merman-render 0.6.1

//! Flowchart final viewBox/content-bounds preparation.

use std::borrow::Cow;

use rustc_hash::FxHashMap;

use super::viewbox_node_bounds::include_flowchart_node_rendered_bounds;
use super::*;

const TITLE_FONT_SIZE_PX: f64 = 18.0;

pub(in crate::svg::parity::flowchart) struct FlowchartRenderedBoundsRequest<'view, 'data> {
    pub ctx: &'view FlowchartRenderCtx<'data>,
    pub layout: &'view FlowchartV2Layout,
    pub subgraph_title_y_shift: f64,
}

pub(in crate::svg::parity::flowchart) struct FlowchartViewboxBoundsRequest<
    'borrow,
    'view,
    'data,
    'title,
> {
    pub ctx: &'view FlowchartRenderCtx<'data>,
    pub render_edges: &'view [Cow<'data, crate::flowchart::FlowEdge>],
    pub base_bounds: Bounds,
    pub diagram_title: Option<&'title str>,
    pub font_family: &'borrow str,
    pub title_top_margin: f64,
    pub timing_enabled: bool,
    pub viewbox_edge_curve_bounds: &'borrow mut std::time::Duration,
    pub detail: &'borrow mut FlowchartRenderDetails,
    pub edge_path_cache: &'borrow mut FxHashMap<&'view str, FlowchartEdgePathCacheEntry>,
}

pub(in crate::svg::parity::flowchart) struct FlowchartViewboxBounds {
    pub diagram_title: Option<String>,
    pub title_anchor_x: f64,
    pub bbox_min_x: f64,
    pub bbox_min_y: f64,
    pub bbox_max_x: f64,
    pub bbox_max_y: f64,
}

pub(in crate::svg::parity::flowchart) fn prepare_flowchart_rendered_bounds<'data, F>(
    request: FlowchartRenderedBoundsRequest<'_, 'data>,
    effective_parent_for_id: &F,
) -> Bounds
where
    F: Fn(&str) -> Option<&'data str>,
{
    let FlowchartRenderedBoundsRequest {
        ctx,
        layout,
        subgraph_title_y_shift,
    } = request;
    let mut lca_scratch: Vec<&str> = Vec::new();

    let y_offset_for_root = |root: Option<&str>| -> f64 {
        if root.is_some() && subgraph_title_y_shift.abs() >= 1e-9 {
            -subgraph_title_y_shift
        } else {
            0.0
        }
    };

    // Mermaid's flowchart-v2 renderer draws the self-loop helper nodes (`labelRect`) as
    // `<g class="label edgeLabel" transform="translate(x, y)">` with a `0.1 x 0.1` rect anchored
    // at the translated origin (top-left). Dagre's `x/y` still represent a node center, but the
    // rendered DOM bbox that drives `setupViewPortForSVG(svg, diagramPadding)` is top-left based.
    // Account for that when approximating the final `svg.getBBox()`.
    let mut b: Option<Bounds> = None;
    let mut include_rect = |min_x: f64, min_y: f64, max_x: f64, max_y: f64| {
        if let Some(ref mut cur) = b {
            cur.min_x = cur.min_x.min(min_x);
            cur.min_y = cur.min_y.min(min_y);
            cur.max_x = cur.max_x.max(max_x);
            cur.max_y = cur.max_y.max(max_y);
        } else {
            b = Some(Bounds {
                min_x,
                min_y,
                max_x,
                max_y,
            });
        }
    };

    for c in &layout.clusters {
        let root = if ctx.recursive_clusters.contains(c.id.as_str()) {
            Some(c.id.as_str())
        } else {
            effective_parent_for_id(&c.id)
        };
        let y_off = y_offset_for_root(root);
        let hw = c.width / 2.0;
        let hh = c.height / 2.0;
        include_rect(c.x - hw, c.y + y_off - hh, c.x + hw, c.y + y_off + hh);

        let lhw = c.title_label.width / 2.0;
        let lhh = c.title_label.height / 2.0;
        include_rect(
            c.title_label.x - lhw,
            c.title_label.y + y_off - lhh,
            c.title_label.x + lhw,
            c.title_label.y + y_off + lhh,
        );
    }

    include_flowchart_node_rendered_bounds(
        ctx,
        &layout.nodes,
        subgraph_title_y_shift,
        effective_parent_for_id,
        &mut include_rect,
    );

