aboutsummaryrefslogtreecommitdiff
path: root/helix-term/src/ui/picker.rs
blob: 0214a391023f6e699561dc425021e34086ca142d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
use crate::{
    alt,
    compositor::{self, Component, Compositor, Context, Event, EventResult},
    ctrl,
    job::Callback,
    key, shift,
    ui::{
        self,
        document::{render_document, LineDecoration, LinePos, TextRenderer},
        EditorView,
    },
};
use futures_util::{future::BoxFuture, FutureExt};
use nucleo::pattern::CaseMatching;
use nucleo::{Config, Nucleo, Utf32String};
use tui::{
    buffer::Buffer as Surface,
    layout::Constraint,
    text::{Span, Spans},
    widgets::{Block, BorderType, Borders, Cell, Table},
};

use tui::widgets::Widget;

use std::{
    collections::HashMap,
    io::Read,
    path::PathBuf,
    sync::{
        atomic::{self, AtomicBool},
        Arc,
    },
};

use crate::ui::{Prompt, PromptEvent};
use helix_core::{
    char_idx_at_visual_offset, fuzzy::MATCHER, movement::Direction,
    text_annotations::TextAnnotations, unicode::segmentation::UnicodeSegmentation, Position,
    Syntax,
};
use helix_view::{
    editor::Action,
    graphics::{CursorKind, Margin, Modifier, Rect},
    theme::Style,
    view::ViewPosition,
    Document, DocumentId, Editor,
};

pub const ID: &str = "picker";
use super::{menu::Item, overlay::Overlay};

pub const MIN_AREA_WIDTH_FOR_PREVIEW: u16 = 72;
/// Biggest file size to preview in bytes
pub const MAX_FILE_SIZE_FOR_PREVIEW: u64 = 10 * 1024 * 1024;

#[derive(PartialEq, Eq, Hash)]
pub enum PathOrId {
    Id(DocumentId),
    Path(PathBuf),
}

impl PathOrId {
    fn get_canonicalized(self) -> Self {
        use PathOrId::*;
        match self {
            Path(path) => Path(helix_core::path::get_canonicalized_path(&path)),
            Id(id) => Id(id),
        }
    }
}

impl From<PathBuf> for PathOrId {
    fn from(v: PathBuf) -> Self {
        Self::Path(v)
    }
}

impl From<DocumentId> for PathOrId {
    fn from(v: DocumentId) -> Self {
        Self::Id(v)
    }
}

type FileCallback<T> = Box<dyn Fn(&Editor, &T) -> Option<FileLocation>>;

/// File path and range of lines (used to align and highlight lines)
pub type FileLocation = (PathOrId, Option<(usize, usize)>);

pub enum CachedPreview {
    Document(Box<Document>),
    Binary,
    LargeFile,
    NotFound,
}

// We don't store this enum in the cache so as to avoid lifetime constraints
// from borrowing a document already opened in the editor.
pub enum Preview<'picker, 'editor> {
    Cached(&'picker CachedPreview),
    EditorDocument(&'editor Document),
}

impl Preview<'_, '_> {
    fn document(&self) -> Option<&Document> {
        match self {
            Preview::EditorDocument(doc) => Some(doc),
            Preview::Cached(CachedPreview::Document(doc)) => Some(doc),
            _ => None,
        }
    }

    /// Alternate text to show for the preview.
    fn placeholder(&self) -> &str {
        match *self {
            Self::EditorDocument(_) => "<Invalid file location>",
            Self::Cached(preview) => match preview {
                CachedPreview::Document(_) => "<Invalid file location>",
                CachedPreview::Binary => "<Binary file>",
                CachedPreview::LargeFile => "<File too large to preview>",
                CachedPreview::NotFound => "<File not found>",
            },
        }
    }
}

fn item_to_nucleo<T: Item>(item: T, editor_data: &T::Data) -> Option<(T, Utf32String)> {
    let row = item.format(editor_data);
    let mut cells = row.cells.iter();
    let mut text = String::with_capacity(row.cell_text().map(|cell| cell.len()).sum());
    let cell = cells.next()?;
    if let Some(cell) = cell.content.lines.first() {
        for span in &cell.0 {
            text.push_str(&span.content);
        }
    }

