// pathfinder/geometry/src/basic/line_segment.rs
//
// Copyright © 2019 The Pathfinder Project Developers.
//
// 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.

//! Line segment types, optimized with SIMD.

use crate::basic::point::Point2DF32;
use crate::util;
use pathfinder_simd::default::F32x4;
use std::ops::{Add, Sub};

#[derive(Clone, Copy, Debug, PartialEq, Default)]
pub struct LineSegmentF32(pub F32x4);

impl LineSegmentF32 {
    #[inline]
    pub fn new(from: &Point2DF32, to: &Point2DF32) -> LineSegmentF32 {
        LineSegmentF32(from.0.concat_xy_xy(to.0))
    }

    #[inline]
    pub fn from(&self) -> Point2DF32 {
        Point2DF32(self.0)
    }

    #[inline]
    pub fn to(&self) -> Point2DF32 {
        Point2DF32(self.0.zwxy())
    }

    #[inline]
    pub fn set_from(&mut self, point: &Point2DF32) {
        self.0 = point.0.concat_xy_zw(self.0)
    }

    #[inline]
    pub fn set_to(&mut self, point: &Point2DF32) {
        self.0 = self.0.concat_xy_xy(point.0)
    }

    #[allow(clippy::wrong_self_convention)]
    #[inline]
    pub fn from_x(&self) -> f32 {
        self.0[0]
    }

    #[allow(clippy::wrong_self_convention)]
    #[inline]
    pub fn from_y(&self) -> f32 {
        self.0[1]
    }

    #[inline]
    pub fn to_x(&self) -> f32 {
        self.0[2]
    }

    #[inline]
    pub fn to_y(&self) -> f32 {
        self.0[3]
    }

    #[inline]
    pub fn set_from_x(&mut self, x: f32) {
        self.0[0] = x
    }

    #[inline]
    pub fn set_from_y(&mut self, y: f32) {
        self.0[1] = y
    }

    #[inline]
    pub fn set_to_x(&mut self, x: f32) {
        self.0[2] = x
    }

    #[inline]
    pub fn set_to_y(&mut self, y: f32) {
        self.0[3] = y
    }

    #[inline]
    pub fn scale(&self, factor: f32) -> LineSegmentF32 {
        LineSegmentF32(self.0 * F32x4::splat(factor))
    }

    #[inline]
    pub fn split(&self, t: f32) -> (LineSegmentF32, LineSegmentF32) {
        debug_assert!(t >= 0.0 && t <= 1.0);
        let (from_from, to_to) = (self.0.xyxy(), self.0.zwzw());
        let d_d = to_to - from_from;
        let mid_mid = from_from + d_d * F32x4::splat(t);
        (LineSegmentF32(from_from.concat_xy_xy(mid_mid)),
         LineSegmentF32(mid_mid.concat_xy_xy(to_to)))
    }

    // Returns the left segment first, followed by the right segment.
    #[inline]
    pub fn split_at_x(&self, x: f32) -> (LineSegmentF32, LineSegmentF32) {
        let (min_part, max_part) = self.split(self.solve_t_for_x(x));
        if min_part.from_x() < max_part.from_x() {
            (min_part, max_part)
        } else {
            (max_part, min_part)
        }
    }

    // Returns the upper segment first, followed by the lower segment.
    #[inline]
    pub fn split_at_y(&self, y: f32) -> (LineSegmentF32, LineSegmentF32) {
        let (min_part, max_part) = self.split(self.solve_t_for_y(y));

        // Make sure we compare `from_y` and `to_y` to properly handle the case in which one of the
        // two segments is zero-length.
        if min_part.from_y() < max_part.to_y() {
            (min_part, max_part)
        } else {
            (max_part, min_part)
        }
    }

    #[inline]
    pub fn solve_t_for_x(&self, x: f32) -> f32 {
        (x - self.from_x()) / (self.to_x() - self.from_x())
    }

    #[inline]
    pub fn solve_t_for_y(&self, y: f32) -> f32 {
        (y - self.from_y()) / (self.to_y() - self.from_y())
    }

    #[inline]
    pub fn solve_x_for_y(&self, y: f32) -> f32 {
        util::lerp(self.from_x(), self.to_x(), self.solve_t_for_y(y))
    }

