use crate::*;

pub trait HasSceneScroll: HasScenes {
    fn scene_scroll (&self) -> usize;
}

pub trait HasTrackScroll: HasTracks {
    fn track_scroll (&self) -> usize;
}

pub trait HasMidiClip {
    fn clip (&self) -> Option<Arc<RwLock<MidiClip>>>;
}

pub trait HasClipsSize {
    fn clips_size (&self) -> &Measure<TuiOut>;
}

pub trait HasClock: Send + Sync {
    fn clock (&self) -> &Clock;
    fn clock_mut (&mut self) -> &mut Clock;
}

pub trait HasDevices {
    fn devices (&self) -> &Vec<Device>;
    fn devices_mut (&mut self) -> &mut Vec<Device>;
}

pub trait HasSelection: Has<Selection> {
    fn selection (&self) -> &Selection { self.get() }
    fn selection_mut (&mut self) -> &mut Selection { self.get_mut() }
}

pub trait HasWidth {
    const MIN_WIDTH: usize;
    /// Increment track width.
    fn width_inc (&mut self);
    /// Decrement track width, down to a hardcoded minimum of [Self::MIN_WIDTH].
    fn width_dec (&mut self);
}

pub trait HasMidiBuffers {
    fn note_buf_mut (&mut self) -> &mut Vec<u8>;
    fn midi_buf_mut (&mut self) -> &mut Vec<Vec<Vec<u8>>>;
}

pub trait HasSequencer {
    fn sequencer (&self) -> &Sequencer;
    fn sequencer_mut (&mut self) -> &mut Sequencer;
}

pub trait HasScene: Has<Option<Scene>> + Send + Sync {
    fn scene (&self) -> Option<&Scene> {
        Has::<Option<Scene>>::get(self).as_ref()
    }
    fn scene_mut (&mut self) -> &mut Option<Scene> {
        Has::<Option<Scene>>::get_mut(self)
    }
}

pub trait HasScenes: Has<Vec<Scene>> + Send + Sync {
    fn scenes (&self) -> &Vec<Scene> {
        Has::<Vec<Scene>>::get(self)
    }
    fn scenes_mut (&mut self) -> &mut Vec<Scene> {
        Has::<Vec<Scene>>::get_mut(self)
    }
    /// Generate the default name for a new scene
    fn scene_default_name (&self) -> Arc<str> {
        format!("s{:3>}", self.scenes().len() + 1).into()
    }
    fn scene_longest_name (&self) -> usize {
        self.scenes().iter().map(|s|s.name.len()).fold(0, usize::max)
    }
}

/// ```
/// struct TestEditorHost(Option<MidiEditor>);
/// has!(Option<MidiEditor>: |self: TestEditorHost|self.0);
/// let mut host = TestEditorHost(Some(MidiEditor::default()));
/// let _ = host.editor();
/// let _ = host.editor_mut();
/// let _ = host.is_editing();
/// let _ = host.editor_w();
/// let _ = host.editor_h();
/// ```
pub trait HasEditor: Has<Option<MidiEditor>> {
    fn editor (&self) -> Option<&MidiEditor> {
        self.get().as_ref()
    }
    fn editor_mut (&mut self) -> Option<&mut MidiEditor> {
        self.get_mut().as_mut()
    }
    fn is_editing (&self) -> bool {
        self.editor().is_some()
    }
    fn editor_w (&self) -> usize {
        self.editor().map(|e|e.size.w()).unwrap_or(0) as usize
    }
    fn editor_h (&self) -> usize {
        self.editor().map(|e|e.size.h()).unwrap_or(0) as usize
    }
}

pub trait HasClips {
    fn clips <'a> (&'a self) -> std::sync::RwLockReadGuard<'a, ClipPool>;
    fn clips_mut <'a> (&'a self) -> std::sync::RwLockWriteGuard<'a, ClipPool>;
    fn add_clip (&self) -> (usize, Arc<RwLock<MidiClip>>) {
        let clip = Arc::new(RwLock::new(MidiClip::new("Clip", true, 384, None, None)));
        self.clips_mut().push(clip.clone());
        (self.clips().len() - 1, clip)
    }
}

