scry-cli 0.4.0

use std::{
    path::{Path, PathBuf},
    sync::mpsc::{self, Receiver, Sender},
    thread,
    time::{Duration, Instant},
};

use anyhow::{Context, Result, bail, ensure};
use ratatui::{
    crossterm::event::{KeyCode, KeyEvent, KeyModifiers},
    style::Stylize,
    text::Span,
};

use crate::{
    embed::{ImageEmbedder, Prompt, TextEmbedder},
    guard,
    output::{clean, clean_path},
    search::{Embedded, Hit, Search, Target},
};

/// While you type, new embeddings join the ranking at most this often, so the images do not
/// move all the time.
const REFRESH: Duration = Duration::from_millis(500);

const NO_MODEL: &str = "this needs the SigLIP 2 model: run scry -q once to download it";

/// What the hits are ranked by.
#[derive(Clone, PartialEq)]
enum Probe {
    Text(String),
    Like(PathBuf),
}

enum Model {
    Unloaded,
    Loading(Receiver<Result<Box<TextEmbedder>>>),
    Ready(Box<TextEmbedder>),
}

/// Embeds the hits that came without an embedding.
struct Images {
    paths: Sender<(usize, PathBuf)>,
    done: Receiver<Embedded>,
    /// Sent and not answered yet.
    pending: usize,
}

impl Images {
    fn send(&mut self, i: usize, path: &Path) {
        if self.paths.send((i, path.to_owned())).is_ok() {
            self.pending += 1;
        }
    }
}

/// Ranks the hits again inside a picker, by a text that you type or by an image. The search
/// still chooses the hits: a ranking only changes their order.
pub struct Ranking {
    /// All hits, in the order and with the scores that the search gave them.
    hits: Vec<Hit>,
    /// The probes that you gave, the newest last. Backspace goes back one.
    history: Vec<Probe>,
    /// The query line, while you type.
    typing: Option<String>,
    text: Model,
    images: Option<Images>,
    /// The board must show a new order.
    stale: bool,
    /// Embeddings came since the last ranking.
    fresh: bool,
    ranked: Instant,
}

impl Ranking {
    pub fn new() -> Self {
        Self {
            hits: Vec::new(),
            history: Vec::new(),
            typing: None,
            text: Model::Unloaded,
            images: None,
            stale: false,
            fresh: false,
            ranked: Instant::now(),
        }
    }

    /// Takes a new hit from the search.
    pub fn add(&mut self, hit: &Hit) {
        if hit.embedding.is_none()
            && let Some(images) = &mut self.images
        {
            images.send(self.hits.len(), &hit.path);
        }
        self.hits.push(hit.clone());
    }

    pub fn typing(&self) -> bool {
        self.typing.is_some()
    }

    /// True when the hits are in an order of their own, not in the order of the search.
    pub fn probing(&self) -> bool {
        self.probe().is_some()
    }

    /// True when only a key can change the ranking.
    pub fn idle(&self) -> bool {
        !self.stale && !matches!(self.text, Model::Loading(_)) && self.pending() == 0
    }

    /// Opens the query line with the text query in use.
    pub fn open(&mut self, search: &Search) -> Result<()> {
        ensure!(TextEmbedder::is_downloaded(), NO_MODEL);
        self.embed_missing(search)?;
        if let Model::Unloaded = self.text {
            let (tx, rx) = mpsc::channel();
            thread::spawn(move || tx.send(guard(TextEmbedder::load).map(Box::new)));
            self.text = Model::Loading(rx);
        }
        self.typing = Some(match self.history.last() {
            Some(Probe::Text(text)) => text.clone(),
            _ => String::new(),
        });
        Ok(())
    }

    /// Ranks by how similar the images look to the one at `path`.
    pub fn like(&mut self, path: &Path, search: &Search) -> Result<()> {
        self.embed_missing(search)?;
        self.push(Probe::Like(path.to_owned()));
        self.stale = true;
        Ok(())
    }

    /// Goes back to the ranking before.
    pub fn back(&mut self) {
        self.stale |= self.history.pop().is_some();
    }

    /// A key while the query line is open. Each change ranks again.
    pub fn key(&mut self, key: KeyEvent) {
        match key.code {
            KeyCode::Enter => match self.typing.take() {
                // The board already shows this ranking.
                Some(text) if !text.trim().is_empty() => self.push(Probe::Text(text)),
                _ => self.stale = true,
            },
            KeyCode::Esc => {
                self.typing = None;
                self.stale = true;
            }
            code => {
                let Some(text) = &mut self.typing else {
                    return;
                };
                let ctrl = key.modifiers.contains(KeyModifiers::CONTROL);
                match code {
                    KeyCode::Backspace => _ = text.pop(),
                    KeyCode::Char('u') if ctrl => text.clear(),
                    KeyCode::Char(c) if !ctrl => text.push(c),
                    _ => return,
                }
                self.stale = true;
            }
        }
    }

