eunoia 0.11.0

//! Bundled plot data — everything a renderer needs in one struct.
//!
//! [`PlotData`] is the convenience output of [`Layout::plot_data`], gathering
//! region polygons, region/set label anchors, and shape outlines into a
//! single value. This is the recommended entry point for binding authors
//! (R, Python, Julia, web) who want to consume eunoia's geometry in one
//! shot rather than calling four separate methods.
//!
//! [`Layout::plot_data`]: crate::Layout::plot_data

use crate::geometry::primitives::Point;
use crate::geometry::shapes::Polygon;
use crate::geometry::traits::{DiagramShape, Polygonize};
use crate::plotting::clip::{polygon_clip_many, ClipOperation};
use crate::plotting::regions::{
    classify_into_pieces, decompose_regions_with, poi_with_holes, RegionPolygons,
};
use crate::spec::{Combination, DiagramSpec};
use std::collections::HashMap;

/// Options controlling [`PlotData`] construction.
///
/// Use [`PlotOptions::default`] for sensible defaults (`n_vertices = 200`,
/// `label_precision = 0.01`, `sliver_threshold = 1e-3`).
///
/// # Polygonal output, not analytical
///
/// Every boundary in the resulting [`PlotData`] is a polygon at
/// `n_vertices` resolution — including the per-set
/// [`shape_outlines`](PlotData::shape_outlines) and the per-region
/// [`pieces`](crate::plotting::RegionPiece). This is intentional: a single
/// uniform polygonal representation lets language bindings (R, Python,
/// Julia, web) round-trip the data through any standard polygon library
/// without needing analytical curve support.
///
/// The trade-off is that high-DPI vector exports (large SVG / PDF) may
/// show faceting on circular boundaries at low `n_vertices`. Raise
/// `n_vertices` (eulerr's default is 200) for smoother edges; or, for
/// crispest set boundaries specifically, render strokes from the
/// analytical shape via [`crate::geometry::traits::Polygonize`] at a
/// higher resolution than the region decomposition uses.
#[derive(Debug, Clone, Copy)]
pub struct PlotOptions {
    /// Number of vertices used when polygonizing each shape (both for region
    /// decomposition and for the per-set outlines). Higher values produce
    /// smoother edges at the cost of more polygon vertices. Matches eulerr's
    /// `n` argument to `plot.euler`, which defaults to `200`.
    pub n_vertices: usize,

    /// Polylabel precision for label-anchor placement, in the same units as
    /// the polygon coordinates. Smaller values yield more accurate anchors
    /// at higher cost.
    pub label_precision: f64,

    /// Minimum net area for a region piece, expressed as a fraction of the
    /// largest piece in the diagram. Pieces below this fraction are
    /// rejected as polygonization artifacts during
    /// [`decompose_regions`](crate::plotting::decompose_regions). Set to
    /// `0.0` to disable filtering.
    ///
    /// Default `1e-3` is calibrated against 200-vertex polygonization seam
    /// slivers (which come in around 0.02 % of the largest piece). Raise
    /// it if you see numerical noise; lower it (or zero it) if you have
    /// legitimate small regions that risk being filtered.
    ///
    /// Scale-invariant: the threshold is a *fraction* of the largest piece,
    /// so it behaves the same on diagrams with radius 1 and radius 1000.
    pub sliver_threshold: f64,
}

impl Default for PlotOptions {
    fn default() -> Self {
        Self {
            n_vertices: 200,
            label_precision: 0.01,
            sliver_threshold: 1e-3,
        }
    }
}

/// Everything a renderer needs to draw a fitted diagram.
///
/// All anchors and polygons live in the same coordinate system as the
/// fitted shapes (no normalisation is applied — the renderer chooses the
/// transform). See [`crate::Layout::plot_data`] for construction and
/// [`crate::plotting::RegionPiece`] for the rendering contract on
/// `regions`.
///
/// # Region keys
///
/// Region-keyed maps (`region_anchors`, `region_areas`) use the canonical
/// `"A&B&C"` string form (the `Display` impl on
/// [`crate::spec::Combination`]) so binding authors can serialise without
/// round-tripping through the [`Combination`] type.
/// Use [`PlotData::pieces_for`] when you need to look up the underlying
/// region pieces by the same string.
#[derive(Debug, Clone)]
pub struct PlotData {
    /// Per-region pieces (outer + holes per connected component) keyed by
    /// set combination. Renderers should fill each piece with the SVG /
    /// Canvas default `fill-rule: nonzero`; orientations are normalised
    /// for that — see [`crate::plotting::RegionPiece`].
    pub regions: RegionPolygons,

