tek/crates/tek_sequencer/src/sequencer.rs

use crate::*;

const CORNERS: CornersTall = CornersTall(NOT_DIM_GREEN);

tui_style!(GRAY_DIM           =
    Some(Color::Gray),             None,            None, Modifier::DIM,     Modifier::empty());
tui_style!(GRAY_NOT_DIM_BOLD  =
    Some(Color::Gray),             None,            None, Modifier::BOLD,    Modifier::DIM);
tui_style!(NOT_DIM_BOLD       =
    None,                          None,            None, Modifier::BOLD,    Modifier::DIM);
tui_style!(NOT_DIM_GREEN      =
    Some(Color::Rgb(96, 255, 32)), Some(COLOR_BG1), None, Modifier::empty(), Modifier::DIM);
tui_style!(NOT_DIM            =
    None,                          None,            None, Modifier::empty(), Modifier::DIM);
tui_style!(WHITE_NOT_DIM_BOLD =
    Some(Color::White),            None,            None, Modifier::BOLD,    Modifier::DIM);
tui_style!(STYLE_LABEL        =
    Some(Color::Reset),            None,            None, Modifier::empty(), Modifier::BOLD);
tui_style!(STYLE_VALUE        =
    Some(Color::White),            None,            None, Modifier::BOLD,    Modifier::DIM);

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Represents the tracks and scenes of the composition.
pub struct Arranger<E: Engine> {
    /// Name of arranger
    pub name:     Arc<RwLock<String>>,
    /// Collection of tracks.
    pub tracks:   Vec<Sequencer<E>>,
    /// Collection of scenes.
    pub scenes:   Vec<Scene>,
    /// Currently selected element.
    pub selected: ArrangerFocus,
    /// Display mode of arranger
    pub mode:     ArrangerViewMode,
    /// Slot for modal dialog displayed on top of app.
    pub modal:    Option<Box<dyn ExitableComponent<E>>>,
    /// Whether the arranger is currently focused
    pub focused:  bool
}

impl<E: Engine> Arranger<E> {
    pub fn new (name: &str) -> Self {
        Self {
            name:     Arc::new(RwLock::new(name.into())),
            mode:     ArrangerViewMode::VerticalCompact2,
            selected: ArrangerFocus::Clip(0, 0),
            scenes:   vec![],
            tracks:   vec![],
            modal:    None,
            focused:  false
        }
    }
    pub fn activate (&mut self) {
        match self.selected {
            ArrangerFocus::Scene(s) => {
                for (track_index, track) in self.tracks.iter_mut().enumerate() {
                    track.sequence = self.scenes[s].clips[track_index];
                    track.reset = true;
                }
            },
            ArrangerFocus::Clip(t, s) => {
                self.tracks[t].sequence = self.scenes[s].clips[t];
                self.tracks[t].reset = true;
            },
            _ => {}
        }
    }
    pub fn sequencer (&self) -> Option<&Sequencer<E>> {
        self.selected.track()
            .map(|track|self.tracks.get(track))
            .flatten()
    }
    pub fn sequencer_mut (&mut self) -> Option<&mut Sequencer<E>> {
        self.selected.track()
            .map(|track|self.tracks.get_mut(track))
            .flatten()
    }
    pub fn show_phrase (&mut self) -> Usually<()> {
        //unimplemented!()
        //let phrase = self.phrase();
        //self.sequencer.show(phrase)
        Ok(())
    }
    pub fn is_first_row (&self) -> bool {
        let selected = self.selected;
        selected.is_mix() || selected.is_track() || match selected {
            ArrangerFocus::Clip(_, s) =>
                s == 0,
            _ => false
        }
    }
    pub fn is_last_row (&self) -> bool {
        let selected = self.selected;
        match selected {
            ArrangerFocus::Scene(s) =>
                s == self.scenes.len() - 1,
            ArrangerFocus::Clip(_, s) =>
                s == self.scenes.len() - 1,
            _ => false
        }
    }
    pub fn track (&self) -> Option<&Sequencer<E>> {
        self.selected.track().map(|t|self.tracks.get(t)).flatten()
    }
    pub fn track_mut (&mut self) -> Option<&mut Sequencer<E>> {
        self.selected.track().map(|t|self.tracks.get_mut(t)).flatten()
    }
    pub fn track_next (&mut self) {
        self.selected.track_next(self.tracks.len() - 1)
    }
    pub fn track_prev (&mut self) {
        self.selected.track_prev()
    }
    pub fn track_add (&mut self, name: Option<&str>) -> Usually<&mut Sequencer<E>> {
        self.tracks.push(name.map_or_else(
            || Sequencer::new(&self.track_default_name()),
            |name| Sequencer::new(name),
        ));
        let index = self.tracks.len() - 1;
        Ok(&mut self.tracks[index])
    }
    pub fn track_del (&mut self) {
        unimplemented!("Arranger::track_del");
    }
    pub fn track_default_name (&self) -> String {
        format!("Track {}", self.tracks.len() + 1)
    }
    pub fn scene (&self) -> Option<&Scene> {
        self.selected.scene().map(|s|self.scenes.get(s)).flatten()
    }
    pub fn scene_mut (&mut self) -> Option<&mut Scene> {
        self.selected.scene().map(|s|self.scenes.get_mut(s)).flatten()
    }
    pub fn scene_next (&mut self) {
        self.selected.scene_next(self.scenes.len() - 1)
    }
    pub fn scene_prev (&mut self) {
        self.selected.scene_prev()
    }
    pub fn scene_add (&mut self, name: Option<&str>) -> Usually<&mut Scene> {
        let clips = vec![None;self.tracks.len()];
        self.scenes.push(match name {
            Some(name) => Scene::new(name, clips),
            None       => Scene::new(&self.scene_default_name(), clips),
        });
        let index = self.scenes.len() - 1;
        Ok(&mut self.scenes[index])
    }
    pub fn scene_del (&mut self) {
        unimplemented!("Arranger::scene_del");
    }
    pub fn scene_default_name (&self) -> String {
        format!("Scene {}", self.scenes.len() + 1)
    }
    pub fn phrase (&self) -> Option<&Arc<RwLock<Phrase>>> {
        let track_id = self.selected.track()?;
        self.tracks.get(track_id)?.phrases.get((*self.scene()?.clips.get(track_id)?)?)
    }
    pub fn phrase_next (&mut self) {
        let track_index = self.selected.track();
        let scene_index = self.selected.scene();
        track_index
            .and_then(|index|self.tracks.get_mut(index).map(|track|(index, track)))
            .and_then(|(track_index, track)|{
                let phrases = track.phrases.len();
                scene_index
                    .and_then(|index|self.scenes.get_mut(index))
                    .and_then(|scene|{
                        if let Some(phrase_index) = scene.clips[track_index] {
                            if phrase_index >= phrases - 1 {
                                scene.clips[track_index] = None;
                            } else {
                                scene.clips[track_index] = Some(phrase_index + 1);
                            }
                        } else if phrases > 0 {
                            scene.clips[track_index] = Some(0);
                        }
                        Some(())
                    })
            });
    }
    pub fn phrase_prev (&mut self) {
        let track_index = self.selected.track();
        let scene_index = self.selected.scene();
        track_index
            .and_then(|index|self.tracks.get_mut(index).map(|track|(index, track)))
            .and_then(|(track_index, track)|{
                let phrases = track.phrases.len();
                scene_index
                    .and_then(|index|self.scenes.get_mut(index))
                    .and_then(|scene|{
                        if let Some(phrase_index) = scene.clips[track_index] {
                            scene.clips[track_index] = if phrase_index == 0 {
                                None
                            } else {
                                Some(phrase_index - 1)
                            };
                        } else if phrases > 0 {
                            scene.clips[track_index] = Some(phrases - 1);
                        }
                        Some(())
                    })
            });
    }
}

impl Arranger<Tui> {
    pub fn rename_selected (&mut self) {
        self.modal = Some(Box::new(ArrangerRenameModal::new(
            self.selected,
            &match self.selected {
                ArrangerFocus::Mix => self.name.clone(),
                ArrangerFocus::Track(t) => self.tracks[t].name.clone(),
                ArrangerFocus::Scene(s) => self.scenes[s].name.clone(),
                ArrangerFocus::Clip(t, s) => self.tracks[t].phrases[s].read().unwrap().name.clone(),
            }
        )));
    }
}

impl Handle<Tui> for Arranger<Tui> {
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        if let Some(modal) = self.modal.as_mut() {
            let result = modal.handle(from)?;
            if modal.exited() {
                self.modal = None;
            }
            return Ok(result)
        }
        match from.event() {
            // mode_switch: switch the display mode
            key!(KeyCode::Char('`')) => {
                self.mode.to_next()
            },
            // cursor_up: move cursor up
            key!(KeyCode::Up) => {
                match self.mode {
                    ArrangerViewMode::Horizontal => self.track_prev(),
                    _ => self.scene_prev(),
                };
                self.show_phrase()?;
            },
            // cursor_down
            key!(KeyCode::Down) => {
                match self.mode {
                    ArrangerViewMode::Horizontal => self.track_next(),
                    _ => self.scene_next(),
                };
                self.show_phrase()?;
            },
            // cursor left
            key!(KeyCode::Left) => {
                match self.mode {
                    ArrangerViewMode::Horizontal => self.scene_prev(),
                    _ => self.track_prev(),
                };
                self.show_phrase()?;
            },
            // cursor right
            key!(KeyCode::Right) => {
                match self.mode {
                    ArrangerViewMode::Horizontal => self.scene_next(),
                    _ => self.track_next(),
                };
                self.show_phrase()?;
            },
            // increment: use next clip here
            key!(KeyCode::Char('.')) => {
                self.phrase_next();
            },
            // decrement: use previous next clip here
            key!(KeyCode::Char(',')) => {
                self.phrase_prev();
            },
            // decrement: use previous clip here
            key!(KeyCode::Enter) => {
                self.activate();
            },
            // scene_add: add a new scene
            key!(Ctrl-KeyCode::Char('a')) => {
                self.scene_add(None)?;
            },
            // track_add: add a new scene
            key!(Ctrl-KeyCode::Char('t')) => {
                self.track_add(None)?;
            },
            // rename: add a new scene
            key!(KeyCode::Char('n')) => {
                self.rename_selected();
            },
            // length: add a new scene
            key!(KeyCode::Char('l')) => {
                todo!();
            },
            // color: set color of item at cursor
            key!(KeyCode::Char('c')) => {
                todo!();
            },
            _ => return Ok(None)
        }
        Ok(Some(true))
    }
}

