#![feature(trait_alias)]

pub use tek_engine;
pub(crate) use ConnectName::*;
pub(crate) use ConnectScope::*;
pub(crate) use ConnectStatus::*;

mod device_struct; pub use self::device_struct::*;
mod device_trait; pub use self::device_trait::*;
mod device_type; pub use self::device_type::*;
mod device_impl;

pub(crate) use ::{
    tek_engine::*,
    tek_engine::tengri::{
        Usually, Perhaps, Has, MaybeHas, has, maybe_has, from,
        input::*,
        output::*,
        tui::*,
        tui::ratatui,
        tui::ratatui::widgets::{Widget, canvas::{Canvas, Line}}, 
        tui::ratatui::prelude::{Rect, Style, Stylize, Buffer, Color::{self, *}},
    },
    std::{
        cmp::Ord,
        ffi::OsString,
        fmt::{Debug, Formatter},
        fs::File,
        path::PathBuf,
        sync::{Arc, RwLock, atomic::{AtomicBool, AtomicUsize, Ordering::Relaxed}},
    }
};

#[cfg(feature = "sampler")] pub(crate) use symphonia::{
    core::{
        formats::Packet,
        codecs::{Decoder, CODEC_TYPE_NULL},
        //errors::Error as SymphoniaError,
        io::MediaSourceStream,
        probe::Hint,
        audio::SampleBuffer,
    },
    default::get_codecs,
};

#[cfg(feature = "lv2")] use std::thread::{spawn, JoinHandle};

#[cfg(feature = "lv2_gui")] use ::winit::{
    application::ApplicationHandler,
    event::WindowEvent,
    event_loop::{ActiveEventLoop, ControlFlow, EventLoop},
    window::{Window, WindowId},
    platform::x11::EventLoopBuilderExtX11
};

/// Define a type alias for iterators of sized items (columns).
macro_rules! def_sizes_iter {
    ($Type:ident => $($Item:ty),+) => {
        pub trait $Type<'a> =
            Iterator<Item=(usize, $(&'a $Item,)+ usize, usize)> + Send + Sync + 'a;
    }
}


pub fn view_transport (
    play: bool,
    bpm:  Arc<RwLock<String>>,
    beat: Arc<RwLock<String>>,
    time: Arc<RwLock<String>>,
) -> impl Content<TuiOut> {
    let theme = ItemTheme::G[96];
    Tui::bg(Black, row!(Bsp::a(
        Fill::XY(Align::w(button_play_pause(play))),
        Fill::XY(Align::e(row!(
            FieldH(theme, "BPM",  bpm),
            FieldH(theme, "Beat", beat),
            FieldH(theme, "Time", time),
        )))
    )))
}

pub fn view_status (
    sel: Option<Arc<str>>,
    sr:  Arc<RwLock<String>>,
    buf: Arc<RwLock<String>>,
    lat: Arc<RwLock<String>>,
) -> impl Content<TuiOut> {
    let theme = ItemTheme::G[96];
    Tui::bg(Black, row!(Bsp::a(
        Fill::XY(Align::w(sel.map(|sel|FieldH(theme, "Selected", sel)))),
        Fill::XY(Align::e(row!(
            FieldH(theme, "SR",  sr),
            FieldH(theme, "Buf", buf),
            FieldH(theme, "Lat", lat),
        )))
    )))
}

pub fn button_play_pause (playing: bool) -> impl Content<TuiOut> {
    let compact = true;//self.is_editing();
    Tui::bg(if playing { Rgb(0, 128, 0) } else { Rgb(128, 64, 0) },
        Either::new(compact,
            Thunk::new(move|to: &mut TuiOut|to.place(&Fixed::X(9, Either::new(playing,
                Tui::fg(Rgb(0, 255, 0),   " PLAYING "),
                Tui::fg(Rgb(255, 128, 0), " STOPPED ")))
            )),
            Thunk::new(move|to: &mut TuiOut|to.place(&Fixed::X(5, Either::new(playing,
                Tui::fg(Rgb(0, 255, 0),   Bsp::s(" 🭍🭑🬽 ", " 🭞🭜🭘 ",)),
                Tui::fg(Rgb(255, 128, 0), Bsp::s(" ▗▄▖ ", " ▝▀▘ ",))))
            ))
        )
    )
}

