ctx_tui/

contexts.rs

use std::path::{Path, PathBuf};
use std::time::SystemTime;

use crate::config::Config;
use crate::errors::{CtxError, Result, msg};
use crate::git::{git, git_quiet, new_command};
use crate::repos;

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Context {
    pub repo: String,
    pub name: String,
    pub path: PathBuf,
}

impl Context {
    pub fn qualified(&self) -> String {
        format!("{}/{}", self.repo, self.name)
    }
}

// Checkouts are renamed to this suffix before removal, so an interrupted
// delete leaves a marked corpse rather than a live-looking, half-gutted
// context. `sweep_deleting` finishes such leftovers.
const DELETING_SUFFIX: &str = ".deleting";

pub fn context_path(cfg: &Config, repo: &str, name: &str) -> PathBuf {
    cfg.contexts_dir.join(repo).join(name)
}

fn mtime(path: &Path) -> Option<SystemTime> {
    std::fs::metadata(path)
        .and_then(|meta| meta.modified())
        .ok()
}

/// Proxy for the last interaction: the latest git activity in the checkout.
///
/// `.git/logs/HEAD` is appended to on commits, checkouts, and resets;
/// `.git/index` is rewritten by staging and status refreshes. Neither sees
/// plain file edits, but agent-driven work touches git constantly.
pub fn last_active(ctx: &Context) -> SystemTime {
    let candidates = [
        ctx.path.join(".git").join("logs").join("HEAD"),
        ctx.path.join(".git").join("index"),
    ];
    candidates
        .iter()
        .filter_map(|path| mtime(path))
        .max()
        .or_else(|| mtime(&ctx.path))
        .unwrap_or(SystemTime::UNIX_EPOCH)
}

fn sorted_dirs(root: &Path) -> Vec<PathBuf> {
    let Ok(entries) = std::fs::read_dir(root) else {
        return Vec::new();
    };
    let mut paths: Vec<PathBuf> = entries.flatten().map(|entry| entry.path()).collect();
    paths.sort();
    paths
}

/// Contexts under a <root>/<repo>/<name> tree, most recently active first.
fn scan(root: &Path) -> Vec<Context> {
    if !root.is_dir() {
        return Vec::new();
    }
    let mut found = Vec::new();
    for repo_dir in sorted_dirs(root) {
        if !repo_dir.is_dir() {
            continue;
        }
        let repo = repo_dir
            .file_name()
            .unwrap_or_default()
            .to_string_lossy()
            .into_owned();
        for ctx_dir in sorted_dirs(&repo_dir) {
            let name = ctx_dir
                .file_name()
                .unwrap_or_default()
                .to_string_lossy()
                .into_owned();
            if name.ends_with(DELETING_SUFFIX) {
                continue;
            }
            if ctx_dir.join(".git").exists() {
                found.push(Context {
                    repo: repo.clone(),
                    name,
                    path: ctx_dir,
                });
            }
        }
    }
    let mut keyed: Vec<(SystemTime, String, Context)> = found
        .into_iter()
        .map(|ctx| (last_active(&ctx), ctx.qualified(), ctx))
        .collect();
    keyed.sort_by(|a, b| b.0.cmp(&a.0).then_with(|| a.1.cmp(&b.1)));
    keyed.into_iter().map(|(_, _, ctx)| ctx).collect()
}

/// All contexts, most recently active first.
pub fn list_contexts(cfg: &Config) -> Vec<Context> {
    scan(&cfg.contexts_dir)
}

/// Resolve a context name; names are globally unique.
pub fn find_context(cfg: &Config, name: &str) -> Result<Context> {
    list_contexts(cfg)
        .into_iter()
        .find(|ctx| ctx.name == name)
        .ok_or_else(|| CtxError::Msg(format!("no context '{name}'")))
}

/// Names are unique across live and archived contexts alike.
///
/// Sharing a name with an archived context would leave that archive
/// unrestorable, so the two pools compete for the same names.
fn check_name_free(cfg: &Config, name: &str, exclude: Option<&Path>) -> Result<()> {
    for ctx in list_contexts(cfg) {
        if ctx.name == name && Some(ctx.path.as_path()) != exclude {
            return msg(format!(
                "context name '{name}' is already used by {}",
                ctx.qualified()
            ));
        }
    }
    for ctx in list_archived(cfg) {
        if ctx.name == name && Some(ctx.path.as_path()) != exclude {
            return msg(format!(
                "context name '{name}' is already used by archived {}",
                ctx.qualified()
            ));
        }
    }
    Ok(())
}

