nornir 0.4.4

//! 🗂 **Funnel** tab — the idea→plan DAG (DAG 2) as an interactive
//! [`egui_snarl`] node graph.
//!
//! A plan is literally a DAG: nodes carrying a `kind` + `status`, wired by
//! dependency edges. We lay it out **topologically** (longest-path layering →
//! one column per rank, deps strictly left of dependents) and render it with
//! egui-snarl, so it pans/zooms/drags like a modern node editor while the
//! topology stays readable. Node + pin tint encode lifecycle
//! (pending/ready/in-progress/done/blocked/failed).
//!
//! Data is read **embedded** (open the funnel `Store` locally) or **remote**
//! (the `Funnel.Show` gRPC RPC), collapsing into [`FunnelView`] — exactly the
//! local-or-remote split the call-graph + warehouse tabs use. Writing the
//! funnel stays where it belongs: the `nornir funnel` CLI and the `funnel_*`
//! MCP tools. This tab is the read/observe surface.

use std::collections::{BTreeMap, HashMap, VecDeque};
use std::path::PathBuf;

use eframe::egui::{self, Color32, Pos2};
use egui_snarl::ui::{PinInfo, SnarlStyle, SnarlViewer};
use egui_snarl::{InPin, InPinId, NodeId, OutPin, OutPinId, Snarl};

use super::funnel_view::{FunnelView, NodeStat, PlanView};

/// Horizontal gap between topological ranks, vertical gap between siblings.
const X_SPACING: f32 = 250.0;
const Y_SPACING: f32 = 120.0;

enum Src {
    Local(PathBuf),
    Remote { endpoint: String, token: String },
}

/// One snarl node = one plan node (the bits the viewer renders).
struct FunnelNode {
    id: String,
    kind: String,
    title: String,
    status: NodeStat,
    targets: Vec<String>,
}

pub struct FunnelTabState {
    src: Src,
    /// Selected workspace (the `nornir-workspace` gRPC header); empty for local.
    workspace: String,
    loaded: bool,
    error: Option<String>,
    view: Option<FunnelView>,
    sel_plan: Option<String>,
    /// The laid-out graph for `built_for`.
    snarl: Snarl<FunnelNode>,
    built_for: Option<String>,
    style: SnarlStyle,
}

impl FunnelTabState {
    pub fn local(root: PathBuf) -> Self {
        Self::with(Src::Local(root), String::new())
    }
    pub fn remote(endpoint: String, token: String, workspace: String) -> Self {
        Self::with(Src::Remote { endpoint, token }, workspace)
    }
    fn with(src: Src, workspace: String) -> Self {
        Self {
            src,
            workspace,
            loaded: false,
            error: None,
            view: None,
            sel_plan: None,
            snarl: Snarl::new(),
            built_for: None,
            style: SnarlStyle::new(),
        }
    }

    /// Re-scope to a different workspace (the picker switched).
    pub(crate) fn set_workspace(&mut self, workspace: String) {
        self.workspace = workspace;
        self.loaded = false;
        self.error = None;
        self.view = None;
        self.sel_plan = None;
        self.built_for = None;
        self.snarl = Snarl::new();
    }

    fn load_view(&self) -> Result<FunnelView, String> {
        match &self.src {
            Src::Local(root) => crate::funnel::Store::open(root)
                .map(|store| FunnelView::from_funnel(&store.funnel))
                .map_err(|e| format!("{e:#}")),
            Src::Remote { endpoint, token } => {
                super::remote::funnel_show(endpoint, token, &self.workspace)
                    .map_err(|e| format!("{e:#}"))
            }
        }
    }

    fn ensure_loaded(&mut self) {
        if self.loaded {
            return;
        }
        self.loaded = true;
        match self.load_view() {
            Ok(v) => {
                if self.sel_plan.is_none() {
                    self.sel_plan = v.plans.first().map(|p| p.id.clone());
                }
                self.view = Some(v);
            }
            Err(e) => self.error = Some(e),
        }
    }

    pub fn draw(&mut self, ui: &mut egui::Ui) {
        self.ensure_loaded();