    for cell in cells {
        text.push(' ');
        if let Some(cell) = cell.content.lines.first() {
            for span in &cell.0 {
                text.push_str(&span.content);
            }
        }
    }
    Some((item, text.into()))
}

pub struct Injector<T: Item> {
    dst: nucleo::Injector<T>,
    editor_data: Arc<T::Data>,
    shutown: Arc<AtomicBool>,
}

impl<T: Item> Clone for Injector<T> {
    fn clone(&self) -> Self {
        Injector {
            dst: self.dst.clone(),
            editor_data: self.editor_data.clone(),
            shutown: self.shutown.clone(),
        }
    }
}

pub struct InjectorShutdown;

impl<T: Item> Injector<T> {
    pub fn push(&self, item: T) -> Result<(), InjectorShutdown> {
        if self.shutown.load(atomic::Ordering::Relaxed) {
            return Err(InjectorShutdown);
        }

        if let Some((item, matcher_text)) = item_to_nucleo(item, &self.editor_data) {
            self.dst.push(item, |dst| dst[0] = matcher_text);
        }
        Ok(())
    }
}

pub struct Picker<T: Item> {
    editor_data: Arc<T::Data>,
    shutdown: Arc<AtomicBool>,
    matcher: Nucleo<T>,

    /// Current height of the completions box
    completion_height: u16,

    cursor: u32,
    prompt: Prompt,
    previous_pattern: String,

    /// Whether to show the preview panel (default true)
    show_preview: bool,
    /// Constraints for tabular formatting
    widths: Vec<Constraint>,

    callback_fn: PickerCallback<T>,

    pub truncate_start: bool,
    /// Caches paths to documents
    preview_cache: HashMap<PathBuf, CachedPreview>,
    read_buffer: Vec<u8>,
    /// Given an item in the picker, return the file path and line number to display.
    file_fn: Option<FileCallback<T>>,
}

impl<T: Item + 'static> Picker<T> {
    pub fn stream(editor_data: T::Data) -> (Nucleo<T>, Injector<T>) {
        let matcher = Nucleo::new(
            Config::DEFAULT,
            Arc::new(helix_event::request_redraw),
            None,
            1,
        );
        let streamer = Injector {
            dst: matcher.injector(),
            editor_data: Arc::new(editor_data),
            shutown: Arc::new(AtomicBool::new(false)),
        };
        (matcher, streamer)
    }

    pub fn new(
        options: Vec<T>,
        editor_data: T::Data,
        callback_fn: impl Fn(&mut Context, &T, Action) + 'static,
    ) -> Self {
        let matcher = Nucleo::new(
            Config::DEFAULT,
            Arc::new(helix_event::request_redraw),
            None,
            1,
        );
        let injector = matcher.injector();
        for item in options {
            if let Some((item, matcher_text)) = item_to_nucleo(item, &editor_data) {
                injector.push(item, |dst| dst[0] = matcher_text);
            }
        }
        Self::with(
            matcher,
            Arc::new(editor_data),
            Arc::new(AtomicBool::new(false)),
            callback_fn,
        )
    }

    pub fn with_stream(
        matcher: Nucleo<T>,
        injector: Injector<T>,
        callback_fn: impl Fn(&mut Context, &T, Action) + 'static,
    ) -> Self {
        Self::with(matcher, injector.editor_data, injector.shutown, callback_fn)
    }

    fn with(
        matcher: Nucleo<T>,
        editor_data: Arc<T::Data>,
        shutdown: Arc<AtomicBool>,
        callback_fn: impl Fn(&mut Context, &T, Action) + 'static,
    ) -> Self {
        let prompt = Prompt::new(
            "".into(),
            None,
            ui::completers::none,
            |_editor: &mut Context, _pattern: &str, _event: PromptEvent| {},
        );