/// Trait for thing that may receive MIDI.
pub trait HasMidiIns {
    fn midi_ins (&self) -> &Vec<MidiInput>;
    fn midi_ins_mut (&mut self) -> &mut Vec<MidiInput>;
    /// Collect MIDI input from app ports (TODO preallocate large buffers)
    fn midi_input_collect <'a> (&'a self, scope: &'a ProcessScope) -> CollectedMidiInput<'a> {
        self.midi_ins().iter()
            .map(|port|port.port().iter(scope)
                .map(|RawMidi { time, bytes }|(time, LiveEvent::parse(bytes)))
                .collect::<Vec<_>>())
            .collect::<Vec<_>>()
    }
    fn midi_ins_with_sizes <'a> (&'a self) ->
        impl Iterator<Item=(usize, &'a Arc<str>, &'a [Connect], usize, usize)> + Send + Sync + 'a
    {
        let mut y = 0;
        self.midi_ins().iter().enumerate().map(move|(i, input)|{
            let height = 1 + input.connections().len();
            let data   = (i, input.port_name(), input.connections(), y, y + height);
            y += height;
            data
        })
    }
}

/// Trait for thing that may output MIDI.
pub trait HasMidiOuts {
    fn midi_outs (&self) -> &Vec<MidiOutput>;
    fn midi_outs_mut (&mut self) -> &mut Vec<MidiOutput>;
    fn midi_outs_with_sizes <'a> (&'a self) ->
        impl Iterator<Item=(usize, &'a Arc<str>, &'a [Connect], usize, usize)> + Send + Sync + 'a
    {
        let mut y = 0;
        self.midi_outs().iter().enumerate().map(move|(i, output)|{
            let height = 1 + output.connections().len();
            let data   = (i, output.port_name(), output.connections(), y, y + height);
            y += height;
            data
        })
    }
    fn midi_outs_emit (&mut self, scope: &ProcessScope) {
        for port in self.midi_outs_mut().iter_mut() {
            port.buffer_emit(scope)
        }
    }
}

pub trait HasTracks: Has<Vec<Track>> + Send + Sync {
    fn tracks (&self) -> &Vec<Track> { Has::<Vec<Track>>::get(self) }
    fn tracks_mut (&mut self) -> &mut Vec<Track> { Has::<Vec<Track>>::get_mut(self) }
    /// Run audio callbacks for every track and every device
    fn process_tracks (&mut self, client: &Client, scope: &ProcessScope) -> Control {
        for track in self.tracks_mut().iter_mut() {
            if Control::Quit == Audio::process(&mut track.sequencer, client, scope) {
                return Control::Quit
            }
            for device in track.devices.iter_mut() {
                if Control::Quit == DeviceAudio(device).process(client, scope) {
                    return Control::Quit
                }
            }
        }
        Control::Continue
    }
    fn track_longest_name (&self) -> usize { self.tracks().iter().map(|s|s.name.len()).fold(0, usize::max) }
    /// Stop all playing clips
    fn tracks_stop_all (&mut self) { for track in self.tracks_mut().iter_mut() { track.sequencer.enqueue_next(None); } }
    /// Stop all playing clips
    fn tracks_launch (&mut self, clips: Option<Vec<Option<Arc<RwLock<MidiClip>>>>>) {
        if let Some(clips) = clips {
            for (clip, track) in clips.iter().zip(self.tracks_mut()) { track.sequencer.enqueue_next(clip.as_ref()); }
        } else {
            for track in self.tracks_mut().iter_mut() { track.sequencer.enqueue_next(None); }
        }
    }
    /// Spacing between tracks.
    const TRACK_SPACING: usize = 0;
}

