nornir 0.4.3

//! Connected **dep graph → call graph** tab.
//!
//! Drill `repo → crate → function calls`. The levels are one nested graph: repos
//! and crates come from `symbol_facts` (and line up with `dep_graph_edges.via`),
//! and the leaf call graph comes from `call_edges` (`caller_path → callee_ident`).
//! Data is read over `Warehouse.Scan` (columns + stringified rows), so this works
//! both **embedded** (local warehouse) and **remote** (against a `nornir-server`,
//! scoped by the `nornir-workspace` header), exactly like the warehouse browser.

use std::collections::HashMap;
use std::path::PathBuf;

use eframe::egui::{self, Color32, FontId, Pos2, Sense, Stroke, Vec2};

use crate::warehouse::iceberg::{IcebergWarehouse, TablePreview};

/// Rows scanned per table. Call graphs are bounded by this; we note truncation.
const SCAN_LIMIT: u32 = 8000;
/// Cap rendered nodes (highest-degree kept) so a huge crate stays legible.
const MAX_NODES: usize = 160;

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

struct Node {
    id: String,
    label: String,
    pos: Pos2,
    deg: usize,
}

pub struct CallGraphState {
    src: Src,
    loaded: bool,
    error: Option<String>,
    /// Distinct repos and their crates, from `symbol_facts`.
    repos: Vec<String>,
    crates_by_repo: HashMap<String, Vec<String>>,
    sel_repo: Option<String>,
    sel_crate: Option<String>,
    /// Cached `call_edges` scan (reused across crate switches).
    call_rows: Option<TablePreview>,
    /// Current laid-out graph.
    nodes: Vec<Node>,
    edges: Vec<(usize, usize)>,
    built_for: Option<(String, String)>,
    truncated: bool,
    pan: Vec2,
    zoom: f32,
}

impl CallGraphState {
    pub fn local(root: PathBuf) -> Self {
        Self::with(Src::Local(root))
    }
    pub fn remote(endpoint: String, token: String) -> Self {
        Self::with(Src::Remote { endpoint, token })
    }
    fn with(src: Src) -> Self {
        Self {
            src,
            loaded: false,
            error: None,
            repos: Vec::new(),
            crates_by_repo: HashMap::new(),
            sel_repo: None,
            sel_crate: None,
            call_rows: None,
            nodes: Vec::new(),
            edges: Vec::new(),
            built_for: None,
            truncated: false,
            pan: Vec2::ZERO,
            zoom: 1.0,
        }
    }

    fn scan(&self, table: &str) -> Result<TablePreview, String> {
        match &self.src {
            Src::Local(root) => IcebergWarehouse::open(root)
                .and_then(|wh| wh.scan_preview(table, SCAN_LIMIT as usize))
                .map_err(|e| format!("{e:#}")),
            Src::Remote { endpoint, token } => {
                super::remote::scan_table(endpoint, token, table, SCAN_LIMIT).map_err(|e| format!("{e:#}"))
            }
        }
    }

    /// Scan `symbol_facts` (for the repo/crate pickers) + `call_edges` once.
    fn ensure_loaded(&mut self) {
        if self.loaded {
            return;
        }
        self.loaded = true;
        let syms = match self.scan("symbol_facts") {
            Ok(p) => p,
            Err(e) => {
                self.error = Some(format!("scan symbol_facts: {e}"));
                return;
            }
        };
        let (Some(ri), Some(ci)) = (col(&syms, "repo"), col(&syms, "crate_name")) else {
            self.error = Some("symbol_facts missing repo/crate_name columns".into());
            return;
        };
        let mut repos: Vec<String> = Vec::new();
        for row in &syms.rows {
            let (repo, krate) = (cell(row, ri), cell(row, ci));
            if repo.is_empty() {
                continue;
            }
            if !repos.contains(&repo) {
                repos.push(repo.clone());
            }
            let cs = self.crates_by_repo.entry(repo).or_default();
            if !krate.is_empty() && !cs.contains(&krate) {
                cs.push(krate);
            }
        }
        repos.sort();
        for cs in self.crates_by_repo.values_mut() {
            cs.sort();
        }
        self.repos = repos;
        if self.sel_repo.is_none() {
            self.sel_repo = self.repos.first().cloned();
        }
        if let Some(r) = &self.sel_repo {
            self.sel_crate = self.crates_by_repo.get(r).and_then(|c| c.first().cloned());
        }

        match self.scan("call_edges") {
            Ok(p) => self.call_rows = Some(p),
            Err(e) => self.error = Some(format!("scan call_edges: {e}")),
        }
    }

