//! Sprites: the unit of the depth sort. A sprite owns world-space
//! primitives and the extent points its sort box is computed from.
//!
//! Every drawing method takes coordinates in the sprite's frame ([`Xf`]):
//! an object placed at (x, y, z) and turned in 90 degree steps draws around
//! its own origin, and the sprite stores world coordinates.

use crate::prim::{Prim, Style, Zs, P2, P3};
use crate::proj::C;
use serde::{Deserialize, Serialize};

/// Placement frame: translate by (x, y, z) after turning `q` quarter turns
/// counter-clockwise (seen from above).
#[derive(Clone, Copy, Debug, Default, PartialEq, Serialize, Deserialize)]
pub struct Xf {
    pub x: f64,
    pub y: f64,
    pub z: f64,
    pub q: u8,
}

impl Xf {
    /// Frame at (x, y, z) turned by `deg` (rounded to a multiple of 90).
    pub fn new(x: f64, y: f64, z: f64, deg: f64) -> Self {
        let q = ((deg / 90.0).round() as i64).rem_euclid(4) as u8;
        Xf { x, y, z, q }
    }
    /// Turn a plan vector into the world.
    #[inline]
    pub fn v(&self, x: f64, y: f64) -> P2 {
        match self.q {
            0 => [x, y],
            1 => [-y, x],
            2 => [-x, -y],
            _ => [y, -x],
        }
    }
    /// World plan vector back into the frame.
    #[inline]
    pub fn v_inv(&self, x: f64, y: f64) -> P2 {
        match self.q {
            0 => [x, y],
            1 => [y, -x],
            2 => [-x, -y],
            _ => [-y, x],
        }
    }
    #[inline]
    pub fn p(&self, x: f64, y: f64) -> P2 {
        let v = self.v(x, y);
        [v[0] + self.x, v[1] + self.y]
    }
    #[inline]
    pub fn p3(&self, p: P3) -> P3 {
        let q = self.p(p[0], p[1]);
        [q[0], q[1], p[2] + self.z]
    }
    #[inline]
    pub fn z(&self, z: f64) -> f64 {
        z + self.z
    }
    /// An axis-aligned rectangle in the frame as a world rectangle.
    pub fn rect(&self, x0: f64, y0: f64, x1: f64, y1: f64) -> [f64; 4] {
        let a = self.p(x0, y0);
        let b = self.p(x1, y1);
        [
            a[0].min(b[0]),
            a[1].min(b[1]),
            a[0].max(b[0]),
            a[1].max(b[1]),
        ]
    }
    pub fn pts(&self, pts: &[P2]) -> Vec<P2> {
        pts.iter().map(|q| self.p(q[0], q[1])).collect()
    }
    /// World point back into the frame.
    pub fn inv(&self, x: f64, y: f64) -> P2 {
        self.v_inv(x - self.x, y - self.y)
    }
}

#[derive(Clone, Debug)]
enum Frame {
    Group {
        cls: String,
        style: String,
        items: Vec<Prim>,
    },
    Seq {
        items: Vec<(P2, Vec<Prim>)>,
        cur: Option<(P2, Vec<Prim>)>,
    },
}

#[derive(Clone, Debug, Default, Serialize, Deserialize)]
pub struct Sprite {
    /// Pick id; every element of the sprite carries it unless it has its own.
    pub id: String,
    /// Extra class on the sprite's `<g>` (e.g. `iso-dim`).
    pub cls: String,
    /// Where the sprite was created ("scene.rhai:42"), shown by the dev viewer.
    pub src: Option<String>,
    /// Scene-document object the sprite belongs to (the Studio selects and
    /// drags by this, tooltips use `id`).
    pub obj: Option<String>,
    pub prims: Vec<Prim>,
    /// Points that span the sprite's sort box (world coordinates).
    pub ext: Vec<P3>,
    /// Frame the drawing methods' coordinates are in.
    #[serde(skip)]
    pub xf: Xf,
    #[serde(skip)]
    frames: Vec<Frame>,
}

/// One item of [`Sprite::seq`]: a plan anchor and the drawing.
pub type SeqItem<'a> = (P2, Box<dyn FnOnce(&mut Sprite) + 'a>);