pub trait HasTrack {
    fn track (&self) -> Option<&Track>;
    fn track_mut (&mut self) -> Option<&mut Track>;
    #[cfg(feature = "port")] fn view_midi_ins_status <'a> (&'a self, theme: ItemTheme) -> impl Content<TuiOut> + 'a {
        self.track().map(move|track|view_ports_status(theme, "MIDI ins:  ", &track.sequencer.midi_ins))
    }
    #[cfg(feature = "port")] fn view_midi_outs_status (&self, theme: ItemTheme) -> impl Content<TuiOut>  + '_ {
        self.track().map(move|track|view_ports_status(theme, "MIDI outs: ", &track.sequencer.midi_outs))
    }
    #[cfg(feature = "port")] fn view_audio_ins_status (&self, theme: ItemTheme) -> impl Content<TuiOut> {
        self.track().map(move|track|view_ports_status(theme, "Audio ins: ", &track.audio_ins()))
    }
    #[cfg(feature = "port")] fn view_audio_outs_status (&self, theme: ItemTheme) -> impl Content<TuiOut> {
        self.track().map(move|track|view_ports_status(theme, "Audio outs:", &track.audio_outs()))
    }
}

pub trait HasPlayClip: HasClock {

    fn reset (&self) -> bool;

    fn reset_mut (&mut self) -> &mut bool;

    fn play_clip (&self) -> &Option<(Moment, Option<Arc<RwLock<MidiClip>>>)>;

    fn play_clip_mut (&mut self) -> &mut Option<(Moment, Option<Arc<RwLock<MidiClip>>>)>;

    fn next_clip (&self) -> &Option<(Moment, Option<Arc<RwLock<MidiClip>>>)>;

    fn next_clip_mut (&mut self) -> &mut Option<(Moment, Option<Arc<RwLock<MidiClip>>>)>;

    fn pulses_since_start (&self) -> Option<f64> {
        if let Some((started, Some(_))) = self.play_clip().as_ref() {
            let elapsed = self.clock().playhead.pulse.get() - started.pulse.get();
            return Some(elapsed)
        }
        None
    }

    fn pulses_since_start_looped (&self) -> Option<(f64, f64)> {
        if let Some((started, Some(clip))) = self.play_clip().as_ref() {
            let elapsed = self.clock().playhead.pulse.get() - started.pulse.get();
            let length  = clip.read().unwrap().length.max(1); // prevent div0 on empty clip
            let times   = (elapsed as usize / length) as f64;
            let elapsed = (elapsed as usize % length) as f64;
            return Some((times, elapsed))
        }
        None
    }

    fn enqueue_next (&mut self, clip: Option<&Arc<RwLock<MidiClip>>>) {
        *self.next_clip_mut() = Some((self.clock().next_launch_instant(), clip.cloned()));
        *self.reset_mut() = true;
    }

    fn play_status (&self) -> impl Content<TuiOut> {
        let (name, color): (Arc<str>, ItemTheme) = if let Some((_, Some(clip))) = self.play_clip() {
            let MidiClip { ref name, color, .. } = *clip.read().unwrap();
            (name.clone(), color)
        } else {
            ("".into(), Tui::g(64).into())
        };
        let time: String = self.pulses_since_start_looped()
            .map(|(times, time)|format!("{:>3}x {:>}", times+1.0, self.clock().timebase.format_beats_1(time)))
            .unwrap_or_else(||String::from("        ")).into();
        FieldV(color, "Now:", format!("{} {}", time, name))
    }

    fn next_status (&self) -> impl Content<TuiOut> {
        let mut time: Arc<str> = String::from("--.-.--").into();
        let mut name: Arc<str> = String::from("").into();
        let mut color = ItemTheme::G[64];
        let clock = self.clock();
        if let Some((t, Some(clip))) = self.next_clip() {
            let clip = clip.read().unwrap();
            name  = clip.name.clone();
            color = clip.color.clone();
            time  = {
                let target  = t.pulse.get();
                let current = clock.playhead.pulse.get();
                if target > current {
                    let remaining = target - current;
                    format!("-{:>}", clock.timebase.format_beats_1(remaining))
                } else {
                    String::new()
                }
            }.into()
        } else if let Some((t, Some(clip))) = self.play_clip() {
            let clip = clip.read().unwrap();
            if clip.looped {
                name  = clip.name.clone();
                color = clip.color.clone();
                let target  = t.pulse.get() + clip.length as f64;
                let current = clock.playhead.pulse.get();
                if target > current {
                    time = format!("-{:>}", clock.timebase.format_beats_0(target - current)).into()
                }
            } else {
                name  = "Stop".to_string().into();
            }
        };
        FieldV(color, "Next:", format!("{} {}", time, name))
    }
}