    /// Hole-aware label anchor for every non-empty region (one anchor per
    /// region, even when the region is fragmented). Computed by
    /// [`RegionPolygons::label_points`] — the pole of inaccessibility of
    /// the highest-clearance piece. Use these for per-region labels such
    /// as element counts.
    pub region_anchors: HashMap<String, Point>,

    /// Net area for every non-empty region — sum of piece areas (each
    /// piece's outer minus its holes). Same coordinate units as the
    /// fitted shapes. Use these for printing fitted-area labels alongside
    /// region anchors without calling [`RegionPolygons::areas`] yourself.
    pub region_areas: HashMap<String, f64>,
    /// Label anchor for every set, with the eulerr-style fallback chain:
    ///
    /// 1. **Hole-aware POI of `shape_i \ ⋃_{j≠i} shape_j`** — the natural
    ///    "S only" lobe, accounting for nested sets as holes.
    /// 2. **Largest containing region's anchor** — for sets with no
    ///    exclusive area (e.g. B fully nested in A → label lands in
    ///    `A&B`), so the label still appears inside the set's actual
    ///    coverage.
    /// 3. **Shape's own POI** — last-resort default; reachable only when
    ///    the set is geometrically empty.
    ///
    /// Use these for per-set labels (e.g. set names). For the un-fallback'd
    /// version that only considers regions, see
    /// [`RegionPolygons::set_label_points`].
    pub set_anchors: HashMap<String, Point>,

    /// Polygonised outline of each set's shape, keyed by set name (so
    /// bindings don't have to rely on positional ordering with
    /// `spec.set_names()`).
    ///
    /// These are produced by polygonizing each analytical shape at
    /// `PlotOptions::n_vertices` — there's no clipping involved, so they
    /// don't have the seam slivers that region decomposition can leave
    /// behind. Use them to draw set strokes directly without visible
    /// seams between exclusive regions, or when you want to overlay the
    /// "outline" view on top of a "filled regions" view.
    ///
    /// # Closing the ring
    ///
    /// Outlines are stored in **open polyline** form: the final vertex is
    /// distinct from the first, and renderers that auto-close (SVG
    /// `<polygon>`, Canvas `closePath()`, R `polygon()`) draw the closing
    /// segment for free. Renderers that draw the polyline literally —
    /// e.g. R's `grid::polylineGrob`, or any line-strip primitive — must
    /// append the first vertex manually before drawing or they'll leave a
    /// gap. The stored form is open because every fill-rule renderer we
    /// know of treats an explicit closing duplicate vertex as a
    /// zero-length segment that can produce stroke artifacts at the
    /// closure point.
    pub shape_outlines: HashMap<String, Polygon>,
}

impl PlotData {
    /// Look up the [`RegionPiece`](crate::plotting::RegionPiece)s for a
    /// region by its canonical combination string (the same key used by
    /// `region_anchors` and `region_areas`). Returns `None` for combos
    /// that correspond to no fitted area.
    ///
    /// Use this to keep all per-region state on a single string key:
    ///
    /// ```ignore
    /// for (combo, anchor) in &plot.region_anchors {
    ///     let pieces = plot.pieces_for(combo).unwrap();
    ///     // … render pieces, place label at anchor …
    /// }
    /// ```
    pub fn pieces_for(&self, combination: &str) -> Option<&Vec<crate::plotting::RegionPiece>> {
        // `Combination::from_str` is `Infallible`, so the parse cannot fail.
        let combo: Combination = combination.parse().unwrap();
        self.regions.get(&combo)
    }