pub fn swap_value <T: Clone + PartialEq, U> (
    target: &mut T, value: &T, returned: impl Fn(T)->U
) -> Perhaps<U> {
    if *target == *value {
        Ok(None)
    } else {
        let mut value = value.clone();
        std::mem::swap(target, &mut value);
        Ok(Some(returned(value)))
    }
}

pub fn toggle_bool <U> (
    target: &mut bool, value: &Option<bool>, returned: impl Fn(Option<bool>)->U
) -> Perhaps<U> {
    let mut value = value.unwrap_or(!*target);
    if value == *target {
        Ok(None)
    } else {
        std::mem::swap(target, &mut value);
        Ok(Some(returned(Some(value))))
    }
}

pub fn device_kinds () -> &'static [&'static str] {
    &[
        #[cfg(feature = "sampler")] "Sampler",
        #[cfg(feature = "lv2")] "Plugin (LV2)",
    ]
}

impl<T: Has<Vec<Device>>> HasDevices for T {
    fn devices (&self) -> &Vec<Device> {
        self.get()
    }
    fn devices_mut (&mut self) -> &mut Vec<Device> {
        self.get_mut()
    }
}

impl Device {
    pub fn name (&self) -> &str {
        match self {
            Self::Sampler(sampler) => sampler.name.as_ref(),
            _ => todo!(),
        }
    }
    pub fn midi_ins (&self) -> &[MidiInput] {
        match self {
            //Self::Sampler(Sampler { midi_in, .. }) => &[midi_in],
            _ => todo!()
        }
    }
    pub fn midi_outs (&self) -> &[MidiOutput] {
        match self {
            Self::Sampler(_) => &[],
            _ => todo!()
        }
    }
    pub fn audio_ins (&self) -> &[AudioInput] {
        match self {
            Self::Sampler(Sampler { audio_ins, .. }) => audio_ins.as_slice(),
            _ => todo!()
        }
    }
    pub fn audio_outs (&self) -> &[AudioOutput] {
        match self {
            Self::Sampler(Sampler { audio_outs, .. }) => audio_outs.as_slice(),
            _ => todo!()
        }
    }
}

audio!(|self: DeviceAudio<'a>, client, scope|{
    use Device::*;
    match self.0 {
        Mute   => { Control::Continue },
        Bypass => { /*TODO*/ Control::Continue },
        #[cfg(feature = "sampler")] Sampler(sampler) => sampler.process(client, scope),
        #[cfg(feature = "lv2")]     Lv2(lv2)         => lv2.process(client, scope),
        #[cfg(feature = "vst2")]    Vst2 => { todo!() }, // TODO
        #[cfg(feature = "vst3")]    Vst3 => { todo!() }, // TODO
        #[cfg(feature = "clap")]    Clap => { todo!() }, // TODO
        #[cfg(feature = "sf2")]     Sf2  => { todo!() }, // TODO
    }
});

def_command!(ClockCommand: |clock: Clock| {
    SeekUsec   { usec:   f64 } => {
        clock.playhead.update_from_usec(*usec); Ok(None) },
    SeekSample { sample: f64 } => {
        clock.playhead.update_from_sample(*sample); Ok(None) },
    SeekPulse  { pulse:  f64 } => {
        clock.playhead.update_from_pulse(*pulse); Ok(None) },
    SetBpm     { bpm:    f64 } => Ok(Some(
        Self::SetBpm { bpm: clock.timebase().bpm.set(*bpm) })),
    SetQuant   { quant:  f64 } => Ok(Some(
        Self::SetQuant { quant: clock.quant.set(*quant) })),
    SetSync    { sync:   f64 } => Ok(Some(
        Self::SetSync { sync: clock.sync.set(*sync) })),

    Play  { position: Option<u32> } => {
        clock.play_from(*position)?; Ok(None) /* TODO Some(Pause(previousPosition)) */ },
    Pause { position: Option<u32> } => {
        clock.pause_at(*position)?; Ok(None) },

