facett-menu 0.1.0

//! **facett-menu** — a uniform, theme-aware **overlay menu system** that sits
//! *above* any facet: right-click [`context_menu`]s, a floating [`CommandPalette`]
//! overlay (Ctrl-K / Ctrl-Shift-P), and classic dropdown [`menu_bar`]s. See
//! `.nornir/design/facett-menu.md`.
//!
//! ## One command set, three surfaces
//! A single [`Command`] type drives all three: the same action is reachable by
//! right-click, by typing in the palette, *and* by id from a headless test
//! ([`CommandPalette::invoke`]) — the house rule that nothing is pointer-only.
//! Commands carry a stable `id`, a `label`, a `group` (section / top-level menu),
//! an optional shortcut hint, an optional icon glyph, and an `enabled` flag.
//!
//! ## Theming
//! Every surface reads the facett [`Theme`](facett_core::Theme) from the egui
//! context ([`facett_core::theme`]) — `panel_bg` / `panel_stroke` / `accent` /
//! `glow` / `text` / `text_dim` — so menus match every component and the sci-fi
//! look. The selected palette row is painted with the theme `accent` plus a
//! layered `glow` bloom; nothing is hardcoded.
//!
//! ```no_run
//! # use facett_menu::{Command, CommandPalette, menu_bar, context_menu};
//! let cmds = vec![
//!     Command::new("copy", "Copy", "Edit"),
//!     Command::new("case.new", "New case", "Case"),
//! ];
//! let mut palette = CommandPalette::default();
//! // each frame, after drawing the deck:
//! # let ctx = egui::Context::default();
//! if let Some(id) = palette.ui(&ctx, &cmds) {
//!     // dispatch `id` ...
//! }
//! ```

use egui::{Align2, Color32, Key, Order, Stroke, Ui, vec2};
use facett_core::theme;

/// A user-invokable action. The same command appears in context menus, the
/// command palette, and menu bars — and can be fired by id from a headless test.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Command {
    /// Stable, headless-addressable id (`"copy"`, `"case.new"`).
    pub id: &'static str,
    /// Shown to the user.
    pub label: String,
    /// Section heading / top-level menu name (`"Edit"`, `"View"`, `"Case"`).
    pub group: &'static str,
    /// Extra search terms (matched by the palette, never shown).
    pub keywords: Vec<&'static str>,
    /// A human-readable shortcut hint shown right-aligned (`"Ctrl+C"`). Display
    /// only — the host owns the real key binding.
    pub shortcut: Option<&'static str>,
    /// Disabled commands are dimmed, unclickable, and never matched by the palette.
    pub enabled: bool,
    /// Optional leading glyph (e.g. an egui-phosphor icon char).
    pub icon: Option<&'static str>,
}

impl Command {
    /// A new, enabled command with no shortcut / icon / keywords.
    pub fn new(id: &'static str, label: impl Into<String>, group: &'static str) -> Self {
        Self { id, label: label.into(), group, keywords: Vec::new(), shortcut: None, enabled: true, icon: None }
    }
    /// Builder: attach a display shortcut hint.
    pub fn shortcut(mut self, s: &'static str) -> Self {
        self.shortcut = Some(s);
        self
    }
    /// Builder: attach a leading icon glyph.
    pub fn icon(mut self, glyph: &'static str) -> Self {
        self.icon = Some(glyph);
        self
    }
    /// Builder: extra search keywords (palette only).
    pub fn keywords(mut self, kw: &[&'static str]) -> Self {
        self.keywords = kw.to_vec();
        self
    }
    /// Builder: set the enabled flag (disabled = dimmed + unmatchable).
    pub fn enabled(mut self, on: bool) -> Self {
        self.enabled = on;
        self
    }

    /// The text the palette fuzzy-matches against: label + id + keywords.
    fn haystack(&self) -> String {
        let mut h = format!("{} {}", self.label, self.id);
        for k in &self.keywords {
            h.push(' ');
            h.push_str(k);
        }
        h.to_lowercase()
    }
}