    for e in &layout.edges {
        let root = lca_for_ids(
            e.from.as_str(),
            e.to.as_str(),
            effective_parent_for_id,
            &mut lca_scratch,
        );
        let y_off = y_offset_for_root(root);
        for lbl in [
            e.label.as_ref(),
            e.start_label_left.as_ref(),
            e.start_label_right.as_ref(),
            e.end_label_left.as_ref(),
            e.end_label_right.as_ref(),
        ]
        .into_iter()
        .flatten()
        {
            let hw = lbl.width / 2.0;
            let hh = lbl.height / 2.0;
            let svg_label_y_offset = if ctx.edge_html_labels { 0.0 } else { 1.0 };
            include_rect(
                lbl.x - hw,
                lbl.y + y_off - hh - svg_label_y_offset,
                lbl.x + hw,
                lbl.y + y_off + hh - svg_label_y_offset,
            );
        }
    }

    b.unwrap_or({
        if layout.nodes.is_empty() && layout.edges.is_empty() && layout.clusters.is_empty() {
            Bounds {
                min_x: 0.0,
                min_y: 0.0,
                max_x: 0.0,
                max_y: 0.0,
            }
        } else {
            Bounds {
                min_x: 0.0,
                min_y: 0.0,
                max_x: 100.0,
                max_y: 100.0,
            }
        }
    })
}

pub(in crate::svg::parity::flowchart) fn prepare_flowchart_viewbox_bounds<'data, F>(
    request: FlowchartViewboxBoundsRequest<'_, '_, 'data, '_>,
    effective_parent_for_id: &F,
) -> FlowchartViewboxBounds
where
    F: Fn(&str) -> Option<&'data str>,
{
    let FlowchartViewboxBoundsRequest {
        ctx,
        render_edges,
        base_bounds,
        diagram_title,
        font_family,
        title_top_margin,
        timing_enabled,
        viewbox_edge_curve_bounds,
        detail,
        edge_path_cache,
    } = request;

    // Mermaid computes the final viewport using `svg.getBBox()` after inserting the title, then
    // applies `setupViewPortForSVG(svg, diagramPadding)`.
    let diagram_title = diagram_title
        .map(str::trim)
        .filter(|t| !t.is_empty())
        .map(str::to_owned);

    let mut bbox_min_x = base_bounds.min_x + ctx.tx;
    let mut bbox_min_y = base_bounds.min_y + ctx.ty;
    let mut bbox_max_x = base_bounds.max_x + ctx.tx;
    let mut bbox_max_y = base_bounds.max_y + ctx.ty;

    bbox_max_y += extra_recursive_root_y(ctx);

    // Mermaid derives the final viewport using `svg.getBBox()` (after rendering). For flowcharts
    // this includes the actual curve geometry generated by D3 (which can extend beyond the routed
    // polyline points). Headlessly, approximate that by unioning a tight bbox over each rendered
    // edge path `d` into our base bbox.
    {
        let _g = timing_enabled
            .then(|| super::super::timing::TimingGuard::new(viewbox_edge_curve_bounds));
        let mut lca_scratch: Vec<&str> = Vec::new();
        let mut scratch = FlowchartEdgeDataPointsScratch::default();
        let mut root_offsets: FxHashMap<&str, FlowchartRootOffsets> =
            FxHashMap::with_capacity_and_hasher(8, Default::default());
        root_offsets.insert(
            "",
            FlowchartRootOffsets {
                origin_x: 0.0,
                origin_y: 0.0,
                abs_top_transform: 0.0,
            },
        );
        for e in render_edges {
            let e = e.as_ref();
            let root_id = {
                let _g = detail_guard(timing_enabled, &mut detail.viewbox_edge_curve_lca);
                lca_for_ids(
                    e.from.as_str(),
                    e.to.as_str(),
                    effective_parent_for_id,
                    &mut lca_scratch,
                )
                .unwrap_or("")
            };
            let off = {
                let _g = detail_guard(timing_enabled, &mut detail.viewbox_edge_curve_offsets);
                *root_offsets.entry(root_id).or_insert_with(|| {
                    flowchart_cluster_root_offsets(ctx, root_id).unwrap_or(FlowchartRootOffsets {
                        origin_x: 0.0,
                        origin_y: 0.0,
                        abs_top_transform: 0.0,
                    })
                })
            };

            let Some(geom) = ({
                detail.viewbox_edge_curve_geom_calls += 1;
                let _g = detail_guard(timing_enabled, &mut detail.viewbox_edge_curve_geom);
                flowchart_compute_edge_path_geom(
                    FlowchartEdgePathGeomRequest {
                        ctx,
                        edge: e,
                        origin_x: off.origin_x,
                        origin_y: off.origin_y,
                        abs_top_transform: off.abs_top_transform,
                        trace_enabled: false,
                        viewbox_current_bounds: Some((
                            bbox_min_x, bbox_min_y, bbox_max_x, bbox_max_y,
                        )),
                    },
                    &mut scratch,
                )
            }) else {
                continue;
            };
            if geom.bounds_skipped_for_viewbox {
                detail.viewbox_edge_curve_geom_skipped_bounds += 1;
            }