pub trait MidiMonitor: HasMidiIns + HasMidiBuffers {
    fn notes_in (&self) -> &Arc<RwLock<[bool;128]>>;
    fn monitoring (&self) -> bool;
    fn monitoring_mut (&mut self) -> &mut bool;
    fn toggle_monitor (&mut self) {
        *self.monitoring_mut() = !self.monitoring();
    }
    fn monitor (&mut self, scope: &ProcessScope) {
    }
}

pub trait MidiRecord: MidiMonitor + HasClock + HasPlayClip {
    fn recording (&self) -> bool;
    fn recording_mut (&mut self) -> &mut bool;
    fn toggle_record (&mut self) {
        *self.recording_mut() = !self.recording();
    }

    fn overdub (&self) -> bool;
    fn overdub_mut (&mut self) -> &mut bool;
    fn toggle_overdub (&mut self) {
        *self.overdub_mut() = !self.overdub();
    }

    fn record_clip (
        &mut self,
        scope:   &ProcessScope,
        started: Moment,
        clip:    &Option<Arc<RwLock<MidiClip>>>,
    ) {
        if let Some(clip) = clip {
            let sample0    = scope.last_frame_time() as usize;
            let start      = started.sample.get() as usize;
            let _recording = self.recording();
            let timebase   = self.clock().timebase().clone();
            let quant      = self.clock().quant.get();
            let mut clip   = clip.write().unwrap();
            let length     = clip.length;
            for input in self.midi_ins_mut().iter() {
                for (sample, event, _bytes) in parse_midi_input(input.port().iter(scope)) {
                    if let LiveEvent::Midi { message, .. } = event {
                        clip.record_event({
                            let sample    = (sample0 + sample - start) as f64;
                            let pulse     = timebase.samples_to_pulse(sample);
                            let quantized = (pulse / quant).round() * quant;
                            quantized as usize % length
                        }, message);
                    }
                }
            }
        }
    }

    fn record_next (&mut self) {
        // TODO switch to next clip and record into it
    }
}

pub trait MidiViewer: Measured<TuiOut> + MidiRange + MidiPoint + Debug + Send + Sync {
    fn buffer_size (&self, clip: &MidiClip) -> (usize, usize);
    fn redraw (&self);
    fn clip (&self) -> &Option<Arc<RwLock<MidiClip>>>;
    fn clip_mut (&mut self) -> &mut Option<Arc<RwLock<MidiClip>>>;
    fn set_clip (&mut self, clip: Option<&Arc<RwLock<MidiClip>>>) {
        *self.clip_mut() = clip.cloned();
        self.redraw();
    }
    /// Make sure cursor is within note range
    fn autoscroll (&self) {
        let note_pos = self.get_note_pos().min(127);
        let note_lo  = self.get_note_lo();
        let note_hi  = self.get_note_hi();
        if note_pos < note_lo {
            self.note_lo().set(note_pos);
        } else if note_pos > note_hi {
            self.note_lo().set((note_lo + note_pos).saturating_sub(note_hi));
        }
    }
    /// Make sure time range is within display
    fn autozoom (&self) {
        if self.time_lock().get() {
            let time_len  = self.get_time_len();
            let time_axis = self.get_time_axis();
            let time_zoom = self.get_time_zoom();
            loop {
                let time_zoom = self.time_zoom().get();
                let time_area = time_axis * time_zoom;
                if time_area > time_len {
                    let next_time_zoom = note_duration_prev(time_zoom);
                    if next_time_zoom <= 1 {
                        break
                    }
                    let next_time_area = time_axis * next_time_zoom;
                    if next_time_area >= time_len {
                        self.time_zoom().set(next_time_zoom);
                    } else {
                        break
                    }
                } else if time_area < time_len {
                    let prev_time_zoom = note_duration_next(time_zoom);
                    if prev_time_zoom > 384 {
                        break
                    }
                    let prev_time_area = time_axis * prev_time_zoom;
                    if prev_time_area <= time_len {
                        self.time_zoom().set(prev_time_zoom);
                    } else {
                        break
                    }
                }
            }
            if time_zoom != self.time_zoom().get() {
                self.redraw()
            }
        }
        //while time_len.div_ceil(time_zoom) > time_axis {
            //println!("\r{time_len} {time_zoom} {time_axis}");
            //time_zoom = Note::next(time_zoom);
        //}
        //self.time_zoom().set(time_zoom);
    }
}