    TogglePlayback { position: u32 } => Ok(if clock.is_rolling() {
        clock.pause_at(Some(*position))?; None
    } else {
        clock.play_from(Some(*position))?; None
    }),
});
def_command!(DeviceCommand: |device: Device| {});
def_command!(ClipCommand: |clip: MidiClip| {
    SetColor { color: Option<ItemTheme> } => {
        //(SetColor [t: usize, s: usize, c: ItemTheme]
            //clip.clip_set_color(t, s, c).map(|o|Self::SetColor(t, s, o)))));
            //("color"   [a: usize, b: usize] Some(Self::SetColor(a.unwrap(), b.unwrap(), ItemTheme::random())))
        todo!()
    },
    SetLoop { looping: Option<bool> } => {
        //(SetLoop  [t: usize, s: usize, l: bool] cmd_todo!("\n\rtodo: {self:?}"))
            //("loop"    [a: usize, b: usize, c: bool] Some(Self::SetLoop(a.unwrap(), b.unwrap(), c.unwrap())))
        todo!()
    }
});
def_command!(BrowseCommand: |browse: Browse| {
    SetVisible => Ok(None),
    SetPath { address: PathBuf } => Ok(None),
    SetSearch { filter: Arc<str> } => Ok(None),
    SetCursor { cursor: usize } => Ok(None),
});
//take!(DeviceCommand|state: Arrangement, iter|state.selected_device().as_ref()
    //.map(|t|Take::take(t, iter)).transpose().map(|x|x.flatten()));

#[cfg(feature = "track")]
pub fn view_track_row_section (
    _theme:     ItemTheme,
    button:     impl Content<TuiOut>,
    button_add: impl Content<TuiOut>,
    content:    impl Content<TuiOut>,
) -> impl Content<TuiOut> {
    Bsp::w(Fill::Y(Fixed::X(4, Align::nw(button_add))),
        Bsp::e(Fixed::X(20, Fill::Y(Align::nw(button))), Fill::XY(Align::c(content))))
}
pub fn wrap (bg: Color, fg: Color, content: impl Content<TuiOut>) -> impl Content<TuiOut> {
    let left  = Tui::fg_bg(bg, Reset, Fixed::X(1, Repeat::Y("▐")));
    let right = Tui::fg_bg(bg, Reset, Fixed::X(1, Repeat::Y("▌")));
    Bsp::e(left, Bsp::w(right, Tui::fg_bg(fg, bg, content)))
}

#[macro_export] macro_rules! has_clip {
    (|$self:ident:$Struct:ident$(<$($L:lifetime),*$($T:ident$(:$U:path)?),*>)?|$cb:expr) => {
        impl $(<$($L),*$($T $(: $U)?),*>)? HasMidiClip for $Struct $(<$($L),*$($T),*>)? {
            fn clip (&$self) -> Option<Arc<RwLock<MidiClip>>> { $cb }
        }
    }
}
def_command!(MidiEditCommand: |editor: MidiEditor| {
    Show { clip: Option<Arc<RwLock<MidiClip>>> } => {
        editor.set_clip(clip.as_ref()); editor.redraw(); Ok(None) },
    DeleteNote => {
        editor.redraw(); todo!() },
    AppendNote    { advance: bool } => {
        editor.put_note(*advance); editor.redraw(); Ok(None) },
    SetNotePos    { pos:    usize } => {
        editor.set_note_pos((*pos).min(127)); editor.redraw(); Ok(None) },
    SetNoteLen    { len:    usize } => {
        editor.set_note_len(*len); editor.redraw(); Ok(None) },
    SetNoteScroll { scroll: usize } => {
        editor.set_note_lo((*scroll).min(127)); editor.redraw(); Ok(None) },
    SetTimePos    { pos:    usize } => {
        editor.set_time_pos(*pos); editor.redraw(); Ok(None) },
    SetTimeScroll { scroll: usize } => {
        editor.set_time_start(*scroll); editor.redraw(); Ok(None) },
    SetTimeZoom   { zoom:   usize } => {
        editor.set_time_zoom(*zoom); editor.redraw(); Ok(None) },
    SetTimeLock   { lock:   bool  } => {
        editor.set_time_lock(*lock); editor.redraw(); Ok(None) },
    // TODO: 1-9 seek markers that by default start every 8th of the clip
});

fn to_key (note: usize) -> &'static str {
    match note % 12 {
        11 | 9 | 7 | 5 | 4 | 2 | 0 => "████▌",
        10 | 8 | 6 | 3 | 1         => "     ",
        _  => unreachable!(),
    }
}

pub(crate) fn note_y_iter (note_lo: usize, note_hi: usize, y0: u16)
    -> impl Iterator<Item=(usize, u16, usize)>
{
    (note_lo..=note_hi).rev().enumerate().map(move|(y, n)|(y, y0 + y as u16, n))
}

fn draw_header (state: &Lv2, to: &mut TuiOut, x: u16, y: u16, w: u16) {
    let style  = Style::default().gray();
    let label1 = format!(" {}", state.name);
    to.blit(&label1, x + 1, y, Some(style.white().bold()));
    if let Some(ref path) = state.path {
        let label2 = format!("{}…", &path[..((w as usize - 10).min(path.len()))]);
        to.blit(&label2, x + 2 + label1.len() as u16, y, Some(style.not_dim()));
    }
    //Ok(Rect { x, y, width: w, height: 1 })
}


