kimun-notes 0.21.0

pub mod citations;
pub mod locate;
pub mod save;

use kimun_core::nfs::VaultPath;
use kimun_core::note::BREADCRUMB_SEP;
use kimun_server_client::dto::ChunkResult;

/// How many trailing `Done` turns feed conversation history sent to the server.
const HISTORY_WINDOW: usize = 5;

/// Human-readable joiner for a chunk's nested heading segments, replacing core's
/// control-char [`BREADCRUMB_SEP`] for display (`"Chapter › Section"`).
const HEADING_JOINER: &str = " \u{203a} ";

/// A single retrieved chunk backing an answer — one row of a **Turn**'s
/// sources, shown in CONTEXT.md's **Sources view** / **Source reader**.
#[derive(Debug, Clone)]
pub struct AskSource {
    pub path: VaultPath,
    pub heading: String,
    /// The chunk's journal date (`YYYY-MM-DD`), when the note is a dated journal
    /// entry — carried separately from `heading` so the two render as distinct,
    /// spaced elements. `None` for a non-journal note.
    pub date: Option<String>,
    pub score: f64,
    pub text: String,
    /// The 1-based `[n]` citation number this source answers to — the explicit
    /// pairing every citation lookup keys on, never vec position. Normalized to
    /// be non-zero at construction (see [`AskSource::from_chunk`]), so no
    /// downstream lookup ever sees the wire's `0` "absent" sentinel.
    pub ordinal: usize,
}

impl AskSource {
    /// Build from a wire chunk at 0-based `position` in its list. The ordinal is
    /// normalized ONCE, here: a server that sends it wins; a `0` (older server
    /// that omits the field) falls back to `position + 1`, which reproduces the
    /// old vec-order convention. Every consumer downstream sees a real ordinal.
    ///
    /// For a journal chunk the wire `title` arrives date-prefixed (e.g.
    /// `2026-04-08Afternoon` — the date stem glued to the section heading with
    /// no separator). We strip that prefix here, keeping `date` and `heading`
    /// separate, mirroring the prompt builder's title handling
    /// (`llmclients::build_prompt`) so both surfaces agree.
    ///
    /// A nested-section chunk's title is core's breadcrumb — the heading path
    /// joined with the control-char [`BREADCRUMB_SEP`] (`"Chapter\x1fSection"`).
    /// We split it and re-join with a readable [`HEADING_JOINER`] so the raw
    /// separator never reaches a Sources row or the reader title; the innermost
    /// segment (which drives section matching in `locate`) is recovered by
    /// [`AskSource::match_heading`].
    pub fn from_chunk(position: usize, c: ChunkResult) -> Self {
        let stripped = strip_date_prefix(&c.title, c.date.as_deref());
        let heading = stripped
            .split(BREADCRUMB_SEP)
            .filter(|s| !s.is_empty())
            .collect::<Vec<_>>()
            .join(HEADING_JOINER);
        Self {
            path: VaultPath::new(&c.path),
            heading,
            date: c.date,
            score: c.similarity_score,
            text: c.content,
            ordinal: if c.ordinal == 0 {
                position + 1
            } else {
                c.ordinal
            },
        }
    }

    /// The innermost heading segment — the one that identifies the retrieved
    /// section within its note, for `locate::section_range`. `heading` is the
    /// full breadcrumb rejoined with [`HEADING_JOINER`] for display, so section
    /// matching takes only the last segment (`"Chapter › Section"` → `"Section"`).
    pub fn match_heading(&self) -> &str {
        self.heading
            .rsplit(HEADING_JOINER)
            .next()
            .unwrap_or(&self.heading)
    }

    /// The heading with its date rejoined for a single-line title (the source
    /// reader's panel title): `"2026-04-08 · Afternoon"` for a journal entry,
    /// the bare heading otherwise.
    pub fn display_heading(&self) -> String {
        match &self.date {
            Some(date) if !self.heading.is_empty() => format!("{date} · {}", self.heading),
            Some(date) => date.clone(),
            None => self.heading.clone(),
        }
    }
}