        if let Some(err) = self.error.clone() {
            ui.colored_label(Color32::RED, err);
            return;
        }
        let Some(view) = self.view.as_ref() else {
            ui.label("loading funnel…");
            return;
        };
        if view.plans.is_empty() {
            ui.vertical_centered(|ui| {
                ui.add_space(40.0);
                ui.heading("🗂 Funnel — no plans yet");
                ui.label("Feed the funnel from the CLI, then it appears here:");
                ui.monospace("nornir funnel submit \"<krav / prompt>\"");
                ui.monospace("nornir funnel plan <idea-id> \"<summary>\"");
                ui.monospace("nornir funnel node <plan-id> --kind … --needs …");
            });
            return;
        }

        // Decide the selected plan, then (re)build the snarl graph if it changed.
        let sel = self
            .sel_plan
            .clone()
            .filter(|s| view.plans.iter().any(|p| &p.id == s))
            .unwrap_or_else(|| view.plans[0].id.clone());
        let to_build = if self.built_for.as_deref() != Some(sel.as_str()) {
            view.plans.iter().find(|p| p.id == sel).cloned()
        } else {
            None
        };
        if let Some(plan) = to_build {
            self.snarl = build_snarl(&plan);
            self.built_for = Some(plan.id.clone());
        }
        self.sel_plan = Some(sel.clone());

        egui::TopBottomPanel::top("funnel_controls").show_inside(ui, |ui| {
            ui.horizontal_wrapped(|ui| {
                ui.label("plan:");
                let cur = self
                    .view
                    .as_ref()
                    .and_then(|v| v.plans.iter().find(|p| p.id == sel))
                    .map(|p| format!("{} · {}", p.id, p.status))
                    .unwrap_or_else(|| sel.clone());
                egui::ComboBox::from_id_source("funnel_plan")
                    .selected_text(cur)
                    .show_ui(ui, |ui| {
                        let plans: Vec<(String, String)> = self
                            .view
                            .as_ref()
                            .map(|v| v.plans.iter().map(|p| (p.id.clone(), p.status.clone())).collect())
                            .unwrap_or_default();
                        for (id, status) in plans {
                            if ui
                                .selectable_label(
                                    self.sel_plan.as_deref() == Some(&id),
                                    format!("{id} · {status}"),
                                )
                                .clicked()
                            {
                                self.sel_plan = Some(id);
                            }
                        }
                    });
                if ui.button("↻ reload").on_hover_text("re-read the funnel").clicked() {
                    self.loaded = false;
                    self.view = None;
                    self.built_for = None;
                }
                ui.separator();
                legend(ui);
            });
        });

        egui::CentralPanel::default().show_inside(ui, |ui| {
            // Plan header: summary + originating idea + DAG size.
            if let Some(plan) = self.view.as_ref().and_then(|v| v.plans.iter().find(|p| p.id == sel)) {
                let edges: usize = plan.nodes.iter().map(|n| n.deps.len()).sum();
                ui.horizontal(|ui| {
                    ui.strong(&plan.summary);
                    ui.weak(format!("· {} nodes, {} deps", plan.nodes.len(), edges));
                });
                if !plan.idea_text.is_empty() {
                    ui.label(
                        egui::RichText::new(format!("💡 {}", plan.idea_text))
                            .italics()
                            .size(11.0)
                            .color(Color32::from_gray(160)),
                    );
                }
                ui.add_space(2.0);
            }
            // The DAG. egui-snarl owns pan/zoom/drag; topology is preset by
            // the layered insert positions.
            let mut viewer = FunnelViewer;
            self.snarl.show(&mut viewer, &self.style, "funnel_snarl_canvas", ui);
        });
    }
}

/// Longest-path layering (Kahn): `layer[n] = 0` for roots, else
/// `1 + max(layer[dep])`. Returns a layer per node, index-aligned with
/// `plan.nodes`. A cycle (shouldn't happen — `apply` rejects them) leaves the
/// unreached nodes at layer 0, which is still drawable.
fn topo_layers(plan: &PlanView) -> Vec<usize> {
    let n = plan.nodes.len();
    let idx: HashMap<&str, usize> =
        plan.nodes.iter().enumerate().map(|(i, nd)| (nd.id.as_str(), i)).collect();

