facett-graphview 0.1.8

//! **DecoratedGraphView** — the egui Facet that paints a [`GraphModel`] under a
//! caller-supplied [`Decorations`] overlay (per-node status **rings** + corner
//! **badges**, plus emphasis **edges** drawn on top), with pan/drag + scroll-zoom
//! and click-to-select (lighting the clicked node's downstream subtree). It is
//! the egui twin of nornir's `src/viz/graph_render.rs::draw_graph` — the same
//! decorations layer the existing `facett-graphview` render model lacked a *view*
//! for (the CPU/GPU rasterizer renders to RGBA; this is the interactive egui
//! pane). Domain-agnostic: facett never learns what a "release gate" is — rings,
//! badges, and cut edges are opaque [`Decorations`].
//!
//! Canonical [`Facet`]: `local()`/`remote()`, `state_json()` (the painted nodes +
//! their decorations + the lit downstream set), `selection_json()`, `caps()`.

use std::collections::{BTreeSet, HashMap, VecDeque};

use facett_core::{Facet, FacetCaps, Semantics};

use crate::model::{Color, Decorations, GraphEdge, GraphModel, GraphNode, NodeDecoration, Pos, BOX_H, BOX_W};

/// The downstream-reachable set (BFS over forward edges) from `seed`, in node-id
/// space — the visual twin of an `arch trace`, used to dim everything off the lit
/// path when a node is selected.
pub fn downstream_of(model: &GraphModel, seed: &str) -> BTreeSet<String> {
    let mut adj: HashMap<&str, Vec<&str>> = HashMap::new();
    for e in &model.edges {
        adj.entry(e.from.as_str()).or_default().push(e.to.as_str());
    }
    let mut lit: BTreeSet<String> = BTreeSet::new();
    let mut q: VecDeque<&str> = VecDeque::new();
    lit.insert(seed.to_string());
    q.push_back(seed);
    while let Some(cur) = q.pop_front() {
        if let Some(outs) = adj.get(cur) {
            for &nxt in outs {
                if lit.insert(nxt.to_string()) {
                    q.push_back(nxt);
                }
            }
        }
    }
    lit
}

/// An interactive, decorated pan/zoom graph pane Facet.
pub struct DecoratedGraphView {
    title: String,
    model: GraphModel,
    decorations: Decorations,
    pan: egui::Vec2,
    zoom: f32,
    selected: Option<String>,
}

impl DecoratedGraphView {
    /// An empty pane titled `title`.
    pub fn new(title: impl Into<String>) -> Self {
        Self {
            title: title.into(),
            model: GraphModel::default(),
            decorations: Decorations::default(),
            pan: egui::Vec2::ZERO,
            zoom: 1.0,
            selected: None,
        }
    }

    /// Set the graph model (nodes already laid out in world space + edges).
    pub fn with_model(mut self, model: GraphModel) -> Self {
        self.model = model;
        self
    }

    /// Set the decorations overlay (rings/badges + emphasis edges).
    pub fn with_decorations(mut self, decorations: Decorations) -> Self {
        self.decorations = decorations;
        self
    }

    /// Re-title (the deck keys facets off [`Facet::title`]).
    pub fn set_title(&mut self, title: impl Into<String>) {
        self.title = title.into();
    }

    /// Reset pan + zoom (the ⊙ fit affordance).
    pub fn fit(&mut self) {
        self.pan = egui::Vec2::ZERO;
        self.zoom = 1.0;
    }

    /// Select a node by id (lights its downstream subtree), or `None` to clear.
    pub fn select(&mut self, id: Option<String>) {
        self.selected = id;
    }

    /// The downstream-lit set for the current selection (empty when none).
    pub fn lit_set(&self) -> BTreeSet<String> {
        self.selected.as_deref().map(|s| downstream_of(&self.model, s)).unwrap_or_default()
    }