/// Points of an axis-aligned rectangle, counter-clockwise from (x0, y0).
pub fn rect(x0: f64, y0: f64, x1: f64, y1: f64) -> Vec<P2> {
    vec![[x0, y0], [x1, y0], [x1, y1], [x0, y1]]
}

impl Sprite {
    pub fn new(id: impl Into<String>, cls: impl Into<String>) -> Self {
        Sprite {
            id: id.into(),
            cls: cls.into(),
            ..Default::default()
        }
    }

    pub fn with_frame(mut self, xf: Xf) -> Self {
        self.xf = xf;
        self
    }

    /// Add a world-space primitive to the open group / sequence item, or to
    /// the sprite.
    pub fn push(&mut self, p: Prim) -> &mut Self {
        match self.frames.last_mut() {
            Some(Frame::Group { items, .. }) => items.push(p),
            Some(Frame::Seq { cur, .. }) => match cur {
                Some((_, items)) => items.push(p),
                // a primitive before the first seq_item starts an item at the origin
                None => *cur = Some(([0.0, 0.0], vec![p])),
            },
            None => self.prims.push(p),
        }
        self
    }

    // ---------------------------------------------------------- extents (frame coordinates)

    pub fn ext(&mut self, x: f64, y: f64, z: f64) -> &mut Self {
        let w = self.xf.p3([x, y, z]);
        self.ext.push(w);
        self
    }

    pub fn ext_box(&mut self, x0: f64, y0: f64, x1: f64, y1: f64, z0: f64, z1: f64) -> &mut Self {
        for z in [z0, z1] {
            self.ext(x0, y0, z)
                .ext(x1, y0, z)
                .ext(x1, y1, z)
                .ext(x0, y1, z);
        }
        self
    }

    fn ext_world(&mut self, pts: &[P2], z: f64) {
        for p in pts {
            self.ext.push([p[0], p[1], z]);
        }
    }

    // ---------------------------------------------------------- solids

    /// Axis-aligned box (`box` in scripts; `box` is a Rust keyword).
    #[allow(clippy::too_many_arguments)]
    pub fn cuboid(
        &mut self,
        x0: f64,
        y0: f64,
        x1: f64,
        y1: f64,
        z0: f64,
        z1: f64,
        st: Style,
    ) -> &mut Self {
        let r = self.xf.rect(x0, y0, x1, y1);
        let (z0, z1) = (self.xf.z(z0), self.xf.z(z1));
        let pts = rect(r[0], r[1], r[2], r[3]);
        self.ext_world(&pts, z0);
        self.ext_world(&pts, z1);
        self.push(Prim::Prism {
            pts,
            z0: Zs::One(z0),
            z1: Zs::One(z1),
            st,
        })
    }

    pub fn prism(&mut self, pts: Vec<P2>, z0: Zs, z1: Zs, st: Style) -> &mut Self {
        let pts = self.xf.pts(&pts);
        let dz = self.xf.z;
        let sh = |z: Zs| match z {
            Zs::One(v) => Zs::One(v + dz),
            Zs::Each(v) => Zs::Each(v.into_iter().map(|q| q + dz).collect()),
        };
        let (z0, z1) = (sh(z0), sh(z1));
        for (i, p) in pts.iter().enumerate() {
            self.ext.push([p[0], p[1], z0.at(i)]);
            self.ext.push([p[0], p[1], z1.at(i)]);
        }
        self.push(Prim::Prism { pts, z0, z1, st })
    }

    pub fn cyl(&mut self, cx: f64, cy: f64, r: f64, z0: f64, z1: f64, st: Style) -> &mut Self {
        self.ext_box(cx - r, cy - r, cx + r, cy + r, z0, z1);
        let c = self.xf.p(cx, cy);
        let (z0, z1) = (self.xf.z(z0), self.xf.z(z1));
        self.push(Prim::Cyl { c, r, z0, z1, st })
    }

    #[allow(clippy::too_many_arguments)]
    pub fn frust(
        &mut self,
        cx: f64,
        cy: f64,
        r0: f64,
        r1: f64,
        z0: f64,
        z1: f64,
        n: u32,
        st: Style,
    ) -> &mut Self {
        let r = r0.max(r1);
        self.ext_box(cx - r, cy - r, cx + r, cy + r, z0, z1);
        let c = self.xf.p(cx, cy);
        let (z0, z1) = (self.xf.z(z0), self.xf.z(z1));
        self.push(Prim::Frust {
            c,
            r0,
            r1,
            z0,
            z1,
            n: n.max(3),
            st,
        })
    }