impl Content for Arranger<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        Layers::new(move |add|{
            //Lozenge(Style::default().fg(Nord::BG2))
                //.draw(&mut to.alter_area(|[x, y, w, h]|[
                    //x.saturating_sub(1),
                    //y.saturating_sub(1),
                    //w + 2,
                    //h + 2,
                //]))
            match self.mode {
                ArrangerViewMode::Horizontal => add(&ArrangerViewHorizontal(&self)),
                ArrangerViewMode::VerticalCompact1 => add(&ArrangerViewVertical(
                    &self,
                    track_clip_name_lengths(self.tracks.as_slice()).as_slice(),
                    (0..=self.scenes.len()).map(|i|(96, 96*i)).collect::<Vec<_>>().as_slice(),
                )),
                ArrangerViewMode::VerticalCompact2 => add(&ArrangerViewVertical(
                    &self,
                    track_clip_name_lengths(self.tracks.as_slice()).as_slice(),
                    (0..=self.scenes.len()).map(|i|(192, 192*i)).collect::<Vec<_>>().as_slice()
                )),
                ArrangerViewMode::VerticalExpanded => add(&ArrangerViewVertical(
                    &self,
                    track_clip_name_lengths(self.tracks.as_slice()).as_slice(),
                    scene_ppqs(self.tracks.as_slice(), self.scenes.as_slice()).as_slice(),
                )),
            }
        })
    }
}

pub fn scene_ppqs <E: Engine> (
    tracks: &[Sequencer<E>],
    scenes: &[Scene]
) -> Vec<(usize, usize)> {
    let mut total = 0;
    let mut scenes: Vec<(usize, usize)> = scenes.iter().map(|scene|{
        let pulses = scene.pulses(tracks).max(96);
        total = total + pulses;
        (pulses, total - pulses)
    }).collect();
    scenes.push((0, total));
    scenes
}

pub fn track_clip_name_lengths <E: Engine> (tracks: &[Sequencer<E>]) -> Vec<(usize, usize)> {
    let mut total = 0;
    let mut lengths: Vec<(usize, usize)> = tracks.iter().map(|track|{
        let len = 4 + track.phrases
            .iter()
            .fold(track.name.read().unwrap().len(), |len, phrase|{
                len.max(phrase.read().unwrap().name.read().unwrap().len())
            });
        total = total + len;
        (len, total - len)
    }).collect();
    lengths.push((0, total));
    lengths
}

impl Focusable<Tui> for Arranger<Tui> {
    fn is_focused (&self) -> bool {
        self.focused
    }
    fn set_focused (&mut self, focused: bool) {
        self.focused = focused
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

#[derive(PartialEq, Clone, Copy)]
/// Represents the current user selection in the arranger
pub enum ArrangerFocus {
    /** The whole mix is selected */
    Mix,
    /// A track is selected.
    Track(usize),
    /// A scene is selected.
    Scene(usize),
    /// A clip (track × scene) is selected.
    Clip(usize, usize),
}

/// Focus identification methods
impl ArrangerFocus {
    pub fn is_mix (&self) -> bool {
        match self { Self::Mix => true, _ => false }
    }
    pub fn is_track (&self) -> bool {
        match self { Self::Track(_) => true, _ => false }
    }
    pub fn is_scene (&self) -> bool {
        match self { Self::Scene(_) => true, _ => false }
    }
    pub fn is_clip (&self) -> bool {
        match self { Self::Clip(_, _) => true, _ => false }
    }
    pub fn track (&self) -> Option<usize> {
        match self {
            Self::Clip(t, _) => Some(*t),
            Self::Track(t)   => Some(*t),
            _ => None
        }
    }
    pub fn track_next (&mut self, last_track: usize) {
        *self = match self {
            Self::Mix        => Self::Track(0),
            Self::Track(t)   => Self::Track(last_track.min(*t + 1)),
            Self::Scene(s)   => Self::Clip(0, *s),
            Self::Clip(t, s) => Self::Clip(last_track.min(*t + 1), *s),
        }
    }
    pub fn track_prev (&mut self) {
        *self = match self {
            Self::Mix      => Self::Mix,
            Self::Scene(s) => Self::Scene(*s),
            Self::Track(t) => if *t == 0 {
                Self::Mix
            } else {
                Self::Track(*t - 1)
            },
            Self::Clip(t, s) => if *t == 0 {
                Self::Scene(*s)
            } else {
                Self::Clip(t.saturating_sub(1), *s)
            }
        }
    }
    pub fn scene (&self) -> Option<usize> {
        match self {
            Self::Clip(_, s) => Some(*s),
            Self::Scene(s)   => Some(*s),
            _ => None
        }
    }
    pub fn scene_next (&mut self, last_scene: usize) {
        *self = match self {
            Self::Mix        => Self::Scene(0),
            Self::Track(t)   => Self::Clip(*t, 0),
            Self::Scene(s)   => Self::Scene(last_scene.min(*s + 1)),
            Self::Clip(t, s) => Self::Clip(*t, last_scene.min(*s + 1)),
        }
    }
    pub fn scene_prev (&mut self) {
        *self = match self {
            Self::Mix      => Self::Mix,
            Self::Track(t) => Self::Track(*t),
            Self::Scene(s) => if *s == 0 {
                Self::Mix
            } else {
                Self::Scene(*s - 1)
            },
            Self::Clip(t, s) => if *s == 0 {
                Self::Track(*t)
            } else {
                Self::Clip(*t, s.saturating_sub(1))
            }
        }
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Display mode of arranger
#[derive(PartialEq)]
pub enum ArrangerViewMode { VerticalExpanded, VerticalCompact1, VerticalCompact2, Horizontal }

/// Arranger display mode can be cycled
impl ArrangerViewMode {
    /// Cycle arranger display mode
    pub fn to_next (&mut self) {
        *self = match self {
            Self::VerticalExpanded => Self::VerticalCompact1,
            Self::VerticalCompact1 => Self::VerticalCompact2,
            Self::VerticalCompact2 => Self::Horizontal,
            Self::Horizontal       => Self::VerticalExpanded,
        }
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct ArrangerViewVertical<'a, 'b, E: Engine>(
    &'a Arranger<E>, &'b [(usize, usize)], &'b [(usize, usize)]
);

impl<'a, 'b> Content for ArrangerViewVertical<'a, 'b, Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        let Self(state, cols, rows) = self;
        let tracks: &[Sequencer<Tui>] = state.tracks.as_ref();
        let scenes = state.scenes.as_ref();
        let offset = 4 + scene_name_max_len(scenes) as u16;
        Layers::new(move |add|{
            add(&ColumnSeparators(offset, cols))?;
            add(&RowSeparators(rows))?;
            add(&CursorFocus(state.focused, state.selected, offset, cols, rows))?;
            add(&Split::down(|add|{
                add(&Push::X(offset, Split::right(move |add|{
                    for (track, (w, _)) in tracks.iter().zip(*cols) {
                        add(&Min::XY(*w as u16, 2, Layers::new(|add|{
                            add(&Background(COLOR_BG1))?;
                            add(&track.name.read().unwrap().as_str())
                        })))?;
                    }
                    Ok(())
                })))?;
                add(&Split::down(move |add| {
                    for (scene, (pulses, _)) in scenes.iter().zip(*rows) {
                        let height = 1.max((pulses / 96) as u16);
                        let playing = scene.is_playing(tracks);
                        add(&Fixed::Y(height, Split::right(move |add| {
                            add(&Fixed::XY(offset.saturating_sub(1), height, Split::right(|add|{
                                add(&if playing { "▶ " } else { "  " })?;
                                add(&scene.name.read().unwrap().as_str())
                            })))?;
                            for (track, (w, _x)) in cols.iter().enumerate() {
                                add(&Fixed::XY(*w as u16, height, Layers::new(move |add|{
                                    let mut color = COLOR_BG0;
                                    if let (Some(track), Some(Some(clip))) = (
                                        tracks.get(track),
                                        scene.clips.get(track),
                                    ) {
                                        if let Some(phrase) = track.phrases.get(*clip) {
                                            add(&Push::X(1, format!(
                                                "{clip:02} {}",
                                                phrase.read().unwrap().name.read().unwrap()
                                            ).as_str()))?;
                                            color = if track.sequence == Some(*clip) {
                                                Nord::PLAYING
                                            } else {
                                                COLOR_BG1
                                            };
                                        }
                                    }
                                    add(&Background(color))
                                })))?;
                            }
                            Ok(())
                        })))?;
                    }
                    Ok(())
                }))
            }))
        })
    }
}