        Self {
            matcher,
            editor_data,
            shutdown,
            cursor: 0,
            prompt,
            previous_pattern: String::new(),
            truncate_start: true,
            show_preview: true,
            callback_fn: Box::new(callback_fn),
            completion_height: 0,
            widths: Vec::new(),
            preview_cache: HashMap::new(),
            read_buffer: Vec::with_capacity(1024),
            file_fn: None,
        }
    }

    pub fn injector(&self) -> Injector<T> {
        Injector {
            dst: self.matcher.injector(),
            editor_data: self.editor_data.clone(),
            shutown: self.shutdown.clone(),
        }
    }

    pub fn truncate_start(mut self, truncate_start: bool) -> Self {
        self.truncate_start = truncate_start;
        self
    }

    pub fn with_preview(
        mut self,
        preview_fn: impl Fn(&Editor, &T) -> Option<FileLocation> + 'static,
    ) -> Self {
        self.file_fn = Some(Box::new(preview_fn));
        // assumption: if we have a preview we are matching paths... If this is ever
        // not true this could be a separate builder function
        self.matcher.update_config(Config::DEFAULT.match_paths());
        self
    }

    pub fn set_options(&mut self, new_options: Vec<T>) {
        self.matcher.restart(false);
        let injector = self.matcher.injector();
        for item in new_options {
            if let Some((item, matcher_text)) = item_to_nucleo(item, &self.editor_data) {
                injector.push(item, |dst| dst[0] = matcher_text);
            }
        }
    }

    /// Move the cursor by a number of lines, either down (`Forward`) or up (`Backward`)
    pub fn move_by(&mut self, amount: u32, direction: Direction) {
        let len = self.matcher.snapshot().matched_item_count();

        if len == 0 {
            // No results, can't move.
            return;
        }

        match direction {
            Direction::Forward => {
                self.cursor = self.cursor.saturating_add(amount) % len;
            }
            Direction::Backward => {
                self.cursor = self.cursor.saturating_add(len).saturating_sub(amount) % len;
            }
        }
    }

    /// Move the cursor down by exactly one page. After the last page comes the first page.
    pub fn page_up(&mut self) {
        self.move_by(self.completion_height as u32, Direction::Backward);
    }

    /// Move the cursor up by exactly one page. After the first page comes the last page.
    pub fn page_down(&mut self) {
        self.move_by(self.completion_height as u32, Direction::Forward);
    }

    /// Move the cursor to the first entry
    pub fn to_start(&mut self) {
        self.cursor = 0;
    }

    /// Move the cursor to the last entry
    pub fn to_end(&mut self) {
        self.cursor = self
            .matcher
            .snapshot()
            .matched_item_count()
            .saturating_sub(1);
    }

    pub fn selection(&self) -> Option<&T> {
        self.matcher
            .snapshot()
            .get_matched_item(self.cursor)
            .map(|item| item.data)
    }

    pub fn toggle_preview(&mut self) {
        self.show_preview = !self.show_preview;
    }

    fn prompt_handle_event(&mut self, event: &Event, cx: &mut Context) -> EventResult {
        if let EventResult::Consumed(_) = self.prompt.handle_event(event, cx) {
            let pattern = self.prompt.line();
            // TODO: better track how the pattern has changed
            if pattern != &self.previous_pattern {
                self.matcher.pattern.reparse(
                    0,
                    pattern,
                    CaseMatching::Smart,
                    pattern.starts_with(&self.previous_pattern),
                );
                self.previous_pattern = pattern.clone();
            }
        }
        EventResult::Consumed(None)
    }

    fn current_file(&self, editor: &Editor) -> Option<FileLocation> {
        self.selection()
            .and_then(|current| (self.file_fn.as_ref()?)(editor, current))
            .map(|(path_or_id, line)| (path_or_id.get_canonicalized(), line))
    }