#[cfg(feature = "lv2_gui")]
pub fn run_lv2_ui (mut ui: LV2PluginUI) -> Usually<JoinHandle<()>> {
    Ok(spawn(move||{
        let event_loop = EventLoop::builder().with_x11().with_any_thread(true).build().unwrap();
        event_loop.set_control_flow(ControlFlow::Wait);
        event_loop.run_app(&mut ui).unwrap()
    }))
}

#[cfg(feature = "lv2_gui")]
fn lv2_ui_instantiate (kind: &str) {
    //let host = Suil
}

pub fn mix_summing <const N: usize> (
    buffer: &mut [Vec<f32>], gain: f32, frames: usize, mut next: impl FnMut()->Option<[f32;N]>,
) -> bool {
    let channels = buffer.len();
    for index in 0..frames {
        if let Some(frame) = next() {
            for (channel, sample) in frame.iter().enumerate() {
                let channel = channel % channels;
                buffer[channel][index] += sample * gain;
            }
        } else {
            return false
        }
    }
    true
}

pub fn mix_average <const N: usize> (
    buffer: &mut [Vec<f32>], gain: f32, frames: usize, mut next: impl FnMut()->Option<[f32;N]>,
) -> bool {
    let channels = buffer.len();
    for index in 0..frames {
        if let Some(frame) = next() {
            for (channel, sample) in frame.iter().enumerate() {
                let channel = channel % channels;
                let value = buffer[channel][index];
                buffer[channel][index] = (value + sample * gain) / 2.0;
            }
        } else {
            return false
        }
    }
    true
}

pub fn to_log10 (samples: &[f32]) -> f32 {
    let total: f32 = samples.iter().map(|x|x.abs()).sum();
    let count = samples.len() as f32;
    10. * (total / count).log10()
}


pub fn to_rms (samples: &[f32]) -> f32 {
    let sum = samples.iter()
        .map(|s|*s)
        .reduce(|sum, sample|sum + sample.abs())
        .unwrap_or(0.0);
    (sum / samples.len() as f32).sqrt()
}

pub fn view_meter <'a> (label: &'a str, value: f32) -> impl Content<TuiOut> + 'a {
    col!(
        FieldH(ItemTheme::G[128], label, format!("{:>+9.3}", value)),
        Fixed::XY(if value >= 0.0 { 13 }
            else if value >= -1.0 { 12 }
            else if value >= -2.0 { 11 }
            else if value >= -3.0 { 10 }
            else if value >= -4.0 { 9  }
            else if value >= -6.0 { 8  }
            else if value >= -9.0 { 7  }
            else if value >= -12.0 { 6 }
            else if value >= -15.0 { 5 }
            else if value >= -20.0 { 4 }
            else if value >= -25.0 { 3 }
            else if value >= -30.0 { 2 }
            else if value >= -40.0 { 1 }
            else { 0 }, 1, Tui::bg(if value >= 0.0  { Red }
                else if value >= -3.0 { Yellow }
                else { Green }, ())))
}