    // dependents[u] = nodes that depend on u; indeg[v] = #known deps of v.
    let mut dependents: Vec<Vec<usize>> = vec![Vec::new(); n];
    let mut indeg = vec![0usize; n];
    for (v, node) in plan.nodes.iter().enumerate() {
        for dep in &node.deps {
            if let Some(&u) = idx.get(dep.as_str()) {
                dependents[u].push(v);
                indeg[v] += 1;
            }
        }
    }

    let mut layer = vec![0usize; n];
    let mut queue: VecDeque<usize> = (0..n).filter(|&i| indeg[i] == 0).collect();
    while let Some(u) = queue.pop_front() {
        for &v in &dependents[u] {
            layer[v] = layer[v].max(layer[u] + 1);
            indeg[v] -= 1;
            if indeg[v] == 0 {
                queue.push_back(v);
            }
        }
    }
    layer
}

/// Lay the plan out as a left→right topological DAG and wire its edges.
fn build_snarl(plan: &PlanView) -> Snarl<FunnelNode> {
    let mut snarl = Snarl::new();
    let layers = topo_layers(plan);

    // Group node indices by layer, preserving id order within a layer.
    let mut by_layer: BTreeMap<usize, Vec<usize>> = BTreeMap::new();
    for (i, &l) in layers.iter().enumerate() {
        by_layer.entry(l).or_default().push(i);
    }
    let max_rows = by_layer.values().map(|v| v.len()).max().unwrap_or(1) as f32;
    let mid = (max_rows - 1.0) * 0.5 * Y_SPACING;

    let mut sid: HashMap<String, NodeId> = HashMap::new();
    for (layer, members) in &by_layer {
        let count = members.len() as f32;
        for (row, &ni) in members.iter().enumerate() {
            let node = &plan.nodes[ni];
            let x = 40.0 + *layer as f32 * X_SPACING;
            // Center each column around the canvas mid-line.
            let y = 40.0 + mid + (row as f32 - (count - 1.0) * 0.5) * Y_SPACING;
            let id = snarl.insert_node(
                Pos2::new(x, y),
                FunnelNode {
                    id: node.id.clone(),
                    kind: node.kind.clone(),
                    title: node.title.clone(),
                    status: node.status,
                    targets: node.targets.clone(),
                },
            );
            sid.insert(node.id.clone(), id);
        }
    }

    // Edge dep -> node: wire dep's single output into node's single input.
    for node in &plan.nodes {
        let Some(&to) = sid.get(&node.id) else { continue };
        for dep in &node.deps {
            if let Some(&from) = sid.get(dep) {
                snarl.connect(OutPinId { node: from, output: 0 }, InPinId { node: to, input: 0 });
            }
        }
    }
    snarl
}

/// Status legend row.
fn legend(ui: &mut egui::Ui) {
    for st in [
        NodeStat::Pending,
        NodeStat::Ready,
        NodeStat::InProgress,
        NodeStat::Done,
        NodeStat::Blocked,
        NodeStat::Failed,
    ] {
        ui.colored_label(st.color(), st.glyph());
        ui.weak(st.label());
        ui.add_space(4.0);
    }
}

/// egui-snarl renderer for funnel nodes. One input pin (incoming deps) and one
/// output pin (dependents); both tinted by status so the wire colours read as
/// progress. Read-only: editing is the CLI/MCP's job, so `connect`/`disconnect`
/// are left as no-ops (the default trait impls would mutate the graph).
struct FunnelViewer;

impl SnarlViewer<FunnelNode> for FunnelViewer {
    fn title(&mut self, node: &FunnelNode) -> String {
        node.id.clone()
    }

    fn inputs(&mut self, _node: &FunnelNode) -> usize {
        1
    }
    fn outputs(&mut self, _node: &FunnelNode) -> usize {
        1
    }