    /// Get (cached) preview for a given path. If a document corresponding
    /// to the path is already open in the editor, it is used instead.
    fn get_preview<'picker, 'editor>(
        &'picker mut self,
        path_or_id: PathOrId,
        editor: &'editor Editor,
    ) -> Preview<'picker, 'editor> {
        match path_or_id {
            PathOrId::Path(path) => {
                let path = &path;
                if let Some(doc) = editor.document_by_path(path) {
                    return Preview::EditorDocument(doc);
                }

                if self.preview_cache.contains_key(path) {
                    return Preview::Cached(&self.preview_cache[path]);
                }

                let data = std::fs::File::open(path).and_then(|file| {
                    let metadata = file.metadata()?;
                    // Read up to 1kb to detect the content type
                    let n = file.take(1024).read_to_end(&mut self.read_buffer)?;
                    let content_type = content_inspector::inspect(&self.read_buffer[..n]);
                    self.read_buffer.clear();
                    Ok((metadata, content_type))
                });
                let preview = data
                    .map(
                        |(metadata, content_type)| match (metadata.len(), content_type) {
                            (_, content_inspector::ContentType::BINARY) => CachedPreview::Binary,
                            (size, _) if size > MAX_FILE_SIZE_FOR_PREVIEW => {
                                CachedPreview::LargeFile
                            }
                            _ => Document::open(path, None, None, editor.config.clone())
                                .map(|doc| CachedPreview::Document(Box::new(doc)))
                                .unwrap_or(CachedPreview::NotFound),
                        },
                    )
                    .unwrap_or(CachedPreview::NotFound);
                self.preview_cache.insert(path.to_owned(), preview);
                Preview::Cached(&self.preview_cache[path])
            }
            PathOrId::Id(id) => {
                let doc = editor.documents.get(&id).unwrap();
                Preview::EditorDocument(doc)
            }
        }
    }

    fn handle_idle_timeout(&mut self, cx: &mut Context) -> EventResult {
        let Some((current_file, _)) = self.current_file(cx.editor) else {
            return EventResult::Consumed(None);
        };

        // Try to find a document in the cache
        let doc = match &current_file {
            PathOrId::Id(doc_id) => doc_mut!(cx.editor, doc_id),
            PathOrId::Path(path) => match self.preview_cache.get_mut(path) {
                Some(CachedPreview::Document(ref mut doc)) => doc,
                _ => return EventResult::Consumed(None),
            },
        };

        let mut callback: Option<compositor::Callback> = None;

        // Then attempt to highlight it if it has no language set
        if doc.language_config().is_none() {
            if let Some(language_config) = doc.detect_language_config(&cx.editor.syn_loader) {
                doc.language = Some(language_config.clone());
                let text = doc.text().clone();
                let loader = cx.editor.syn_loader.clone();
                let job = tokio::task::spawn_blocking(move || {
                    let syntax = language_config.highlight_config(&loader.scopes()).and_then(
                        |highlight_config| Syntax::new(text.slice(..), highlight_config, loader),
                    );
                    let callback = move |editor: &mut Editor, compositor: &mut Compositor| {
                        let Some(syntax) = syntax else {
                            log::info!("highlighting picker item failed");
                            return;
                        };
                        let picker = match compositor.find::<Overlay<Self>>() {
                            Some(Overlay { content, .. }) => Some(content),
                            None => compositor
                                .find::<Overlay<DynamicPicker<T>>>()
                                .map(|overlay| &mut overlay.content.file_picker),
                        };
                        let Some(picker) = picker
                        else {
                            log::info!("picker closed before syntax highlighting finished");
                            return;
                        };
                        // Try to find a document in the cache
                        let doc = match current_file {
                            PathOrId::Id(doc_id) => doc_mut!(editor, &doc_id),
                            PathOrId::Path(path) => match picker.preview_cache.get_mut(&path) {
                                Some(CachedPreview::Document(ref mut doc)) => doc,
                                _ => return,
                            },
                        };
                        doc.syntax = Some(syntax);
                    };
                    Callback::EditorCompositor(Box::new(callback))
                });
                let tmp: compositor::Callback = Box::new(move |_, ctx| {
                    ctx.jobs
                        .callback(job.map(|res| res.map_err(anyhow::Error::from)))
                });
                callback = Some(Box::new(tmp))
            }
        }