/// Subsequence fuzzy score: `None` if `needle`'s chars don't appear in order in
/// `haystack`. Otherwise a higher score is a better match — contiguous runs and
/// matches at word starts (after a space / `.` / `_`) are rewarded, and a tighter
/// overall span scores higher. An empty needle matches everything with score 0.
fn fuzzy_score(needle: &str, haystack: &str) -> Option<i32> {
    if needle.is_empty() {
        return Some(0);
    }
    let hay: Vec<char> = haystack.chars().collect();
    let mut score = 0i32;
    let mut hi = 0usize;
    let mut first = None;
    let mut last = 0usize;
    let mut prev_matched = false;
    for nc in needle.chars() {
        // advance to the next occurrence of nc
        let mut found = false;
        while hi < hay.len() {
            if hay[hi] == nc {
                found = true;
                break;
            }
            hi += 1;
        }
        if !found {
            return None;
        }
        if first.is_none() {
            first = Some(hi);
        }
        last = hi;
        score += 1;
        if prev_matched {
            score += 5; // contiguous run bonus
        }
        let at_word_start = hi == 0 || matches!(hay[hi - 1], ' ' | '.' | '_' | '-' | '/');
        if at_word_start {
            score += 3;
        }
        prev_matched = true;
        hi += 1;
    }
    // tighter span is better; penalise sprawl gently
    let span = last - first.unwrap_or(0);
    score -= span as i32 / 4;
    Some(score)
}

/// The commands an enabled palette query matches, best-ranked first. Public so a
/// host (or a headless test) can reproduce exactly what the palette would show.
/// Ties keep registry order (stable sort) so the layout is deterministic.
pub fn rank<'a>(query: &str, commands: &'a [Command]) -> Vec<&'a Command> {
    let q = query.to_lowercase();
    let mut scored: Vec<(i32, usize, &Command)> = commands
        .iter()
        .enumerate()
        .filter(|(_, c)| c.enabled)
        .filter_map(|(i, c)| fuzzy_score(&q, &c.haystack()).map(|s| (s, i, c)))
        .collect();
    // higher score first; ties → original order
    scored.sort_by(|a, b| b.0.cmp(&a.0).then(a.1.cmp(&b.1)));
    scored.into_iter().map(|(_, _, c)| c).collect()
}

/// A floating, theme-aware **command palette** overlay. Opened by Ctrl-K /
/// Ctrl-Shift-P (or [`CommandPalette::open`]), it paints a scrim + a centered
/// search box + a fuzzy-filtered, keyboard-navigable command list above
/// everything (`Order::Foreground`). Pure data between frames; draw it once per
/// frame *after* your deck so it lands on top.
#[derive(Default)]
pub struct CommandPalette {
    open: bool,
    query: String,
    cursor: usize,
    invoked: Option<&'static str>,
}

impl CommandPalette {
    /// Open the palette, clearing the query and selection.
    pub fn open(&mut self) {
        self.open = true;
        self.query.clear();
        self.cursor = 0;
    }
    /// Close the palette (does not clear `invoked`).
    pub fn close(&mut self) {
        self.open = false;
    }
    /// Is the overlay currently showing?
    pub fn is_open(&self) -> bool {
        self.open
    }
    /// The last command fired (by pick or [`invoke`](Self::invoke)).
    pub fn invoked(&self) -> Option<&'static str> {
        self.invoked
    }
    /// Current query text (observable for tests).
    pub fn query(&self) -> &str {
        &self.query
    }
    /// Current highlighted-row index, into [`rank`]'s result for the query.
    pub fn cursor(&self) -> usize {
        self.cursor
    }

    /// Move the selection by `delta`, **wrapping** within `len` rows. No-op when
    /// `len == 0`. Up at the top wraps to the bottom; down at the bottom wraps to
    /// the top. Split out so headless tests can drive nav without drawing.
    pub fn move_cursor(&mut self, delta: i32, len: usize) {
        if len == 0 {
            self.cursor = 0;
            return;
        }
        let n = len as i32;
        self.cursor = (((self.cursor as i32 + delta) % n + n) % n) as usize;
    }

    /// Headless: fire a command by id without drawing (CLI / test parity). Sets
    /// `invoked`, closes the palette, and echoes the id back.
    pub fn invoke(&mut self, id: &'static str) -> &'static str {
        self.invoked = Some(id);
        self.open = false;
        id
    }

    /// Observable state for the introspection dump.
    pub fn state_json(&self, commands: &[Command]) -> serde_json::Value {
        serde_json::json!({
            "open": self.open,
            "query": self.query,
            "cursor": self.cursor,
            "commands": commands.iter().map(|c| c.id).collect::<Vec<_>>(),
            "hits": rank(&self.query, commands).iter().map(|c| c.id).collect::<Vec<_>>(),
            "invoked": self.invoked,
        })
    }