/// Reject names that break the paths, branches, or commands they feed.
fn check_name(name: &str, branch: &str) -> Result<()> {
    if name.trim().is_empty() {
        return msg("context name must not be empty");
    }
    if name.contains('/') || name == "." || name == ".." {
        return msg(format!(
            "context name '{name}' must be a single path component"
        ));
    }
    if name.starts_with('-') {
        return msg(format!("context name '{name}' must not start with '-'"));
    }
    if name.ends_with(DELETING_SUFFIX) {
        return msg(format!(
            "context name '{name}' must not end with '{DELETING_SUFFIX}'"
        ));
    }
    // cwd="/": the process's own cwd may have been deleted under it.
    let check = new_command("git")
        .args(["check-ref-format", &format!("refs/heads/{branch}")])
        .current_dir("/")
        .output();
    if !check.map(|output| output.status.success()).unwrap_or(false) {
        return msg(format!(
            "context name '{name}' does not make a valid branch name ('{branch}')"
        ));
    }
    Ok(())
}

#[rustfmt::skip]
const ADJECTIVES: &[&str] = &[
    "amber", "bold", "brave", "breezy", "bright", "calm", "cheeky", "clever",
    "cosmic", "cozy", "curious", "daring", "dapper", "dusty", "eager", "fancy",
    "fluffy", "frosty", "fuzzy", "gentle", "golden", "happy", "hazy", "holy",
    "humble", "jolly", "keen", "lively", "lucky", "mellow", "merry", "mighty",
    "misty", "nimble", "perky", "plucky", "proud", "quiet", "rosy", "rusty",
    "shiny", "sleepy", "sly", "snappy", "snug", "stormy", "sunny", "swift",
    "vivid", "witty",
];

#[rustfmt::skip]
const ANIMALS: &[&str] = &[
    "badger", "bear", "beaver", "bison", "crane", "dingo", "dolphin", "eagle",
    "falcon", "ferret", "finch", "fox", "gecko", "goose", "hare", "hawk",
    "heron", "husky", "jaguar", "koala", "lemur", "llama", "lynx", "magpie",
    "marmot", "moose", "narwhal", "otter", "owl", "panda", "pelican", "penguin",
    "puffin", "quail", "raccoon", "raven", "robin", "seal", "sparrow", "stork",
    "swan", "tiger", "toucan", "trout", "turtle", "walrus", "weasel", "wombat",
    "wren", "yak",
];

/// A free adjective-animal name for when the user would rather not pick one.
pub fn random_name(cfg: &Config) -> Result<String> {
    random_name_from(cfg, ADJECTIVES, ANIMALS)
}

fn random_name_from(cfg: &Config, adjectives: &[&str], animals: &[&str]) -> Result<String> {
    use rand::RngExt;

    let taken: std::collections::HashSet<String> = list_contexts(cfg)
        .into_iter()
        .chain(list_archived(cfg))
        .map(|ctx| ctx.name)
        .collect();
    let free: Vec<String> = adjectives
        .iter()
        .flat_map(|adjective| {
            animals
                .iter()
                .map(move |animal| format!("{adjective}-{animal}"))
        })
        .filter(|name| !taken.contains(name))
        .collect();
    if free.is_empty() {
        return msg("all generated names are taken; pick one yourself");
    }
    let pick = rand::rng().random_range(0..free.len());
    Ok(free[pick].clone())
}

pub fn create_context(cfg: &Config, repo: &str, name: &str, base: Option<&str>) -> Result<Context> {
    // Spaces are welcome in context names but not in branch names; dash them
    // out. Anything else unfit for a branch is rejected, not rewritten.
    let branch = format!("{}{}", cfg.branch_prefix, name.replace(' ', "-"));
    check_name(name, &branch)?;
    let mirror = repos::repo_path(cfg, repo);
    if !mirror.exists() {
        return msg(format!(
            "repo '{repo}' is not registered (ctx repo add <url>)"
        ));
    }
    check_name_free(cfg, name, None)?;
    let path = context_path(cfg, repo, name);