        // QUESTION: do we want to compute inlay hints in pickers too ? Probably not for now
        // but it could be interesting in the future

        EventResult::Consumed(callback)
    }

    fn render_picker(&mut self, area: Rect, surface: &mut Surface, cx: &mut Context) {
        let status = self.matcher.tick(10);
        let snapshot = self.matcher.snapshot();
        if status.changed {
            self.cursor = self
                .cursor
                .min(snapshot.matched_item_count().saturating_sub(1))
        }

        let text_style = cx.editor.theme.get("ui.text");
        let selected = cx.editor.theme.get("ui.text.focus");
        let highlight_style = cx.editor.theme.get("special").add_modifier(Modifier::BOLD);

        // -- Render the frame:
        // clear area
        let background = cx.editor.theme.get("ui.background");
        surface.clear_with(area, background);

        // don't like this but the lifetime sucks
        let block = Block::default().borders(Borders::ALL);

        // calculate the inner area inside the box
        let inner = block.inner(area);

        block.render(area, surface);

        // -- Render the input bar:

        let area = inner.clip_left(1).with_height(1);
        // render the prompt first since it will clear its background
        self.prompt.render(area, surface, cx);

        let count = format!(
            "{}{}/{}",
            if status.running { "(running) " } else { "" },
            snapshot.matched_item_count(),
            snapshot.item_count(),
        );
        surface.set_stringn(
            (area.x + area.width).saturating_sub(count.len() as u16 + 1),
            area.y,
            &count,
            (count.len()).min(area.width as usize),
            text_style,
        );

        // -- Separator
        let sep_style = cx.editor.theme.get("ui.background.separator");
        let borders = BorderType::line_symbols(BorderType::Plain);
        for x in inner.left()..inner.right() {
            if let Some(cell) = surface.get_mut(x, inner.y + 1) {
                cell.set_symbol(borders.horizontal).set_style(sep_style);
            }
        }

        // -- Render the contents:
        // subtract area of prompt from top
        let inner = inner.clip_top(2);
        let rows = inner.height as u32;
        let offset = self.cursor - (self.cursor % std::cmp::max(1, rows));
        let cursor = self.cursor.saturating_sub(offset);
        let end = offset
            .saturating_add(rows)
            .min(snapshot.matched_item_count());
        let mut indices = Vec::new();
        let mut matcher = MATCHER.lock();
        matcher.config = Config::DEFAULT;
        if self.file_fn.is_some() {
            matcher.config.set_match_paths()
        }

        let options = snapshot.matched_items(offset..end).map(|item| {
            snapshot.pattern().column_pattern(0).indices(
                item.matcher_columns[0].slice(..),
                &mut matcher,
                &mut indices,
            );
            indices.sort_unstable();
            indices.dedup();
            let mut row = item.data.format(&self.editor_data);

            let mut grapheme_idx = 0u32;
            let mut indices = indices.drain(..);
            let mut next_highlight_idx = indices.next().unwrap_or(u32::MAX);
            if self.widths.len() < row.cells.len() {
                self.widths.resize(row.cells.len(), Constraint::Length(0));
            }
            let mut widths = self.widths.iter_mut();
            for cell in &mut row.cells {
                let Some(Constraint::Length(max_width)) = widths.next() else {
                    unreachable!();
                };

