/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

use geom::point::Point2D;
use geom::rect::Rect;

use std::default::Default;
use std::num::{NumCast, One, Zero};
use std::fmt;

// An Au is an "App Unit" and represents 1/60th of a CSS pixel.  It was
// originally proposed in 2002 as a standard unit of measure in Gecko.
// See https://bugzilla.mozilla.org/show_bug.cgi?id=177805 for more info.
#[deriving(Clone, Eq, Ord, Zero)]
pub struct Au(pub i32);

impl Default for Au {
    #[inline]
    fn default() -> Au {
        Au(0)
    }
}

impl fmt::Show for Au {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let Au(n) = *self;
        write!(f.buf, "Au({})", n)
    }}

impl Add<Au,Au> for Au {
    #[inline]
    fn add(&self, other: &Au) -> Au {
        let Au(s) = *self;
        let Au(o) = *other;
        Au(s + o)
    }
}

impl Sub<Au,Au> for Au {
    #[inline]
    fn sub(&self, other: &Au) -> Au {
        let Au(s) = *self;
        let Au(o) = *other;
        Au(s - o)
    }

}

impl Mul<Au,Au> for Au {
    #[inline]
    fn mul(&self, other: &Au) -> Au {
        let Au(s) = *self;
        let Au(o) = *other;
        Au(s * o)
    }
}

impl Div<Au,Au> for Au {
    #[inline]
    fn div(&self, other: &Au) -> Au {
        let Au(s) = *self;
        let Au(o) = *other;
        Au(s / o)
    }
}

impl Rem<Au,Au> for Au {
    #[inline]
    fn rem(&self, other: &Au) -> Au {
        let Au(s) = *self;
        let Au(o) = *other;
        Au(s % o)
    }
}

impl Neg<Au> for Au {
    #[inline]
    fn neg(&self) -> Au {
        let Au(s) = *self;
        Au(-s)
    }
}

impl One for Au {
    #[inline]
    fn one() -> Au { Au(1) }
}

impl Num for Au {}

#[inline]
pub fn min(x: Au, y: Au) -> Au { if x < y { x } else { y } }
#[inline]
pub fn max(x: Au, y: Au) -> Au { if x > y { x } else { y } }

impl NumCast for Au {
    #[inline]
    fn from<T:ToPrimitive>(n: T) -> Option<Au> {
        Some(Au(n.to_i32().unwrap()))
    }
}

impl ToPrimitive for Au {
    #[inline]
    fn to_i64(&self) -> Option<i64> {
        let Au(s) = *self;
        Some(s as i64)
    }

    #[inline]
    fn to_u64(&self) -> Option<u64> {
        let Au(s) = *self;
        Some(s as u64)
    }

    #[inline]
    fn to_f32(&self) -> Option<f32> {
        let Au(s) = *self;
        s.to_f32()
    }

    #[inline]
    fn to_f64(&self) -> Option<f64> {
        let Au(s) = *self;
        s.to_f64()
    }
}

impl Au {
    /// FIXME(pcwalton): Workaround for lack of cross crate inlining of newtype structs!
    #[inline]
    pub fn new(value: i32) -> Au {
        Au(value)
    }

    #[inline]
    pub fn scale_by(self, factor: f64) -> Au {
        let Au(s) = self;
        Au(((s as f64) * factor) as i32)
    }

    #[inline]
    pub fn from_px(px: int) -> Au {
        NumCast::from(px * 60).unwrap()
    }

    #[inline]
    pub fn to_nearest_px(&self) -> int {
        let Au(s) = *self;
        ((s as f64) / 60f64).round() as int
    }

    #[inline]
    pub fn to_snapped(&self) -> Au {
        let Au(s) = *self;
        let res = s % 60i32;
        return if res >= 30i32 { return Au(s - res + 60i32) }
                       else { return Au(s - res) };
    }

    #[inline]
    pub fn from_pt(pt: f64) -> Au {
        from_px(pt_to_px(pt) as int)
    }

    #[inline]
    pub fn from_frac_px(px: f64) -> Au {
        Au((px * 60f64) as i32)
    }

    #[inline]
    pub fn min(x: Au, y: Au) -> Au {
        let Au(xi) = x;
        let Au(yi) = y;
        if xi < yi { x } else { y }
    }

    #[inline]
    pub fn max(x: Au, y: Au) -> Au {
        let Au(xi) = x;
        let Au(yi) = y;
        if xi > yi { x } else { y }
    }
}

// assumes 72 points per inch, and 96 px per inch
pub fn pt_to_px(pt: f64) -> f64 {
    pt / 72f64 * 96f64
}

// assumes 72 points per inch, and 96 px per inch
pub fn px_to_pt(px: f64) -> f64 {
    px / 96f64 * 72f64
}

pub fn from_frac_px(px: f64) -> Au {
    Au((px * 60f64) as i32)
}

pub fn from_px(px: int) -> Au {
    NumCast::from(px * 60).unwrap()
}

pub fn to_px(au: Au) -> int {
    let Au(a) = au;
    (a / 60) as int
}

pub fn to_frac_px(au: Au) -> f64 {
    let Au(a) = au;
    (a as f64) / 60f64
}

// assumes 72 points per inch, and 96 px per inch
pub fn from_pt(pt: f64) -> Au {
    from_px((pt / 72f64 * 96f64) as int)
}

// assumes 72 points per inch, and 96 px per inch
pub fn to_pt(au: Au) -> f64 {
    let Au(a) = au;
    (a as f64) / 60f64 * 72f64 / 96f64
}

/// Returns true if the rect contains the given point. Points on the top or left sides of the rect
/// are considered inside the rectangle, while points on the right or bottom sides of the rect are
/// not considered inside the rectangle.
pub fn rect_contains_point<T:Ord + Add<T,T>>(rect: Rect<T>, point: Point2D<T>) -> bool {
    point.x >= rect.origin.x && point.x < rect.origin.x + rect.size.width &&
        point.y >= rect.origin.y && point.y < rect.origin.y + rect.size.height
}