    let (base, fetch_base) = match base {
        None => {
            repos::update_repo(cfg, repo)?;
            (repos::default_branch(cfg, repo)?, false)
        }
        // The mirror only carries the default branch; fetch the base into the context.
        Some(base) => (base.to_string(), true),
    };
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent)?;
    }
    // A directory that predates the clone is not ours to delete on failure.
    let preexisting = path.exists();
    let ctx = Context {
        repo: repo.to_string(),
        name: name.to_string(),
        path: path.clone(),
    };
    let checkout = || -> Result<()> {
        git_quiet(
            &["clone", &mirror.to_string_lossy(), &path.to_string_lossy()],
            None,
        )?;
        let url = repos::repo_url(cfg, repo)?;
        git_quiet(&["remote", "set-url", "origin", &url], Some(&path))?;
        if fetch_base && git_quiet(&["fetch", "origin", &base], Some(&path)).is_err() {
            remove_context(&ctx)?;
            return msg(format!("branch '{base}' not found on origin of '{repo}'"));
        }
        if !fetch_base
            && !git_quiet(
                &["for-each-ref", &format!("refs/heads/{branch}")],
                Some(&path),
            )?
            .is_empty()
        {
            // The clone's default branch may already bear the requested name
            // (e.g. a context named after it); adopt it instead of forking it.
            git_quiet(&["checkout", &branch], Some(&path))?;
        } else if !git_quiet(
            &["for-each-ref", &format!("refs/remotes/origin/{base}")],
            Some(&path),
        )?
        .is_empty()
        {
            git_quiet(
                &[
                    "checkout",
                    "--no-track",
                    "-b",
                    &branch,
                    &format!("origin/{base}"),
                ],
                Some(&path),
            )?;
        } else {
            // An empty repo has no commit to branch from; start the work branch unborn.
            git_quiet(&["checkout", "--no-track", "-b", &branch], Some(&path))?;
        }
        Ok(())
    };
    if let Err(err) = checkout() {
        // A half-made checkout would squat on the name; leave nothing behind.
        if !preexisting {
            let _ = std::fs::remove_dir_all(&path);
        }
        return Err(err);
    }
    Ok(ctx)
}

pub fn archive_path(cfg: &Config, repo: &str, name: &str) -> PathBuf {
    cfg.archive_dir.join(repo).join(name)
}

/// All archived contexts, most recently active first.
pub fn list_archived(cfg: &Config) -> Vec<Context> {
    scan(&cfg.archive_dir)
}

/// Resolve an archived context by name.
pub fn find_archived(cfg: &Config, name: &str) -> Result<Context> {
    list_archived(cfg)
        .into_iter()
        .find(|ctx| ctx.name == name)
        .ok_or_else(|| CtxError::Msg(format!("no archived context '{name}'")))
}

/// Resolve a context name among live and archived contexts alike.
pub fn find_any(cfg: &Config, name: &str) -> Result<Context> {
    list_contexts(cfg)
        .into_iter()
        .chain(list_archived(cfg))
        .find(|ctx| ctx.name == name)
        .ok_or_else(|| CtxError::Msg(format!("no context '{name}'")))
}

pub fn is_archived(cfg: &Config, ctx: &Context) -> bool {
    ctx.path.starts_with(&cfg.archive_dir)
}

/// Move a directory, falling back to copy-and-delete across filesystems.
fn move_dir(src: &Path, dest: &Path) -> std::io::Result<()> {
    match std::fs::rename(src, dest) {
        Err(err) if err.kind() == std::io::ErrorKind::CrossesDevices => {
            copy_tree(src, dest)?;
            std::fs::remove_dir_all(src)
        }
        result => result,
    }
}

fn copy_tree(src: &Path, dest: &Path) -> std::io::Result<()> {
    std::fs::create_dir_all(dest)?;
    for entry in std::fs::read_dir(src)? {
        let entry = entry?;
        let target = dest.join(entry.file_name());
        let kind = entry.file_type()?;
        if kind.is_symlink() {
            // Recreate symlinks (checkouts carry them, and a dangling or
            // directory link would fail a dereferencing copy).
            std::os::unix::fs::symlink(std::fs::read_link(entry.path())?, &target)?;
        } else if kind.is_dir() {
            copy_tree(&entry.path(), &target)?;
        } else {
            std::fs::copy(entry.path(), &target)?;
        }
    }
    Ok(())
}

/// Move a context's checkout into the archive.
pub fn archive_context(cfg: &Config, ctx: &Context) -> Result<Context> {
    check_name_free(cfg, &ctx.name, Some(&ctx.path))?;
    let dest = archive_path(cfg, &ctx.repo, &ctx.name);
    if dest.exists() {
        return msg(format!("'{}' is already archived", ctx.qualified()));
    }
    if let Some(parent) = dest.parent() {
        std::fs::create_dir_all(parent)?;
    }
    move_dir(&ctx.path, &dest)?;
    Ok(Context {
        repo: ctx.repo.clone(),
        name: ctx.name.clone(),
        path: dest,
    })
}

