotParams: ident),*>) => {
        /// Creates a new isometry from a translation and a rotation axis-angle.
        ///
        /// # Example
        ///
        /// ```
        /// # #[macro_use] extern crate approx;
        /// # use std::f32;
        /// # use nalgebra::{Isometry3, IsometryMatrix3, Point3, Vector3};
        /// let axisangle = Vector3::y() * f32::consts::FRAC_PI_2;
        /// let translation = Vector3::new(1.0, 2.0, 3.0);
        /// // Point and vector being transformed in the tests.
        /// let pt = Point3::new(4.0, 5.0, 6.0);
        /// let vec = Vector3::new(4.0, 5.0, 6.0);
        ///
        /// // Isometry with its rotation part represented as a UnitQuaternion
        /// let iso = Isometry3::new(translation, axisangle);
        /// assert_relative_eq!(iso * pt, Point3::new(7.0, 7.0, -1.0), epsilon = 1.0e-6);
        /// assert_relative_eq!(iso * vec, Vector3::new(6.0, 5.0, -4.0), epsilon = 1.0e-6);
        ///
        /// // Isometry with its rotation part represented as a Rotation3 (a 3x3 rotation matrix).
        /// let iso = IsometryMatrix3::new(translation, axisangle);
        /// assert_relative_eq!(iso * pt, Point3::new(7.0, 7.0, -1.0), epsilon = 1.0e-6);
        /// assert_relative_eq!(iso * vec, Vector3::new(6.0, 5.0, -4.0), epsilon = 1.0e-6);
        /// ```
        #[inline]
        pub fn new(translation: Vector3<N>, axisangle: Vector3<N>) -> Self {
            Self::from_parts(
                Translation::from(translation),
                $RotId::<$($RotParams),*>::from_scaled_axis(axisangle))
        }

        /// Creates a new isometry from the given translation coordinates.
        #[inline]
        pub fn translation(x: N, y: N, z: N) -> Self {
            Self::from_parts(Translation3::new(x, y, z), $RotId::identity())
        }

        /// Creates a new isometry from the given rotation angle.
        #[inline]
        pub fn rotation(axisangle: Vector3<N>) -> Self {
            Self::new(Vector3::zeros(), axisangle)
        }
    }
);

macro_rules! look_at_isometry_construction_impl(
    ($RotId: ident < $($RotParams: ident),*>) => {
        /// Creates an isometry that corresponds to the local frame of an observer standing at the
        /// point `eye` and looking toward `target`.
        ///
        /// It maps the `z` axis to the view direction `target - eye`and the origin to the `eye`.
        ///
        /// # Arguments
        ///   * eye - The observer position.
        ///   * target - The target position.
        ///   * up - Vertical direction. The only requirement of this parameter is to not be collinear
        ///   to `eye - at`. Non-collinearity is not checked.
        ///
        /// # Example
        ///
        /// ```
        /// # #[macro_use] extern crate approx;
        /// # use std::f32;
        /// # use nalgebra::{Isometry3, IsometryMatrix3, Point3, Vector3};
        /// let eye = Point3::new(1.0, 2.0, 3.0);
        /// let target = Point3::new(2.0, 2.0, 3.0);
        /// let up = Vector3::y();
        ///
        /// // Isometry with its rotation part represented as a UnitQuaternion
        /// let iso = Isometry3::face_towards(&eye, &target, &up);
        /// assert_eq!(iso * Point3::origin(), eye);
        /// assert_relative_eq!(iso * Vector3::z(), Vector3::x());
        ///
        /// // Isometry with its rotation part represented as Rotation3 (a 3x3 rotation matrix).
        /// let iso = IsometryMatrix3::face_towards(&eye, &target, &up);
        /// assert_eq!(iso * Point3::origin(), eye);
        /// assert_relative_eq!(iso * Vector3::z(), Vector3::x());
        /// ```
        #[inline]
        pub fn face_towards(eye:    &Point3<N>,
                            target: &Point3<N>,
                            up:     &Vector3<N>)
                            -> Self {
            Self::from_parts(
                Translation::from(eye.coords.clone()),
                $RotId::face_towards(&(target - eye), up))
        }

        /// Deprecated: Use [Isometry::face_towards] instead.
        #[deprecated(note="renamed to `face_towards`")]
        pub fn new_observer_frame(eye:    &Point3<N>,
                                  target: &Point3<N>,
                                  up:     &Vector3<N>)
                                  -> Self {
            Self::face_towards(eye, target, up)
        }