pub fn view_meters (values: &[f32;2]) -> impl Content<TuiOut> + use<'_> {
    let left  = format!("L/{:>+9.3}", values[0]);
    let right = format!("R/{:>+9.3}", values[1]);
    Bsp::s(left, right)
}
def_command!(PoolCommand: |pool: Pool| {
    // Toggle visibility of pool
    Show { visible: bool } => { pool.visible = *visible; Ok(Some(Self::Show { visible: !visible })) },
    // Select a clip from the clip pool
    Select { index: usize } => { pool.set_clip_index(*index); Ok(None) },
    // Update the contents of the clip pool
    Clip { command: PoolClipCommand } => Ok(command.execute(pool)?.map(|command|Self::Clip{command})),
    // Rename a clip
    Rename { command: RenameCommand } => Ok(command.delegate(pool, |command|Self::Rename{command})?),
    // Change the length of a clip
    Length { command: CropCommand } => Ok(command.delegate(pool, |command|Self::Length{command})?),
    // Import from file
    Import { command: BrowseCommand } => Ok(if let Some(browse) = pool.browse.as_mut() {
        command.delegate(browse, |command|Self::Import{command})?
    } else {
        None
    }),
    // Export to file
    Export { command: BrowseCommand } => Ok(if let Some(browse) = pool.browse.as_mut() {
        command.delegate(browse, |command|Self::Export{command})?
    } else {
        None
    }),
});
def_command!(PoolClipCommand: |pool: Pool| {
    Delete { index: usize } => {
        let index = *index;
        let clip = pool.clips_mut().remove(index).read().unwrap().clone();
        Ok(Some(Self::Add { index, clip }))
    },
    Swap { index: usize, other: usize } => {
        let index = *index;
        let other = *other;
        pool.clips_mut().swap(index, other);
        Ok(Some(Self::Swap { index, other }))
    },
    Export { index: usize, path: PathBuf } => {
        todo!("export clip to midi file");
    },
    Add { index: usize, clip: MidiClip } => {
        let index = *index;
        let mut index = index;
        let clip = Arc::new(RwLock::new(clip.clone()));
        let mut clips = pool.clips_mut();
        if index >= clips.len() {
            index = clips.len();
            clips.push(clip)
        } else {
            clips.insert(index, clip);
        }
        Ok(Some(Self::Delete { index }))
    },
    Import { index: usize, path: PathBuf } => {
        let index = *index;
        let bytes = std::fs::read(&path)?;
        let smf = Smf::parse(bytes.as_slice())?;
        let mut t = 0u32;
        let mut events = vec![];
        for track in smf.tracks.iter() {
            for event in track.iter() {
                t += event.delta.as_int();
                if let TrackEventKind::Midi { channel, message } = event.kind {
                    events.push((t, channel.as_int(), message));
                }
            }
        }
        let mut clip = MidiClip::new("imported", true, t as usize + 1, None, None);
        for event in events.iter() {
            clip.notes[event.0 as usize].push(event.2);
        }
        Ok(Self::Add { index, clip }.execute(pool)?)
    },
    SetName { index: usize, name: Arc<str> } => {
        let index = *index;
        let clip = &mut pool.clips_mut()[index];
        let old_name = clip.read().unwrap().name.clone();
        clip.write().unwrap().name = name.clone();
        Ok(Some(Self::SetName { index, name: old_name }))
    },
    SetLength { index: usize, length: usize } => {
        let index = *index;
        let clip = &mut pool.clips_mut()[index];
        let old_len = clip.read().unwrap().length;
        clip.write().unwrap().length = *length;
        Ok(Some(Self::SetLength { index, length: old_len }))
    },
    SetColor { index: usize, color: ItemColor } => {
        let index = *index;
        let mut color = ItemTheme::from(*color);
        std::mem::swap(&mut color, &mut pool.clips()[index].write().unwrap().color);
        Ok(Some(Self::SetColor { index, color: color.base }))
    },
});