pub trait AddScene: HasScenes + HasTracks {
    /// Add multiple scenes
    fn scenes_add (&mut self, n: usize) -> Usually<()> {
        let scene_color_1 = ItemColor::random();
        let scene_color_2 = ItemColor::random();
        for i in 0..n {
            let _ = self.scene_add(None, Some(
                scene_color_1.mix(scene_color_2, i as f32 / n as f32).into()
            ))?;
        }
        Ok(())
    }
    /// Add a scene
    fn scene_add (&mut self, name: Option<&str>, color: Option<ItemTheme>)
        -> Usually<(usize, &mut Scene)>
    {
        let scene = Scene {
            name:  name.map_or_else(||self.scene_default_name(), |x|x.to_string().into()),
            clips: vec![None;self.tracks().len()],
            color: color.unwrap_or_else(ItemTheme::random),
        };
        self.scenes_mut().push(scene);
        let index = self.scenes().len() - 1;
        Ok((index, &mut self.scenes_mut()[index]))
    }
}

pub trait ClipsView: TracksView + ScenesView {

    fn view_scenes_clips <'a> (&'a self)
        -> impl Content<TuiOut> + 'a
    {
        self.clips_size().of(Fill::XY(Bsp::a(
            Fill::XY(Align::se(Tui::fg(Green, format!("{}x{}", self.clips_size().w(), self.clips_size().h())))),
            Thunk::new(|to: &mut TuiOut|for (
                track_index, track, _, _
            ) in self.tracks_with_sizes() {
                to.place(&Fixed::X(track.width as u16,
                    Fill::Y(self.view_track_clips(track_index, track))))
            }))))
    }

    fn view_track_clips <'a> (&'a self, track_index: usize, track: &'a Track) -> impl Content<TuiOut> + 'a {
        Thunk::new(move|to: &mut TuiOut|for (
            scene_index, scene, ..
        ) in self.scenes_with_sizes() {
            let (name, theme): (Arc<str>, ItemTheme) = if let Some(Some(clip)) = &scene.clips.get(track_index) {
                let clip = clip.read().unwrap();
                (format!(" ⏹ {}", &clip.name).into(), clip.color)
            } else {
                (" ⏹ -- ".into(), ItemTheme::G[32])
            };
            let fg = theme.lightest.rgb;
            let mut outline = theme.base.rgb;
            let bg = if self.selection().track() == Some(track_index)
                && self.selection().scene() == Some(scene_index)
            {
                outline = theme.lighter.rgb;
                theme.light.rgb
            } else if self.selection().track() == Some(track_index)
                || self.selection().scene() == Some(scene_index)
            {
                outline = theme.darkest.rgb;
                theme.base.rgb
            } else {
                theme.dark.rgb
            };
            let w = if self.selection().track() == Some(track_index)
                && let Some(editor) = self.editor ()
            {
                (editor.measure_width() as usize).max(24).max(track.width)
            } else {
                track.width
            } as u16;
            let y = if self.selection().scene() == Some(scene_index)
                && let Some(editor) = self.editor ()
            {
                (editor.measure_height() as usize).max(12)
            } else {
                Self::H_SCENE as usize
            } as u16;

            to.place(&Fixed::XY(w, y, Bsp::b(
                Fill::XY(Outer(true, Style::default().fg(outline))),
                Fill::XY(Bsp::b(
                    Bsp::b(
                        Tui::fg_bg(outline, bg, Fill::XY("")),
                        Fill::XY(Align::nw(Tui::fg_bg(fg, bg, Tui::bold(true, name)))),
                    ),
                    Fill::XY(When::new(self.selection().track() == Some(track_index)
                      && self.selection().scene() == Some(scene_index)
                      && self.is_editing(), self.editor())))))));
        })
    }