    /// Read the open/close hotkeys for this frame (Ctrl-K / Ctrl-Shift-P open,
    /// Esc closes). Call from a host that wants the palette toggled even on a
    /// frame it doesn't draw; [`ui`](Self::ui) calls this itself.
    pub fn handle_hotkeys(&mut self, ctx: &egui::Context) {
        ctx.input(|i| {
            let cmd = i.modifiers.command;
            if cmd && i.key_pressed(Key::K) {
                self.open = true;
                self.query.clear();
                self.cursor = 0;
            }
            if cmd && i.modifiers.shift && i.key_pressed(Key::P) {
                self.open = true;
                self.query.clear();
                self.cursor = 0;
            }
            if i.key_pressed(Key::Escape) {
                self.open = false;
            }
        });
    }

    /// Draw the overlay (scrim + search box + fuzzy-filtered list) above
    /// everything, handling Ctrl-K to open, arrows (wrapping) to navigate, Enter
    /// to pick, Esc to close. Returns the chosen command id, if any. No-op (and
    /// returns `None`) while closed.
    pub fn ui(&mut self, ctx: &egui::Context, commands: &[Command]) -> Option<&'static str> {
        self.handle_hotkeys(ctx);
        if !self.open {
            return None;
        }

        // Theme: read via a throwaway pass-free path — the context holds it.
        let th = ctx.data(|d| d.get_temp::<facett_core::Theme>(egui::Id::new("facett_theme"))).unwrap_or_default();
        let screen = ctx.content_rect();

        // Scrim behind the palette.
        egui::Area::new("facett_palette_scrim".into())
            .order(Order::Foreground)
            .fixed_pos(screen.min)
            .interactable(false)
            .show(ctx, |ui| {
                ui.painter().rect_filled(screen, 0.0, Color32::from_black_alpha(160));
            });

        let mut chosen = None;
        egui::Area::new("facett_palette".into())
            .order(Order::Foreground)
            .anchor(Align2::CENTER_TOP, vec2(0.0, 80.0))
            .show(ctx, |ui| {
                egui::Frame::popup(ui.style())
                    .fill(th.panel_bg)
                    .stroke(Stroke::new(1.0, th.panel_stroke))
                    .show(ui, |ui| {
                        ui.set_width(520.0);

                        let edit = ui.add(
                            egui::TextEdit::singleline(&mut self.query).hint_text("Type a command…").desired_width(f32::INFINITY),
                        );
                        edit.request_focus();

                        let hits = rank(&self.query, commands);

                        // Keyboard nav (wrapping) + Enter/Esc. Read before the
                        // TextEdit had a chance to swallow the arrows is not
                        // possible here, but arrows aren't consumed by a
                        // singleline edit, so this is fine.
                        let (down, up, enter) = ui.input(|i| {
                            (i.key_pressed(Key::ArrowDown), i.key_pressed(Key::ArrowUp), i.key_pressed(Key::Enter))
                        });
                        if down {
                            self.move_cursor(1, hits.len());
                        }
                        if up {
                            self.move_cursor(-1, hits.len());
                        }
                        if hits.is_empty() {
                            self.cursor = 0;
                        } else if self.cursor >= hits.len() {
                            self.cursor = hits.len() - 1;
                        }

                        ui.separator();

                        for (i, c) in hits.iter().enumerate() {
                            let sel = i == self.cursor;
                            let row = row_text(c);
                            let resp = ui.selectable_label(sel, row);
                            if sel {
                                // accent underline + glow bloom on the selected row
                                let r = resp.rect;
                                let p = ui.painter();
                                for w in 1..=4 {
                                    let a = (70 / w) as u8;
                                    let g = Color32::from_rgba_unmultiplied(th.glow.r(), th.glow.g(), th.glow.b(), a);
                                    p.line_segment(
                                        [r.left_bottom() + vec2(0.0, w as f32), r.right_bottom() + vec2(0.0, w as f32)],
                                        Stroke::new(1.0, g),
                                    );
                                }
                                p.line_segment([r.left_bottom(), r.right_bottom()], Stroke::new(1.5, th.accent));
                            }
                            if resp.clicked() {
                                chosen = Some(c.id);
                            }
                        }

                        if hits.is_empty() {
                            ui.weak("No matching commands");
                        }

                        if enter {
                            chosen = hits.get(self.cursor).map(|c| c.id);
                        }
                    });
            });

        if let Some(id) = chosen {
            self.open = false;
            self.invoked = Some(id);
        }
        chosen
    }
}