        /// Builds a right-handed look-at view matrix.
        ///
        /// It maps the view direction `target - eye` to the **negative** `z` axis to and the `eye` to the origin.
        /// This conforms to the common notion of right handed camera look-at **view matrix** from
        /// the computer graphics community, i.e. the camera is assumed to look toward its local `-z` axis.
        ///
        /// # Arguments
        ///   * eye - The eye position.
        ///   * target - The target position.
        ///   * up - A vector approximately aligned with required the vertical axis. The only
        ///   requirement of this parameter is to not be collinear to `target - eye`.
        ///
        /// # Example
        ///
        /// ```
        /// # #[macro_use] extern crate approx;
        /// # use std::f32;
        /// # use nalgebra::{Isometry3, IsometryMatrix3, Point3, Vector3};
        /// let eye = Point3::new(1.0, 2.0, 3.0);
        /// let target = Point3::new(2.0, 2.0, 3.0);
        /// let up = Vector3::y();
        ///
        /// // Isometry with its rotation part represented as a UnitQuaternion
        /// let iso = Isometry3::look_at_rh(&eye, &target, &up);
        /// assert_eq!(iso * eye, Point3::origin());
        /// assert_relative_eq!(iso * Vector3::x(), -Vector3::z());
        ///
        /// // Isometry with its rotation part represented as Rotation3 (a 3x3 rotation matrix).
        /// let iso = IsometryMatrix3::look_at_rh(&eye, &target, &up);
        /// assert_eq!(iso * eye, Point3::origin());
        /// assert_relative_eq!(iso * Vector3::x(), -Vector3::z());
        /// ```
        #[inline]
        pub fn look_at_rh(eye:    &Point3<N>,
                          target: &Point3<N>,
                          up:     &Vector3<N>)
                          -> Self {
            let rotation = $RotId::look_at_rh(&(target - eye), up);
            let trans    = &rotation * (-eye);

            Self::from_parts(Translation::from(trans.coords), rotation)
        }

        /// Builds a left-handed look-at view matrix.
        ///
        /// It maps the view direction `target - eye` to the **positive** `z` axis and the `eye` to the origin.
        /// This conforms to the common notion of right handed camera look-at **view matrix** from
        /// the computer graphics community, i.e. the camera is assumed to look toward its local `z` axis.
        ///
        /// # Arguments
        ///   * eye - The eye position.
        ///   * target - The target position.
        ///   * up - A vector approximately aligned with required the vertical axis. The only
        ///   requirement of this parameter is to not be collinear to `target - eye`.
        ///
        /// # Example
        ///
        /// ```
        /// # #[macro_use] extern crate approx;
        /// # use std::f32;
        /// # use nalgebra::{Isometry3, IsometryMatrix3, Point3, Vector3};
        /// let eye = Point3::new(1.0, 2.0, 3.0);
        /// let target = Point3::new(2.0, 2.0, 3.0);
        /// let up = Vector3::y();
        ///
        /// // Isometry with its rotation part represented as a UnitQuaternion
        /// let iso = Isometry3::look_at_lh(&eye, &target, &up);
        /// assert_eq!(iso * eye, Point3::origin());
        /// assert_relative_eq!(iso * Vector3::x(), Vector3::z());
        ///
        /// // Isometry with its rotation part represented as Rotation3 (a 3x3 rotation matrix).
        /// let iso = IsometryMatrix3::look_at_lh(&eye, &target, &up);
        /// assert_eq!(iso * eye, Point3::origin());
        /// assert_relative_eq!(iso * Vector3::x(), Vector3::z());
        /// ```
        #[inline]
        pub fn look_at_lh(eye:    &Point3<N>,
                          target: &Point3<N>,
                          up:     &Vector3<N>)
                          -> Self {
            let rotation = $RotId::look_at_lh(&(target - eye), up);
            let trans    = &rotation * (-eye);

            Self::from_parts(Translation::from(trans.coords), rotation)
        }
    }
);

/// # Construction from a 3D vector and/or an axis-angle
impl<N: SimdRealField> Isometry3<N>
where
    N::Element: SimdRealField,
{
    basic_isometry_construction_impl!(UnitQuaternion<N>);
}

impl<N: SimdRealField> IsometryMatrix3<N>
where
    N::Element: SimdRealField,
{
    basic_isometry_construction_impl!(Rotation3<N>);
}

/// # Construction from a 3D eye position and target point
impl<N: SimdRealField> Isometry3<N>
where
    N::Element: SimdRealField,
{
    look_at_isometry_construction_impl!(UnitQuaternion<N>);
}

impl<N: SimdRealField> IsometryMatrix3<N>
where
    N::Element: SimdRealField,
{
    look_at_isometry_construction_impl!(Rotation3<N>);
}