}

pub trait TracksView: ScenesView + HasMidiIns + HasMidiOuts + HasTrackScroll + Measured<TuiOut> {

    fn tracks_width_available (&self) -> u16 {
        (self.measure_width() as u16).saturating_sub(40)
    }

    /// Iterate over tracks with their corresponding sizes.
    fn tracks_with_sizes (&self) -> impl TracksSizes<'_> {
        let _editor_width = self.editor().map(|e|e.measure_width());
        let _active_track = self.selection().track();
        let mut x = 0;
        self.tracks().iter().enumerate().map_while(move |(index, track)|{
            let width = track.width.max(8);
            if x + width < self.clips_size().w() as usize {
                let data = (index, track, x, x + width);
                x += width + Self::TRACK_SPACING;
                Some(data)
            } else {
                None
            }
        })
    }

    fn view_track_names (&self, theme: ItemTheme) -> impl Content<TuiOut> {
        let track_count = self.tracks().len();
        let scene_count = self.scenes().len();
        let selected = self.selection();
        let button = Bsp::s(
            button_3("t", "rack ", format!("{}{track_count}", selected.track()
                .map(|track|format!("{track}/")).unwrap_or_default()), false),
            button_3("s", "cene ", format!("{}{scene_count}", selected.scene()
                .map(|scene|format!("{scene}/")).unwrap_or_default()), false));
        let button_2 = Bsp::s(
            button_2("T", "+", false),
            button_2("S", "+", false));
        view_track_row_section(theme, button, button_2, Tui::bg(theme.darker.rgb,
            Fixed::Y(2, Thunk::new(|to: &mut TuiOut|{
                for (index, track, x1, _x2) in self.tracks_with_sizes() {
                    to.place(&Push::X(x1 as u16, Fixed::X(track_width(index, track),
                        Tui::bg(if selected.track() == Some(index) {
                            track.color.light.rgb
                        } else {
                            track.color.base.rgb
                        }, Bsp::s(Fill::X(Align::nw(Bsp::e(
                            format!("·t{index:02} "),
                            Tui::fg(Rgb(255, 255, 255), Tui::bold(true, &track.name))
                        ))), "")))  ));}}))))
    }

    fn view_track_outputs <'a> (&'a self, theme: ItemTheme, _h: u16) -> impl Content<TuiOut> {
        view_track_row_section(theme,
            Bsp::s(Fill::X(Align::w(button_2("o", "utput", false))),
                Thunk::new(|to: &mut TuiOut|for port in self.midi_outs().iter() {
                    to.place(&Fill::X(Align::w(port.port_name())));
                })),
            button_2("O", "+", false),
            Tui::bg(theme.darker.rgb, Align::w(Thunk::new(|to: &mut TuiOut|{
                for (index, track, _x1, _x2) in self.tracks_with_sizes() {
                    to.place(&Fixed::X(track_width(index, track),
                        Align::nw(Fill::Y(Map::south(1, ||track.sequencer.midi_outs.iter(),
                            |port, index|Tui::fg(Rgb(255, 255, 255),
                                Fixed::Y(1, Tui::bg(track.color.dark.rgb, Fill::X(Align::w(
                                    format!("·o{index:02} {}", port.port_name())))))))))));}}))))
    }

