// Copyright 2013 The Servo Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! A group of side offsets, which correspond to top/left/bottom/right for borders, padding,
//! and margins in CSS.

use crate::length::Length;
use crate::num::Zero;
use core::fmt;
use core::ops::{Add, Neg};
use core::marker::PhantomData;
use core::cmp::{Eq, PartialEq};
use core::hash::{Hash};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use crate::Vector2D;

/// A group of 2D side offsets, which correspond to top/right/bottom/left for borders, padding,
/// and margins in CSS, optionally tagged with a unit.
#[repr(C)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[cfg_attr(feature = "serde", serde(bound(serialize = "T: Serialize", deserialize = "T: Deserialize<'de>")))]
pub struct SideOffsets2D<T, U> {
    pub top: T,
    pub right: T,
    pub bottom: T,
    pub left: T,
    #[doc(hidden)]
    pub _unit: PhantomData<U>,
}

impl<T: Copy, U> Copy for SideOffsets2D<T, U> {}

impl<T: Clone, U> Clone for SideOffsets2D<T, U> {
    fn clone(&self) -> Self {
        SideOffsets2D {
            top: self.top.clone(),
            right: self.right.clone(),
            bottom: self.bottom.clone(),
            left: self.left.clone(),
            _unit: PhantomData,
        }
    }
}

impl<T, U> Eq for SideOffsets2D<T, U> where T: Eq {}

impl<T, U> PartialEq for SideOffsets2D<T, U>
    where T: PartialEq
{
    fn eq(&self, other: &Self) -> bool {
        self.top == other.top &&
            self.right == other.right &&
            self.bottom == other.bottom &&
            self.left == other.left
    }
}

impl<T, U> Hash for SideOffsets2D<T, U>
    where T: Hash
{
    fn hash<H: core::hash::Hasher>(&self, h: &mut H) {
        self.top.hash(h);
        self.right.hash(h);
        self.bottom.hash(h);
        self.left.hash(h);
    }
}

impl<T: fmt::Debug, U> fmt::Debug for SideOffsets2D<T, U> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "({:?},{:?},{:?},{:?})",
            self.top, self.right, self.bottom, self.left
        )
    }
}

impl<T: Default, U> Default for SideOffsets2D<T, U> {
    fn default() -> Self {
        SideOffsets2D {
            top: Default::default(),
            right: Default::default(),
            bottom: Default::default(),
            left: Default::default(),
            _unit: PhantomData,
        }
    }
}

impl<T, U> SideOffsets2D<T, U> {
    /// Constructor taking a scalar for each side.
    ///
    /// Sides are specified in top-right-bottom-left order following
    /// CSS's convention.
    pub const fn new(top: T, right: T, bottom: T, left: T) -> Self {
        SideOffsets2D {
            top,
            right,
            bottom,
            left,
            _unit: PhantomData,
        }
    }

    /// Constructor taking a typed Length for each side.
    ///
    /// Sides are specified in top-right-bottom-left order following
    /// CSS's convention.
    pub fn from_lengths(
        top: Length<T, U>,
        right: Length<T, U>,
        bottom: Length<T, U>,
        left: Length<T, U>,
    ) -> Self {
        SideOffsets2D::new(top.0, right.0, bottom.0, left.0)
    }

    /// Construct side offsets from min and a max vector offsets.
    ///
    /// The outer rect of the resulting side offsets is equivalent to translating
    /// a rectangle's upper-left corner with the min vector and translating the
    /// bottom-right corner with the max vector.
    pub fn from_vectors_outer(min: Vector2D<T, U>, max: Vector2D<T,U>) -> Self
    where
        T: Neg<Output = T>
    {
        SideOffsets2D {
            left: -min.x,
            top: -min.y,
            right: max.x,
            bottom: max.y,
            _unit: PhantomData,
        }
    }

    /// Construct side offsets from min and a max vector offsets.
    ///
    /// The inner rect of the resulting side offsets is equivalent to translating
    /// a rectangle's upper-left corner with the min vector and translating the
    /// bottom-right corner with the max vector.
    pub fn from_vectors_inner(min: Vector2D<T, U>, max: Vector2D<T,U>) -> Self
    where
        T: Neg<Output = T>
    {
        SideOffsets2D {
            left: min.x,
            top: min.y,
            right: -max.x,
            bottom: -max.y,
            _unit: PhantomData,
        }
    }
}

impl<T: Copy, U> SideOffsets2D<T, U> {
    /// Constructor setting the same value to all sides, taking a scalar value directly.
    pub fn new_all_same(all: T) -> Self {
        SideOffsets2D::new(all, all, all, all)
    }

    /// Constructor setting the same value to all sides, taking a typed Length.
    pub fn from_length_all_same(all: Length<T, U>) -> Self {
        SideOffsets2D::new_all_same(all.0)
    }
}

impl<T, U> SideOffsets2D<T, U>
where
    T: Add<T, Output = T> + Copy,
{
    pub fn horizontal(&self) -> T {
        self.left + self.right
    }

    pub fn vertical(&self) -> T {
        self.top + self.bottom
    }
}

impl<T, U> Add for SideOffsets2D<T, U>
where
    T: Add<T, Output = T>,
{
    type Output = Self;
    fn add(self, other: Self) -> Self {
        SideOffsets2D::new(
            self.top + other.top,
            self.right + other.right,
            self.bottom + other.bottom,
            self.left + other.left,
        )
    }
}

impl<T: Zero, U> SideOffsets2D<T, U> {
    /// Constructor, setting all sides to zero.
    pub fn zero() -> Self {
        SideOffsets2D::new(Zero::zero(), Zero::zero(), Zero::zero(), Zero::zero())
    }
}

#[test]
fn from_vectors() {
    use crate::{vec2, point2};
    type Box2D = crate::default::Box2D<i32>;

    let b = Box2D {
        min: point2(10, 10),
        max: point2(20, 20),
    };

    let outer = b.outer_box(SideOffsets2D::from_vectors_outer(vec2(-1, -2), vec2(3, 4)));
    let inner = b.inner_box(SideOffsets2D::from_vectors_inner(vec2(1, 2), vec2(-3, -4)));

    assert_eq!(outer, Box2D { min: point2(9, 8), max: point2(23, 24) });
    assert_eq!(inner, Box2D { min: point2(11, 12), max: point2(17, 16) });
}