    /// Build + lay out the call graph for the selected (repo, crate).
    fn build_graph(&mut self) {
        let (Some(repo), Some(krate)) = (self.sel_repo.clone(), self.sel_crate.clone()) else {
            self.nodes.clear();
            self.edges.clear();
            return;
        };
        if self.built_for.as_ref() == Some(&(repo.clone(), krate.clone())) {
            return;
        }
        self.built_for = Some((repo.clone(), krate.clone()));
        self.nodes.clear();
        self.edges.clear();
        self.truncated = false;

        let Some(rows) = &self.call_rows else { return };
        let (Some(ri), Some(ci), Some(fi), Some(ti)) = (
            col(rows, "repo"),
            col(rows, "crate_name"),
            col(rows, "caller_path"),
            col(rows, "callee_ident"),
        ) else {
            self.error = Some("call_edges missing expected columns".into());
            return;
        };

        // Collect raw edges for this crate, counting node degree.
        let mut deg: HashMap<String, usize> = HashMap::new();
        let mut raw: Vec<(String, String)> = Vec::new();
        for row in &rows.rows {
            if cell(row, ri) != repo || cell(row, ci) != krate {
                continue;
            }
            let (from, to) = (short(&cell(row, fi)), short(&cell(row, ti)));
            if from.is_empty() || to.is_empty() {
                continue;
            }
            *deg.entry(from.clone()).or_default() += 1;
            *deg.entry(to.clone()).or_default() += 1;
            raw.push((from, to));
        }

        // Cap to the highest-degree nodes for legibility.
        let mut keep: Vec<String> = deg.keys().cloned().collect();
        keep.sort_by(|a, b| deg[b].cmp(&deg[a]).then(a.cmp(b)));
        if keep.len() > MAX_NODES {
            keep.truncate(MAX_NODES);
            self.truncated = true;
        }
        let mut idx: HashMap<String, usize> = HashMap::new();
        let n = keep.len().max(1) as f32;
        for (i, id) in keep.iter().enumerate() {
            // Seed deterministically on a circle (no RNG → resume-safe).
            let ang = std::f32::consts::TAU * (i as f32) / n;
            idx.insert(id.clone(), self.nodes.len());
            self.nodes.push(Node {
                id: id.clone(),
                label: id.clone(),
                pos: Pos2::new(220.0 * ang.cos(), 220.0 * ang.sin()),
                deg: deg[id],
            });
        }
        for (from, to) in raw {
            if let (Some(&a), Some(&b)) = (idx.get(&from), idx.get(&to)) {
                if a != b {
                    self.edges.push((a, b));
                }
            }
        }
        self.layout();
        self.pan = Vec2::ZERO;
        self.zoom = 1.0;
    }

    /// Tiny Fruchterman–Reingold force layout (deterministic).
    fn layout(&mut self) {
        let n = self.nodes.len();
        if n < 2 {
            return;
        }
        let area = 640.0 * 480.0;
        let k = (area / n as f32).sqrt();
        let mut disp = vec![Vec2::ZERO; n];
        for _ in 0..120 {
            for d in disp.iter_mut() {
                *d = Vec2::ZERO;
            }
            // Repulsion (all pairs).
            for i in 0..n {
                for j in (i + 1)..n {
                    let mut delta = self.nodes[i].pos - self.nodes[j].pos;
                    let mut dist = delta.length();
                    if dist < 0.01 {
                        delta = Vec2::new(0.1 * (i as f32 + 1.0), 0.1);
                        dist = delta.length();
                    }
                    let force = (k * k) / dist;
                    let push = delta / dist * force;
                    disp[i] += push;
                    disp[j] -= push;
                }
            }
            // Attraction (edges).
            for &(a, b) in &self.edges {
                let delta = self.nodes[a].pos - self.nodes[b].pos;
                let dist = delta.length().max(0.01);
                let force = (dist * dist) / k;
                let pull = delta / dist * force;
                disp[a] -= pull;
                disp[b] += pull;
            }
            for i in 0..n {
                let d = disp[i];
                let len = d.length().max(0.01);
                self.nodes[i].pos += d / len * len.min(16.0);
            }
        }
    }