    /// Sloped slab (stair flight, ramp) over x0..x1, rising from y0 (za) to
    /// y1 (zb), th thick.
    #[allow(clippy::too_many_arguments)]
    pub fn slope(
        &mut self,
        x0: f64,
        x1: f64,
        y0: f64,
        y1: f64,
        za: f64,
        zb: f64,
        th: f64,
        mat: &str,
    ) -> &mut Self {
        let zt = vec![za, za, zb, zb];
        let zb_: Vec<f64> = zt.iter().map(|z| z - th).collect();
        self.prism(
            rect(x0, y0, x1, y1),
            Zs::Each(zb_),
            Zs::Each(zt),
            Style::mat(mat),
        )
    }

    // ---------------------------------------------------------- surfaces

    /// Openings on the vertical face a -> b (outward normal on the right).
    pub fn open(
        &mut self,
        a: P2,
        b: P2,
        list: Vec<[f64; 4]>,
        cls: &str,
        id: Option<String>,
    ) -> &mut Self {
        let (a, b) = (self.xf.p(a[0], a[1]), self.xf.p(b[0], b[1]));
        let dz = self.xf.z;
        let list: Vec<[f64; 4]> = list
            .into_iter()
            .map(|q| [q[0], q[1], q[2] + dz, q[3] + dz])
            .collect();
        let (dx, dy) = (b[0] - a[0], b[1] - a[1]);
        let l = (dx * dx + dy * dy).sqrt().max(1e-9);
        let (ux, uy) = (dx / l, dy / l);
        for q in &list {
            self.ext.push([a[0] + ux * q[0], a[1] + uy * q[0], q[2]]);
            self.ext.push([a[0] + ux * q[1], a[1] + uy * q[1], q[3]]);
        }
        self.push(Prim::Open {
            a,
            b,
            list,
            cls: cls.into(),
            id,
        })
    }

    pub fn flat(
        &mut self,
        polys: Vec<Vec<P2>>,
        z: f64,
        cls: &str,
        id: Option<String>,
    ) -> &mut Self {
        let polys: Vec<Vec<P2>> = polys.iter().map(|p| self.xf.pts(p)).collect();
        let z = self.xf.z(z);
        for p in &polys {
            self.ext_world(p, z);
        }
        self.push(Prim::Flat {
            polys,
            z,
            cls: cls.into(),
            id,
        })
    }

    pub fn lines(&mut self, segs: Vec<[f64; 4]>, z: f64, cls: &str) -> &mut Self {
        let segs: Vec<[f64; 4]> = segs
            .into_iter()
            .map(|s| {
                let a = self.xf.p(s[0], s[1]);
                let b = self.xf.p(s[2], s[3]);
                [a[0], a[1], b[0], b[1]]
            })
            .collect();
        let z = self.xf.z(z);
        for s in &segs {
            self.ext.push([s[0], s[1], z]);
            self.ext.push([s[2], s[3], z]);
        }
        self.push(Prim::Lines {
            segs,
            z,
            cls: cls.into(),
            id: None,
        })
    }

    pub fn disc(
        &mut self,
        cx: f64,
        cy: f64,
        z: f64,
        r: f64,
        cls: &str,
        id: Option<String>,
    ) -> &mut Self {
        self.ext_box(cx - r, cy - r, cx + r, cy + r, z, z);
        let c = self.xf.p(cx, cy);
        let z = self.xf.z(z);
        self.push(Prim::Disc {
            c,
            z,
            r,
            cls: cls.into(),
            id,
        })
    }

    /// Planar 3D polygon shaded by its normal (see [`Prim::Face`]).
    pub fn face(
        &mut self,
        pts: Vec<P3>,
        mat: &str,
        id: Option<String>,
        two_sided: bool,
    ) -> &mut Self {
        let pts: Vec<P3> = pts.into_iter().map(|p| self.xf.p3(p)).collect();
        self.ext.extend(pts.iter().copied());
        self.push(Prim::Face {
            pts,
            mat: mat.into(),
            id,
            two_sided,
        })
    }