    /// The hits in a new order, when the board must show one.
    pub fn poll(&mut self) -> Result<Option<Vec<Hit>>> {
        self.receive()?;
        let refresh = self.fresh && self.typing.is_some() && self.ranked.elapsed() >= REFRESH;
        if !self.stale && !refresh {
            return Ok(None);
        }
        let target = match self.probe() {
            None => None,
            Some(probe) => match self.target(&probe) {
                Ok(Some(target)) => Some(target),
                Ok(None) => return Ok(None),
                Err(e) => {
                    // The next poll shows the ranking before.
                    self.typing = None;
                    self.history.retain(|p| *p != probe);
                    return Err(e);
                }
            },
        };
        self.stale = false;
        self.fresh = false;
        self.ranked = Instant::now();
        Ok(Some(match target {
            Some(target) => rank(&self.hits, &target),
            None => self.hits.clone(),
        }))
    }

    /// Facts for the status line.
    pub fn status(&self) -> Vec<Span<'static>> {
        let mut spans = Vec::new();
        match (&self.typing, self.history.last()) {
            (Some(text), _) => spans.push(format!("/{}▏ ", clean(text)).yellow().bold()),
            (None, Some(Probe::Text(text))) => spans.push(format!("/{}  ", clean(text)).yellow()),
            (None, Some(Probe::Like(path))) => {
                let name = path.file_name().map_or(path.as_path(), Path::new);
                spans.push(format!("*{}  ", clean_path(name)).yellow());
            }
            (None, None) => {}
        }
        if self.typing.is_some() && matches!(self.text, Model::Loading(_)) {
            spans.push("loading the text model  ".dim());
        }
        if self.pending() > 0 {
            spans.push(format!("{} not ranked yet  ", self.pending()).dim());
        }
        spans
    }

    fn probe(&self) -> Option<Probe> {
        match &self.typing {
            Some(text) if !text.trim().is_empty() => Some(Probe::Text(text.clone())),
            _ => self.history.last().cloned(),
        }
    }

    /// The target of `probe`, or `None` while its embedding is not ready.
    fn target(&self, probe: &Probe) -> Result<Option<Target>> {
        Ok(match probe {
            Probe::Text(text) => match &self.text {
                Model::Ready(model) => Some(Target::Text {
                    query: model.embed(&Prompt::new(text))?,
                    not: Vec::new(),
                }),
                _ => None,
            },
            Probe::Like(path) => match self.embedding(path) {
                Some(image) => Some(Target::Like(image)),
                None if self.pending() > 0 => None,
                None => bail!("cannot read {}", clean_path(path)),
            },
        })
    }

    fn push(&mut self, probe: Probe) {
        if self.history.last() != Some(&probe) {
            self.history.push(probe);
        }
    }

    fn embedding(&self, path: &Path) -> Option<Vec<f32>> {
        let hit = self.hits.iter().find(|h| h.path == path)?;
        hit.embedding.as_deref().map(<[f32]>::to_vec)
    }

    fn pending(&self) -> usize {
        self.images.as_ref().map_or(0, |images| images.pending)
    }

    /// Starts to embed the hits that came without an embedding, so that a ranking can take them
    /// in.
    fn embed_missing(&mut self, search: &Search) -> Result<()> {
        if self.images.is_some() || self.hits.iter().all(|h| h.embedding.is_some()) {
            return Ok(());
        }
        ensure!(ImageEmbedder::is_downloaded(), NO_MODEL);
        let (paths, done) = search.embed(ImageEmbedder::load()?);
        let mut images = Images {
            paths,
            done,
            pending: 0,
        };
        for (i, hit) in self.hits.iter().enumerate() {
            if hit.embedding.is_none() {
                images.send(i, &hit.path);
            }
        }
        self.images = Some(images);
        Ok(())
    }