                // merge index highlights on top of existing hightlights
                let mut span_list = Vec::new();
                let mut current_span = String::new();
                let mut current_style = Style::default();
                let mut width = 0;

                let spans: &[Span] = cell.content.lines.first().map_or(&[], |it| it.0.as_slice());
                for span in spans {
                    // this looks like a bug on first glance, we are iterating
                    // graphemes but treating them as char indices. The reason that
                    // this is correct is that nucleo will only ever consider the first char
                    // of a grapheme (and discard the rest of the grapheme) so the indices
                    // returned by nucleo are essentially grapheme indecies
                    for grapheme in span.content.graphemes(true) {
                        let style = if grapheme_idx == next_highlight_idx {
                            next_highlight_idx = indices.next().unwrap_or(u32::MAX);
                            span.style.patch(highlight_style)
                        } else {
                            span.style
                        };
                        if style != current_style {
                            if !current_span.is_empty() {
                                span_list.push(Span::styled(current_span, current_style))
                            }
                            current_span = String::new();
                            current_style = style;
                        }
                        current_span.push_str(grapheme);
                        grapheme_idx += 1;
                    }
                    width += span.width();
                }

                span_list.push(Span::styled(current_span, current_style));
                if width as u16 > *max_width {
                    *max_width = width as u16;
                }
                *cell = Cell::from(Spans::from(span_list));

                // spacer
                if grapheme_idx == next_highlight_idx {
                    next_highlight_idx = indices.next().unwrap_or(u32::MAX);
                }
                grapheme_idx += 1;
            }

            row
        });

        let table = Table::new(options)
            .style(text_style)
            .highlight_style(selected)
            .highlight_symbol(" > ")
            .column_spacing(1)
            .widths(&self.widths);

        use tui::widgets::TableState;

        table.render_table(
            inner,
            surface,
            &mut TableState {
                offset: 0,
                selected: Some(cursor as usize),
            },
            self.truncate_start,
        );
    }

    fn render_preview(&mut self, area: Rect, surface: &mut Surface, cx: &mut Context) {
        // -- Render the frame:
        // clear area
        let background = cx.editor.theme.get("ui.background");
        let text = cx.editor.theme.get("ui.text");
        surface.clear_with(area, background);

        // don't like this but the lifetime sucks
        let block = Block::default().borders(Borders::ALL);

        // calculate the inner area inside the box
        let inner = block.inner(area);
        // 1 column gap on either side
        let margin = Margin::horizontal(1);
        let inner = inner.inner(&margin);
        block.render(area, surface);

        if let Some((path, range)) = self.current_file(cx.editor) {
            let preview = self.get_preview(path, cx.editor);
            let doc = match preview.document() {
                Some(doc)
                    if range.map_or(true, |(start, end)| {
                        start <= end && end <= doc.text().len_lines()
                    }) =>
                {
                    doc
                }
                _ => {
                    let alt_text = preview.placeholder();
                    let x = inner.x + inner.width.saturating_sub(alt_text.len() as u16) / 2;
                    let y = inner.y + inner.height / 2;
                    surface.set_stringn(x, y, alt_text, inner.width as usize, text);
                    return;
                }
            };

            let mut offset = ViewPosition::default();
            if let Some((start_line, end_line)) = range {
                let height = end_line - start_line;
                let text = doc.text().slice(..);
                let start = text.line_to_char(start_line);
                let middle = text.line_to_char(start_line + height / 2);
                if height < inner.height as usize {
                    let text_fmt = doc.text_format(inner.width, None);
                    let annotations = TextAnnotations::default();
                    (offset.anchor, offset.vertical_offset) = char_idx_at_visual_offset(
                        text,
                        middle,
                        // align to middle
                        -(inner.height as isize / 2),
                        0,
                        &text_fmt,
                        &annotations,
                    );
                    if start < offset.anchor {
                        offset.anchor = start;
                        offset.vertical_offset = 0;
                    }
                } else {
                    offset.anchor = start;
                }
            }

            let mut highlights = EditorView::doc_syntax_highlights(
                doc,
                offset.anchor,
                area.height,
                &cx.editor.theme,
            );
            for spans in EditorView::doc_diagnostics_highlights(doc, &cx.editor.theme) {
                if spans.is_empty() {
                    continue;
                }
                highlights = Box::new(helix_core::syntax::merge(highlights, spans));
            }
            let mut decorations: Vec<Box<dyn LineDecoration>> = Vec::new();