    fn view_track_inputs <'a> (&'a self, theme: ItemTheme) -> impl Content<TuiOut> {
        let mut h = 0u16;
        for track in self.tracks().iter() {
            h = h.max(track.sequencer.midi_ins.len() as u16);
        }
        let content = Thunk::new(move|to: &mut TuiOut|for (index, track, _x1, _x2) in self.tracks_with_sizes() {
            to.place(&Fixed::XY(track_width(index, track), h + 1,
                Align::nw(Bsp::s(
                    Tui::bg(track.color.base.rgb,
                        Fill::X(Align::w(row!(
                            Either::new(track.sequencer.monitoring, Tui::fg(Green, "●mon "), "·mon "),
                            Either::new(track.sequencer.recording,  Tui::fg(Red, "●rec "), "·rec "),
                            Either::new(track.sequencer.overdub,    Tui::fg(Yellow, "●dub "), "·dub "),
                        )))),
                    Map::south(1, ||track.sequencer.midi_ins.iter(),
                        |port, index|Tui::fg_bg(Rgb(255, 255, 255), track.color.dark.rgb,
                            Fill::X(Align::w(format!("·i{index:02} {}", port.port_name())))))))));
        });
        view_track_row_section(theme, button_2("i", "nput", false), button_2("I", "+", false),
            Tui::bg(theme.darker.rgb, Align::w(content)))
    }

}

pub trait ScenesView: HasEditor + HasSelection + HasSceneScroll + HasClipsSize + Send + Sync {

    /// Default scene height.
    const H_SCENE:  usize = 2;

    /// Default editor height.
    const H_EDITOR: usize = 15;

    fn h_scenes (&self) -> u16;

    fn w_side   (&self) -> u16;

    fn w_mid    (&self) -> u16;

    fn scenes_with_sizes (&self) -> impl ScenesSizes<'_> {
        let mut y = 0;
        self.scenes().iter().enumerate().skip(self.scene_scroll()).map_while(move|(s, scene)|{
            let height = if self.selection().scene() == Some(s) && self.editor().is_some() {
                8
            } else {
                Self::H_SCENE
            };
            if y + height <= self.clips_size().h() as usize {
                let data = (s, scene, y, y + height);
                y += height;
                Some(data)
            } else {
                None
            }
        })
    }

    fn view_scenes_names (&self) -> impl Content<TuiOut> {
        Fixed::X(20, Thunk::new(|to: &mut TuiOut|for (index, scene, ..) in self.scenes_with_sizes() {
            to.place(&self.view_scene_name(index, scene));
        }))
    }

    fn view_scene_name <'a> (&'a self, index: usize, scene: &'a Scene) -> impl Content<TuiOut> + 'a {
        let h = if self.selection().scene() == Some(index) && let Some(_editor) = self.editor() {
            7
        } else {
            Self::H_SCENE as u16
        };
        let bg = if self.selection().scene() == Some(index) {
            scene.color.light.rgb
        } else {
            scene.color.base.rgb
        };
        let a = Fill::X(Align::w(Bsp::e(format!("·s{index:02} "),
            Tui::fg(Tui::g(255), Tui::bold(true, &scene.name)))));
        let b = When::new(self.selection().scene() == Some(index) && self.is_editing(),
            Fill::XY(Align::nw(Bsp::s(
                self.editor().as_ref().map(|e|e.clip_status()),
                self.editor().as_ref().map(|e|e.edit_status())))));
        Fixed::XY(20, h, Tui::bg(bg, Align::nw(Bsp::s(a, b))))
    }

}

/// May create new MIDI input ports.
pub trait AddMidiIn {
    fn midi_in_add (&mut self) -> Usually<()>;
}

/// May create new MIDI output ports.
pub trait AddMidiOut {
    fn midi_out_add (&mut self) -> Usually<()>;
}

pub trait RegisterPorts: HasJack<'static> {
    /// Register a MIDI input port.
    fn midi_in (&self, name: &impl AsRef<str>, connect: &[Connect]) -> Usually<MidiInput>;
    /// Register a MIDI output port.
    fn midi_out (&self, name: &impl AsRef<str>, connect: &[Connect]) -> Usually<MidiOutput>;
    /// Register an audio input port.
    fn audio_in (&self, name: &impl AsRef<str>, connect: &[Connect]) -> Usually<AudioInput>;
    /// Register an audio output port.
    fn audio_out (&self, name: &impl AsRef<str>, connect: &[Connect]) -> Usually<AudioOutput>;
}