pub fn scene_name_max_len (scenes: &[Scene]) -> usize {
    scenes.iter()
        .map(|s|s.name.read().unwrap().len())
        .fold(0, usize::max)
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct ColumnSeparators<'a>(u16, &'a [(usize, usize)]);

impl<'a> Widget for ColumnSeparators<'a> {
    type Engine = Tui;
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        let Self(offset, cols) = self;
        let style = Some(Style::default().fg(Nord::SEPARATOR));
        for (_, x) in cols.iter() {
            let x = offset + area.x() + *x as u16 - 1;
            for y in area.y()..area.y2() {
                to.blit(&"▎", x, y, style);
            }
        }
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct RowSeparators<'a>(&'a [(usize, usize)]);

impl<'a> Widget for RowSeparators<'a> {
    type Engine = Tui;
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        let Self(rows) = self;
        for (_, y) in rows.iter() {
            let y = area.y() + (*y / 96) as u16 + 1;
            if y >= to.buffer.area.height {
                break
            }
            for x in area.x()..area.x2().saturating_sub(2) {
                if x < to.buffer.area.x && y < to.buffer.area.y {
                    let cell = to.buffer.get_mut(x, y);
                    cell.modifier = Modifier::UNDERLINED;
                    cell.underline_color = Nord::SEPARATOR;
                }
            }
        }
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct CursorFocus<'a>(
    bool, ArrangerFocus, u16, &'a [(usize, usize)], &'a [(usize, usize)]
);

impl<'a> Widget for CursorFocus<'a> {
    type Engine = Tui;
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        let Self(focused, selected, offset, cols, rows) = *self;
        let get_track_area = |t: usize| [
            offset + area.x() + cols[t].1 as u16 - 1,
            area.y(),
            cols[t].0 as u16,
            area.h()
        ];
        let get_scene_area = |s: usize| [
            area.x(),
            2 + area.y() + (rows[s].1 / 96) as u16,
            area.w(),
            (rows[s].0 / 96) as u16
        ];
        let get_clip_area = |t: usize, s: usize| [
            offset + area.x() + cols[t].1 as u16 - 1,
            2 + area.y() + (rows[s].1 / 96) as u16,
            cols[t].0 as u16,
            (rows[s].0 / 96) as u16
        ];
        let mut track_area: Option<[u16;4]> = None;
        let mut scene_area: Option<[u16;4]> = None;
        let mut clip_area:  Option<[u16;4]> = None;
        let area = match selected {
            ArrangerFocus::Mix => {
                if focused {
                    to.fill_bg(area, COLOR_BG0);
                }
                area
            },
            ArrangerFocus::Track(t) => {
                track_area = Some(get_track_area(t));
                area
            },
            ArrangerFocus::Scene(s) => {
                scene_area = Some(get_scene_area(s));
                area
            },
            ArrangerFocus::Clip(t, s) => {
                track_area = Some(get_track_area(t));
                scene_area = Some(get_scene_area(s));
                clip_area  = Some(get_clip_area(t, s));
                area
            },
        };
        if let Some([x, y, width, height]) = track_area {
            to.fill_fg([x, y, 1, height], COLOR_BG5);
            to.fill_fg([x + width, y, 1, height], COLOR_BG5);
        }
        if let Some([_, y, _, height]) = scene_area {
            to.fill_ul([area.x(), y - 1, area.w(), 1], COLOR_BG5);
            to.fill_ul([area.x(), y + height - 1, area.w(), 1], COLOR_BG5);
        }
        if focused {
            if let Some(clip_area) = clip_area {
                to.fill_bg(clip_area, COLOR_BG0);
            } else if let Some(track_area) = track_area {
                to.fill_bg(track_area, COLOR_BG0);
            } else if let Some(scene_area) = scene_area {
                to.fill_bg(scene_area, COLOR_BG0);
            }
        }
        //Ok(Some(area))
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct ArrangerViewHorizontal<'a, E: Engine>(
    &'a Arranger<E>
);

impl<'a> Content for ArrangerViewHorizontal<'a, Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        let Arranger { tracks, focused, selected, scenes, .. } = self.0;
        let tracks = tracks.as_slice();
        Layers::new(|add|{
            add(&focused.then_some(Background(COLOR_BG0)))?;
            add(&Split::right(|add|{
                add(&TrackNameColumn(tracks, *selected))?;
                add(&TrackMonitorColumn(tracks))?;
                add(&TrackRecordColumn(tracks))?;
                add(&TrackOverdubColumn(tracks))?;
                add(&TrackEraseColumn(tracks))?;
                add(&TrackGainColumn(tracks))?;
                add(&TrackScenesColumn(tracks, scenes.as_slice(), *selected))?;
                Ok(())
            }))
        })
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct TrackNameColumn<'a>(&'a [Sequencer<Tui>], ArrangerFocus);

impl<'a> Widget for TrackNameColumn<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, _to: &mut TuiOutput) -> Usually<()> {
        todo!();
        //let Self(tracks, selected) = self;
        //let yellow = Some(Style::default().yellow().bold().not_dim());
        //let white  = Some(Style::default().white().bold().not_dim());
        //let area = to.area();
        //let area = [area.x(), area.y(), 3 + 5.max(track_name_max_len(tracks)) as u16, area.h()];
        //let offset = 0; // track scroll offset
        //for y in 0..area.h() {
            //if y == 0 {
                //to.blit(&"Mixer", area.x() + 1, area.y() + y, Some(DIM))?;
            //} else if y % 2 == 0 {
                //let index = (y as usize - 2) / 2 + offset;
                //if let Some(track) = tracks.get(index) {
                    //let selected = selected.track() == Some(index);
                    //let style = if selected { yellow } else { white };
                    //to.blit(&format!(" {index:>02} "), area.x(), area.y() + y, style)?;
                    //to.blit(&*track.name.read().unwrap(), area.x() + 4, area.y() + y, style)?;
                //}
            //}
        //}
        //Ok(Some(area))
    }
}

pub fn track_name_max_len <E: Engine> (tracks: &[Sequencer<E>]) -> usize {
    tracks.iter()
        .map(|s|s.name.read().unwrap().len())
        .fold(0, usize::max)
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct TrackMonitorColumn<'a>(&'a [Sequencer<Tui>]);

impl<'a> Widget for TrackMonitorColumn<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, _to: &mut TuiOutput) -> Usually<()> {
        todo!();
        //let Self(tracks) = self;
        //let mut area = to.area();
        //let on  = Some(Style::default().not_dim().green().bold());
        //let off = Some(DIM);
        //area.x += 1;
        //for y in 0..area.h() {
            //if y == 0 {
                ////" MON ".blit(to.buffer, area.x, area.y + y, style2)?;
            //} else if y % 2 == 0 {
                //let index = (y as usize - 2) / 2;
                //if let Some(track) = tracks.get(index) {
                    //let style = if track.monitoring { on } else { off };
                    //to.blit(&" MON ", area.x(), area.y() + y, style)?;
                //} else {
                    //area.height = y;
                    //break
                //}
            //}
        //}
        //area.width = 4;
        //Ok(Some(area))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct TrackRecordColumn<'a>(&'a [Sequencer<Tui>]);

impl<'a> Widget for TrackRecordColumn<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, _to: &mut TuiOutput) -> Usually<()> {
        todo!();
        //let Self(tracks) = self;
        //let mut area = to.area();
        //let on  = Some(Style::default().not_dim().red().bold());
        //let off = Some(Style::default().dim());
        //area.x += 1;
        //for y in 0..area.h() {
            //if y == 0 {
                ////" REC ".blit(to.buffer, area.x, area.y + y, style2)?;
            //} else if y % 2 == 0 {
                //let index = (y as usize - 2) / 2;
                //if let Some(track) = tracks.get(index) {
                    //let style = if track.recording { on } else { off };
                    //to.blit(&" REC ", area.x(), area.y() + y, style)?;
                //} else {
                    //area.height = y;
                    //break
                //}
            //}
        //}
        //area.width = 4;
        //Ok(Some(area))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct TrackOverdubColumn<'a>(&'a [Sequencer<Tui>]);

impl<'a> Widget for TrackOverdubColumn<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, _to: &mut TuiOutput) -> Usually<()> {
        todo!();
        //let Self(tracks) = self;
        //let mut area = to.area();
        //let on  = Some(Style::default().not_dim().yellow().bold());
        //let off = Some(Style::default().dim());
        //area.x = area.x + 1;
        //for y in 0..area.h() {
            //if y == 0 {
                ////" OVR ".blit(to.buffer, area.x, area.y + y, style2)?;
            //} else if y % 2 == 0 {
                //let index = (y as usize - 2) / 2;
                //if let Some(track) = tracks.get(index) {
                    //to.blit(&" OVR ", area.x(), area.y() + y, if track.overdub {
                        //on
                    //} else {
                        //off
                    //})?;
                //} else {
                    //area.height = y;
                    //break
                //}
            //}
        //}
        //area.width = 4;
        //Ok(Some(area))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct TrackEraseColumn<'a>(&'a [Sequencer<Tui>]);