    /// **Discovery-contract `local()`** — a realistic 4-node DAG (a → b, a → c,
    /// b → d, c → d) decorated with a green coverage ring on `a`, an amber badge
    /// on `b`, and an emphasis "cut" edge `d → a` (dashed, labelled), so the pane
    /// paints real chips, rings, a badge, and an overlay edge with no host.
    pub fn local() -> Self {
        let n = |id: &str, label: &str, x: f32, y: f32, fill: Color| GraphNode {
            id: id.into(),
            label: label.into(),
            fill,
            stroke: Color::WHITE,
            pos: Pos::new(x, y),
        };
        let e = |from: &str, to: &str, dashed: bool| GraphEdge {
            from: from.into(),
            to: to.into(),
            color: Color::rgb(200, 200, 220),
            dashed,
            label: None,
        };
        let model = GraphModel {
            nodes: vec![
                n("a", "alpha", 0.0, 0.0, Color::rgb(60, 90, 160)),
                n("b", "beta", 260.0, -90.0, Color::rgb(60, 140, 90)),
                n("c", "gamma", 260.0, 90.0, Color::rgb(160, 90, 60)),
                n("d", "delta", 520.0, 0.0, Color::rgb(120, 90, 160)),
            ],
            edges: vec![e("a", "b", false), e("a", "c", false), e("b", "d", false), e("c", "d", false)],
        };
        let mut nodes = HashMap::new();
        nodes.insert(
            "a".to_string(),
            NodeDecoration { ring: Some(Color::rgb(90, 200, 140)), ..Default::default() },
        );
        nodes.insert(
            "b".to_string(),
            NodeDecoration {
                badge: Some("⚠".into()),
                badge_color: Some(Color::rgb(230, 180, 60)),
                ..Default::default()
            },
        );
        let decorations = Decorations {
            nodes,
            edges: vec![GraphEdge {
                from: "d".into(),
                to: "a".into(),
                color: Color::rgb(230, 90, 90),
                dashed: true,
                label: Some("cut".into()),
            }],
        };
        Self::new("DecoratedGraph").with_model(model).with_decorations(decorations)
    }

    /// **Discovery-contract `remote()`** — same surface, re-titled; the variant a
    /// host builds from a server-streamed model. Kept so the matrix sees both ctors.
    pub fn remote() -> Self {
        let mut v = Self::local();
        v.title = "DecoratedGraph (remote)".into();
        v
    }

    fn col(c: Color) -> egui::Color32 {
        c.into()
    }
}

impl Facet for DecoratedGraphView {
    fn title(&self) -> &str {
        &self.title
    }

    fn ui(&mut self, ui: &mut egui::Ui) {
        let th = facett_core::theme(ui);
        if self.zoom <= 0.0 {
            self.zoom = 1.0;
        }

        // ── header: counts + a fit button ─────────────────────────────────
        ui.horizontal_wrapped(|ui| {
            ui.label(
                egui::RichText::new(format!("{} nodes · {} edges", self.model.nodes.len(), self.model.edges.len()))
                    .color(th.text)
                    .strong(),
            );
            ui.separator();
            ui.label(
                egui::RichText::new(format!("{} ring(s) · {} badge(s)",
                    self.decorations.nodes.values().filter(|d| d.ring.is_some()).count(),
                    self.decorations.nodes.values().filter(|d| d.badge.is_some()).count(),
                ))
                .color(th.text_dim),
            );
            if ui.button("⊙ fit").clicked() {
                self.fit();
            }
        });
        ui.separator();

        let (resp, painter) = ui.allocate_painter(ui.available_size(), egui::Sense::click_and_drag());
        painter.rect_filled(resp.rect, 4.0, th.bg);
        if resp.dragged() {
            self.pan += resp.drag_delta();
        }
        if resp.hovered() {
            let scroll = ui.input(|i| i.smooth_scroll_delta.y);
            if scroll != 0.0 {
                self.zoom = (self.zoom * (1.0 + scroll * 0.001)).clamp(0.25, 4.0);
            }
        }
        let origin = resp.rect.center() + self.pan;
        let zoom = self.zoom;
        let project = |p: Pos| origin + egui::vec2(p.x, p.y) * zoom;

        // click-to-select.
        if let Some(click) = resp.clicked().then(|| resp.interact_pointer_pos()).flatten() {
            let hit = self.model.nodes.iter().find_map(|nd| {
                let c = project(nd.pos);
                let rect = egui::Rect::from_center_size(c, egui::vec2(BOX_W, BOX_H) * zoom);
                rect.contains(click).then(|| nd.id.clone())
            });
            self.selected = hit;
        }

        let lit = self.lit_set();
        let highlighting = self.selected.is_some();
        let dim = |c: egui::Color32| c.linear_multiply(0.22);

        let idx: HashMap<&str, &GraphNode> =
            self.model.nodes.iter().map(|n| (n.id.as_str(), n)).collect();