/// One palette/menu row label: `icon  label … shortcut` (icon/shortcut omitted
/// when absent). The group is *not* appended here — the menu bar / context menu
/// already group by it; the palette shows it via the trailing dim group below.
fn row_text(c: &Command) -> String {
    let mut s = String::new();
    if let Some(ic) = c.icon {
        s.push_str(ic);
        s.push(' ');
    }
    s.push_str(&c.label);
    s.push_str("   ·  ");
    s.push_str(c.group);
    if let Some(sc) = c.shortcut {
        s.push_str("   ");
        s.push_str(sc);
    }
    s
}

/// A right-click **context menu** built from the same [`Command`] set. Call from
/// inside `response.context_menu(|ui| { … })` — or use [`attach_context_menu`] to
/// wrap a [`Response`](egui::Response) directly. Commands are grouped by their
/// `group` with separators between groups; disabled commands render dimmed and
/// unclickable. Returns the chosen id (and closes the menu) when one is picked.
pub fn context_menu(ui: &mut Ui, commands: &[Command]) -> Option<&'static str> {
    let th = theme(ui);
    let mut chosen = None;
    let mut last_group: Option<&'static str> = None;
    for c in commands {
        if last_group.is_some() && last_group != Some(c.group) {
            ui.separator();
        }
        last_group = Some(c.group);

        let btn = egui::Button::new(menu_label(c)).wrap_mode(egui::TextWrapMode::Extend);
        let resp = ui.add_enabled(c.enabled, btn);
        // theme-aware hover accent
        if resp.hovered() && c.enabled {
            let r = resp.rect;
            ui.painter().line_segment([r.left_bottom(), r.right_bottom()], Stroke::new(1.0, th.accent));
        }
        if resp.clicked() {
            chosen = Some(c.id);
            ui.close();
        }
    }
    chosen
}

/// Attach a theme-aware right-click [`context_menu`] to any
/// [`Response`](egui::Response), threading the picked command id out through
/// `on_pick`. The closure fires at most once, on the frame an item is clicked.
///
/// ```no_run
/// # use facett_menu::{Command, attach_context_menu};
/// # let ui: &mut egui::Ui = todo!();
/// let cmds = [Command::new("copy", "Copy", "Edit")];
/// let resp = ui.label("right-click me");
/// attach_context_menu(&resp, &cmds, |id| { /* dispatch id */ let _ = id; });
/// ```
pub fn attach_context_menu(response: &egui::Response, commands: &[Command], mut on_pick: impl FnMut(&'static str)) {
    response.context_menu(|ui| {
        if let Some(id) = context_menu(ui, commands) {
            on_pick(id);
        }
    });
}

/// A classic **menu bar** from grouped commands: each distinct `group` becomes a
/// top-level dropdown (`File` / `Edit` / …) holding its commands, in first-seen
/// order. Theme-aware via the facett `Theme`. Returns the chosen id, if any.
/// Call inside an `egui::menu::bar(ui, |ui| { … })` or a top panel.
pub fn menu_bar(ui: &mut Ui, commands: &[Command]) -> Option<&'static str> {
    let mut chosen = None;
    egui::MenuBar::new().ui(ui, |ui| {
        // first-seen group order
        let mut groups: Vec<&'static str> = Vec::new();
        for c in commands {
            if !groups.contains(&c.group) {
                groups.push(c.group);
            }
        }
        for g in groups {
            ui.menu_button(g, |ui| {
                let in_group: Vec<&Command> = commands.iter().filter(|c| c.group == g).collect();
                for c in in_group {
                    let btn = egui::Button::new(menu_label(c)).wrap_mode(egui::TextWrapMode::Extend);
                    let resp = ui.add_enabled(c.enabled, btn);
                    if resp.clicked() {
                        chosen = Some(c.id);
                        ui.close();
                    }
                }
            });
        }
    });
    chosen
}

/// A menu/context-menu row label: `icon  label … shortcut` (no group — the menu
/// already groups). Right-padding before the shortcut keeps it loosely aligned.
fn menu_label(c: &Command) -> String {
    let mut s = String::new();
    if let Some(ic) = c.icon {
        s.push_str(ic);
        s.push(' ');
    }
    s.push_str(&c.label);
    if let Some(sc) = c.shortcut {
        s.push_str("      ");
        s.push_str(sc);
    }
    s
}