    /// Build a `PlotData` directly from a slice of fitted shapes plus the
    /// spec they were fitted against. The companion to
    /// [`crate::Layout::plot_data`] for consumers who don't hold a `Layout`
    /// — for example, an FFI binding that hands fitted shape parameters
    /// back to the host language and re-receives them later so the user
    /// can replot at a different `n_vertices` without re-fitting.
    ///
    /// `shapes[i]` is taken to correspond to `spec.set_names()[i]`. Any
    /// shapes whose set was pruned during preprocessing (empty sets) should
    /// be reinserted at their spec position before calling this — exactly
    /// the contract `Layout` upholds for its own shape list.
    ///
    /// # Examples
    ///
    /// ```
    /// use eunoia::{DiagramSpecBuilder, Fitter, InputType};
    /// use eunoia::geometry::shapes::Circle;
    /// use eunoia::plotting::{PlotData, PlotOptions};
    ///
    /// let spec = DiagramSpecBuilder::new()
    ///     .set("A", 5.0)
    ///     .set("B", 3.0)
    ///     .intersection(&["A", "B"], 1.0)
    ///     .input_type(InputType::Exclusive)
    ///     .build()
    ///     .unwrap();
    ///
    /// let layout = Fitter::<Circle>::new(&spec).seed(42).fit().unwrap();
    /// let shapes: Vec<Circle> = spec
    ///     .set_names()
    ///     .iter()
    ///     .map(|n| *layout.shape_for_set(n).unwrap())
    ///     .collect();
    ///
    /// // Same output as `layout.plot_data(&spec, PlotOptions::default())`.
    /// let plot = PlotData::from_shapes(&shapes, &spec, PlotOptions::default());
    /// assert!(plot.shape_outlines.contains_key("A"));
    /// ```
    pub fn from_shapes<S>(shapes: &[S], spec: &DiagramSpec, options: PlotOptions) -> PlotData
    where
        S: DiagramShape + Polygonize,
    {
        build_plot_data(shapes, spec, options)
    }
}

pub(crate) fn build_plot_data<S>(shapes: &[S], spec: &DiagramSpec, options: PlotOptions) -> PlotData
where
    S: DiagramShape + Polygonize,
{
    let regions = decompose_regions_with(
        shapes,
        spec.set_names(),
        spec,
        options.n_vertices,
        options.sliver_threshold,
    );
    let region_anchors_combo = regions.label_points(options.label_precision);
    let region_anchors: HashMap<String, Point> = region_anchors_combo
        .iter()
        .map(|(combo, p)| (combo.to_string(), *p))
        .collect();
    let region_areas: HashMap<String, f64> = regions
        .areas()
        .into_iter()
        .map(|(combo, a)| (combo.to_string(), a))
        .collect();
    let outline_vec: Vec<Polygon> = shapes
        .iter()
        .map(|s| s.polygonize(options.n_vertices))
        .collect();
    let set_anchors = compute_set_anchors(
        &outline_vec,
        spec.set_names(),
        &regions,
        &region_anchors_combo,
        options.label_precision,
    );
    let shape_outlines: HashMap<String, Polygon> = spec
        .set_names()
        .iter()
        .zip(outline_vec.iter())
        .map(|(name, poly)| (name.clone(), poly.clone()))
        .collect();

    PlotData {
        regions,
        region_anchors,
        region_areas,
        set_anchors,
        shape_outlines,
    }
}

/// Computes a label anchor for each set by finding the pole of inaccessibility
/// of `shape_i \ ⋃_{j≠i} shape_j`, using i_overlay's polygon difference and
/// the same piece classifier the region decomposition uses. So an "A only"
/// region with B/C/D as holes gets a hole-aware POI in the donut, and a
/// fully-nested B falls back to the largest containing region (e.g. `A&B`).
///
/// Sliver filtering is handled inside the classifier-and-clipper pipeline:
/// pieces below the relative-area threshold are rejected during piece
/// construction, so callers don't need a separate threshold here.
fn compute_set_anchors(
    shape_outlines: &[Polygon],
    set_names: &[String],
    regions: &RegionPolygons,
    region_anchors: &HashMap<Combination, Point>,
    precision: f64,
) -> HashMap<String, Point> {
    let mut result = HashMap::new();
    if shape_outlines.is_empty() {
        return result;
    }

    for (i, name) in set_names.iter().enumerate() {
        if i >= shape_outlines.len() {
            continue;
        }