/// Strip a leading journal `date` prefix from a wire `title`, mirroring the
/// server prompt builder's logic (`llmclients::build_prompt`): trim, drop the
/// date prefix if present, trim again. With no date, or a title that doesn't
/// start with it, the (trimmed) title is returned unchanged.
fn strip_date_prefix(title: &str, date: Option<&str>) -> String {
    let trimmed = title.trim();
    match date {
        Some(date) => trimmed
            .strip_prefix(date)
            .map(|rest| rest.trim().to_string())
            .unwrap_or_else(|| trimmed.to_string()),
        None => trimmed.to_string(),
    }
}

/// A turn's lifecycle. `Streaming` is reserved for a future streaming feature
/// and is never constructed in v1.
#[allow(dead_code)]
pub enum TurnStatus {
    Thinking,
    Streaming,
    Done,
    Error(String),
}

/// One question/answer exchange (CONTEXT.md: **Turn**). Always knows its own sources.
pub struct Turn {
    pub id: u64,
    pub question: String,
    pub answer: String,
    pub sources: Vec<AskSource>,
    pub status: TurnStatus,
}

impl Turn {
    /// Resolve a `[n]` citation to the source it addresses — matched by the
    /// source's `ordinal`, NOT its position in `sources`. This is the single
    /// seam every citation lookup goes through, so the pairing survives any
    /// reorder of the sources vec. `None` for a citation with no matching
    /// source (a gap — e.g. the model cited `[2]` but ordinal 2 was dropped).
    pub fn source_for_citation(&self, n: usize) -> Option<&AskSource> {
        self.sources.iter().find(|s| s.ordinal == n)
    }
}

/// The running ask conversation (CONTEXT.md: **Thread**): an ordered list of
/// turns plus which one is selected for viewing.
#[derive(Default)]
pub struct Thread {
    turns: Vec<Turn>,
    next_id: u64,
    selected: usize,
}

impl Thread {
    /// Append a new `Thinking` turn for `question`, select it, and return its id.
    pub fn ask(&mut self, question: String) -> u64 {
        let id = self.bump();
        self.turns.push(Turn {
            id,
            question,
            answer: String::new(),
            sources: vec![],
            status: TurnStatus::Thinking,
        });
        self.selected = self.turns.len() - 1;
        id
    }

    /// Resolve a `Thinking` turn into `Done`. Returns `false` (no-op) for an
    /// unknown id or a turn that isn't currently `Thinking` (stale completion).
    pub fn complete(&mut self, id: u64, answer: String, sources: Vec<AskSource>) -> bool {
        let Some(turn) = self.thinking_turn_mut(id) else {
            return false;
        };
        turn.answer = answer;
        turn.sources = sources;
        turn.status = TurnStatus::Done;
        true
    }

    /// Resolve a `Thinking` turn into `Error`. Same stale-completion rules as `complete`.
    pub fn fail(&mut self, id: u64, error: String) -> bool {
        let Some(turn) = self.thinking_turn_mut(id) else {
            return false;
        };
        turn.status = TurnStatus::Error(error);
        true
    }

    /// Rewind a `Done`/`Error` turn back to `Thinking`, keeping its sources, and
    /// return its question so the caller can re-issue the request.
    pub fn regenerate(&mut self, id: u64) -> Option<String> {
        let turn = self.turns.iter_mut().find(|t| t.id == id)?;
        if matches!(turn.status, TurnStatus::Thinking | TurnStatus::Streaming) {
            return None;
        }
        turn.status = TurnStatus::Thinking;
        Some(turn.question.clone())
    }