def_command!(RenameCommand: |pool: Pool| {
    Begin => unreachable!(),
    Cancel => {
        if let Some(PoolMode::Rename(clip, ref mut old_name)) = pool.mode_mut().clone() {
            pool.clips()[clip].write().unwrap().name = old_name.clone().into();
        }
        Ok(None)
    },
    Confirm => {
        if let Some(PoolMode::Rename(_clip, ref mut old_name)) = pool.mode_mut().clone() {
            let old_name = old_name.clone(); *pool.mode_mut() = None; return Ok(Some(Self::Set { value: old_name }))
        }
        Ok(None)
    },
    Set { value: Arc<str> } => {
        if let Some(PoolMode::Rename(clip, ref mut _old_name)) = pool.mode_mut().clone() {
            pool.clips()[clip].write().unwrap().name = value.clone();
        }
        Ok(None)
    },
});
def_command!(CropCommand: |pool: Pool| {
    Begin => unreachable!(),
    Cancel => { if let Some(PoolMode::Length(..)) = pool.mode_mut().clone() { *pool.mode_mut() = None; } Ok(None) },
    Set { length: usize } => {
        if let Some(PoolMode::Length(clip, ref mut length, ref mut _focus))
            = pool.mode_mut().clone()
        {
            let old_length;
            {
                let clip = pool.clips()[clip].clone();//.write().unwrap();
                old_length = Some(clip.read().unwrap().length);
                clip.write().unwrap().length = *length;
            }
            *pool.mode_mut() = None;
            return Ok(old_length.map(|length|Self::Set { length }))
        }
        Ok(None)
    },
    Next => {
        if let Some(PoolMode::Length(_clip, ref mut _length, ref mut focus)) = pool.mode_mut().clone() { focus.next() }; Ok(None)
    },
    Prev => {
        if let Some(PoolMode::Length(_clip, ref mut _length, ref mut focus)) = pool.mode_mut().clone() { focus.prev() }; Ok(None)
    },
    Inc => {
        if let Some(PoolMode::Length(_clip, ref mut length, ref mut focus)) = pool.mode_mut().clone() {
            match focus {
                ClipLengthFocus::Bar  => { *length += 4 * PPQ },
                ClipLengthFocus::Beat => { *length += PPQ     },
                ClipLengthFocus::Tick => { *length += 1       },
            }
        }
        Ok(None)
    },
    Dec => {
        if let Some(PoolMode::Length(_clip, ref mut length, ref mut focus)) = pool.mode_mut().clone() {
            match focus {
                ClipLengthFocus::Bar  => { *length = length.saturating_sub(4 * PPQ) },
                ClipLengthFocus::Beat => { *length = length.saturating_sub(PPQ)     },
                ClipLengthFocus::Tick => { *length = length.saturating_sub(1)       },
            }
        }
        Ok(None)
    }
});
def_command!(MidiInputCommand: |port: MidiInput| {
    Close => todo!(),
    Connect { midi_out: Arc<str> } => todo!(),
});
def_command!(MidiOutputCommand: |port: MidiOutput| {
    Close => todo!(),
    Connect { midi_in: Arc<str> } => todo!(),
});
def_command!(AudioInputCommand: |port: AudioInput| {
    Close => todo!(),
    Connect { audio_out: Arc<str> } => todo!(),
});
def_command!(AudioOutputCommand: |port: AudioOutput| {
    Close => todo!(),
    Connect { audio_in: Arc<str> } => todo!(),
});
def_sizes_iter!(InputsSizes  => MidiInput);
def_sizes_iter!(OutputsSizes => MidiOutput);
def_sizes_iter!(PortsSizes   => Arc<str>, [Connect]);
def_sizes_iter!(ScenesSizes => Scene);

fn draw_info (sample: Option<&Arc<RwLock<Sample>>>) -> impl Content<TuiOut> + use<'_> {
    When::new(sample.is_some(), Thunk::new(move|to: &mut TuiOut|{
        let sample = sample.unwrap().read().unwrap();
        let theme  = sample.color;
        to.place(&row!(
            FieldH(theme, "Name",   format!("{:<10}", sample.name.clone())),
            FieldH(theme, "Length", format!("{:<8}",  sample.channels[0].len())),
            FieldH(theme, "Start",  format!("{:<8}",  sample.start)),
            FieldH(theme, "End",    format!("{:<8}",  sample.end)),
            FieldH(theme, "Trans",  "0"),
            FieldH(theme, "Gain",   format!("{}",     sample.gain)),
        ))
    }))
}

fn draw_info_v (sample: Option<&Arc<RwLock<Sample>>>) -> impl Content<TuiOut> + use<'_> {
    Either::new(sample.is_some(), Thunk::new(move|to: &mut TuiOut|{
        let sample = sample.unwrap().read().unwrap();
        let theme  = sample.color;
        to.place(&Fixed::X(20, col!(
            Fill::X(Align::w(FieldH(theme, "Name  ", format!("{:<10}", sample.name.clone())))),
            Fill::X(Align::w(FieldH(theme, "Length", format!("{:<8}",  sample.channels[0].len())))),
            Fill::X(Align::w(FieldH(theme, "Start ", format!("{:<8}",  sample.start)))),
            Fill::X(Align::w(FieldH(theme, "End   ", format!("{:<8}",  sample.end)))),
            Fill::X(Align::w(FieldH(theme, "Trans ", "0"))),
            Fill::X(Align::w(FieldH(theme, "Gain  ", format!("{}",     sample.gain)))),
        )))
    }), Thunk::new(|to: &mut TuiOut|to.place(&Tui::fg(Red, col!(
        Tui::bold(true, "× No sample."),
        "[r] record",
        "[Shift-F9] import",
    )))))
}