impl<'a> Widget for TrackEraseColumn<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, _to: &mut TuiOutput) -> Usually<()> {
        todo!();
        //let Self(tracks) = self;
        //let mut area = to.area();
        //let off = Some(Style::default().dim());
        //area.x = area.x + 1;
        //for y in 0..area.h() {
            //if y == 0 {
                ////" DEL ".blit(to.buffer, area.x, area.y + y, style2)?;
            //} else if y % 2 == 0 {
                //let index = (y as usize - 2) / 2;
                //if let Some(_) = tracks.get(index) {
                    //to.blit(&" DEL ", area.x(), area.y() + y, off)?;
                //} else {
                    //area.height = y;
                    //break
                //}
            //}
        //}
        //area.width = 4;
        //Ok(Some(area))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct TrackGainColumn<'a>(&'a [Sequencer<Tui>]);

impl<'a> Widget for TrackGainColumn<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, _to: &mut TuiOutput) -> Usually<()> {
        todo!();
        //let Self(tracks) = self;
        //let mut area = to.area();
        //let off = Some(Style::default().dim());
        //area.x = area.x() + 1;
        //for y in 0..area.h() {
            //if y == 0 {
                ////" GAIN ".blit(to.buffer, area.x, area.y + y, style2)?;
            //} else if y % 2 == 0 {
                //let index = (y as usize - 2) / 2;
                //if let Some(_) = tracks.get(index) {
                    //to.blit(&" +0.0 ", area.x(), area.y() + y, off)?;
                //} else {
                    //area.height = y;
                    //break
                //}
            //}
        //}
        //area.width = 7;
        //Ok(Some(area))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct TrackScenesColumn<'a>(&'a [Sequencer<Tui>], &'a [Scene], ArrangerFocus);

impl<'a> Widget for TrackScenesColumn<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let Self(tracks, scenes, selected) = self;
        let area = to.area();
        let mut x2 = 0;
        let [x, y, _, height] = area;
        for (scene_index, scene) in scenes.iter().enumerate() {
            let active_scene = selected.scene() == Some(scene_index);
            let sep = Some(if active_scene {
                Style::default().yellow().not_dim()
            } else {
                Style::default().dim()
            });
            for y in y+1..y+height {
                to.blit(&"│", x + x2, y, sep);
            }
            let name = scene.name.read().unwrap();
            let mut x3 = name.len() as u16;
            to.blit(&*name, x + x2, y, sep);
            for (i, clip) in scene.clips.iter().enumerate() {
                let active_track = selected.track() == Some(i);
                if let Some(clip) = clip {
                    let y2 = y + 2 + i as u16 * 2;
                    let label = match tracks[i].phrases.get(*clip) {
                        Some(phrase) => &format!("{}", phrase.read().unwrap().name.read().unwrap()),
                        None => "...."
                    };
                    to.blit(&label, x + x2, y2, Some(if active_track && active_scene {
                        Style::default().not_dim().yellow().bold()
                    } else {
                        Style::default().not_dim()
                    }));
                    x3 = x3.max(label.len() as u16)
                }
            }
            x2 = x2 + x3 + 1;
        }
        //Ok(Some([x, y, x2, height]))
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Appears on first run (i.e. if state dir is missing).
pub struct ArrangerRenameModal<E: Engine> {
    _engine: std::marker::PhantomData<E>,
    done:   bool,
    target: ArrangerFocus,
    value:  String,
    result: Arc<RwLock<String>>,
    cursor: usize
}

impl<E: Engine> ArrangerRenameModal<E> {
    pub fn new (target: ArrangerFocus, value: &Arc<RwLock<String>>) -> Self {
        Self {
            _engine: Default::default(),
            done: false,
            target,
            value:  value.read().unwrap().clone(),
            cursor: value.read().unwrap().len(),
            result: value.clone(),
        }
    }
}

impl Widget for ArrangerRenameModal<Tui> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        let y = area.y() + area.h() / 2;
        let bg_area = [1, y - 1, area.w() - 2, 3];
        to.fill_bg(bg_area, Nord::BG0);
        Lozenge(Style::default().bold().white().dim()).draw(to.with_rect(bg_area));
        let label = match self.target {
            ArrangerFocus::Mix => "Rename project:",
            ArrangerFocus::Track(_) => "Rename track:",
            ArrangerFocus::Scene(_) => "Rename scene:",
            ArrangerFocus::Clip(_, _) => "Rename clip:",
        };
        let style = Some(Style::default().not_bold().white().not_dim());
        to.blit(&label, area.x() + 3, y, style);
        let style = Some(Style::default().bold().white().not_dim());
        to.blit(&self.value, area.x() + 3 + label.len() as u16 + 1, y, style);
        let style = Some(Style::default().bold().white().not_dim().reversed());
        to.blit(&"▂", area.x() + 3 + label.len() as u16 + 1 + self.cursor as u16, y, style);
        //Ok(Some(area))
        Ok(())
    }
}

impl Handle<Tui> for ArrangerRenameModal<Tui> {
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        match from.event() {
            TuiEvent::Input(Event::Key(k)) => {
                match k.code {
                    KeyCode::Esc => {
                        self.exit();
                    },
                    KeyCode::Enter => {
                        *self.result.write().unwrap() = self.value.clone();
                        self.exit();
                    },
                    KeyCode::Left => {
                        self.cursor = self.cursor.saturating_sub(1);
                    },
                    KeyCode::Right => {
                        self.cursor = self.value.len().min(self.cursor + 1)
                    },
                    KeyCode::Backspace => {
                        let last = self.value.len().saturating_sub(1);
                        self.value = format!("{}{}",
                            &self.value[0..self.cursor.min(last)],
                            &self.value[self.cursor.min(last)..last]
                        );
                        self.cursor = self.cursor.saturating_sub(1)
                    }
                    KeyCode::Char(c) => {
                        self.value.insert(self.cursor, c);
                        self.cursor = self.value.len().min(self.cursor + 1)
                    },
                    _ => {}
                }
                Ok(Some(true))
            },
            _ => Ok(None),
        }
    }
}

impl<E: Engine + Send> Exit for ArrangerRenameModal<E> {
    fn exited (&self) -> bool {
        self.done
    }
    fn exit (&mut self) {
        self.done = true
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Phrase editor.
pub struct Sequencer<E: Engine> {
    pub name:      Arc<RwLock<String>>,
    pub mode:      bool,
    pub focused:   bool,
    pub entered:   bool,

    pub phrase:    Option<Arc<RwLock<Phrase>>>,
    pub transport: Option<Arc<RwLock<TransportToolbar<E>>>>,
    pub buffer:    BigBuffer,
    pub keys:      Buffer,
    /// Highlight input keys
    pub keys_in:  [bool; 128],
    /// Highlight output keys
    pub keys_out: [bool; 128],

    pub now:       usize,
    pub ppq:       usize,
    pub note_axis: FixedAxis<usize>,
    pub time_axis: ScaledAxis<usize>,
    /// Play input through output.
    pub monitoring: bool,
    /// Write input to sequence.
    pub recording:  bool,
    /// Overdub input to sequence.
    pub overdub:    bool,
    /// Map: tick -> MIDI events at tick
    pub phrases:    Vec<Arc<RwLock<Phrase>>>,
    /// Phrase selector
    pub sequence:   Option<usize>,
    /// Output from current sequence.
    pub midi_out:   Option<Port<MidiOut>>,
    /// MIDI output buffer
    midi_out_buf:   Vec<Vec<Vec<u8>>>,
    /// Send all notes off
    pub reset:      bool, // TODO?: after Some(nframes)
    /// Highlight keys on piano roll.
    pub notes_in:   [bool;128],
    /// Highlight keys on piano roll.
    pub notes_out:  [bool;128],
}