    /// The last `HISTORY_WINDOW` `Done` turns before the newest in-flight
    /// (`Thinking`/`Streaming`) turn, as `(question, answer)` pairs with
    /// citation markers stripped.
    pub fn history(&self) -> Vec<(String, String)> {
        let boundary = self
            .turns
            .iter()
            .rposition(|t| matches!(t.status, TurnStatus::Thinking | TurnStatus::Streaming))
            .unwrap_or(self.turns.len());
        // Want the LAST `HISTORY_WINDOW` Dones, not the first: `.rev()` needs
        // a `DoubleEndedIterator`, which `Filter` only gets because the slice
        // `.iter()` underneath it is one. `.rev().take(N)` then walks from
        // the end to grab those last N (in reverse order); the explicit
        // `.reverse()` below restores chronological order.
        let mut done: Vec<_> = self.turns[..boundary]
            .iter()
            .filter(|t| matches!(t.status, TurnStatus::Done))
            .rev()
            .take(HISTORY_WINDOW)
            .collect();
        done.reverse();
        done.into_iter()
            .map(|t| (t.question.clone(), citations::strip(&t.answer)))
            .collect()
    }

    /// The currently selected turn, if any.
    pub fn selected(&self) -> Option<&Turn> {
        self.turns.get(self.selected)
    }

    /// Move the selection to the previous (older) turn, if any.
    pub fn select_prev(&mut self) {
        self.selected = self.selected.saturating_sub(1);
    }

    /// Move the selection to the next (newer) turn, if any.
    pub fn select_next(&mut self) {
        if self.selected + 1 < self.turns.len() {
            self.selected += 1;
        }
    }

    /// Select the most recent turn.
    pub fn select_last(&mut self) {
        self.selected = self.turns.len().saturating_sub(1);
    }

    /// Select the turn at `idx` directly, clamped to the valid range.
    /// No-op on an empty thread — there is no turn to select.
    pub fn select_index(&mut self, idx: usize) {
        if self.turns.is_empty() {
            return;
        }
        self.selected = idx.min(self.turns.len() - 1);
    }

    /// Drop all turns, resetting the thread.
    pub fn clear(&mut self) {
        self.turns.clear();
        self.selected = 0;
    }

    /// All turns, oldest first.
    pub fn turns(&self) -> &[Turn] {
        &self.turns
    }

    /// Whether the thread has no turns.
    pub fn is_empty(&self) -> bool {
        self.turns.is_empty()
    }

    fn bump(&mut self) -> u64 {
        let id = self.next_id;
        self.next_id += 1;
        id
    }

    fn thinking_turn_mut(&mut self, id: u64) -> Option<&mut Turn> {
        self.turns
            .iter_mut()
            .find(|t| t.id == id && matches!(t.status, TurnStatus::Thinking))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use kimun_server_client::dto::ChunkResult;

    fn ask_source(path: &str, ordinal: usize) -> AskSource {
        AskSource {
            path: VaultPath::new(path),
            heading: "h".into(),
            date: None,
            score: 1.0,
            text: String::new(),
            ordinal,
        }
    }

    fn turn_with_sources(sources: Vec<AskSource>) -> Turn {
        Turn {
            id: 0,
            question: "q".into(),
            answer: String::new(),
            sources,
            status: TurnStatus::Done,
        }
    }

    #[test]
    fn source_for_citation_matches_by_ordinal_not_position() {
        // Sources deliberately shuffled: vec position 0 holds ordinal 3.
        let turn = turn_with_sources(vec![
            ask_source("c.md", 3),
            ask_source("a.md", 1),
            ask_source("b.md", 2),
        ]);
        // `[1]` resolves to the ordinal-1 source, wherever it sits in the vec.
        assert_eq!(
            turn.source_for_citation(1).unwrap().path.to_string(),
            "a.md"
        );
        assert_eq!(
            turn.source_for_citation(2).unwrap().path.to_string(),
            "b.md"
        );
        assert_eq!(
            turn.source_for_citation(3).unwrap().path.to_string(),
            "c.md"
        );
    }

    #[test]
    fn source_for_citation_returns_none_for_a_gap() {
        // Ordinal 2 was dropped: a `[2]` citation has no source to resolve to.
        let turn = turn_with_sources(vec![ask_source("a.md", 1), ask_source("c.md", 3)]);
        assert!(turn.source_for_citation(2).is_none());
    }