            {
                let _g = detail_guard(timing_enabled, &mut detail.viewbox_edge_curve_bbox_union);
                if let Some(pb) = geom.pb {
                    bbox_min_x = bbox_min_x.min(pb.min_x + off.origin_x);
                    bbox_min_y = bbox_min_y.min(pb.min_y + off.abs_top_transform);
                    bbox_max_x = bbox_max_x.max(pb.max_x + off.origin_x);
                    bbox_max_y = bbox_max_y.max(pb.max_y + off.abs_top_transform);
                }

                edge_path_cache.insert(
                    e.id.as_str(),
                    FlowchartEdgePathCacheEntry {
                        origin_x: off.origin_x,
                        origin_y: off.origin_y,
                        geom,
                    },
                );
            }
        }
    }

    // Mermaid centers the title using the pre-title `getBBox()` of the rendered root group.
    let title_anchor_x = (bbox_min_x + bbox_max_x) / 2.0;

    if let Some(title) = diagram_title.as_deref() {
        let title_style = TextStyle {
            font_family: Some(font_family.to_string()),
            font_size: TITLE_FONT_SIZE_PX,
            font_weight: None,
        };
        let (title_left, title_right) = ctx.measurer.measure_svg_title_bbox_x(title, &title_style);
        let baseline_y = -title_top_margin;
        let (ascent, descent) = crate::text::svg_title_bbox_vertical_extents_px(&title_style);

        bbox_min_x = bbox_min_x.min(title_anchor_x - title_left);
        bbox_max_x = bbox_max_x.max(title_anchor_x + title_right);
        bbox_min_y = bbox_min_y.min(baseline_y - ascent);
        bbox_max_y = bbox_max_y.max(baseline_y + descent);
    }

    FlowchartViewboxBounds {
        diagram_title,
        title_anchor_x,
        bbox_min_x,
        bbox_min_y,
        bbox_max_x,
        bbox_max_y,
    }
}

fn lca_for_ids<'a, F>(
    a: &str,
    b: &str,
    effective_parent_for_id: &F,
    scratch: &mut Vec<&'a str>,
) -> Option<&'a str>
where
    F: Fn(&str) -> Option<&'a str>,
{
    scratch.clear();
    let mut cur = effective_parent_for_id(a);
    while let Some(p) = cur {
        scratch.push(p);
        cur = effective_parent_for_id(p);
    }

    let mut cur = effective_parent_for_id(b);
    while let Some(p) = cur {
        if scratch.contains(&p) {
            return Some(p);
        }
        cur = effective_parent_for_id(p);
    }
    None
}

fn extra_recursive_root_y(ctx: &FlowchartRenderCtx<'_>) -> f64 {
    fn effective_parent<'a>(
        parent: &'a FxHashMap<&'a str, &'a str>,
        subgraphs_by_id: &'a FxHashMap<&'a str, &'a crate::flowchart::FlowSubgraph>,
        recursive_clusters: &FxHashSet<&'a str>,
        id: &str,
    ) -> Option<&'a str> {
        let mut cur = parent.get(id).copied();
        while let Some(p) = cur {
            if subgraphs_by_id.contains_key(p) && !recursive_clusters.contains(p) {
                cur = parent.get(p).copied();
                continue;
            }
            return Some(p);
        }
        None
    }

    let mut max_y: f64 = 0.0;
    for &cid in &ctx.recursive_clusters {
        let Some(cluster) = ctx.layout_clusters_by_id.get(cid) else {
            continue;
        };
        let my_parent = effective_parent(
            &ctx.parent,
            &ctx.subgraphs_by_id,
            &ctx.recursive_clusters,
            cid,
        );
        let has_empty_sibling = ctx.subgraphs_by_id.iter().any(|(&id, &sg)| {
            id != cid
                && sg.nodes.is_empty()
                && ctx.layout_clusters_by_id.contains_key(id)
                && effective_parent(
                    &ctx.parent,
                    &ctx.subgraphs_by_id,
                    &ctx.recursive_clusters,
                    id,
                ) == my_parent
        });
        if has_empty_sibling {
            max_y = max_y.max(cluster.offset_y.max(0.0) * 2.0);
        }
    }
    max_y
}