verbs/diff/

context.rs

// SPDX-License-Identifier: Apache-2.0
//! Attach live context annotations to an existing [`DiffReport`].
//!
//! `context set` writes a Context state-attachment. `diff --context` must
//! populate the existing report fields from that attachment — the same
//! store `context get` reads — without a second view RPC.

use anyhow::Result;
use objects::{
    object::{
        Annotation, AnnotationStatus, ContentHash, ContextTarget, State, StateAttachmentBody,
    },
    store::ObjectStore,
};
use repo::{ChangedPathFilters, Repository, StateAttachmentKind};

use super::types::{ContextSnippet, DiffReport, FileContextEntry};

/// Fill `report.context` and `report.broader_guidance` from one Context
/// attachment snapshot.
///
/// Selection:
/// - changed report paths (including a rename `old_path`) when present;
/// - otherwise the requested `path_filters` on a clean / filtered-empty
///   tree, so `diff --context -- lib.rs` still rides;
/// - otherwise every active file annotation (unfiltered clean tree).
pub fn attach_show_context(
    repo: &Repository,
    report: &mut DiffReport,
    state: &State,
    path_filters: &[String],
) -> Result<()> {
    let Some(context_root) = context_root_for_state(repo, state)? else {
        report.context = Some(Vec::new());
        report.broader_guidance = Some(Vec::new());
        return Ok(());
    };

    let mut change_paths: Vec<String> = report
        .changes
        .iter()
        .flat_map(|change| std::iter::once(change.path.clone()).chain(change.old_path.clone()))
        .collect();
    change_paths.sort();
    change_paths.dedup();
    let filters = ChangedPathFilters::try_from_paths(path_filters)?;

    let listed = repo.list_context_entries(&context_root, None)?;
    let mut file_entries = Vec::new();
    let mut broader_guidance = Vec::new();
    for entry in listed {
        match entry.target {
            ContextTarget::File { path } => {
                if !file_path_requested(&path, &change_paths, &filters) {
                    continue;
                }
                let annotations = active_snippets(&entry.blob.annotations);
                if !annotations.is_empty() {
                    file_entries.push(FileContextEntry { path, annotations });
                }
            }
            ContextTarget::State { state_id } if state_id == state.state_id => {
                broader_guidance = active_snippets(&entry.blob.annotations);
            }
            ContextTarget::State { .. } => {}
        }
    }
    report.context = Some(file_entries);
    report.broader_guidance = Some(broader_guidance);
    Ok(())
}

/// HEAD / current-state used by worktree diffs.
pub fn worktree_context_state(repo: &Repository) -> Result<Option<State>> {
    if let Some(state) = repo.current_state()? {
        return Ok(Some(state));
    }
    let Some(id) = repo.head()? else {
        return Ok(None);
    };
    Ok(repo.store().get_state(&id)?)
}

pub(crate) fn summarize_context(content: &str) -> String {
    let first_line = content
        .lines()
        .find(|line| !line.trim().is_empty())
        .unwrap_or("");
    let char_count = first_line.chars().count();
    if char_count <= 88 {
        first_line.to_string()
    } else {
        format!("{}...", first_line.chars().take(85).collect::<String>())
    }
}

fn context_root_for_state(repo: &Repository, state: &State) -> Result<Option<ContentHash>> {
    Ok(repo
        .latest_state_attachment(&state.state_id, StateAttachmentKind::Context)?
        .and_then(|attachment| match attachment.body {
            StateAttachmentBody::Context(hash) => Some(hash),
            _ => None,
        }))
}

fn file_path_requested(path: &str, change_paths: &[String], filters: &ChangedPathFilters) -> bool {
    if !change_paths.is_empty() {
        return change_paths.iter().any(|changed| changed == path);
    }
    filters.is_empty() || filters.matches(path)
}

fn active_snippets(annotations: &[Annotation]) -> Vec<ContextSnippet> {
    annotations
        .iter()
        .filter(|annotation| annotation.status == AnnotationStatus::Active)
        .filter_map(|annotation| {
            annotation
                .current_revision()
                .map(|revision| ContextSnippet {
                    annotation_id: annotation.annotation_id.clone(),
                    kind: revision.kind.to_string(),
                    content: summarize_context(&revision.content),
                    revision_count: annotation.revisions.len(),
                })
        })
        .collect()
}