/// Move an archived checkout back among the live contexts.
pub fn unarchive_context(cfg: &Config, ctx: &Context) -> Result<Context> {
    check_name_free(cfg, &ctx.name, Some(&ctx.path))?;
    let dest = context_path(cfg, &ctx.repo, &ctx.name);
    if let Some(parent) = dest.parent() {
        std::fs::create_dir_all(parent)?;
    }
    move_dir(&ctx.path, &dest)?;
    Ok(Context {
        repo: ctx.repo.clone(),
        name: ctx.name.clone(),
        path: dest,
    })
}

/// The checkout's branch, read from `.git/HEAD` to spare a subprocess.
///
/// Anything but a symbolic ref to a branch (e.g. a detached HEAD's raw
/// hash) reads as no branch, like `git branch --show-current`. So does an
/// unreadable HEAD: a checkout damaged on disk must not break listings.
pub fn current_branch(ctx: &Context) -> String {
    let Ok(head) = std::fs::read_to_string(ctx.path.join(".git").join("HEAD")) else {
        return String::new();
    };
    head.trim()
        .strip_prefix("ref: refs/heads/")
        .unwrap_or("")
        .to_string()
}

pub fn is_dirty(ctx: &Context) -> Result<bool> {
    Ok(!git(&["status", "--porcelain"], Some(&ctx.path))?.is_empty())
}

pub fn unpushed_commits(ctx: &Context) -> Result<Vec<String>> {
    let out = git(
        &["log", "--branches", "--not", "--remotes", "--oneline"],
        Some(&ctx.path),
    )?;
    if out.is_empty() {
        return Ok(Vec::new());
    }
    Ok(out.lines().map(str::to_string).collect())
}

pub fn remove_context(ctx: &Context) -> Result<()> {
    let name = ctx.path.file_name().unwrap_or_default().to_string_lossy();
    let doomed = ctx.path.with_file_name(format!("{name}{DELETING_SUFFIX}"));
    if doomed.exists() {
        let _ = std::fs::remove_dir_all(&doomed);
    }
    std::fs::rename(&ctx.path, &doomed)?;
    std::fs::remove_dir_all(&doomed)?;
    Ok(())
}

/// Finish removals that a crash or kill interrupted mid-delete.
pub fn sweep_deleting(cfg: &Config) {
    for root in [&cfg.contexts_dir, &cfg.archive_dir] {
        if !root.is_dir() {
            continue;
        }
        for repo_dir in sorted_dirs(root) {
            if !repo_dir.is_dir() {
                continue;
            }
            for entry in sorted_dirs(&repo_dir) {
                if entry.to_string_lossy().ends_with(DELETING_SUFFIX) && entry.is_dir() {
                    let _ = std::fs::remove_dir_all(&entry);
                }
            }
        }
    }
}

/// Permanently delete every archived context.
pub fn empty_archive(cfg: &Config) -> Result<()> {
    for ctx in list_archived(cfg) {
        remove_context(&ctx)?;
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::testutil::{TestEnv, commit_file, commit_lfs_file, git, lfs_available, test_env};

    fn registered() -> (TestEnv, PathBuf) {
        let env = test_env();
        let origin = env.origin();
        repos::add_repo(&env.cfg, &origin.to_string_lossy(), None).unwrap();
        (env, origin)
    }

    fn create(env: &TestEnv, repo: &str, name: &str) -> Context {
        create_context(&env.cfg, repo, name, None).unwrap()
    }

    #[test]
    fn create_checks_out_the_repo() {
        let (env, _origin) = registered();

        let ctx = create(&env, "origin", "feat");

        assert_eq!(ctx.path, env.cfg.contexts_dir.join("origin").join("feat"));
        assert!(ctx.path.join("README.md").exists());
    }

    #[test]
    fn create_starts_a_branch_named_after_the_context() {
        let (env, _origin) = registered();

        let ctx = create(&env, "origin", "feat");

        assert_eq!(current_branch(&ctx), "feat");
    }

    #[test]
    fn create_adopts_an_existing_local_branch() {
        // "main" already exists in the fresh clone as its default branch. The
        // context checks it out instead of failing to create a branch of that name.
        let (env, _origin) = registered();

        let ctx = create(&env, "origin", "main");

        assert_eq!(current_branch(&ctx), "main");
        // No second branch was forked; the existing one is all there is.
        assert_eq!(
            git(&["branch", "--format=%(refname:short)"], &ctx.path),
            "main"
        );
    }