fn draw_status (sample: Option<&Arc<RwLock<Sample>>>) -> impl Content<TuiOut> {
    Tui::bold(true, Tui::fg(Tui::g(224), sample
        .map(|sample|{
            let sample = sample.read().unwrap();
            format!("Sample {}-{}", sample.start, sample.end)
        })
        .unwrap_or_else(||"No sample".to_string())))
}

fn draw_sample (
    to: &mut TuiOut, x: u16, y: u16, note: Option<&u7>, sample: &Sample, focus: bool
) -> Usually<usize> {
    let style = if focus { Style::default().green() } else { Style::default() };
    if focus {
        to.blit(&"🬴", x+1, y, Some(style.bold()));
    }
    let label1 = format!("{:3} {:12}",
        note.map(|n|n.to_string()).unwrap_or(String::default()),
        sample.name);
    let label2 = format!("{:>6} {:>6}  +0.0",
        sample.start,
        sample.end);
    to.blit(&label1, x+2, y, Some(style.bold()));
    to.blit(&label2, x+3+label1.len()as u16, y, Some(style));
    Ok(label1.len() + label2.len() + 4)
}

fn read_sample_data (_: &str) -> Usually<(usize, Vec<Vec<f32>>)> {
    todo!();
}

fn scan (dir: &PathBuf) -> Usually<(Vec<OsString>, Vec<OsString>)> {
    let (mut subdirs, mut files) = std::fs::read_dir(dir)?
        .fold((vec!["..".into()], vec![]), |(mut subdirs, mut files), entry|{
            let entry = entry.expect("failed to read drectory entry");
            let meta = entry.metadata().expect("failed to read entry metadata");
            if meta.is_file() {
                files.push(entry.file_name());
            } else if meta.is_dir() {
                subdirs.push(entry.file_name());
            }
            (subdirs, files)
        });
    subdirs.sort();
    files.sort();
    Ok((subdirs, files))
}

def_command!(SamplerCommand: |sampler: Sampler| {
    RecordToggle { slot: usize } => {
        let slot = *slot;
        let recording = sampler.recording.as_ref().map(|x|x.0);
        let _ = Self::RecordFinish.execute(sampler)?;
        // autoslice: continue recording at next slot
        if recording != Some(slot) {
            Self::RecordBegin { slot }.execute(sampler)
        } else {
            Ok(None)
        }
    },
    RecordBegin { slot: usize } => {
        let slot = *slot;
        sampler.recording = Some((
            slot,
            Some(Arc::new(RwLock::new(Sample::new(
                "Sample", 0, 0, vec![vec![];sampler.audio_ins.len()]
            ))))
        ));
        Ok(None)
    },
    RecordFinish => {
        let _prev_sample = sampler.recording.as_mut().map(|(index, sample)|{
            std::mem::swap(sample, &mut sampler.mapped[*index]);
            sample
        }); // TODO: undo
        Ok(None)
    },
    RecordCancel => {
        sampler.recording = None;
        Ok(None)
    },
    PlaySample { slot: usize } => {
        let slot = *slot;
        if let Some(ref sample) = sampler.mapped[slot] {
            sampler.voices.write().unwrap().push(Sample::play(sample, 0, &u7::from(128)));
        }
        Ok(None)
    },
    StopSample { slot: usize } => {
        let slot = *slot;
        todo!();
        Ok(None)
    },
});

def_command!(FileBrowserCommand: |sampler: Sampler|{
    //("begin"   []            Some(Self::Begin))
    //("cancel"  []            Some(Self::Cancel))
    //("confirm" []            Some(Self::Confirm))
    //("select"  [i: usize]    Some(Self::Select(i.expect("no index"))))
    //("chdir"   [p: PathBuf]  Some(Self::Chdir(p.expect("no path"))))
    //("filter"  [f: Arc<str>] Some(Self::Filter(f.expect("no filter")))))
});
def_command!(SceneCommand: |scene: Scene| {
    SetSize { size: usize } => { todo!() },
    SetZoom { size: usize } => { todo!() },
    SetName  { name:  Arc<str>  } =>
        swap_value(&mut scene.name, name, |name|Self::SetName{name}),
    SetColor { color: ItemTheme } =>
        swap_value(&mut scene.color, color, |color|Self::SetColor{color}),
});
def_sizes_iter!(TracksSizes => Track);
def_command!(TrackCommand: |track: Track| {
    Stop => { track.sequencer.enqueue_next(None); Ok(None) },
    SetMute { mute: Option<bool> } => todo!(),
    SetSolo { solo: Option<bool> } => todo!(),
    SetSize { size: usize } => todo!(),
    SetZoom { zoom: usize } => todo!(),
    SetName { name: Arc<str> } =>
        swap_value(&mut track.name, name, |name|Self::SetName { name }),
    SetColor { color: ItemTheme } =>
        swap_value(&mut track.color, color, |color|Self::SetColor { color }),
    SetRec { rec: Option<bool> } =>
        toggle_bool(&mut track.sequencer.recording, rec, |rec|Self::SetRec { rec }),
    SetMon { mon: Option<bool> } =>
        toggle_bool(&mut track.sequencer.monitoring, mon, |mon|Self::SetMon { mon }),
});