impl<E: Engine> Sequencer<E> {
    pub fn new (name: &str) -> Self {
        Self {
            name:         Arc::new(RwLock::new(name.into())),
            monitoring:   false,
            recording:    false,
            overdub:      true,
            phrases:      vec![],
            sequence:     None,
            midi_out:     None,
            midi_out_buf: vec![Vec::with_capacity(16);16384],
            reset:        true,
            notes_in:     [false;128],
            notes_out:    [false;128],
            buffer:       Default::default(),
            keys:         keys_vert(),
            entered:      false,
            focused:      false,
            mode:         false,
            keys_in:      [false;128],
            keys_out:     [false;128],
            phrase:       None,
            now:          0,
            ppq:          96,
            transport:    None,
            note_axis: FixedAxis { start: 12, point: Some(36) },
            time_axis: ScaledAxis { start: 0, scale: 24, point: Some(0) },
        }
    }
    pub fn toggle_monitor (&mut self) {
        self.monitoring = !self.monitoring;
    }
    pub fn toggle_record (&mut self) {
        self.recording = !self.recording;
    }
    pub fn toggle_overdub (&mut self) {
        self.overdub = !self.overdub;
    }
    pub fn process (
        &mut self,
        input:    Option<MidiIter>,
        timebase: &Arc<Timebase>,
        playing:  Option<TransportState>,
        started:  Option<(usize, usize)>,
        quant:    usize,
        reset:    bool,
        scope:    &ProcessScope,
        (frame0, frames): (usize, usize),
        (_usec0,  _usecs):  (usize, usize),
        period:   f64,
    ) {
        if self.midi_out.is_some() {
            // Clear the section of the output buffer that we will be using
            for frame in &mut self.midi_out_buf[0..frames] {
                frame.clear();
            }
            // Emit "all notes off" at start of buffer if requested
            if self.reset {
                all_notes_off(&mut self.midi_out_buf);
                self.reset = false;
            } else if reset {
                all_notes_off(&mut self.midi_out_buf);
            }
        }
        if let (
            Some(TransportState::Rolling), Some((start_frame, _)), Some(phrase)
        ) = (
            playing, started, self.sequence.and_then(|id|self.phrases.get_mut(id))
        ) {
            phrase.read().map(|phrase|{
                if self.midi_out.is_some() {
                    phrase.process_out(
                        &mut self.midi_out_buf,
                        &mut self.notes_out,
                        timebase,
                        (frame0.saturating_sub(start_frame), frames, period)
                    );
                }
            }).unwrap();
            let mut phrase = phrase.write().unwrap();
            let length = phrase.length;
            // Monitor and record input
            if input.is_some() && (self.recording || self.monitoring) {
                // For highlighting keys and note repeat
                for (frame, event, bytes) in parse_midi_input(input.unwrap()) {
                    match event {
                        LiveEvent::Midi { message, .. } => {
                            if self.monitoring {
                                self.midi_out_buf[frame].push(bytes.to_vec())
                            }
                            if self.recording {
                                phrase.record_event({
                                    let pulse = timebase.frame_to_pulse(
                                        (frame0 + frame - start_frame) as f64
                                    );
                                    let quantized = (
                                        pulse / quant as f64
                                    ).round() as usize * quant;
                                    let looped = quantized % length;
                                    looped
                                }, message);
                            }
                            match message {
                                MidiMessage::NoteOn { key, .. } => {
                                    self.notes_in[key.as_int() as usize] = true;
                                }
                                MidiMessage::NoteOff { key, .. } => {
                                    self.notes_in[key.as_int() as usize] = false;
                                },
                                _ => {}
                            }
                        },
                        _ => {}
                    }
                }
            }
        } else if input.is_some() && self.midi_out.is_some() && self.monitoring {
            for (frame, event, bytes) in parse_midi_input(input.unwrap()) {
                self.process_monitor_event(frame, &event, bytes)
            }
        }
        if let Some(out) = &mut self.midi_out {
            write_midi_output(&mut out.writer(scope), &self.midi_out_buf, frames);
        }
    }

    #[inline]
    fn process_monitor_event (&mut self, frame: usize, event: &LiveEvent, bytes: &[u8]) {
        match event {
            LiveEvent::Midi { message, .. } => {
                self.write_to_output_buffer(frame, bytes);
                self.process_monitor_message(&message);
            },
            _ => {}
        }
    }

    #[inline] fn write_to_output_buffer (&mut self, frame: usize, bytes: &[u8]) {
        self.midi_out_buf[frame].push(bytes.to_vec());
    }

    #[inline]
    fn process_monitor_message (&mut self, message: &MidiMessage) {
        match message {
            MidiMessage::NoteOn { key, .. } => {
                self.notes_in[key.as_int() as usize] = true;
            }
            MidiMessage::NoteOff { key, .. } => {
                self.notes_in[key.as_int() as usize] = false;
            },
            _ => {}
        }
    }
    /// Select which pattern to display. This pre-renders it to the buffer at full resolution.
    pub fn show (&mut self, phrase: Option<&Arc<RwLock<Phrase>>>) -> Usually<()> {
        self.phrase = phrase.map(Clone::clone);
        if let Some(ref phrase) = self.phrase {
            let width = usize::MAX.min(phrase.read().unwrap().length);
            let mut buffer = BigBuffer::new(width, 64);
            let phrase = phrase.read().unwrap();
            fill_seq_bg(&mut buffer, phrase.length, self.ppq)?;
            fill_seq_fg(&mut buffer, &phrase)?;
            self.buffer = buffer;
        } else {
            self.buffer = Default::default();
        }
        Ok(())
    }

    pub(crate) fn style_focus (&self) -> Option<Style> {
        Some(if self.focused {
            Style::default().green().not_dim()
        } else {
            Style::default().green().dim()
        })
    }

    pub(crate) fn style_timer_step (now: usize, step: usize, next_step: usize) -> Style {
        if step <= now && now < next_step {
            Style::default().yellow().bold().not_dim()
        } else {
            Style::default()
        }
    }

    pub fn index_to_color (&self, index: u16, default: Color) -> Color {
        let index = index as usize;
        if self.keys_in[index] && self.keys_out[index] {
            Color::Yellow
        } else if self.keys_in[index] {
            Color::Red
        } else if self.keys_out[index] {
            Color::Green
        } else {
            default
        }
    }
}

/// Add "all notes off" to the start of a buffer.
pub fn all_notes_off (output: &mut MIDIChunk) {
    let mut buf = vec![];
    let msg = MidiMessage::Controller { controller: 123.into(), value: 0.into() };
    let evt = LiveEvent::Midi { channel: 0.into(), message: msg };
    evt.write(&mut buf).unwrap();
    output[0].push(buf);
}

/// Return boxed iterator of MIDI events
pub fn parse_midi_input (input: MidiIter) -> Box<dyn Iterator<Item=(usize, LiveEvent, &[u8])> + '_> {
    Box::new(input.map(|RawMidi { time, bytes }|(
        time as usize,
        LiveEvent::parse(bytes).unwrap(),
        bytes
    )))
}

/// Write to JACK port from output buffer (containing notes from sequence and/or monitor)
pub fn write_midi_output (writer: &mut MidiWriter, output: &MIDIChunk, frames: usize) {
    for time in 0..frames {
        for event in output[time].iter() {
            writer.write(&RawMidi { time: time as u32, bytes: &event })
                .expect(&format!("{event:?}"));
        }
    }
}

/// MIDI message serialized to bytes
pub type MIDIMessage = Vec<u8>;

/// Collection of serialized MIDI messages
pub type MIDIChunk = [Vec<MIDIMessage>];

impl Sequencer<Tui> {
    const H_KEYS_OFFSET: usize = 5;
}

impl Content for Sequencer<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        Split::right(move |add|{
            add(&Split::down(|add|{
                add(&SequenceName(&self))?;
                add(&SequenceRange)?;
                add(&SequenceLoopRange)?;
                add(&SequenceNoteRange)?;
                Ok(())
            }))?;
            add(&Layers::new(|add|{
                add(&SequenceKeys(&self))?;
                add(&self.phrase.as_ref().map(|phrase|SequenceTimer(&self, phrase.clone())))?;
                add(&SequenceNotes(&self))?;
                add(&SequenceCursor(&self))?;
                add(&SequenceZoom(&self))
            }))
        })
    }
}

impl Handle<Tui> for Sequencer<Tui> {
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        match from.event() {
            // NONE, "seq_cursor_up",    "move cursor up", |sequencer: &mut Sequencer| {
            key!(KeyCode::Up) => {
                match self.entered {
                    true  => { self.note_axis.point_dec(); },
                    false => { self.note_axis.start_dec(); },
                }
                Ok(Some(true))
            },
            // NONE, "seq_cursor_down",  "move cursor down", |self: &mut Sequencer| {
            key!(KeyCode::Down) => {
                match self.entered {
                    true  => { self.note_axis.point_inc(); },
                    false => { self.note_axis.start_inc(); },
                }
                Ok(Some(true))
            },
            // NONE, "seq_cursor_left",  "move cursor up", |self: &mut Sequencer| {
            key!(KeyCode::Left) => {
                match self.entered {
                    true  => { self.time_axis.point_dec(); },
                    false => { self.time_axis.start_dec(); },
                }
                Ok(Some(true))
            },
            // NONE, "seq_cursor_right", "move cursor up", |self: &mut Sequencer| {
            key!(KeyCode::Right) => {
                match self.entered {
                    true  => { self.time_axis.point_inc(); },
                    false => { self.time_axis.start_inc(); },
                }
                Ok(Some(true))
            },
            // NONE, "seq_mode_switch", "switch the display mode", |self: &mut Sequencer| {
            key!(KeyCode::Char('`')) => {
                self.mode = !self.mode;
                Ok(Some(true))
            },
            _ => Ok(None)
        }
    }
}

fn nth_octave (index: u16) -> &'static str {
    match index {
        0  =>  "-1",
        1  =>  "0",
        2  =>  "1",
        3  =>  "2",
        4  =>  "3",
        5  =>  "4",
        6  =>  "5",
        7  =>  "6",
        8  =>  "7",
        9  =>  "8",
        10 =>  "9",
        _  => unreachable!()
    }
}

fn key_colors (index: u16) -> (Color, Color) {
    match index % 6 {
        0 => (Color::White, Color::Black),
        1 => (Color::White, Color::Black),
        2 => (Color::White, Color::White),
        3 => (Color::Black, Color::White),
        4 => (Color::Black, Color::White),
        5 => (Color::Black, Color::White),
        _ => unreachable!()
    }
}

fn fill_seq_bg (buf: &mut BigBuffer, length: usize, ppq: usize) -> Usually<()> {
    for x in 0..buf.width {
        if x as usize >= length {
            break
        }
        let style = Style::default();
        buf.get_mut(x, 0).map(|cell|{
            cell.set_char('-');
            cell.set_style(style);
        });
        for y in 0 .. buf.height {
            buf.get_mut(x, y).map(|cell|{
                cell.set_char(char_seq_bg(ppq, x as u16));
                cell.set_fg(Color::Gray);
                cell.modifier = Modifier::DIM;
            });
        }
    }
    Ok(())
}

fn char_seq_bg (ppq: usize, x: u16) -> char {
    if ppq == 0 {
        '·'
    } else if x % (4 * ppq as u16) == 0 {
        '│'
    } else if x % ppq as u16 == 0 {
        '╎'
    } else {
        '·'
    }
}