            if let Some((start, end)) = range {
                let style = cx
                    .editor
                    .theme
                    .try_get("ui.highlight")
                    .unwrap_or_else(|| cx.editor.theme.get("ui.selection"));
                let draw_highlight = move |renderer: &mut TextRenderer, pos: LinePos| {
                    if (start..=end).contains(&pos.doc_line) {
                        let area = Rect::new(
                            renderer.viewport.x,
                            renderer.viewport.y + pos.visual_line,
                            renderer.viewport.width,
                            1,
                        );
                        renderer.surface.set_style(area, style)
                    }
                };
                decorations.push(Box::new(draw_highlight))
            }

            render_document(
                surface,
                inner,
                doc,
                offset,
                // TODO: compute text annotations asynchronously here (like inlay hints)
                &TextAnnotations::default(),
                highlights,
                &cx.editor.theme,
                &mut decorations,
                &mut [],
            );
        }
    }
}

impl<T: Item + 'static + Send + Sync> Component for Picker<T> {
    fn render(&mut self, area: Rect, surface: &mut Surface, cx: &mut Context) {
        // +---------+ +---------+
        // |prompt   | |preview  |
        // +---------+ |         |
        // |picker   | |         |
        // |         | |         |
        // +---------+ +---------+

        let render_preview =
            self.show_preview && self.file_fn.is_some() && area.width > MIN_AREA_WIDTH_FOR_PREVIEW;

        let picker_width = if render_preview {
            area.width / 2
        } else {
            area.width
        };

        let picker_area = area.with_width(picker_width);
        self.render_picker(picker_area, surface, cx);

        if render_preview {
            let preview_area = area.clip_left(picker_width);
            self.render_preview(preview_area, surface, cx);
        }
    }

    fn handle_event(&mut self, event: &Event, ctx: &mut Context) -> EventResult {
        if let Event::IdleTimeout = event {
            return self.handle_idle_timeout(ctx);
        }
        // TODO: keybinds for scrolling preview

        let key_event = match event {
            Event::Key(event) => *event,
            Event::Paste(..) => return self.prompt_handle_event(event, ctx),
            Event::Resize(..) => return EventResult::Consumed(None),
            _ => return EventResult::Ignored(None),
        };

        let close_fn = |picker: &mut Self| {
            // if the picker is very large don't store it as last_picker to avoid
            // excessive memory consumption
            let callback: compositor::Callback = if picker.matcher.snapshot().item_count() > 100_000
            {
                Box::new(|compositor: &mut Compositor, _ctx| {
                    // remove the layer
                    compositor.pop();
                })
            } else {
                // stop streaming in new items in the background, really we should
                // be restarting the stream somehow once the picker gets
                // reopened instead (like for an FS crawl) that would also remove the
                // need for the special case above but that is pretty tricky
                picker.shutdown.store(true, atomic::Ordering::Relaxed);
                Box::new(|compositor: &mut Compositor, _ctx| {
                    // remove the layer
                    compositor.last_picker = compositor.pop();
                })
            };
            EventResult::Consumed(Some(callback))
        };

        // So that idle timeout retriggers
        ctx.editor.reset_idle_timer();

        match key_event {
            shift!(Tab) | key!(Up) | ctrl!('p') => {
                self.move_by(1, Direction::Backward);
            }
            key!(Tab) | key!(Down) | ctrl!('n') => {
                self.move_by(1, Direction::Forward);
            }
            key!(PageDown) | ctrl!('d') => {
                self.page_down();
            }
            key!(PageUp) | ctrl!('u') => {
                self.page_up();
            }
            key!(Home) => {
                self.to_start();
            }
            key!(End) => {
                self.to_end();
            }
            key!(Esc) | ctrl!('c') => return close_fn(self),
            alt!(Enter) => {
                if let Some(option) = self.selection() {
                    (self.callback_fn)(ctx, option, Action::Load);
                }
            }
            key!(Enter) => {
                if let Some(option) = self.selection() {
                    (self.callback_fn)(ctx, option, Action::Replace);
                }
                return close_fn(self);
            }
            ctrl!('s') => {
                if let Some(option) = self.selection() {
                    (self.callback_fn)(ctx, option, Action::HorizontalSplit);
                }
                return close_fn(self);
            }
            ctrl!('v') => {
                if let Some(option) = self.selection() {
                    (self.callback_fn)(ctx, option, Action::VerticalSplit);
                }
                return close_fn(self);
            }
            ctrl!('t') => {
                self.toggle_preview();
            }
            _ => {
                self.prompt_handle_event(event, ctx);
            }
        }