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

        egui::TopBottomPanel::top("cg_controls").show_inside(ui, |ui| {
            ui.horizontal_wrapped(|ui| {
                ui.label("repo:");
                let cur_repo = self.sel_repo.clone().unwrap_or_default();
                egui::ComboBox::from_id_source("cg_repo")
                    .selected_text(if cur_repo.is_empty() { "—".into() } else { cur_repo.clone() })
                    .show_ui(ui, |ui| {
                        for r in self.repos.clone() {
                            if ui.selectable_label(self.sel_repo.as_deref() == Some(&r), &r).clicked() {
                                self.sel_repo = Some(r.clone());
                                self.sel_crate =
                                    self.crates_by_repo.get(&r).and_then(|c| c.first().cloned());
                                self.built_for = None;
                            }
                        }
                    });
                ui.separator();
                ui.label("crate:");
                let crates = self
                    .sel_repo
                    .as_ref()
                    .and_then(|r| self.crates_by_repo.get(r))
                    .cloned()
                    .unwrap_or_default();
                let cur_crate = self.sel_crate.clone().unwrap_or_default();
                egui::ComboBox::from_id_source("cg_crate")
                    .selected_text(if cur_crate.is_empty() { "—".into() } else { cur_crate.clone() })
                    .show_ui(ui, |ui| {
                        for c in crates {
                            if ui.selectable_label(self.sel_crate.as_deref() == Some(&c), &c).clicked() {
                                self.sel_crate = Some(c);
                                self.built_for = None;
                            }
                        }
                    });
                ui.separator();
                if ui.button("↻ reload").clicked() {
                    self.loaded = false;
                    self.call_rows = None;
                    self.crates_by_repo.clear();
                    self.repos.clear();
                    self.built_for = None;
                    self.error = None;
                }
                if ui.button("⊙ fit").clicked() {
                    self.pan = Vec2::ZERO;
                    self.zoom = 1.0;
                }
            });
        });

        self.build_graph();

        egui::CentralPanel::default().show_inside(ui, |ui| {
            if let Some(err) = &self.error {
                ui.colored_label(Color32::RED, err);
                return;
            }
            if self.nodes.is_empty() {
                ui.label(
                    "no call edges for this crate (pick another repo/crate; \
                     monitoring fills call_edges as it republishes)",
                );
                return;
            }
            let (resp, painter) =
                ui.allocate_painter(ui.available_size(), Sense::click_and_drag());
            if resp.dragged() {
                self.pan += resp.drag_delta();
            }
            if resp.hovered() {
                let scroll = ui.input(|i| i.raw_scroll_delta.y);
                if scroll != 0.0 {
                    self.zoom = (self.zoom * (1.0 + scroll * 0.001)).clamp(0.2, 4.0);
                }
            }
            let origin = resp.rect.center() + self.pan;
            let tf = |p: Pos2| origin + p.to_vec2() * self.zoom;

            // Edges with a small arrowhead toward the callee.
            for &(a, b) in &self.edges {
                let (pa, pb) = (tf(self.nodes[a].pos), tf(self.nodes[b].pos));
                painter.line_segment([pa, pb], Stroke::new(1.0, Color32::from_gray(90)));
                let dir = (pb - pa).normalized();
                let head = pb - dir * (6.0 + 4.0 * self.zoom);
                let perp = Vec2::new(-dir.y, dir.x) * 3.0;
                painter.line_segment([pb, head + perp], Stroke::new(1.0, Color32::from_gray(120)));
                painter.line_segment([pb, head - perp], Stroke::new(1.0, Color32::from_gray(120)));
            }
            // Nodes: radius + color scale with call degree.
            for node in &self.nodes {
                let p = tf(node.pos);
                let r = (3.0 + (node.deg as f32).sqrt() * 1.6) * self.zoom.clamp(0.6, 2.0);
                painter.circle_filled(p, r, heat(node.deg));
                if self.zoom > 0.85 || node.deg >= 4 {
                    painter.text(
                        p + Vec2::new(r + 2.0, -r),
                        egui::Align2::LEFT_BOTTOM,
                        &node.label,
                        FontId::proportional(11.0),
                        Color32::from_gray(210),
                    );
                }
            }
            let (repo, krate) = self.built_for.clone().unwrap_or_default();
            let note = format!(
                "{repo} · {krate} — {} fns, {} calls{}  ·  drag to pan, scroll to zoom",
                self.nodes.len(),
                self.edges.len(),
                if self.truncated { format!(" (top {MAX_NODES})") } else { String::new() }
            );
            painter.text(
                resp.rect.left_top() + Vec2::new(8.0, 8.0),
                egui::Align2::LEFT_TOP,
                note,
                FontId::proportional(12.0),
                Color32::from_gray(160),
            );
        });
    }
}

/// Column index by name in a [`TablePreview`].
fn col(p: &TablePreview, name: &str) -> Option<usize> {
    p.columns.iter().position(|c| c == name)
}

fn cell(row: &[String], i: usize) -> String {
    row.get(i).cloned().unwrap_or_default()
}

/// Last `::`-segment of a path, for compact node labels.
fn short(path: &str) -> String {
    path.rsplit("::").next().unwrap_or(path).to_string()
}

/// Degree → warm color (cool=few calls, hot=hub).
fn heat(deg: usize) -> Color32 {
    let t = (deg as f32 / 12.0).clamp(0.0, 1.0);
    let r = (90.0 + 150.0 * t) as u8;
    let g = (150.0 - 60.0 * t) as u8;
    let b = (200.0 - 150.0 * t) as u8;
    Color32::from_rgb(r, g, b)
}