fn fill_seq_fg (buf: &mut BigBuffer, phrase: &Phrase) -> Usually<()> {
    let mut notes_on = [false;128];
    for x in 0..buf.width {
        if x as usize >= phrase.length {
            break
        }
        if let Some(notes) = phrase.notes.get(x as usize) {
            if phrase.percussive {
                for note in notes {
                    match note {
                        MidiMessage::NoteOn { key, .. } =>
                            notes_on[key.as_int() as usize] = true,
                        _ => {}
                    }
                }
            } else {
                for note in notes {
                    match note {
                        MidiMessage::NoteOn { key, .. } =>
                            notes_on[key.as_int() as usize] = true,
                        MidiMessage::NoteOff { key, .. } =>
                            notes_on[key.as_int() as usize] = false,
                        _ => {}
                    }
                }
            }
            for y in 0..buf.height/2 {
                if y >= 64 {
                    break
                }
                if let Some(block) = half_block(
                    notes_on[y as usize * 2],
                    notes_on[y as usize * 2 + 1],
                ) {
                    buf.get_mut(x, y).map(|cell|{
                        cell.set_char(block);
                        cell.set_fg(Color::White);
                    });
                }
            }
            if phrase.percussive {
                notes_on.fill(false);
            }
        }
    }
    Ok(())
}

pub(crate) fn keys_vert () -> Buffer {
    let area = [0, 0, 5, 64];
    let mut buffer = Buffer::empty(Rect {
        x: area.x(), y: area.y(), width: area.w(), height: area.h()
    });
    buffer_update(&mut buffer, area, &|cell, x, y| {
        let y = 63 - y;
        match x {
            0 => {
                cell.set_char('▀');
                let (fg, bg) = key_colors(6 - y % 6);
                cell.set_fg(fg);
                cell.set_bg(bg);
            },
            1 => {
                cell.set_char('▀');
                cell.set_fg(Color::White);
                cell.set_bg(Color::White);
            },
            2 => if y % 6 == 0 {
                cell.set_char('C');
            },
            3 => if y % 6 == 0 {
                cell.set_symbol(nth_octave(y / 6));
            },
            _ => {}
        }
    });
    buffer
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SequenceName<'a>(&'a Sequencer<Tui>);

impl<'a> Widget for SequenceName<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let [x, y, ..] = to.area();
        let frame = [x, y, 10, 4];
        Lozenge(Style::default().fg(Nord::BG2)).draw(to.with_rect(frame))?;
        to.blit(&"Name:", x + 1, y + 1, Some(STYLE_LABEL));
        to.blit(&*self.0.name.read().unwrap(), x + 1, y + 2, Some(STYLE_VALUE));
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SequenceRange;

impl Widget for SequenceRange {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let [x, y, ..] = to.area();
        let frame = [x, y, 10, 6];
        Lozenge(Style::default().fg(Nord::BG2)).draw(to.with_rect(frame))?;
        to.blit(&"Start:  ", x + 1, y + 1, Some(STYLE_LABEL));
        to.blit(&"   1.1.1", x + 1, y + 2, Some(STYLE_VALUE));
        to.blit(&"End:    ", x + 1, y + 3, Some(STYLE_LABEL));
        to.blit(&"   2.1.1", x + 1, y + 4, Some(STYLE_VALUE));
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SequenceLoopRange;

impl Widget for SequenceLoopRange {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let [x, y, ..] = to.area();
        let range = [x, y, 10, 7];
        Lozenge(Style::default().fg(Nord::BG2)).draw(to.with_rect(range))?;
        to.blit(&"Loop [ ]", x + 1, y + 1, Some(STYLE_LABEL));
        to.blit(&"From:   ", x + 1, y + 2, Some(STYLE_LABEL));
        to.blit(&"   1.1.1", x + 1, y + 3, Some(STYLE_VALUE));
        to.blit(&"Length: ", x + 1, y + 4, Some(STYLE_LABEL));
        to.blit(&"   1.0.0", x + 1, y + 5, Some(STYLE_VALUE));
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SequenceNoteRange;

impl Widget for SequenceNoteRange {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let [x, y, ..] = to.area();
        let range = [x, y, 10, 9];
        Lozenge(Style::default().fg(Nord::BG2)).draw(to.with_rect(range))?;
        to.blit(&"Notes:  ", x + 1, y + 1, Some(STYLE_LABEL));
        to.blit(&"C#0-C#9 ", x + 1, y + 2, Some(STYLE_VALUE));
        to.blit(&"[  /2  ]", x + 1, y + 3, Some(STYLE_LABEL));
        to.blit(&"[  x2  ]", x + 1, y + 4, Some(STYLE_LABEL));
        to.blit(&"[ Rev  ]", x + 1, y + 5, Some(STYLE_LABEL));
        to.blit(&"[ Inv  ]", x + 1, y + 6, Some(STYLE_LABEL));
        to.blit(&"[ Dup  ]", x + 1, y + 7, Some(STYLE_LABEL));
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SequenceKeys<'a>(&'a Sequencer<Tui>);

impl<'a> Widget for SequenceKeys<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        if area.h() < 2 {
            return Ok(())
        }
        let area = [area.x(), area.y() + 1, 5, area.h() - 2];
        to.buffer_update(area, &|cell, x, y|{
            let y = y + self.0.note_axis.start as u16;
            if x < self.0.keys.area.width && y < self.0.keys.area.height {
                *cell = self.0.keys.get(x, y).clone()
            }
        });
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SequenceNotes<'a>(&'a Sequencer<Tui>);

impl<'a> Widget for SequenceNotes<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        if area.h() < 2 {
            return Ok(())//Some(area))
        }
        let area = [
            area.x() + Sequencer::H_KEYS_OFFSET as u16,
            area.y() + 1,
            area.w().saturating_sub(Sequencer::H_KEYS_OFFSET as u16),
            area.h().saturating_sub(2),
        ];
        to.buffer_update(area, &move |cell, x, y|{
            let src_x = ((x as usize + self.0.time_axis.start) * self.0.time_axis.scale) as usize;
            let src_y = (y as usize + self.0.note_axis.start) as usize;
            if src_x < self.0.buffer.width && src_y < self.0.buffer.height - 1 {
                let src = self.0.buffer.get(src_x, self.0.buffer.height - src_y);
                src.map(|src|{
                    cell.set_symbol(src.symbol());
                    cell.set_fg(src.fg);
                });
            }
        });
        Ok(())//Some(area))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SequenceCursor<'a>(&'a Sequencer<Tui>);

impl<'a> Widget for SequenceCursor<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        if let (Some(time), Some(note)) = (self.0.time_axis.point, self.0.note_axis.point) {
            let x = area.x() + Sequencer::H_KEYS_OFFSET as u16 + time as u16;
            let y = area.y() + 1 + note as u16 / 2;
            let c = if note % 2 == 0 { "▀" } else { "▄" };
            to.blit(&c, x, y, self.0.style_focus());
            Ok(())
        } else {
            //Ok(Some([0,0,0,0]))
            Ok(())
        }
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

struct SequenceZoom<'a>(&'a Sequencer<Tui>);

impl<'a> Widget for SequenceZoom<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        let quant = ppq_to_name(self.0.time_axis.scale);
        let quant_x = area.x() + area.w() - 1 - quant.len() as u16;
        let quant_y = area.y() + area.h() - 2;
        to.blit(&quant, quant_x, quant_y, self.0.style_focus());
        Ok(())
    }
}

struct SequenceTimer<'a>(&'a Sequencer<Tui>, Arc<RwLock<Phrase>>);

impl<'a> Widget for SequenceTimer<'a> {
    type Engine = Tui;
    fn layout (&self, _to: [u16;2]) -> Perhaps<[u16;2]> {
        todo!()
    }
    fn render (&self, to: &mut TuiOutput) -> Usually<()> {
        let area = to.area();
        let phrase = self.1.read().unwrap();
        let (time0, time_z, now) = (
            self.0.time_axis.start, self.0.time_axis.scale, self.0.now % phrase.length
        );
        let [x, _, width, _] = area;
        let x2 = x as usize + Sequencer::H_KEYS_OFFSET;
        let x3 = x as usize + width as usize;
        for x in x2..x3 {
            let step = (time0 + x2) * time_z;
            let next_step = (time0 + x2 + 1) * time_z;
            let style = Sequencer::<Tui>::style_timer_step(now, step as usize, next_step as usize);
            to.blit(&"-", x as u16, area.y(), Some(style));
        }
        //return Ok(Some([area.x(), area.y(), area.w(), 1]))
        Ok(())
    }
}