    #[test]
    fn create_applies_the_branch_prefix() {
        let (mut env, _origin) = registered();
        env.cfg.branch_prefix = "mb/".to_string();

        let ctx = create(&env, "origin", "feat");

        assert_eq!(current_branch(&ctx), "mb/feat");
    }

    #[test]
    fn create_maps_name_spaces_to_branch_dashes() {
        let (env, _origin) = registered();

        let ctx = create(&env, "origin", "two words");

        assert_eq!(current_branch(&ctx), "two-words");
        assert_eq!(find_context(&env.cfg, "two words").unwrap(), ctx);
    }

    #[test]
    fn create_smudges_lfs_files_from_the_mirror() {
        if !lfs_available() {
            return;
        }
        let env = test_env();
        let origin = env.origin();
        commit_lfs_file(&origin, "data.bin", "payload\n");
        repos::add_repo(&env.cfg, &origin.to_string_lossy(), None).unwrap();
        // Only the mirror's LFS store may serve the checkout.
        std::fs::remove_dir_all(origin.join(".git").join("lfs")).unwrap();

        let ctx = create(&env, "origin", "feat");

        assert_eq!(
            std::fs::read_to_string(ctx.path.join("data.bin")).unwrap(),
            "payload\n"
        );
    }

    #[test]
    fn failed_clone_leaves_nothing_behind() {
        if !lfs_available() {
            return;
        }
        let env = test_env();
        let origin = env.origin();
        commit_lfs_file(&origin, "data.bin", "x\n");
        repos::add_repo(&env.cfg, &origin.to_string_lossy(), None).unwrap();
        // A mirror missing LFS objects fails the clone's checkout; the explicit
        // base skips the mirror update that would repopulate the store.
        std::fs::remove_dir_all(repos::repo_path(&env.cfg, "origin").join("lfs")).unwrap();

        let result = create_context(&env.cfg, "origin", "feat", Some("main"));

        assert!(matches!(result, Err(CtxError::Git(_))));
        assert!(!env.cfg.contexts_dir.join("origin").join("feat").exists());
    }

    #[test]
    fn failed_clone_spares_a_preexisting_directory() {
        let (env, _origin) = registered();
        let path = env.cfg.contexts_dir.join("origin").join("feat");
        std::fs::create_dir_all(&path).unwrap();
        std::fs::write(path.join("keep.txt"), "x\n").unwrap();

        let result = create_context(&env.cfg, "origin", "feat", None);

        assert!(matches!(result, Err(CtxError::Git(_))));
        assert!(path.join("keep.txt").exists());
    }

    #[test]
    fn create_rejects_an_empty_name() {
        let (env, _origin) = registered();

        for name in ["", "   "] {
            let err = create_context(&env.cfg, "origin", name, None).expect_err("must reject");
            assert!(err.to_string().contains("must not be empty"));
        }
    }

    #[test]
    fn create_rejects_path_like_names() {
        let (env, _origin) = registered();

        for name in ["a/b", ".", ".."] {
            let err = create_context(&env.cfg, "origin", name, None).expect_err("must reject");
            assert!(err.to_string().contains("single path component"));
        }
        assert_eq!(list_contexts(&env.cfg), vec![]);
    }

    #[test]
    fn create_rejects_an_option_like_name() {
        let (env, _origin) = registered();

        let err = create_context(&env.cfg, "origin", "-feat", None).expect_err("must reject");

        assert!(err.to_string().contains("must not start with '-'"));
    }

    #[test]
    fn create_rejects_names_unfit_for_branches() {
        let (env, _origin) = registered();

        for name in [
            "feat~1",
            "a..b",
            "what?",
            "tab\there",
            ".hidden",
            "feat.lock",
        ] {
            let err = create_context(&env.cfg, "origin", name, None).expect_err("must reject");
            assert!(err.to_string().contains("valid branch name"));
        }
        assert_eq!(list_contexts(&env.cfg), vec![]);
    }

    #[test]
    fn create_points_the_remote_at_the_registered_url() {
        let (env, origin) = registered();

        let ctx = create(&env, "origin", "feat");

        assert_eq!(
            git(&["remote", "get-url", "origin"], &ctx.path),
            origin.to_string_lossy()
        );
    }