pub(crate) fn track_width (_index: usize, track: &Track) -> u16 {
    track.width as u16
}

fn view_track_header (theme: ItemTheme, content: impl Content<TuiOut>) -> impl Content<TuiOut> {
    Fixed::X(12, Tui::bg(theme.darker.rgb, Fill::X(Align::e(content))))
}

fn view_ports_status <'a, T: JackPort> (theme: ItemTheme, title: &'a str, ports: &'a [T])
    -> impl Content<TuiOut> + use<'a, T>
{
    let ins   = ports.len() as u16;
    let frame = Outer(true, Style::default().fg(Tui::g(96)));
    let iter  = move||ports.iter();
    let names = Map::south(1, iter, move|port, index|Fill::Y(Align::w(format!(" {index} {}", port.port_name()))));
    let field = FieldV(theme, title, names);
    Fixed::XY(20, 1 + ins, frame.enclose(Fixed::XY(20, 1 + ins, field)))
}

pub(crate) fn per_track_top <'a, T: Content<TuiOut> + 'a, U: TracksSizes<'a>> (
    tracks:   impl Fn() -> U + Send + Sync + 'a,
    callback: impl Fn(usize, &'a Track)->T + Send + Sync + 'a
) -> impl Content<TuiOut> + 'a {
    Align::x(Tui::bg(Reset, Map::new(tracks,
        move|(index, track, x1, x2): (usize, &'a Track, usize, usize), _|{
            let width = (x2 - x1) as u16;
            map_east(x1 as u16, width, Fixed::X(width, Tui::fg_bg(
                track.color.lightest.rgb,
                track.color.base.rgb,
                callback(index, track))))})))
}

pub(crate) fn per_track <'a, T: Content<TuiOut> + 'a, U: TracksSizes<'a>> (
    tracks:   impl Fn() -> U + Send + Sync + 'a,
    callback: impl Fn(usize, &'a Track)->T + Send + Sync + 'a
) -> impl Content<TuiOut> + 'a {
    per_track_top(tracks, move|index, track|Fill::Y(Align::y(callback(index, track))))
}

pub(crate) fn io_ports <'a, T: PortsSizes<'a>> (
    fg: Color, bg: Color, iter: impl Fn()->T + Send + Sync + 'a
) -> impl Content<TuiOut> + 'a {
    Map::new(iter, move|(
        _index, name, connections, y, y2
    ): (usize, &'a Arc<str>, &'a [Connect], usize, usize), _|
        map_south(y as u16, (y2-y) as u16, Bsp::s(
            Fill::Y(Tui::bold(true, Tui::fg_bg(fg, bg, Align::w(Bsp::e(&" 󰣲 ", name))))),
            Map::new(||connections.iter(), move|connect: &'a Connect, index|map_south(index as u16, 1,
                Fill::Y(Align::w(Tui::bold(false, Tui::fg_bg(fg, bg,
                    &connect.info)))))))))
}

#[cfg(feature = "vst2")]
fn set_vst_plugin <E: Engine> (
    host: &Arc<Mutex<Plugin<E>>>, _path: &str
) -> Usually<PluginKind> {
    let mut loader = ::vst::host::PluginLoader::load(
        &std::path::Path::new("/nix/store/ij3sz7nqg5l7v2dygdvzy3w6cj62bd6r-helm-0.9.0/lib/lxvst/helm.so"),
        host.clone()
    )?;
    Ok(PluginKind::VST2 {
        instance: loader.instance()?
    })
}