        // edges first.
        let draw_edge = |e: &GraphEdge, emphasise: bool| {
            let (Some(fa), Some(fb)) = (idx.get(e.from.as_str()), idx.get(e.to.as_str())) else {
                return;
            };
            let on_trace = highlighting && lit.contains(&e.from) && lit.contains(&e.to);
            let a = project(fa.pos) + egui::vec2(BOX_W * 0.5 * zoom, 0.0);
            let b = project(fb.pos) - egui::vec2(BOX_W * 0.5 * zoom, 0.0);
            let mut color = Self::col(e.color);
            if !emphasise && highlighting && !on_trace {
                color = dim(color);
            }
            let w = if emphasise { 2.6 } else if on_trace { 2.4 } else { 1.4 };
            if e.dashed {
                // sampled dashed line.
                let n = 16;
                for i in 0..n {
                    if i % 2 == 0 {
                        let t0 = i as f32 / n as f32;
                        let t1 = (i + 1) as f32 / n as f32;
                        painter.line_segment([a.lerp(b, t0), a.lerp(b, t1)], egui::Stroke::new(w, color));
                    }
                }
            } else {
                painter.line_segment([a, b], egui::Stroke::new(w, color));
            }
            // arrowhead.
            let dir = (b - a).normalized();
            let perp = egui::vec2(-dir.y, dir.x);
            let head = 6.0 * zoom.clamp(0.6, 1.6);
            painter.line_segment([b, b - dir * head + perp * head * 0.5], egui::Stroke::new(w, color));
            painter.line_segment([b, b - dir * head - perp * head * 0.5], egui::Stroke::new(w, color));
            if let Some(lbl) = &e.label {
                if zoom > 0.45 && !lbl.is_empty() {
                    painter.text(
                        a.lerp(b, 0.5) - egui::vec2(0.0, 6.0 * zoom),
                        egui::Align2::CENTER_BOTTOM,
                        lbl,
                        egui::FontId::proportional(10.0 * zoom.clamp(0.7, 1.3)),
                        if emphasise { color } else { th.text_dim },
                    );
                }
            }
        };
        for e in &self.model.edges {
            draw_edge(e, false);
        }
        for e in &self.decorations.edges {
            draw_edge(e, true);
        }

        // chips.
        for nd in &self.model.nodes {
            let c = project(nd.pos);
            let on_trace = highlighting && lit.contains(&nd.id);
            let mut fill = Self::col(nd.fill);
            let mut stroke = Self::col(nd.stroke);
            if highlighting && !on_trace {
                fill = dim(fill);
                stroke = dim(stroke);
            }
            let rect = egui::Rect::from_center_size(c, egui::vec2(BOX_W, BOX_H) * zoom);
            painter.rect_filled(rect, 5.0 * zoom, fill);

            let deco = self.decorations.nodes.get(&nd.id);
            let ring = if self.selected.as_deref() == Some(nd.id.as_str()) {
                egui::Stroke::new(3.0, th.accent)
            } else if let Some(rc) = deco.and_then(|d| d.ring) {
                let rc = Self::col(rc);
                egui::Stroke::new(2.4, if highlighting && !on_trace { dim(rc) } else { rc })
            } else {
                egui::Stroke::new(1.4, stroke)
            };
            painter.rect_stroke(rect, 5.0 * zoom, ring, egui::epaint::StrokeKind::Outside);

            if zoom > 0.45 {
                painter.text(
                    c,
                    egui::Align2::CENTER_CENTER,
                    &nd.label,
                    egui::FontId::proportional(11.0 * zoom.clamp(0.7, 1.4)),
                    th.text,
                );
                if let Some(badge) = deco.and_then(|d| d.badge.as_deref()) {
                    let bc = deco.and_then(|d| d.badge_color).map(Self::col).unwrap_or(th.text);
                    painter.text(
                        rect.right_top() + egui::vec2(-2.0, 1.0),
                        egui::Align2::RIGHT_TOP,
                        badge,
                        egui::FontId::proportional(12.0 * zoom.clamp(0.7, 1.4)),
                        if highlighting && !on_trace { dim(bc) } else { bc },
                    );
                }
            }
        }

        // pane-level a11y summary.
        resp.widget_info(|| {
            Semantics::image(format!(
                "decorated graph — {} nodes, {} edges, selected {}",
                self.model.nodes.len(),
                self.model.edges.len(),
                self.selected.as_deref().unwrap_or("none"),
            ))
            .widget_info()
        });