/// A collection of phrases to play on each track.
#[derive(Default)]
pub struct Scene {
    pub name:  Arc<RwLock<String>>,
    pub clips: Vec<Option<usize>>,
}

impl Scene {
    pub fn from_edn <'a, 'e> (args: &[Edn<'e>]) -> Usually<Self> {
        let mut name  = None;
        let mut clips = vec![];
        edn!(edn in args {
            Edn::Map(map) => {
                let key = map.get(&Edn::Key(":name"));
                if let Some(Edn::Str(n)) = key {
                    name = Some(*n);
                } else {
                    panic!("unexpected key in scene '{name:?}': {key:?}")
                }
            },
            Edn::Symbol("_") => {
                clips.push(None);
            },
            Edn::Int(i) => {
                clips.push(Some(*i as usize));
            },
            _ => panic!("unexpected in scene '{name:?}': {edn:?}")
        });
        let scene = Self::new(name.unwrap_or(""), clips);
        Ok(scene)
    }
    pub fn new (name: impl AsRef<str>, clips: impl AsRef<[Option<usize>]>) -> Self {
        let name = Arc::new(RwLock::new(name.as_ref().into()));
        let clips = clips.as_ref().iter().map(|x|x.clone()).collect();
        Self { name, clips, }
    }
    /// Returns the pulse length of the longest phrase in the scene
    pub fn pulses <E: Engine> (&self, tracks: &[Sequencer<E>]) -> usize {
        self.clips.iter().enumerate()
            .filter_map(|(i, c)|c
                .map(|c|tracks
                    .get(i)
                    .map(|track|track
                        .phrases
                        .get(c))))
            .filter_map(|p|p)
            .filter_map(|p|p)
            .fold(0, |a, p|a.max(p.read().unwrap().length))
    }
    /// Returns true if all phrases in the scene are currently playing
    pub fn is_playing <E: Engine> (&self, tracks: &[Sequencer<E>]) -> bool {
        self.clips.iter().enumerate()
            .all(|(track_index, phrase_index)|match phrase_index {
                Some(i) => tracks
                    .get(track_index)
                    .map(|track|track.sequence == Some(*i))
                    .unwrap_or(false),
                None => true
            })
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

#[derive(Debug)]
/// A MIDI sequence.
pub struct Phrase {
    pub name:   Arc<RwLock<String>>,
    pub length: usize,
    pub notes:  PhraseData,
    pub looped: Option<(usize, usize)>,
    /// All notes are displayed with minimum length
    pub percussive: bool
}

pub type PhraseData = Vec<Vec<MidiMessage>>;

impl Default for Phrase {
    fn default () -> Self {
        Self::new("", 0, None)
    }
}

impl Phrase {
    pub fn new (name: &str, length: usize, notes: Option<PhraseData>) -> Self {
        Self {
            name:   Arc::new(RwLock::new(name.into())),
            length,
            notes:  notes.unwrap_or(vec![Vec::with_capacity(16);length]),
            looped: Some((0, length)),
            percussive: true,
        }
    }
    pub fn record_event (&mut self, pulse: usize, message: MidiMessage) {
        if pulse >= self.length {
            panic!("extend phrase first")
        }
        self.notes[pulse].push(message);
    }
    /// Check if a range `start..end` contains MIDI Note On `k`
    pub fn contains_note_on (&self, k: u7, start: usize, end: usize) -> bool {
        //panic!("{:?} {start} {end}", &self);
        for events in self.notes[start.max(0)..end.min(self.notes.len())].iter() {
            for event in events.iter() {
                match event {
                    MidiMessage::NoteOn {key,..} => {
                        if *key == k {
                            return true
                        }
                    }
                    _ => {}
                }
            }
        }
        return false
    }
    /// Write a chunk of MIDI events to an output port.
    pub fn process_out (
        &self,
        output:   &mut MIDIChunk,
        notes_on: &mut [bool;128],
        timebase: &Arc<Timebase>,
        (frame0, frames, _): (usize, usize, f64),
    ) {
        let mut buf = Vec::with_capacity(8);
        for (time, tick) in Ticks(timebase.pulse_per_frame()).between_frames(
            frame0, frame0 + frames
        ) {
            let tick = tick % self.length;
            for message in self.notes[tick].iter() {
                buf.clear();
                let channel = 0.into();
                let message = *message;
                LiveEvent::Midi { channel, message }.write(&mut buf).unwrap();
                output[time as usize].push(buf.clone());
                match message {
                    MidiMessage::NoteOn  { key, .. } => notes_on[key.as_int() as usize] = true,
                    MidiMessage::NoteOff { key, .. } => notes_on[key.as_int() as usize] = false,
                    _ => {}
                }
            }
        }
    }
    pub fn from_edn <'e> (ppq: usize, args: &[Edn<'e>]) -> Usually<Self> {
        let mut phrase = Self::default();
        let mut name   = String::new();
        let mut beats  = 0usize;
        let mut steps  = 0usize;
        edn!(edn in args {
            Edn::Map(map) => {
                if let Some(Edn::Str(n)) = map.get(&Edn::Key(":name")) {
                    name = String::from(*n);
                }
                if let Some(Edn::Int(b)) = map.get(&Edn::Key(":beats")) {
                    beats = *b as usize;
                    phrase.length = ppq * beats;
                    for _ in phrase.notes.len()..phrase.length {
                        phrase.notes.push(Vec::with_capacity(16))
                    }
                }
                if let Some(Edn::Int(s)) = map.get(&Edn::Key(":steps")) {
                    steps = *s as usize;
                }
            },
            Edn::List(args) => {
                let time = (match args.get(0) {
                    Some(Edn::Key(text)) => text[1..].parse::<f64>()?,
                    Some(Edn::Int(i))       => *i as f64,
                    Some(Edn::Double(f))    => f64::from(*f),
                    _ => panic!("unexpected in phrase '{name}': {:?}", args.get(0)),
                } * beats as f64 * ppq as f64 / steps as f64) as usize;
                for edn in args[1..].iter() {
                    match edn {
                        Edn::List(args) => if let (
                            Some(Edn::Int(key)),
                            Some(Edn::Int(vel)),
                        ) = (
                            args.get(0),
                            args.get(1),
                        ) {
                            let (key, vel) = (
                                u7::from((*key as u8).min(127)),
                                u7::from((*vel as u8).min(127)),
                            );
                            phrase.notes[time].push(MidiMessage::NoteOn { key, vel })
                        } else {
                            panic!("unexpected list in phrase '{name}'")
                        },
                        _ => panic!("unexpected in phrase '{name}': {edn:?}")
                    }
                }
            },
            _ => panic!("unexpected in phrase '{name}': {edn:?}"),
        });
        *phrase.name.write().unwrap() = name;
        Ok(phrase)
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

/// Stores and displays time-related state.
pub struct TransportToolbar<E: Engine> {
    /// Enable metronome?
    pub metronome: bool,
    /// Current sample rate, tempo, and PPQ.
    pub timebase:  Arc<Timebase>,
    /// JACK client handle (needs to not be dropped for standalone mode to work).
    pub jack:      Option<JackClient>,
    /// JACK transport handle.
    pub transport: Option<Transport>,
    /// Quantization factor
    /// Global frame and usec at which playback started
    pub started:   Option<(usize, usize)>,

    pub focused:   bool,
    pub focus:     usize,
    pub playing:   TransportPlayPauseButton<E>,
    pub bpm:       TransportBPM<E>,
    pub quant:     TransportQuantize<E>,
    pub sync:      TransportSync<E>,
    pub clock:     TransportClock<E>,
}

impl<E: Engine> TransportToolbar<E> {
    pub fn standalone () -> Usually<Arc<RwLock<Self>>> where Self: 'static {
        let mut transport = Self::new(None);
        transport.focused = true;
        let jack = JackClient::Inactive(
            Client::new("tek_transport", ClientOptions::NO_START_SERVER)?.0
        );
        transport.transport = Some(jack.transport());
        transport.playing.transport = Some(jack.transport());
        let transport = Arc::new(RwLock::new(transport));
        transport.write().unwrap().jack = Some(
            jack.activate(
                &transport.clone(),
                |state: &Arc<RwLock<TransportToolbar<E>>>, client, scope| {
                    state.write().unwrap().process(client, scope)
                }
            )?
        );
        Ok(transport)
    }
    pub fn new (transport: Option<Transport>) -> Self {
        let timebase = Arc::new(Timebase::default());
        Self {
            focused: false,
            focus:   0,

            playing:   TransportPlayPauseButton {
                _engine: Default::default(),
                transport: None,
                value:     Some(TransportState::Stopped),
                focused:   true
            },
            bpm:       TransportBPM {
                _engine: Default::default(),
                value:   timebase.bpm(),
                focused: false
            },
            quant:     TransportQuantize {
                _engine: Default::default(),
                value:   24,
                focused: false
            },
            sync:      TransportSync {
                _engine: Default::default(),
                value:   timebase.ppq() as usize * 4,
                focused: false
            },
            clock:     TransportClock {
                _engine: Default::default(),
                frame:   0,
                pulse:   0,
                ppq:     0,
                usecs:   0,
                focused: false
            },

            transport,
            timebase,
            metronome: false,
            started:   None,
            jack:      None,
        }
    }
    pub fn toggle_play (&mut self) -> Usually<()> {
        self.playing.toggle()?;
        Ok(())
    }
    pub fn update (&mut self, scope: &ProcessScope) -> (bool, usize, usize, usize, usize, f64) {
        let CycleTimes {
            current_frames,
            current_usecs,
            next_usecs,
            period_usecs
        } = scope.cycle_times().unwrap();
        let chunk_size = scope.n_frames() as usize;
        let transport = self.transport.as_ref().unwrap().query().unwrap();
        self.clock.frame = transport.pos.frame() as usize;
        let mut reset = false;
        if self.playing.value != Some(transport.state) {
            match transport.state {
                TransportState::Rolling => {
                    self.started = Some((
                        current_frames as usize,
                        current_usecs  as usize,
                    ));
                },
                TransportState::Stopped => {
                    self.started = None;
                    reset = true;
                },
                _ => {}
            }
        }
        self.playing.value = Some(transport.state);
        (
            reset,
            current_frames as usize,
            chunk_size as usize,
            current_usecs as usize,
            next_usecs as usize,
            period_usecs as f64
        )
    }
    pub fn bpm (&self) -> usize {
        self.timebase.bpm() as usize
    }
    pub fn ppq (&self) -> usize {
        self.timebase.ppq() as usize
    }
    pub fn pulse (&self) -> usize {
        self.timebase.frame_to_pulse(self.clock.frame as f64) as usize
    }
    pub fn usecs (&self) -> usize {
        self.timebase.frame_to_usec(self.clock.frame as f64) as usize
    }
    pub fn quant (&self) -> usize {
        self.quant.value
    }
    pub fn sync (&self) -> usize {
        self.sync.value
    }
}