    #[test]
    fn create_includes_the_latest_origin_commits() {
        let (env, origin) = registered();
        commit_file(&origin, "new.txt", "x\n");

        let ctx = create(&env, "origin", "feat");

        assert!(ctx.path.join("new.txt").exists());
    }

    #[test]
    fn create_from_a_base_branch() {
        let (env, origin) = registered();
        git(&["branch", "other"], &origin);
        commit_file(&origin, "on-main.txt", "x\n");

        let ctx = create_context(&env.cfg, "origin", "feat", Some("other")).unwrap();

        assert_eq!(current_branch(&ctx), "feat");
        assert!(!ctx.path.join("on-main.txt").exists());
    }

    #[test]
    fn create_with_a_missing_base_fails_cleanly() {
        let (env, _origin) = registered();

        let err =
            create_context(&env.cfg, "origin", "feat", Some("nope")).expect_err("must reject");

        assert!(err.to_string().contains("branch 'nope' not found"));
        assert_eq!(list_contexts(&env.cfg), vec![]);
    }

    #[test]
    fn create_rejects_a_taken_name() {
        let (env, _origin) = registered();
        create(&env, "origin", "feat");

        let err = create_context(&env.cfg, "origin", "feat", None).expect_err("must reject");

        assert!(err.to_string().contains("already used by origin/feat"));
    }

    #[test]
    fn create_rejects_an_unregistered_repo() {
        let env = test_env();

        let err = create_context(&env.cfg, "nope", "feat", None).expect_err("must reject");

        assert!(err.to_string().contains("not registered"));
    }

    #[test]
    fn create_from_an_empty_repo() {
        let env = test_env();
        let origin = env.make_origin("empty", true);
        repos::add_repo(&env.cfg, &origin.to_string_lossy(), None).unwrap();

        let ctx = create(&env, "empty", "feat");

        assert_eq!(current_branch(&ctx), "feat");
        // Listing must not choke on the missing reflog/index of an unborn branch.
        assert_eq!(list_contexts(&env.cfg), vec![ctx]);
    }

    #[test]
    fn random_name_pairs_an_adjective_with_an_animal() {
        let env = test_env();

        let name = random_name(&env.cfg).unwrap();
        let (adjective, animal) = name.split_once('-').unwrap();

        assert!(ADJECTIVES.contains(&adjective));
        assert!(ANIMALS.contains(&animal));
    }

    #[test]
    fn random_name_avoids_live_and_archived_names() {
        let (env, _origin) = registered();
        let ctx = create(&env, "origin", "holy-tiger");
        archive_context(&env.cfg, &ctx).unwrap();

        let name = random_name_from(&env.cfg, &["holy"], &["tiger", "otter"]).unwrap();

        assert_eq!(name, "holy-otter");
    }

    #[test]
    fn random_name_fails_when_all_names_are_taken() {
        let (env, _origin) = registered();
        create(&env, "origin", "holy-tiger");

        let err = random_name_from(&env.cfg, &["holy"], &["tiger"]).expect_err("must fail");

        assert!(err.to_string().contains("all generated names are taken"));
    }

    #[test]
    fn list_contexts_returns_created_contexts() {
        let (env, _origin) = registered();

        let created = create(&env, "origin", "feat");

        assert_eq!(list_contexts(&env.cfg), vec![created]);
    }

    fn set_activity(ctx: &Context, when: i64) {
        for rel in [".git/logs/HEAD", ".git/index"] {
            set_mtime(&ctx.path.join(rel), when);
        }
    }

    fn set_mtime(path: &Path, when: i64) {
        let file = std::fs::OpenOptions::new().write(true).open(path).unwrap();
        file.set_times(
            std::fs::FileTimes::new()
                .set_accessed(SystemTime::UNIX_EPOCH + std::time::Duration::from_secs(when as u64))
                .set_modified(SystemTime::UNIX_EPOCH + std::time::Duration::from_secs(when as u64)),
        )
        .unwrap();
    }

    #[test]
    fn list_contexts_sorts_most_recently_active_first() {
        let (env, _origin) = registered();
        let older = create(&env, "origin", "older");
        let newer = create(&env, "origin", "newer");
        set_activity(&older, 1_000);
        set_activity(&newer, 2_000);

        assert_eq!(list_contexts(&env.cfg), vec![newer.clone(), older.clone()]);

        set_activity(&older, 3_000);

        assert_eq!(list_contexts(&env.cfg), vec![older, newer]);
    }

    #[test]
    fn index_activity_alone_counts_as_recency() {
        let (env, _origin) = registered();
        let quiet = create(&env, "origin", "quiet");
        let staged = create(&env, "origin", "staged");
        set_activity(&quiet, 1_000);
        set_activity(&staged, 1_000);

        set_mtime(&staged.path.join(".git").join("index"), 2_000);