    #[test]
    fn from_chunk_falls_back_to_position_when_ordinal_absent() {
        let wire = ChunkResult {
            path: "a.md".into(),
            title: "t".into(),
            date: None,
            content: String::new(),
            hash: String::new(),
            similarity_score: 0.9,
            ordinal: 0, // older server: field absent → 0
        };
        // 0-based position 4 → 1-based ordinal 5.
        assert_eq!(AskSource::from_chunk(4, wire).ordinal, 5);
    }

    #[test]
    fn from_chunk_honors_a_server_assigned_ordinal() {
        let wire = ChunkResult {
            path: "a.md".into(),
            title: "t".into(),
            date: None,
            content: String::new(),
            hash: String::new(),
            similarity_score: 0.9,
            ordinal: 7,
        };
        // Server ordinal wins over position.
        assert_eq!(AskSource::from_chunk(0, wire).ordinal, 7);
    }

    #[test]
    fn from_chunk_splits_a_date_prefixed_journal_title() {
        // The server glues the date stem onto the section heading with no
        // separator ("2026-04-08Afternoon"); date and heading must come apart.
        let wire = ChunkResult {
            path: "journal/2026-04-08.md".into(),
            title: "2026-04-08Afternoon".into(),
            date: Some("2026-04-08".into()),
            content: String::new(),
            hash: String::new(),
            similarity_score: 0.9,
            ordinal: 1,
        };
        let src = AskSource::from_chunk(0, wire);
        assert_eq!(src.heading, "Afternoon");
        assert_eq!(src.date.as_deref(), Some("2026-04-08"));
        assert_eq!(src.display_heading(), "2026-04-08 · Afternoon");
    }

    #[test]
    fn from_chunk_renders_a_nested_breadcrumb_title_readably() {
        // A nested-section chunk's title is core's breadcrumb, joined with the
        // control-char separator; it must render as "Chapter › Section" and the
        // raw U+001F must never survive.
        let wire = ChunkResult {
            path: "notes/book.md".into(),
            title: format!("Chapter{}Section", kimun_core::note::BREADCRUMB_SEP),
            date: None,
            content: String::new(),
            hash: String::new(),
            similarity_score: 0.5,
            ordinal: 1,
        };
        let src = AskSource::from_chunk(0, wire);
        assert_eq!(src.heading, "Chapter \u{203a} Section");
        assert!(!src.heading.contains('\u{1f}'), "no control char leaks");
        assert_eq!(src.display_heading(), "Chapter \u{203a} Section");
        // Section matching keys on the innermost segment only.
        assert_eq!(src.match_heading(), "Section");
    }

    #[test]
    fn nested_source_locates_via_the_innermost_heading() {
        use crate::ask::locate;
        // A note where the retrieved section sits under a nested heading. The
        // chunk text is absent verbatim, so resolution falls through to the
        // innermost-heading match — proving `match_heading` feeds `locate`.
        let wire = ChunkResult {
            path: "notes/book.md".into(),
            title: format!("Chapter{}Section", kimun_core::note::BREADCRUMB_SEP),
            date: None,
            content: "normalized, not verbatim".into(),
            hash: String::new(),
            similarity_score: 0.5,
            ordinal: 1,
        };
        let src = AskSource::from_chunk(0, wire);
        let note = "# Chapter\nintro\n## Section\nthe real body\n";
        let r = locate::section_range(note, src.match_heading(), &src.text).unwrap();
        assert!(note[r].contains("the real body"));
    }

    #[test]
    fn from_chunk_leaves_a_non_journal_title_unchanged() {
        let wire = ChunkResult {
            path: "notes/ideas.md".into(),
            title: "Project Ideas".into(),
            date: None,
            content: String::new(),
            hash: String::new(),
            similarity_score: 0.5,
            ordinal: 1,
        };
        let src = AskSource::from_chunk(0, wire);
        assert_eq!(src.heading, "Project Ideas");
        assert_eq!(src.date, None);
        assert_eq!(src.display_heading(), "Project Ideas");
    }

    fn done(thread: &mut Thread, q: &str, a: &str) {
        let id = thread.ask(q.to_string());
        assert!(thread.complete(id, a.to_string(), vec![]));
    }