    /// 3D polygons as one path with a fixed class.
    pub fn poly(&mut self, polys: Vec<Vec<P3>>, cls: &str, id: Option<String>) -> &mut Self {
        let polys: Vec<Vec<P3>> = polys
            .into_iter()
            .map(|p| p.into_iter().map(|q| self.xf.p3(q)).collect())
            .collect();
        for p in &polys {
            self.ext.extend(p.iter().copied());
        }
        self.push(Prim::Poly {
            polys,
            cls: cls.into(),
            id,
        })
    }

    // ---------------------------------------------------------- screen-space details

    /// Circle of r screen units (not part of the sort box: add `ext` if it
    /// sticks out of the sprite).
    pub fn circle(&mut self, at: P3, r: f64, off: P2, cls: &str) -> &mut Self {
        let at = self.xf.p3(at);
        self.push(Prim::Circle {
            at,
            r,
            off,
            cls: cls.into(),
            id: None,
        })
    }

    pub fn stem(&mut self, x: f64, y: f64, z0: f64, z1: f64, w: f64, cls: &str) -> &mut Self {
        self.ext(x, y, z0).ext(x, y, z1);
        let at = self.xf.p(x, y);
        let (z0, z1) = (self.xf.z(z0), self.xf.z(z1));
        self.push(Prim::Stem {
            at,
            z0,
            z1,
            w,
            cls: cls.into(),
            id: None,
        })
    }

    /// A head (ball of radius r metres) centred at z.
    pub fn head(&mut self, x: f64, y: f64, z: f64, r: f64) -> &mut Self {
        self.ext(x, y, z + r);
        self.circle([x, y, z], r * C * 1.2, [0.0, 0.0], "iso-headc")
    }

    /// Standing figure: torso cylinder and head.
    pub fn person(&mut self, x: f64, y: f64, z: f64, cls: &str) -> &mut Self {
        self.cyl(x, y, 0.2, z, z + 1.2, Style::mat(cls).no_top());
        self.ext(x, y, z + 1.65);
        self.circle([x, y, z + 1.45], 0.2 * C * 1.2, [0.0, 0.0], "iso-headc")
    }

    /// Seated figure: torso and head.
    pub fn sit(&mut self, x: f64, y: f64, z: f64, cls: &str) -> &mut Self {
        self.cyl(x, y, 0.21, z + 0.42, z + 1.12, Style::mat(cls).no_top());
        self.head(x, y, z + 1.32, 0.2)
    }

    pub fn led(&mut self, x: f64, y: f64, z: f64, cls: &str) -> &mut Self {
        let c = if cls.is_empty() {
            "iso-led".to_string()
        } else {
            format!("iso-led {cls}")
        };
        self.circle([x, y, z], 0.9, [0.0, 0.0], &c)
    }

    pub fn puffs(&mut self, x: f64, y: f64, z: f64, kind: &str, n: u32, dur: f64) -> &mut Self {
        let at = self.xf.p3([x, y, z]);
        self.push(Prim::Puffs {
            at,
            kind: kind.into(),
            n: n.max(1),
            dur,
        })
    }

    pub fn fan(&mut self, x: f64, y: f64, z: f64, r: f64) -> &mut Self {
        let at = self.xf.p3([x, y, z]);
        self.push(Prim::Fan { at, r })
    }

    pub fn raw(&mut self, at: Option<P3>, svg: impl Into<String>) -> &mut Self {
        let at = at.map(|a| self.xf.p3(a));
        self.push(Prim::Raw {
            at,
            svg: svg.into(),
        })
    }

    // ---------------------------------------------------------- structure

    /// Open a `<g class style>`; close it with [`Sprite::end_group`].
    pub fn begin_group(&mut self, cls: &str, style: &str) -> &mut Self {
        self.frames.push(Frame::Group {
            cls: cls.into(),
            style: style.into(),
            items: vec![],
        });
        self
    }

    pub fn end_group(&mut self) -> &mut Self {
        if let Some(Frame::Group { cls, style, items }) = self.frames.pop() {
            self.push(Prim::Group { cls, style, items });
        }
        self
    }