        assert_eq!(list_contexts(&env.cfg), vec![staged, quiet]);
    }

    #[test]
    fn find_context_resolves_by_name() {
        let (env, _origin) = registered();

        let created = create(&env, "origin", "feat");

        assert_eq!(find_context(&env.cfg, "feat").unwrap(), created);
    }

    #[test]
    fn find_context_rejects_unknown_names() {
        let env = test_env();

        let err = find_context(&env.cfg, "feat").expect_err("must reject");

        assert!(err.to_string().contains("no context 'feat'"));
    }

    #[test]
    fn fresh_context_is_clean() {
        let (env, _origin) = registered();

        let ctx = create(&env, "origin", "feat");

        assert!(!is_dirty(&ctx).unwrap());
        assert_eq!(unpushed_commits(&ctx).unwrap(), Vec::<String>::new());
    }

    #[test]
    fn uncommitted_file_makes_context_dirty() {
        let (env, _origin) = registered();
        let ctx = create(&env, "origin", "feat");

        std::fs::write(ctx.path.join("scratch.txt"), "x\n").unwrap();

        assert!(is_dirty(&ctx).unwrap());
    }

    #[test]
    fn local_commit_counts_as_unpushed() {
        let (env, _origin) = registered();
        let ctx = create(&env, "origin", "feat");

        commit_file(&ctx.path, "work.txt", "x\n");

        assert_eq!(unpushed_commits(&ctx).unwrap().len(), 1);
    }

    #[test]
    fn archive_moves_the_checkout_out_of_the_contexts() {
        let (env, _origin) = registered();
        let ctx = create(&env, "origin", "feat");

        let archived = archive_context(&env.cfg, &ctx).unwrap();

        assert_eq!(
            archived.path,
            env.cfg.archive_dir.join("origin").join("feat")
        );
        assert!(archived.path.join("README.md").exists());
        assert_eq!(list_contexts(&env.cfg), vec![]);
        assert_eq!(list_archived(&env.cfg), vec![archived]);
    }

    #[test]
    fn archive_keeps_the_context_name_reserved() {
        let (env, _origin) = registered();
        let archived = archive_context(&env.cfg, &create(&env, "origin", "feat")).unwrap();

        let err = create_context(&env.cfg, "origin", "feat", None).expect_err("must reject");

        assert!(
            err.to_string()
                .contains("already used by archived origin/feat")
        );
        assert_eq!(list_archived(&env.cfg), vec![archived]);
    }

    #[test]
    fn archive_refuses_to_move_onto_an_occupied_path() {
        let (env, _origin) = registered();
        let ctx = create(&env, "origin", "feat");
        std::fs::create_dir_all(env.cfg.archive_dir.join("origin").join("feat")).unwrap();

        let err = archive_context(&env.cfg, &ctx).expect_err("must reject");

        assert!(err.to_string().contains("already archived"));
        assert_eq!(list_contexts(&env.cfg), vec![ctx]);
    }

    #[test]
    fn find_archived_resolves_by_name() {
        let (env, _origin) = registered();
        let archived = archive_context(&env.cfg, &create(&env, "origin", "feat")).unwrap();

        assert_eq!(find_archived(&env.cfg, "feat").unwrap(), archived);
    }

    #[test]
    fn find_any_resolves_live_and_archived_contexts() {
        let (env, _origin) = registered();
        let archived = archive_context(&env.cfg, &create(&env, "origin", "cold")).unwrap();
        let live = create(&env, "origin", "hot");

        assert_eq!(find_any(&env.cfg, "cold").unwrap(), archived);
        assert_eq!(find_any(&env.cfg, "hot").unwrap(), live);
    }

    #[test]
    fn find_any_rejects_unknown_names() {
        let env = test_env();

        let err = find_any(&env.cfg, "feat").expect_err("must reject");

        assert!(err.to_string().contains("no context 'feat'"));
    }

    #[test]
    fn find_archived_rejects_unknown_names() {
        let env = test_env();

        let err = find_archived(&env.cfg, "feat").expect_err("must reject");

        assert!(err.to_string().contains("no archived context 'feat'"));
    }

    #[test]
    fn unarchive_restores_the_context() {
        let (env, _origin) = registered();
        let created = create(&env, "origin", "feat");
        let archived = archive_context(&env.cfg, &created).unwrap();

        let restored = unarchive_context(&env.cfg, &archived).unwrap();

        assert_eq!(restored, created);
        assert_eq!(list_contexts(&env.cfg), vec![created]);
        assert_eq!(list_archived(&env.cfg), vec![]);
    }