    #[test]
    fn ask_appends_a_thinking_turn_and_selects_it() {
        let mut t = Thread::default();
        let id = t.ask("q?".into());
        assert_eq!(t.turns().len(), 1);
        assert!(matches!(t.selected().unwrap().status, TurnStatus::Thinking));
        assert_eq!(t.selected().unwrap().id, id);
    }

    #[test]
    fn history_takes_last_five_done_turns_and_strips_citations() {
        let mut t = Thread::default();
        for i in 0..7 {
            done(&mut t, &format!("q{i}"), &format!("a{i} [1]"));
        }
        t.ask("new".into()); // the in-flight turn history is built for
        let h = t.history();
        assert_eq!(h.len(), 5);
        assert_eq!(h[0].0, "q2");
        assert_eq!(h[4].1, "a6"); // "[1]" stripped
    }

    #[test]
    fn stale_completion_is_dropped() {
        let mut t = Thread::default();
        let id = t.ask("q".into());
        t.clear();
        assert!(!t.complete(id, "late".into(), vec![]));
        assert!(t.is_empty());
    }

    #[test]
    fn stale_fail_is_dropped() {
        let mut t = Thread::default();
        let id = t.ask("q".into());
        t.clear();
        assert!(!t.fail(id, "late error".into()));
        assert!(t.is_empty());
    }

    #[test]
    fn history_skips_error_turns_but_keeps_the_dones_around_them() {
        let mut t = Thread::default();
        done(&mut t, "q0", "a0");
        let err_id = t.ask("q1".into());
        t.fail(err_id, "boom".into());
        done(&mut t, "q2", "a2");
        let h = t.history();
        assert_eq!(h.len(), 2, "the Error turn itself is not in history");
        assert_eq!(h[0].0, "q0");
        assert_eq!(h[1].0, "q2");
    }

    #[test]
    fn regenerate_returns_none_for_unknown_id_or_a_thinking_turn() {
        let mut t = Thread::default();
        assert!(t.regenerate(999).is_none(), "unknown id");
        let id = t.ask("q".into()); // still Thinking
        assert!(
            t.regenerate(id).is_none(),
            "in-flight turn can't regenerate"
        );
    }

    #[test]
    fn select_prev_and_select_next_clamp_at_the_ends() {
        let mut t = Thread::default();
        done(&mut t, "q0", "a0");
        done(&mut t, "q1", "a1"); // selected == q1

        t.select_prev();
        assert_eq!(t.selected().unwrap().question, "q0");
        t.select_prev(); // already at 0: clamp, no panic
        assert_eq!(t.selected().unwrap().question, "q0");

        t.select_next();
        assert_eq!(t.selected().unwrap().question, "q1");
        t.select_next(); // already at the end: clamp
        assert_eq!(t.selected().unwrap().question, "q1");
    }

    #[test]
    fn select_index_clamps_to_valid_range_and_noops_on_empty() {
        let mut t = Thread::default();
        t.select_index(3); // empty thread: no-op, no panic
        assert!(t.selected().is_none());

        done(&mut t, "q0", "a0");
        done(&mut t, "q1", "a1");
        done(&mut t, "q2", "a2");
        t.select_index(1);
        assert_eq!(t.selected().unwrap().question, "q1");
        t.select_index(100);
        assert_eq!(
            t.selected().unwrap().question,
            "q2",
            "clamps to the last turn"
        );
    }

    #[test]
    fn regenerate_rewinds_a_done_turn_keeping_sources() {
        let mut t = Thread::default();
        let id = t.ask("q".into());
        let src = AskSource {
            path: kimun_core::nfs::VaultPath::new("a.md"),
            heading: "h".into(),
            date: None,
            score: 0.9,
            text: "body".into(),
            ordinal: 1,
        };
        t.complete(id, "a".into(), vec![src]);
        assert_eq!(t.regenerate(id).as_deref(), Some("q"));
        let turn = t.selected().unwrap();
        assert!(matches!(turn.status, TurnStatus::Thinking));
        assert_eq!(turn.sources.len(), 1, "regenerate reuses the same sources");
    }
}