    /// Start a back-to-front sequence; each [`Sprite::seq_item`] starts an
    /// item anchored at a plan point; [`Sprite::end_seq`] closes it.
    pub fn begin_seq(&mut self) -> &mut Self {
        self.frames.push(Frame::Seq {
            items: vec![],
            cur: None,
        });
        self
    }

    pub fn seq_item(&mut self, at: P2) -> &mut Self {
        let at = self.xf.p(at[0], at[1]);
        if let Some(Frame::Seq { items, cur }) = self.frames.last_mut() {
            if let Some(c) = cur.take() {
                items.push(c);
            }
            *cur = Some((at, vec![]));
        }
        self
    }

    pub fn end_seq(&mut self) -> &mut Self {
        if let Some(Frame::Seq { mut items, cur }) = self.frames.pop() {
            if let Some(c) = cur {
                items.push(c);
            }
            self.push(Prim::Seq { items });
        }
        self
    }

    /// Draw items back to front by the depth of their anchor.
    pub fn seq(&mut self, items: Vec<SeqItem<'_>>) -> &mut Self {
        self.begin_seq();
        for (at, f) in items {
            self.seq_item(at);
            f(self);
        }
        self.end_seq()
    }

    /// Close any group or sequence left open (returns how many were open).
    pub fn finish(&mut self) -> usize {
        let n = self.frames.len();
        while let Some(f) = self.frames.last() {
            match f {
                Frame::Group { .. } => {
                    self.end_group();
                }
                Frame::Seq { .. } => {
                    self.end_seq();
                }
            }
        }
        n
    }

    pub fn is_empty(&self) -> bool {
        self.prims.is_empty()
    }

    /// World bounding box of the extent points: [x0, y0, z0, x1, y1, z1].
    pub fn world_box(&self) -> Option<[f64; 6]> {
        if self.ext.is_empty() {
            return None;
        }
        let mut b = [f64::MAX, f64::MAX, f64::MAX, f64::MIN, f64::MIN, f64::MIN];
        for e in &self.ext {
            for k in 0..3 {
                b[k] = b[k].min(e[k]);
                b[k + 3] = b[k + 3].max(e[k]);
            }
        }
        Some(b)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn box_extents_span_eight_corners() {
        let mut s = Sprite::new("a", "");
        s.cuboid(0.0, 0.0, 2.0, 3.0, 0.0, 4.0, Style::mat("iso-wall"));
        assert_eq!(s.ext.len(), 8);
        assert_eq!(s.prims.len(), 1);
    }

    #[test]
    fn frame_moves_and_turns_a_box() {
        let mut s = Sprite::new("a", "").with_frame(Xf::new(10.0, 20.0, 1.0, 90.0));
        // 4 m along local x, 2 m along local y, centred: after a quarter turn 2 m along x, 4 m along y
        s.cuboid(-2.0, -1.0, 2.0, 1.0, 0.0, 3.0, Style::mat("x"));
        let b = s.world_box().unwrap();
        assert_eq!(b, [9.0, 18.0, 1.0, 11.0, 22.0, 4.0]);
    }

    #[test]
    fn frame_round_trips_points() {
        for deg in [0.0, 90.0, 180.0, 270.0, -90.0, 450.0] {
            let f = Xf::new(3.0, -4.0, 0.0, deg);
            let w = f.p(1.5, 2.5);
            let l = f.inv(w[0], w[1]);
            assert!(
                (l[0] - 1.5).abs() < 1e-12 && (l[1] - 2.5).abs() < 1e-12,
                "{deg}"
            );
        }
    }

    #[test]
    fn groups_and_sequences_nest() {
        let mut s = Sprite::new("a", "");
        s.begin_group("iso-a", "");
        s.begin_seq();
        s.seq_item([0.0, 0.0]);
        s.cuboid(0.0, 0.0, 1.0, 1.0, 0.0, 1.0, Style::mat("x"));
        s.seq_item([5.0, 0.0]);
        s.cuboid(5.0, 0.0, 6.0, 1.0, 0.0, 1.0, Style::mat("x"));
        s.end_seq();
        s.end_group();
        assert_eq!(s.prims.len(), 1);
        match &s.prims[0] {
            Prim::Group { items, .. } => match &items[0] {
                Prim::Seq { items } => assert_eq!(items.len(), 2),
                p => panic!("{p:?}"),
            },
            p => panic!("{p:?}"),
        }
    }

    #[test]
    fn finish_closes_open_frames() {
        let mut s = Sprite::new("a", "");
        s.begin_group("g", "");
        s.cuboid(0.0, 0.0, 1.0, 1.0, 0.0, 1.0, Style::mat("x"));
        assert_eq!(s.finish(), 1);
        assert!(matches!(s.prims[0], Prim::Group { .. }));
    }
}