        EventResult::Consumed(None)
    }

    fn cursor(&self, area: Rect, editor: &Editor) -> (Option<Position>, CursorKind) {
        let block = Block::default().borders(Borders::ALL);
        // calculate the inner area inside the box
        let inner = block.inner(area);

        // prompt area
        let area = inner.clip_left(1).with_height(1);

        self.prompt.cursor(area, editor)
    }

    fn required_size(&mut self, (width, height): (u16, u16)) -> Option<(u16, u16)> {
        self.completion_height = height.saturating_sub(4);
        Some((width, height))
    }

    fn id(&self) -> Option<&'static str> {
        Some(ID)
    }
}
impl<T: Item> Drop for Picker<T> {
    fn drop(&mut self) {
        // ensure we cancel any ongoing background threads streaming into the picker
        self.shutdown.store(true, atomic::Ordering::Relaxed)
    }
}

type PickerCallback<T> = Box<dyn Fn(&mut Context, &T, Action)>;

/// Returns a new list of options to replace the contents of the picker
/// when called with the current picker query,
pub type DynQueryCallback<T> =
    Box<dyn Fn(String, &mut Editor) -> BoxFuture<'static, anyhow::Result<Vec<T>>>>;

/// A picker that updates its contents via a callback whenever the
/// query string changes. Useful for live grep, workspace symbols, etc.
pub struct DynamicPicker<T: ui::menu::Item + Send + Sync> {
    file_picker: Picker<T>,
    query_callback: DynQueryCallback<T>,
    query: String,
}

impl<T: ui::menu::Item + Send + Sync> DynamicPicker<T> {
    pub fn new(file_picker: Picker<T>, query_callback: DynQueryCallback<T>) -> Self {
        Self {
            file_picker,
            query_callback,
            query: String::new(),
        }
    }
}

impl<T: Item + Send + Sync + 'static> Component for DynamicPicker<T> {
    fn render(&mut self, area: Rect, surface: &mut Surface, cx: &mut Context) {
        self.file_picker.render(area, surface, cx);
    }

    fn handle_event(&mut self, event: &Event, cx: &mut Context) -> EventResult {
        let event_result = self.file_picker.handle_event(event, cx);
        let current_query = self.file_picker.prompt.line();

        if !matches!(event, Event::IdleTimeout) || self.query == *current_query {
            return event_result;
        }

        self.query.clone_from(current_query);

        let new_options = (self.query_callback)(current_query.to_owned(), cx.editor);

        cx.jobs.callback(async move {
            let new_options = new_options.await?;
            let callback = Callback::EditorCompositor(Box::new(move |editor, compositor| {
                // Wrapping of pickers in overlay is done outside the picker code,
                // so this is fragile and will break if wrapped in some other widget.
                let picker = match compositor.find_id::<Overlay<DynamicPicker<T>>>(ID) {
                    Some(overlay) => &mut overlay.content.file_picker,
                    None => return,
                };
                picker.set_options(new_options);
                editor.reset_idle_timer();
            }));
            anyhow::Ok(callback)
        });
        EventResult::Consumed(None)
    }

    fn cursor(&self, area: Rect, ctx: &Editor) -> (Option<Position>, CursorKind) {
        self.file_picker.cursor(area, ctx)
    }

    fn required_size(&mut self, viewport: (u16, u16)) -> Option<(u16, u16)> {
        self.file_picker.required_size(viewport)
    }

    fn id(&self) -> Option<&'static str> {
        Some(ID)
    }
}