    fn show_header(
        &mut self,
        node: NodeId,
        _inputs: &[InPin],
        _outputs: &[OutPin],
        ui: &mut egui::Ui,
        _scale: f32,
        snarl: &mut Snarl<FunnelNode>,
    ) {
        let n = &snarl[node];
        ui.horizontal(|ui| {
            ui.colored_label(n.status.color(), n.status.glyph());
            ui.strong(&n.id);
            if !n.kind.is_empty() {
                ui.label(egui::RichText::new(&n.kind).monospace().size(11.0).color(Color32::from_gray(170)));
            }
        });
    }

    fn has_body(&mut self, node: &FunnelNode) -> bool {
        !node.title.is_empty() || !node.targets.is_empty()
    }

    fn show_body(
        &mut self,
        node: NodeId,
        _inputs: &[InPin],
        _outputs: &[OutPin],
        ui: &mut egui::Ui,
        _scale: f32,
        snarl: &mut Snarl<FunnelNode>,
    ) {
        let n = &snarl[node];
        ui.vertical(|ui| {
            ui.set_max_width(190.0);
            if !n.title.is_empty() {
                ui.label(egui::RichText::new(&n.title).size(11.0));
            }
            if !n.targets.is_empty() {
                ui.label(
                    egui::RichText::new(format!("→ {}", n.targets.join(", ")))
                        .size(10.0)
                        .color(Color32::from_gray(150)),
                );
            }
            ui.colored_label(n.status.color(), n.status.label());
        });
    }

    fn show_input(
        &mut self,
        pin: &InPin,
        _ui: &mut egui::Ui,
        _scale: f32,
        snarl: &mut Snarl<FunnelNode>,
    ) -> PinInfo {
        let color = snarl.get_node(pin.id.node).map(|n| n.status.color()).unwrap_or(Color32::GRAY);
        PinInfo::circle().with_fill(color)
    }

    fn show_output(
        &mut self,
        pin: &OutPin,
        _ui: &mut egui::Ui,
        _scale: f32,
        snarl: &mut Snarl<FunnelNode>,
    ) -> PinInfo {
        let color = snarl.get_node(pin.id.node).map(|n| n.status.color()).unwrap_or(Color32::GRAY);
        PinInfo::triangle().with_fill(color)
    }

    // Read-only canvas: ignore user-drawn wires.
    fn connect(&mut self, _from: &OutPin, _to: &InPin, _snarl: &mut Snarl<FunnelNode>) {}
}

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

    fn node(id: &str, deps: &[&str]) -> NodeView {
        NodeView {
            id: id.into(),
            kind: "test".into(),
            title: String::new(),
            status: NodeStat::Pending,
            targets: Vec::new(),
            deps: deps.iter().map(|s| s.to_string()).collect(),
        }
    }

    /// Longest-path layering: a dependent sits one rank past its deepest dep.
    #[test]
    fn topo_layers_longest_path() {
        // n1,n2 roots; n3←n1; n4←n2; n5←{n3,n2} (so n5 = max(1,0)+1 = 2).
        let plan = PlanView {
            id: "p-001".into(),
            summary: String::new(),
            status: "active".into(),
            idea_text: String::new(),
            nodes: vec![
                node("n-1", &[]),
                node("n-2", &[]),
                node("n-3", &["n-1"]),
                node("n-4", &["n-2"]),
                node("n-5", &["n-3", "n-2"]),
            ],
        };
        let layers = topo_layers(&plan);
        assert_eq!(layers, vec![0, 0, 1, 1, 2]);
    }

    /// Unknown dep ids are ignored (never panic, treated as no edge).
    #[test]
    fn topo_layers_tolerates_dangling_dep() {
        let plan = PlanView {
            id: "p-002".into(),
            summary: String::new(),
            status: "draft".into(),
            idea_text: String::new(),
            nodes: vec![node("n-1", &["nope"]), node("n-2", &["n-1"])],
        };
        let layers = topo_layers(&plan);
        assert_eq!(layers, vec![0, 1]);

        // And the graph builds with the right node + wire counts.
        let snarl = build_snarl(&plan);
        assert_eq!(snarl.nodes().count(), 2);
        assert_eq!(snarl.wires().count(), 1);
    }
}