pub trait JackPort: HasJack<'static> {
    type Port: PortSpec + Default;
    type Pair: PortSpec + Default;
    fn new (jack: &Jack<'static>, name: &impl AsRef<str>, connect: &[Connect])
        -> Usually<Self> where Self: Sized;
    fn register (jack: &Jack<'static>, name: &impl AsRef<str>) -> Usually<Port<Self::Port>> {
        jack.with_client(|c|c.register_port::<Self::Port>(name.as_ref(), Default::default()))
            .map_err(|e|e.into())
    }
    fn port_name (&self) -> &Arc<str>;
    fn connections (&self) -> &[Connect];
    fn port (&self) -> &Port<Self::Port>;
    fn port_mut (&mut self) -> &mut Port<Self::Port>;
    fn into_port (self) -> Port<Self::Port> where Self: Sized;
    fn close (self) -> Usually<()> where Self: Sized {
        let jack = self.jack().clone();
        Ok(jack.with_client(|c|c.unregister_port(self.into_port()))?)
    }
    fn ports (&self, re_name: Option<&str>, re_type: Option<&str>, flags: PortFlags) -> Vec<String> {
        self.with_client(|c|c.ports(re_name, re_type, flags))
    }
    fn port_by_id (&self, id: u32) -> Option<Port<Unowned>> {
        self.with_client(|c|c.port_by_id(id))
    }
    fn port_by_name (&self, name: impl AsRef<str>) -> Option<Port<Unowned>> {
        self.with_client(|c|c.port_by_name(name.as_ref()))
    }
    fn connect_to_matching <'k> (&'k self) -> Usually<()> {
        for connect in self.connections().iter() {
            //panic!("{connect:?}");
            let status = match &connect.name {
                Exact(name) => self.connect_exact(name),
                RegExp(re)  => self.connect_regexp(re, connect.scope),
            }?;
            *connect.status.write().unwrap() = status;
        }
        Ok(())
    }
    fn connect_exact <'k> (&'k self, name: &str) ->
        Usually<Vec<(Port<Unowned>, Arc<str>, ConnectStatus)>>
    {
        self.with_client(move|c|{
            let mut status = vec![];
            for port in c.ports(None, None, PortFlags::empty()).iter() {
                if port.as_str() == &*name {
                    if let Some(port) = c.port_by_name(port.as_str()) {
                        let port_status = self.connect_to_unowned(&port)?;
                        let name = port.name()?.into();
                        status.push((port, name, port_status));
                        if port_status == Connected {
                            break
                        }
                    }
                }
            }
            Ok(status)
        })
    }
    fn connect_regexp <'k> (
        &'k self, re: &str, scope: ConnectScope
    ) -> Usually<Vec<(Port<Unowned>, Arc<str>, ConnectStatus)>> {
        self.with_client(move|c|{
            let mut status = vec![];
            let ports = c.ports(Some(&re), None, PortFlags::empty());
            for port in ports.iter() {
                if let Some(port) = c.port_by_name(port.as_str()) {
                    let port_status = self.connect_to_unowned(&port)?;
                    let name = port.name()?.into();
                    status.push((port, name, port_status));
                    if port_status == Connected && scope == One {
                        break
                    }
                }
            }
            Ok(status)
        })
    }
    /** Connect to a matching port by name. */
    fn connect_to_name (&self, name: impl AsRef<str>) -> Usually<ConnectStatus> {
        self.with_client(|c|if let Some(ref port) = c.port_by_name(name.as_ref()) {
            self.connect_to_unowned(port)
        } else {
            Ok(Missing)
        })
    }
    /** Connect to a matching port by reference. */
    fn connect_to_unowned (&self, port: &Port<Unowned>) -> Usually<ConnectStatus> {
        self.with_client(|c|Ok(if let Ok(_) = c.connect_ports(self.port(), port) {
            Connected
        } else if let Ok(_) = c.connect_ports(port, self.port()) {
            Connected
        } else {
            Mismatch
        }))
    }
    /** Connect to an owned matching port by reference. */
    fn connect_to_owned (&self, port: &Port<Self::Pair>) -> Usually<ConnectStatus> {
        self.with_client(|c|Ok(if let Ok(_) = c.connect_ports(self.port(), port) {
            Connected
        } else if let Ok(_) = c.connect_ports(port, self.port()) {
            Connected
        } else {
            Mismatch
        }))
    }
}