    #[inline]
    pub fn solve_y_for_x(&self, x: f32) -> f32 {
        util::lerp(self.from_y(), self.to_y(), self.solve_t_for_x(x))
    }

    #[inline]
    pub fn reversed(&self) -> LineSegmentF32 {
        LineSegmentF32(self.0.zwxy())
    }

    #[inline]
    pub fn upper_point(&self) -> Point2DF32 {
        if self.from_y() < self.to_y() {
            self.from()
        } else {
            self.to()
        }
    }

    #[inline]
    pub fn min_x(&self) -> f32 {
        f32::min(self.from_x(), self.to_x())
    }

    #[inline]
    pub fn max_x(&self) -> f32 {
        f32::max(self.from_x(), self.to_x())
    }

    #[inline]
    pub fn min_y(&self) -> f32 {
        f32::min(self.from_y(), self.to_y())
    }

    #[inline]
    pub fn max_y(&self) -> f32 {
        f32::max(self.from_y(), self.to_y())
    }

    #[inline]
    pub fn y_winding(&self) -> i32 {
        if self.from_y() < self.to_y() {
            1
        } else {
            -1
        }
    }

    // Reverses if necessary so that the from point is above the to point. Calling this method
    // again will undo the transformation.
    #[inline]
    pub fn orient(&self, y_winding: i32) -> LineSegmentF32 {
        if y_winding >= 0 {
            *self
        } else {
            self.reversed()
        }
    }

    // TODO(pcwalton): Optimize with SIMD.
    #[inline]
    pub fn square_length(&self) -> f32 {
        let (dx, dy) = (self.to_x() - self.from_x(), self.to_y() - self.from_y());
        dx * dx + dy * dy
    }

    // Given a line equation of the form `ax + by + c = 0`, returns a vector of the form
    // `[a, b, c, 0]`.
    //
    // TODO(pcwalton): Optimize.
    #[inline]
    pub fn line_coords(&self) -> F32x4 {
        let from = F32x4::new(self.0[0], self.0[1], 1.0, 0.0);
        let to = F32x4::new(self.0[2], self.0[3], 1.0, 0.0);
        from.cross(to)
    }

    #[inline]
    pub fn vector(&self) -> Point2DF32 {
        self.to() - self.from()
    }

    // http://www.cs.swan.ac.uk/~cssimon/line_intersection.html
    pub fn intersection_t(&self, other: &LineSegmentF32) -> Option<f32> {
        let d0d1 = self.vector().0.concat_xy_xy(other.vector().0);
        let offset = other.from() - self.from();
        let factors = d0d1.concat_wz_yx(offset.0);
        let terms = d0d1 * factors;
        let denom = terms[0] - terms[1];
        if f32::abs(denom) < EPSILON {
            return None;
        }
        return Some((terms[3] - terms[2]) / denom);

        const EPSILON: f32 = 0.0001;
    }

    #[inline]
    pub fn sample(&self, t: f32) -> Point2DF32 {
        self.from() + self.vector().scale(t)
    }

    #[inline]
    pub fn offset(&self, distance: f32) -> LineSegmentF32 {
        if self.is_zero_length() {
            *self
        } else {
            *self + self.vector().yx().normalize().scale_xy(Point2DF32::new(-distance, distance))
        }
    }

    #[inline]
    pub fn is_zero_length(&self) -> bool {
        self.vector().is_zero()
    }
}

impl Add<Point2DF32> for LineSegmentF32 {
    type Output = LineSegmentF32;
    #[inline]
    fn add(self, point: Point2DF32) -> LineSegmentF32 {
        LineSegmentF32(self.0 + point.0.xyxy())
    }
}

impl Sub<Point2DF32> for LineSegmentF32 {
    type Output = LineSegmentF32;
    #[inline]
    fn sub(self, point: Point2DF32) -> LineSegmentF32 {
        LineSegmentF32(self.0 - point.0.xyxy())
    }
}

#[derive(Clone, Copy, Debug)]
#[repr(transparent)]
pub struct LineSegmentU4(pub u16);

#[derive(Clone, Copy, Debug)]
#[repr(transparent)]
pub struct LineSegmentU8(pub u32);