    /// Takes the text model and the embeddings that are ready.
    fn receive(&mut self) -> Result<()> {
        if let Model::Loading(rx) = &self.text
            && let Ok(loaded) = rx.try_recv()
        {
            match loaded {
                Ok(model) => self.text = Model::Ready(model),
                Err(e) => {
                    self.text = Model::Unloaded;
                    self.typing = None;
                    self.history.retain(|p| !matches!(p, Probe::Text(_)));
                    self.stale = true;
                    return Err(e).context("cannot load the text model");
                }
            }
        }
        let Some(images) = &mut self.images else {
            return Ok(());
        };
        for answer in images.done.try_iter().collect::<Vec<_>>() {
            let Ok((i, embedding)) = answer else {
                self.images = None;
                return answer.map(drop).context("cannot embed the images");
            };
            images.pending -= 1;
            self.hits[i].embedding = embedding;
            self.fresh = true;
        }
        Ok(())
    }
}

/// The hits by `target`, best first. Equal scores go by path. Hits without an embedding keep
/// their order, at the end.
fn rank(hits: &[Hit], target: &Target) -> Vec<Hit> {
    let mut ranked: Vec<Hit> = (hits.iter())
        .map(|hit| Hit {
            score: hit.embedding.as_deref().and_then(|e| target.score(e)),
            ..hit.clone()
        })
        .collect();
    ranked.sort_by(|a, b| match (a.score, b.score) {
        (Some(x), Some(y)) => y.total_cmp(&x).then_with(|| a.path.cmp(&b.path)),
        (x, y) => y.is_some().cmp(&x.is_some()),
    });
    ranked
}

#[cfg(test)]
mod tests {
    use std::sync::Arc;

    use super::*;

    fn hit(name: &str, embedding: Option<[f32; 2]>) -> Hit {
        Hit {
            embedding: embedding.map(|e| Arc::from(e.as_slice())),
            ..Hit::new(name.into())
        }
    }

    fn names(hits: Option<Vec<Hit>>) -> Vec<String> {
        let hits = hits.expect("a new order");
        hits.iter().map(|h| h.path.display().to_string()).collect()
    }

    fn press(ranking: &mut Ranking, code: KeyCode) {
        ranking.key(KeyEvent::from(code));
    }

    #[test]
    fn rank_puts_the_best_first_and_the_unknown_last() {
        let hits = [
            hit("z", None),
            hit("b", Some([0.0, 1.0])),
            hit("a", None),
            hit("d", Some([1.0, 0.0])),
            hit("c", Some([1.0, 0.0])),
        ];
        let ranked = rank(&hits, &Target::Like(vec![1.0, 0.0]));
        let order: Vec<_> = (ranked.iter())
            .map(|h| (h.path.to_str().unwrap(), h.score))
            .collect();
        let want = [
            ("c", Some(1.0)),
            ("d", Some(1.0)),
            ("b", Some(0.0)),
            ("z", None),
            ("a", None),
        ];
        assert_eq!(order, want);
    }

    #[test]
    fn like_ranks_and_back_restores_the_search_order() {
        let search = Search::empty();
        let mut ranking = Ranking::new();
        for h in [
            hit("a", Some([1.0, 0.0])),
            hit("b", Some([0.0, 1.0])),
            hit("c", Some([0.6, 0.8])),
        ] {
            ranking.add(&h);
        }
        assert!(ranking.poll().unwrap().is_none());
        ranking.like(Path::new("b"), &search).unwrap();
        assert!(ranking.probing());
        assert_eq!(names(ranking.poll().unwrap()), ["b", "c", "a"]);
        assert!(ranking.idle());
        ranking.back();
        assert!(!ranking.probing());
        let restored = ranking.poll().unwrap().unwrap();
        assert!(restored.iter().all(|h| h.score.is_none()));
        assert_eq!(names(Some(restored)), ["a", "b", "c"]);
    }

    #[test]
    fn the_query_line_edits_and_keeps_or_drops_the_text() {
        let mut ranking = Ranking::new();
        ranking.typing = Some(String::new());
        for c in "cats".chars() {
            press(&mut ranking, KeyCode::Char(c));
        }
        press(&mut ranking, KeyCode::Backspace);
        assert!(ranking.probe() == Some(Probe::Text("cat".into())));
        ranking.key(KeyEvent::new(KeyCode::Char('u'), KeyModifiers::CONTROL));
        assert!(ranking.probe().is_none());
        press(&mut ranking, KeyCode::Char('x'));
        press(&mut ranking, KeyCode::Esc);
        assert!(!ranking.typing() && ranking.history.is_empty());

        ranking.typing = Some("dog".into());
        press(&mut ranking, KeyCode::Enter);
        assert!(ranking.history == [Probe::Text("dog".into())]);
        ranking.typing = Some(" ".into());
        press(&mut ranking, KeyCode::Enter);
        assert_eq!(ranking.history.len(), 1, "a blank query keeps the ranking");
    }
}