impl<E: Engine> Audio for TransportToolbar<E> {
    fn process (&mut self, _: &Client, scope: &ProcessScope) -> Control {
        self.update(&scope);
        Control::Continue
    }
}

impl Handle<Tui> for TransportToolbar<Tui> {
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        match from.event() {
            key!(KeyCode::Left)  => { self.focus_prev(); },
            key!(KeyCode::Right) => { self.focus_next(); },
            _ => return self.focused_mut().handle(from)
        }
        Ok(Some(true))
    }
}

impl Content for TransportToolbar<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        Split::right(|add|{
            let focus_wrap = |focused, component|Layers::new(move |add|{
                if focused {
                    add(&CORNERS)?;
                    add(&Background(COLOR_BG1))?;
                }
                add(component)
            });
            add(&focus_wrap(self.focused && self.playing.focused, &self.playing))?;
            add(&focus_wrap(self.focused && self.bpm.focused,     &self.bpm))?;
            add(&focus_wrap(self.focused && self.quant.focused,   &self.quant))?;
            add(&focus_wrap(self.focused && self.sync.focused,    &self.sync))?;
            add(&focus_wrap(self.focused && self.clock.focused,   &self.clock))?;
            Ok(())
        })
    }
}

impl Focus<5, Tui> for TransportToolbar<Tui> {
    fn focus (&self) -> usize {
        self.focus
    }
    fn focus_mut (&mut self) -> &mut usize {
        &mut self.focus
    }
    fn focusable (&self) -> [&dyn Focusable<Tui>;5] {
        [
            &self.playing as &dyn Focusable<Tui>,
            &self.bpm     as &dyn Focusable<Tui>,
            &self.quant   as &dyn Focusable<Tui>,
            &self.sync    as &dyn Focusable<Tui>,
            &self.clock   as &dyn Focusable<Tui>,
        ]
    }
    fn focusable_mut (&mut self) -> [&mut dyn Focusable<Tui>;5] {
        [
            &mut self.playing as &mut dyn Focusable<Tui>,
            &mut self.bpm     as &mut dyn Focusable<Tui>,
            &mut self.quant   as &mut dyn Focusable<Tui>,
            &mut self.sync    as &mut dyn Focusable<Tui>,
            &mut self.clock   as &mut dyn Focusable<Tui>,
        ]
    }
}

impl Focusable<Tui> for TransportToolbar<Tui> {
    fn is_focused (&self) -> bool {
        self.focused
    }
    fn set_focused (&mut self, focused: bool) {
        self.focused = focused
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

pub struct TransportPlayPauseButton<E: Engine> {
    pub _engine: PhantomData<E>,
    pub transport: Option<Transport>,
    pub value:     Option<TransportState>,
    pub focused:   bool
}
impl<E: Engine> TransportPlayPauseButton<E> {
    fn toggle (&mut self) -> Usually<()> {
        let transport = self.transport.as_ref().unwrap();
        self.value = match self.value.expect("1st frame has not been processed yet") {
            TransportState::Stopped => {
                transport.start()?;
                Some(TransportState::Starting)
            },
            _ => {
                transport.stop()?;
                transport.locate(0)?;
                Some(TransportState::Stopped)
            },
        };
        Ok(())
    }
}
impl Focusable<Tui> for TransportPlayPauseButton<Tui> {
    fn is_focused (&self) -> bool {
        self.focused
    }
    fn set_focused (&mut self, focused: bool) {
        self.focused = focused
    }
}
impl Handle<Tui> for TransportPlayPauseButton<Tui> {
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        match from.event() {
            key!(KeyCode::Enter) => self.toggle().map(|_|Some(true)),
            _ => Ok(None)
        }
    }
}
impl Content for TransportPlayPauseButton<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        Layers::new(|add|{
            add(&Push::X(1, Min::XY(11, 2, Styled(match self.value {
                Some(TransportState::Stopped)  => Some(GRAY_DIM.bold()),
                Some(TransportState::Starting) => Some(GRAY_NOT_DIM_BOLD),
                Some(TransportState::Rolling)  => Some(WHITE_NOT_DIM_BOLD),
                _ => unreachable!(),
            }, match self.value {
                Some(TransportState::Rolling)  => "▶ PLAYING",
                Some(TransportState::Starting) => "READY ...",
                Some(TransportState::Stopped)  => "⏹ STOPPED",
                _ => unreachable!(),
            }))))?;
            Ok(())
        })
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

pub struct TransportBPM<E: Engine> {
    pub _engine: PhantomData<E>,
    pub value:   f64,
    pub focused: bool
}
impl Focusable<Tui> for TransportBPM<Tui> {
    fn is_focused (&self) -> bool {
        self.focused
    }
    fn set_focused (&mut self, focused: bool) {
        self.focused = focused
    }
}
impl Handle<Tui> for TransportBPM<Tui> { 
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        match from.event() {
            key!(KeyCode::Char(',')) => { self.value -= 1.0; },
            key!(KeyCode::Char('.')) => { self.value += 1.0; },
            key!(KeyCode::Char('<')) => { self.value -= 0.001; },
            key!(KeyCode::Char('>')) => { self.value += 0.001; },
            _ => return Ok(None)
        }
        Ok(Some(true))
    }
}
impl Content for TransportBPM<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        let Self { value, .. } = self;
        Outset::X(1u16, Split::down(move |add|{
            add(&"BPM")?;
            add(&format!("{}.{:03}", *value as usize, (value * 1000.0) % 1000.0).as_str())
        }))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

pub struct TransportQuantize<E: Engine> {
    pub _engine: PhantomData<E>,
    pub value:   usize,
    pub focused: bool
}
impl Focusable<Tui> for TransportQuantize<Tui> {
    fn is_focused (&self) -> bool {
        self.focused
    }
    fn set_focused (&mut self, focused: bool) {
        self.focused = focused
    }
}
impl Handle<Tui> for TransportQuantize<Tui> {
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        match from.event() {
            key!(KeyCode::Char(',')) => {
                self.value = prev_note_length(self.value);
                Ok(Some(true))
            },
            key!(KeyCode::Char('.')) => {
                self.value = next_note_length(self.value);
                Ok(Some(true))
            },
            _ => Ok(None)
        }
    }
}
impl Content for TransportQuantize<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        let Self { value, .. } = self;
        Outset::X(1u16, Split::down(|add|{
            add(&"QUANT")?;
            add(&ppq_to_name(*value as usize))
        }))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

pub struct TransportSync<E: Engine> {
    pub _engine: PhantomData<E>,
    pub value:   usize,
    pub focused: bool
}
impl Focusable<Tui> for TransportSync<Tui> {
    fn is_focused (&self) -> bool {
        self.focused
    }
    fn set_focused (&mut self, focused: bool) {
        self.focused = focused
    }
}
impl Handle<Tui> for TransportSync<Tui> {
    fn handle (&mut self, from: &TuiInput) -> Perhaps<bool> {
        match from.event() {
            key!(KeyCode::Char(',')) => {
                self.value = prev_note_length(self.value);
                Ok(Some(true))
            },
            key!(KeyCode::Char('.')) => {
                self.value = next_note_length(self.value);
                Ok(Some(true))
            },
            _ => Ok(None)
        }
    }
}
impl Content for TransportSync<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        let Self { value, .. } = self;
        Outset::X(1u16, Split::down(|add|{
            add(&"SYNC")?;
            add(&ppq_to_name(*value as usize))
        }))
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

pub struct TransportClock<E: Engine> {
    pub _engine: PhantomData<E>,
    pub frame:   usize,
    pub pulse:   usize,
    pub ppq:     usize,
    pub usecs:   usize,
    pub focused: bool,
}
impl Focusable<Tui> for TransportClock<Tui> {
    fn is_focused (&self) -> bool {
        self.focused
    }
    fn set_focused (&mut self, focused: bool) {
        self.focused = focused
    }
}
impl Handle<Tui> for TransportClock<Tui> {
    fn handle (&mut self, _: &TuiInput) -> Perhaps<bool> {
        Ok(None)
    }
}
impl Content for TransportClock<Tui> {
    type Engine = Tui;
    fn content (&self) -> impl Widget<Engine = Tui> {
        let Self { frame: _frame, pulse, ppq, usecs, .. } = self;
        Layers::new(move|add|{
            let (beats, pulses)    = if *ppq > 0 { (pulse / ppq, pulse % ppq) } else { (0, 0) };
            let (bars, beats)      = ((beats / 4) + 1, (beats % 4) + 1);
            let (seconds, msecs)   = (usecs / 1000000, usecs / 1000 % 1000);
            let (minutes, seconds) = (seconds / 60, seconds % 60);
            add(&Outset::X(1u16, Split::down(|add|{
                add(&format!("{bars}.{beats}.{pulses:02}").as_str())?;
                add(&format!("{minutes}:{seconds:02}:{msecs:03}").as_str())
            })))
        })
    }
}