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

    fn sample() -> Vec<Command> {
        vec![
            Command::new("copy", "Copy", "Edit").shortcut("Ctrl+C"),
            Command::new("cut", "Cut", "Edit").enabled(false),
            Command::new("paste", "Paste", "Edit"),
            Command::new("case.new", "New case", "Case").keywords(&["create", "investigation"]),
            Command::new("case.open", "Open case", "Case"),
            Command::new("view.zoom", "Zoom in", "View"),
        ]
    }

    #[test]
    fn fuzzy_matches_subsequence_only() {
        // "nc" is a subsequence of "new case"
        assert!(fuzzy_score("nc", "new case").is_some());
        // "zzz" is not in "copy"
        assert!(fuzzy_score("zzz", "copy").is_none());
        // empty needle matches with score 0
        assert_eq!(fuzzy_score("", "anything"), Some(0));
    }

    #[test]
    fn fuzzy_prefers_word_start_and_contiguous() {
        // contiguous prefix "cop" beats scattered "cpy"
        let contiguous = fuzzy_score("cop", "copy").unwrap();
        let scattered = fuzzy_score("cy", "copy").unwrap();
        assert!(contiguous > scattered, "contiguous {contiguous} should beat scattered {scattered}");
    }

    #[test]
    fn rank_filters_disabled_and_ranks_relevant_first() {
        let cmds = sample();
        // "Cut" is disabled → never appears
        let hits = rank("", &cmds);
        assert!(hits.iter().all(|c| c.id != "cut"), "disabled command must be filtered out");
        // querying "case" surfaces the two case commands ahead of the rest
        let hits = rank("case", &cmds);
        assert!(hits.len() >= 2);
        assert!(hits[0].group == "Case" && hits[1].group == "Case", "case.* should rank first, got {:?}", hits.iter().map(|c| c.id).collect::<Vec<_>>());
    }

    #[test]
    fn rank_matches_keywords_not_just_label() {
        let cmds = sample();
        // "investigation" is a keyword of case.new, not in any label
        let hits = rank("investigation", &cmds);
        assert_eq!(hits.first().map(|c| c.id), Some("case.new"));
    }

    #[test]
    fn cursor_wraps_both_directions() {
        let mut p = CommandPalette::default();
        let len = 3;
        // down past the end wraps to 0
        p.move_cursor(1, len); // 1
        p.move_cursor(1, len); // 2
        p.move_cursor(1, len); // wrap → 0
        assert_eq!(p.cursor(), 0);
        // up from 0 wraps to len-1
        p.move_cursor(-1, len);
        assert_eq!(p.cursor(), len - 1);
        // empty list keeps cursor at 0
        p.move_cursor(1, 0);
        assert_eq!(p.cursor(), 0);
    }

    #[test]
    fn invoke_sets_invoked_and_closes() {
        let mut p = CommandPalette::default();
        p.open();
        assert!(p.is_open());
        let id = p.invoke("copy");
        assert_eq!(id, "copy");
        assert_eq!(p.invoked(), Some("copy"));
        assert!(!p.is_open(), "invoke closes the palette");
    }

    #[test]
    fn state_json_carries_hits_and_invoked() {
        let cmds = sample();
        let mut p = CommandPalette::default();
        p.open();
        p.invoke("case.new");
        let j = p.state_json(&cmds);
        assert_eq!(j["invoked"], "case.new");
        // every registered command id is listed
        assert_eq!(j["commands"].as_array().unwrap().len(), cmds.len());
        // disabled "cut" is absent from hits
        let hits: Vec<&str> = j["hits"].as_array().unwrap().iter().map(|v| v.as_str().unwrap()).collect();
        assert!(!hits.contains(&"cut"));
    }

    #[test]
    fn command_builders_compose() {
        let c = Command::new("x", "X", "G").shortcut("Ctrl+X").icon(">").keywords(&["a", "b"]).enabled(false);
        assert_eq!(c.shortcut, Some("Ctrl+X"));
        assert_eq!(c.icon, Some(">"));
        assert_eq!(c.keywords, vec!["a", "b"]);
        assert!(!c.enabled);
    }

    #[test]
    fn disabled_command_never_matched_by_palette() {
        // even an exact id query can't surface a disabled command
        let cmds = sample();
        let hits = rank("cut", &cmds);
        assert!(hits.iter().all(|c| c.id != "cut"));
    }
}