        #[cfg(feature = "testmatrix")]
        facett_core::testmatrix::emit(
            "facett-graphview::DecoratedGraphView::ui",
            "ui_render",
            !self.model.nodes.is_empty(),
            &format!("nodes={} edges={} lit={}", self.model.nodes.len(), self.model.edges.len(), lit.len()),
        );
    }

    fn state_json(&self) -> serde_json::Value {
        let lit = self.lit_set();
        serde_json::json!({
            "title": self.title,
            "node_count": self.model.nodes.len(),
            "edge_count": self.model.edges.len(),
            "decoration_edges": self.decorations.edges.len(),
            "rings": self.decorations.nodes.values().filter(|d| d.ring.is_some()).count(),
            "badges": self.decorations.nodes.values().filter(|d| d.badge.is_some()).count(),
            "selected": self.selected,
            "lit": lit.iter().cloned().collect::<Vec<_>>(),
            "zoom": self.zoom,
            "nodes": self.model.nodes.iter().map(|n| {
                let d = self.decorations.nodes.get(&n.id);
                serde_json::json!({
                    "id": n.id,
                    "label": n.label,
                    "x": n.pos.x,
                    "y": n.pos.y,
                    "ring": d.and_then(|d| d.ring).is_some(),
                    "badge": d.and_then(|d| d.badge.clone()),
                })
            }).collect::<Vec<_>>(),
            "edges": self.model.edges.iter().map(|e| serde_json::json!({
                "from": e.from, "to": e.to, "dashed": e.dashed,
            })).collect::<Vec<_>>(),
        })
    }

    fn selection_json(&self) -> serde_json::Value {
        match &self.selected {
            Some(id) => serde_json::json!({ "node": id, "downstream": self.lit_set().iter().cloned().collect::<Vec<_>>() }),
            None => serde_json::Value::Null,
        }
    }

    /// Themed (chips/rings follow the palette) + resizable + selectable (a node
    /// drill-in) + navigable (pan/drag + scroll-zoom + fit).
    fn caps(&self) -> FacetCaps {
        FacetCaps::NONE.themeable().resizable().selectable().navigable()
    }

    fn as_any_mut(&mut self) -> Option<&mut dyn std::any::Any> {
        Some(self)
    }
}

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

    #[test]
    fn downstream_is_bfs_closure_from_seed() {
        let v = DecoratedGraphView::local();
        // a → b, a → c, b → d, c → d. Downstream of a = all; of b = {b, d}.
        let from_a = downstream_of(&v.model, "a");
        assert!(from_a.contains("a") && from_a.contains("b") && from_a.contains("c") && from_a.contains("d"));
        let from_b = downstream_of(&v.model, "b");
        assert!(from_b.contains("b") && from_b.contains("d"));
        assert!(!from_b.contains("a"), "BFS is forward-only");
        assert!(!from_b.contains("c"), "c is not downstream of b");
    }

    /// inject-assert (LAW 6): the local view seeds a real decorated graph; assert
    /// its `state_json` reports the nodes, the ring + badge decorations, the
    /// emphasis edge, and — after a selection — the lit downstream set.
    #[test]
    fn local_view_reports_decorations_and_selection() {
        let mut v = DecoratedGraphView::local();
        let j = v.state_json();
        assert_eq!(<DecoratedGraphView as Facet>::title(&v), "DecoratedGraph");
        assert_eq!(j["node_count"], 4);
        assert_eq!(j["edge_count"], 4);
        assert_eq!(j["decoration_edges"], 1, "the dashed cut edge");
        assert_eq!(j["rings"], 1, "a green coverage ring on `a`");
        assert_eq!(j["badges"], 1, "a ⚠ badge on `b`");
        // node `a` carries a ring, `b` carries the badge text.
        let nodes = j["nodes"].as_array().unwrap();
        let a = nodes.iter().find(|n| n["id"] == "a").unwrap();
        assert_eq!(a["ring"], true);
        let b = nodes.iter().find(|n| n["id"] == "b").unwrap();
        assert_eq!(b["badge"], "⚠");
        // no selection → null + empty lit set.
        assert_eq!(j["selected"], serde_json::Value::Null);
        assert!(j["lit"].as_array().unwrap().is_empty());

        // select `b` → the lit set is its downstream {b, d}.
        v.select(Some("b".into()));
        let j2 = v.state_json();
        assert_eq!(j2["selected"], "b");
        let lit: BTreeSet<String> =
            j2["lit"].as_array().unwrap().iter().map(|x| x.as_str().unwrap().to_string()).collect();
        assert_eq!(lit, ["b", "d"].iter().map(|s| s.to_string()).collect::<BTreeSet<_>>());
        let sel = v.selection_json();
        assert_eq!(sel["node"], "b");
    }

    #[test]
    fn fit_resets_pan_and_zoom() {
        let mut v = DecoratedGraphView::local();
        v.pan = egui::vec2(20.0, 10.0);
        v.zoom = 2.5;
        v.fit();
        assert_eq!(v.pan, egui::Vec2::ZERO);
        assert_eq!(v.zoom, 1.0);
        assert_eq!(<DecoratedGraphView as Facet>::title(&DecoratedGraphView::remote()), "DecoratedGraph (remote)");
    }
}