    #[test]
    fn unarchive_rejects_a_name_taken_by_a_live_context() {
        let (env, _origin) = registered();
        let stale = archive_context(&env.cfg, &create(&env, "origin", "old")).unwrap();
        let live = create(&env, "origin", "feat");
        // Archives predating global uniqueness can still clash with a live name.
        let clash = stale.path.with_file_name("feat");
        std::fs::rename(&stale.path, &clash).unwrap();

        let err = unarchive_context(
            &env.cfg,
            &Context {
                repo: "origin".to_string(),
                name: "feat".to_string(),
                path: clash.clone(),
            },
        )
        .expect_err("must reject");

        assert!(err.to_string().contains("already used by origin/feat"));
        assert!(live.path.exists());
        assert!(clash.exists());
    }

    #[test]
    fn copy_tree_preserves_symlinks() {
        // The cross-filesystem fallback must move symlinks as symlinks:
        // dereferencing breaks relative links, and dangling ones error.
        let env = test_env();
        let src = env.root().join("src");
        std::fs::create_dir_all(src.join("sub")).unwrap();
        std::fs::write(src.join("sub").join("real.txt"), "x\n").unwrap();
        std::os::unix::fs::symlink("sub/real.txt", src.join("file-link")).unwrap();
        std::os::unix::fs::symlink("sub", src.join("dir-link")).unwrap();
        std::os::unix::fs::symlink("nowhere", src.join("dangling")).unwrap();

        let dest = env.root().join("dest");
        copy_tree(&src, &dest).unwrap();

        for (link, points_to) in [
            ("file-link", "sub/real.txt"),
            ("dir-link", "sub"),
            ("dangling", "nowhere"),
        ] {
            assert_eq!(
                std::fs::read_link(dest.join(link)).unwrap(),
                PathBuf::from(points_to)
            );
        }
    }

    #[test]
    fn current_branch_tolerates_a_damaged_checkout() {
        // A context whose removal was interrupted must not break listings.
        let (env, _origin) = registered();
        let ctx = create(&env, "origin", "feat");
        std::fs::remove_file(ctx.path.join(".git").join("HEAD")).unwrap();

        assert_eq!(current_branch(&ctx), "");
    }

    #[test]
    fn remove_context_deletes_the_checkout() {
        let (env, _origin) = registered();
        let ctx = create(&env, "origin", "feat");

        remove_context(&ctx).unwrap();

        assert_eq!(list_contexts(&env.cfg), vec![]);
        assert_eq!(
            sorted_dirs(&env.cfg.contexts_dir.join("origin")),
            vec![] as Vec<PathBuf>
        );
    }

    #[test]
    fn interrupted_removals_are_hidden_and_swept() {
        let (env, _origin) = registered();
        let kept = create(&env, "origin", "live");
        let doomed = create(&env, "origin", "feat");
        // An interrupted remove_context leaves the renamed checkout behind.
        let leftover = doomed.path.with_file_name("feat.deleting");
        std::fs::rename(&doomed.path, &leftover).unwrap();

        assert_eq!(list_contexts(&env.cfg), vec![kept.clone()]);

        sweep_deleting(&env.cfg);

        assert!(!leftover.exists());
        assert_eq!(list_contexts(&env.cfg), vec![kept]);
    }

    #[test]
    fn remove_context_replaces_a_stale_leftover() {
        let (env, _origin) = registered();
        let ctx = create(&env, "origin", "feat");
        let stale = ctx.path.with_file_name("feat.deleting");
        std::fs::create_dir(&stale).unwrap();
        std::fs::write(stale.join("junk"), "x\n").unwrap();

        remove_context(&ctx).unwrap();

        assert!(!ctx.path.exists());
        assert!(!stale.exists());
    }

    #[test]
    fn create_rejects_names_reserved_for_deletion() {
        let (env, _origin) = registered();

        let err =
            create_context(&env.cfg, "origin", "feat.deleting", None).expect_err("must reject");

        assert!(err.to_string().contains(".deleting"));
    }

    #[test]
    fn empty_archive_deletes_all_archived_contexts() {
        let (env, _origin) = registered();
        archive_context(&env.cfg, &create(&env, "origin", "one")).unwrap();
        archive_context(&env.cfg, &create(&env, "origin", "two")).unwrap();
        let kept = create(&env, "origin", "live");

        empty_archive(&env.cfg).unwrap();

        assert_eq!(list_archived(&env.cfg), vec![]);
        assert_eq!(list_contexts(&env.cfg), vec![kept]);
    }
}