        // Build the union of all other shapes (one polygon, possibly with
        // disconnected pieces and/or holes — all preserved as separate rings).
        let mut others_union: Vec<Polygon> = Vec::new();
        for (j, other) in shape_outlines.iter().enumerate() {
            if j == i {
                continue;
            }
            if others_union.is_empty() {
                others_union.push(other.clone());
            } else {
                others_union = polygon_clip_many(&others_union, other, ClipOperation::Union);
            }
        }

        // shape_i minus the union of the rest, then classify the resulting
        // ring set into outer-with-holes pieces. If `others_union` is empty
        // (single-set diagram) the result is just `shape_i`.
        let exclusive_rings: Vec<Polygon> = if others_union.is_empty() {
            vec![shape_outlines[i].clone()]
        } else {
            let mut acc = vec![shape_outlines[i].clone()];
            for clip in &others_union {
                acc = polygon_clip_many(&acc, clip, ClipOperation::Difference);
                if acc.is_empty() {
                    break;
                }
            }
            acc
        };

        let pieces = classify_into_pieces(exclusive_rings);

        // Drop pieces that are tiny relative to the shape itself — these are
        // polygonization seam artifacts when the set is geometrically nested
        // inside another, and would otherwise drag the label onto a sliver.
        let shape_area = shape_outlines[i].area();
        let max_piece_area = pieces.iter().map(|p| p.area()).fold(0.0_f64, f64::max);
        let kept: Vec<_> = if shape_area > 0.0 && max_piece_area < shape_area * 1e-3 {
            Vec::new()
        } else {
            pieces.into_iter().filter(|p| p.area() > 0.0).collect()
        };

        // Hole-aware POI on the (possibly hole-bearing) exclusive pieces.
        let anchor = poi_with_holes(&kept, precision).map(|(p, _)| p);

        // Fallback chain: largest-area containing region (eulerr behaviour
        // for nested sets), then the shape's own POI as a last resort.
        let anchor =
            anchor.or_else(|| largest_containing_region_anchor(name, regions, region_anchors));
        let anchor = anchor.or_else(|| {
            let (p, _) = shape_outlines[i].pole_of_inaccessibility_with_distance(precision);
            Some(p)
        });

        if let Some(point) = anchor {
            result.insert(name.clone(), point);
        }
    }

    result
}

/// Picks the anchor of the largest-area region whose combination contains
/// `name`, or `None` if the set never appears in any non-empty region.
/// "Largest area" sums the absolute polygon areas of every piece in the
/// region — matches the JS `fallbackSetLabels` heuristic this replaces.
fn largest_containing_region_anchor(
    name: &str,
    regions: &RegionPolygons,
    region_anchors: &HashMap<Combination, Point>,
) -> Option<Point> {
    let mut best: Option<(&Combination, f64)> = None;
    for (combo, polys) in regions.iter() {
        if !combo.sets().iter().any(|s| s == name) {
            continue;
        }
        let area: f64 = polys.iter().map(|p| p.area()).sum();
        if best.map(|(_, a)| area > a).unwrap_or(true) {
            best = Some((combo, area));
        }
    }
    best.and_then(|(combo, _)| region_anchors.get(combo).copied())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::fitter::Fitter;
    use crate::geometry::shapes::Circle;
    use crate::spec::{DiagramSpecBuilder, InputType};

    #[test]
    fn test_plot_options_default() {
        let opts = PlotOptions::default();
        assert_eq!(opts.n_vertices, 200);
        assert!((opts.label_precision - 0.01).abs() < 1e-12);
    }