#[cfg(test)]
mod tests {
    use objects::object::{
        Annotation, AnnotationKind, AnnotationScope, Attribution, ContextBlob, ContextTarget,
        Principal, StateAttachment, StateAttachmentBody,
    };
    use repo::Repository;
    use tempfile::TempDir;

    use super::{attach_show_context, summarize_context};
    use crate::diff::types::{DiffReport, FileChange};

    fn annotate_state(repo: &Repository, path: &str, content: &str) -> objects::object::State {
        std::fs::write(repo.root().join(path), "seed\n").expect("write seed file");
        let state = repo
            .snapshot_with_attribution(
                Some("seed".into()),
                None,
                Attribution::human(Principal::new("Test", "test@example.com")),
            )
            .expect("snapshot seed");
        let target = ContextTarget::file(path).expect("file target");
        let blob = ContextBlob::new(vec![Annotation::new(
            AnnotationScope::File,
            AnnotationKind::Invariant,
            content.to_string(),
            Vec::new(),
            "test@example.com".to_string(),
            1_700_000_000,
            None,
            Some(state.state_id),
        )]);
        let root = repo
            .set_context_blob(None, &target, &blob)
            .expect("store context blob");
        repo.put_state_attachment(&StateAttachment {
            state_id: state.state_id,
            body: StateAttachmentBody::Context(root),
            attribution: Attribution::human(Principal::new("test", "test@example.com")),
            created_at: chrono::Utc::now(),
            supersedes: None,
        })
        .expect("attach context");
        state
    }

    fn report_with(paths: &[&str]) -> DiffReport {
        let changes = paths
            .iter()
            .map(|path| FileChange {
                path: (*path).to_string(),
                kind: "modified".to_string(),
                ..FileChange::default()
            })
            .collect();
        DiffReport::new(Some("HEAD".to_string()), None, changes, None, None, None)
    }

    fn annotation_content(report: &DiffReport, path: &str) -> Option<String> {
        report.context.as_ref().and_then(|entries| {
            entries.iter().find_map(|entry| {
                (entry.path == path)
                    .then(|| entry.annotations.first().map(|a| a.content.clone()))
                    .flatten()
            })
        })
    }

    #[test]
    fn context_set_attachment_rides_diff_for_changed_path() {
        let temp = TempDir::new().expect("tempdir");
        let repo = Repository::init_default(temp.path()).expect("init");
        let state = annotate_state(&repo, "lib.rs", "must stay lowercase");
        let mut report = report_with(&["lib.rs"]);

        attach_show_context(&repo, &mut report, &state, &[]).expect("attach");

        assert_eq!(
            annotation_content(&report, "lib.rs").as_deref(),
            Some("must stay lowercase")
        );
    }

    #[test]
    fn context_set_attachment_rides_clean_diff_when_unanchored() {
        let temp = TempDir::new().expect("tempdir");
        let repo = Repository::init_default(temp.path()).expect("init");
        let state = annotate_state(&repo, "lib.rs", "visible without a file change");
        let mut report = report_with(&[]);

        attach_show_context(&repo, &mut report, &state, &[]).expect("attach");

        assert_eq!(
            annotation_content(&report, "lib.rs").as_deref(),
            Some("visible without a file change")
        );
    }

    #[test]
    fn path_filter_on_clean_tree_looks_up_requested_paths() {
        let temp = TempDir::new().expect("tempdir");
        let repo = Repository::init_default(temp.path()).expect("init");
        let state = annotate_state(&repo, "lib.rs", "requested path still rides");
        let mut matching = report_with(&[]);
        attach_show_context(&repo, &mut matching, &state, &["lib.rs".to_string()])
            .expect("attach matching filter");
        assert_eq!(
            annotation_content(&matching, "lib.rs").as_deref(),
            Some("requested path still rides")
        );

        let mut other = report_with(&[]);
        attach_show_context(&repo, &mut other, &state, &["other.rs".to_string()])
            .expect("attach other filter");
        assert!(
            other
                .context
                .as_ref()
                .is_none_or(|entries| entries.is_empty()),
            "unrelated path filter must stay quiet"
        );
    }

    #[test]
    fn path_filter_does_not_dump_unrelated_annotations() {
        let temp = TempDir::new().expect("tempdir");
        let repo = Repository::init_default(temp.path()).expect("init");
        let state = annotate_state(&repo, "lib.rs", "not this path");
        let mut report = report_with(&[]);

        attach_show_context(&repo, &mut report, &state, &["other.rs".to_string()]).expect("attach");

        assert!(
            report
                .context
                .as_ref()
                .is_none_or(|entries| entries.is_empty()),
            "filtered empty change set must not list every annotation"
        );
    }

    #[test]
    fn summarize_context_truncates_on_char_boundary_not_byte_index() {
        let first_line = format!("{}中中", "a".repeat(83));
        assert!(first_line.len() > 88);
        assert!(!first_line.is_char_boundary(85));
        let summary = summarize_context(&format!("{first_line}\nsecond line"));
        assert_eq!(summary, first_line);
    }

    #[test]
    fn summarize_context_char_cap_truncates_multibyte_line() {
        let first_line = format!("{}中中中", "a".repeat(86));
        assert!(first_line.chars().count() > 88);
        let summary = summarize_context(&first_line);
        let expected = format!("{}...", "a".repeat(85));
        assert_eq!(summary, expected);
    }

    #[test]
    fn summarize_context_ascii_truncation_unchanged() {
        let line = "b".repeat(90);
        let summary = summarize_context(&line);
        assert_eq!(summary, format!("{}...", "b".repeat(85)));
    }
}