    #[test]
    fn test_clip_difference_with_nested_circle_returns_two_rings() {
        use crate::geometry::primitives::Point;
        use crate::geometry::shapes::Circle;
        use crate::geometry::traits::Polygonize;
        use crate::plotting::clip::{polygon_clip, ClipOperation};

        let a = Circle::new(Point::new(0.0, 0.0), 5.0).polygonize(64);
        let b = Circle::new(Point::new(0.0, 0.0), 1.0).polygonize(32);
        let result = polygon_clip(&a, &b, ClipOperation::Difference);

        let mut pos = 0;
        let mut neg = 0;
        for r in &result {
            let mut s = 0.0;
            let v = r.vertices();
            for i in 0..v.len() {
                let j = (i + 1) % v.len();
                s += v[i].x() * v[j].y() - v[j].x() * v[i].y();
            }
            if s > 0.0 {
                pos += 1;
            } else if s < 0.0 {
                neg += 1;
            }
        }
        eprintln!(
            "polygon_clip(A=r5, B=r1, Difference) returned {} rings: {} CCW (outer), {} CW (hole)",
            result.len(),
            pos,
            neg
        );
        for (i, r) in result.iter().enumerate() {
            let v = r.vertices();
            let mut s = 0.0;
            for j in 0..v.len() {
                let k = (j + 1) % v.len();
                s += v[j].x() * v[k].y() - v[k].x() * v[j].y();
            }
            eprintln!(
                "  ring {}: {} verts, signed_area={:.3}, first vertex=({:.3}, {:.3})",
                i,
                v.len(),
                s / 2.0,
                v[0].x(),
                v[0].y()
            );
        }
        // Expect at least one outer + one hole.
        assert!(pos >= 1, "expected at least one outer (CCW) ring");
        assert!(neg >= 1, "expected at least one hole (CW) ring");
    }

    /// When B, C, D are nested inside A, the set anchor for A must land in
    /// A's exclusive ("A only") lobe — not at A's geometric centre, where
    /// the inner circles overlap it. Regression test for the `eulerr`
    /// comparison reported by users after the eunoia-backend switch.
    #[test]
    fn test_set_anchor_avoids_nested_inner_sets() {
        let spec = DiagramSpecBuilder::new()
            .set("A", 30.0)
            .intersection(&["A", "B"], 3.0)
            .intersection(&["A", "C"], 3.0)
            .intersection(&["A", "D"], 3.0)
            .intersection(&["A", "B", "C"], 0.6)
            .intersection(&["A", "B", "D"], 0.6)
            .intersection(&["A", "C", "D"], 0.6)
            .intersection(&["A", "B", "C", "D"], 1.0)
            .input_type(InputType::Exclusive)
            .build()
            .unwrap();

        let layout = Fitter::<Circle>::new(&spec).seed(1).fit().unwrap();
        let plot = layout.plot_data(&spec, PlotOptions::default());

        let a_anchor = plot.set_anchors.get("A").expect("missing label for A");
        let a_circle = layout.shape_for_set("A").unwrap();

        for inner in ["B", "C", "D"] {
            let c = layout.shape_for_set(inner).unwrap();
            let dx = a_anchor.x() - c.center().x();
            let dy = a_anchor.y() - c.center().y();
            assert!(
                dx * dx + dy * dy > c.radius() * c.radius(),
                "label A at ({:.3}, {:.3}) overlaps inner set {} (center=({:.3}, {:.3}), r={:.3})",
                a_anchor.x(),
                a_anchor.y(),
                inner,
                c.center().x(),
                c.center().y(),
                c.radius(),
            );
        }
        let dx = a_anchor.x() - a_circle.center().x();
        let dy = a_anchor.y() - a_circle.center().y();
        assert!(dx * dx + dy * dy <= a_circle.radius() * a_circle.radius());
    }

    #[test]
    fn test_plot_data_two_circles() {
        let spec = DiagramSpecBuilder::new()
            .set("A", 5.0)
            .set("B", 3.0)
            .intersection(&["A", "B"], 1.0)
            .input_type(InputType::Exclusive)
            .build()
            .unwrap();

        let layout = Fitter::<Circle>::new(&spec).seed(42).fit().unwrap();
        let plot = layout.plot_data(&spec, PlotOptions::default());

        // Region polygons + region anchors should agree on which regions exist.
        for combo in plot.regions.iter().map(|(c, _)| c) {
            assert!(plot.region_anchors.contains_key(&combo.to_string()));
        }
        // One outline per set.
        assert_eq!(plot.shape_outlines.len(), spec.set_names().len());
        // One set anchor per set.
        for name in spec.set_names() {
            assert!(plot.set_anchors.contains_key(name));
        }
    }
}