ite_cli/

tree.rs

//! Source-neutral tree model at the center of the application. Filesystem and
//! JSON adapters build its flat node arena; `app` navigates it and `ui` renders
//! it through the `tui_treelistview::TreeModel` implementation.
//!
//! Consumers read nodes only through `Tree` accessors. The stored representation
//! is private so source-specific payloads—including filesystem names and spans
//! into retained JSON—can change without touching the app, renderer, or picker.
//! Accessors return owned values because those values may be derived on demand.

use std::ffi::OsString;
use std::ops::Range;
use std::path::{Path, PathBuf};
use std::sync::Arc;

use tui_treelistview::{TreeChildren, TreeModel, TreeRevision};

pub type NodeId = usize;

/// Values used when the focused node is accepted or passed to a shell binding.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct ActionValues {
    /// Text written to stdout when the node is accepted.
    pub output: OsString,
    /// Text written to stdout by the alternate accept action.
    pub alternate_output: OsString,
    /// Value exported to shell bindings as `$path`.
    pub path: OsString,
    /// Value exported to shell bindings as `$relpath`.
    pub relpath: OsString,
}

impl ActionValues {
    pub fn new(
        output: impl Into<OsString>,
        path: impl Into<OsString>,
        relpath: impl Into<OsString>,
    ) -> Self {
        let output = output.into();
        Self {
            alternate_output: output.clone(),
            output,
            path: path.into(),
            relpath: relpath.into(),
        }
    }

    pub fn with_alternate_output(mut self, output: impl Into<OsString>) -> Self {
        self.alternate_output = output.into();
        self
    }
}

/// Display and action values stored verbatim.
#[derive(Debug)]
struct Explicit {
    name: String,
    detail: Option<String>,
    action: ActionValues,
}

/// How a JSON node is addressed within its parent.
#[derive(Clone, Debug)]
pub(crate) enum JsonKey {
    /// The synthetic `$` root of a single-rooted document.
    Root,
    /// The synthetic root of a JSONL document: the virtual array of records.
    JsonlRoot,
    /// An object member; the span covers the raw key token, quotes included.
    Member { key_span: Range<u32> },
    /// An array element.
    Index(u32),
}

/// Per-node data that differs by source.
#[derive(Debug)]
enum Payload {
    /// Stored verbatim (tests, transitional). Boxed so the variant does not
    /// inflate every filesystem or JSON node.
    Explicit(Box<Explicit>),
    /// A filesystem entry's final path component. Kept as raw `OsString` so
    /// non-UTF-8 names survive into the derived paths handed to shell
    /// bindings; only the displayed name goes through `to_string_lossy`.
    Fs { file_name: OsString },
    /// A JSON value: its byte span in the retained input plus how it is
    /// addressed within its parent. Everything else is derived.
    /// `child_count` is the immediate-child count discovered when the parent
    /// was scanned; `None` until known (unvalidated JSONL records).
    Json {
        span: Range<u32>,
        key: JsonKey,
        child_count: Option<u32>,
    },
    /// A span that failed to scan (a corrupt JSONL record): kept selectable,
    /// rendered as an error leaf whose raw text is the alternate output.
    JsonError { span: Range<u32>, key: JsonKey },
}

#[derive(Debug)]
struct Node {
    parent: Option<NodeId>,
    children: Vec<NodeId>,
    is_container: bool,
    depth: usize,
    /// False while the node's children (or, for a pending scalar record, its
    /// validation) have not been computed yet.
    children_loaded: bool,
    payload: Payload,
}

#[derive(Debug, Default)]
pub struct Tree {
    nodes: Vec<Node>,
    roots: Vec<NodeId>,
    view_root: Option<NodeId>,
    revision: TreeRevision,
    /// The scanned directory (canonicalized) filesystem paths derive from.
    fs_root: Option<PathBuf>,
    /// Whether the scan ignores ignore-files; lazy walks must match.
    fs_no_ignore: bool,
    /// The raw JSON input document that `Payload::Json` spans index into.
    /// Shared so materialization can read it while appending nodes.
    json_source: Option<Arc<Vec<u8>>>,
    /// Nodes whose children/validation are still pending.
    unloaded: usize,
    /// Arena-order sweep position for [`Tree::index_some`].
    cursor: NodeId,
    /// Messages for spans that failed to scan, for the banner and exit report.
    errors: Vec<String>,
}

impl Tree {
    pub fn new() -> Self {
        Self::default()
    }

    /// A tree over a directory scan rooted at `root` (canonicalized);
    /// filesystem nodes derive their paths from it and lazy directory walks
    /// reuse the scan's ignore setting.
    pub(crate) fn new_fs(root: PathBuf, no_ignore: bool) -> Self {
        Self {
            fs_root: Some(root),
            fs_no_ignore: no_ignore,
            ..Self::default()
        }
    }

    pub(crate) fn fs_no_ignore(&self) -> bool {
        self.fs_no_ignore
    }

    pub fn push(
        &mut self,
        parent: Option<NodeId>,
        name: impl Into<String>,
        is_container: bool,
        action: ActionValues,
    ) -> NodeId {
        self.push_with_detail(parent, name, None, is_container, action)
    }

    pub fn push_with_detail(
        &mut self,
        parent: Option<NodeId>,
        name: impl Into<String>,
        detail: Option<String>,
        is_container: bool,
        action: ActionValues,
    ) -> NodeId {
        self.push_node(
            parent,
            is_container,
            true,
            Payload::Explicit(Box::new(Explicit {
                name: name.into(),
                detail,
                action,
            })),
        )
    }

    /// Append a filesystem entry; its action values are derived on demand.
    /// Directories start unloaded — their contents come from a lazy walk.
    pub(crate) fn push_fs(
        &mut self,
        parent: Option<NodeId>,
        file_name: impl Into<OsString>,
        is_container: bool,
    ) -> NodeId {
        self.push_node(
            parent,
            is_container,
            !is_container,
            Payload::Fs {
                file_name: file_name.into(),
            },
        )
    }

    /// Append a JSON value node; its display and action values are derived on
    /// demand from the retained input bytes.
    pub(crate) fn push_json(
        &mut self,
        parent: Option<NodeId>,
        span: Range<u32>,
        key: JsonKey,
        is_container: bool,
        child_count: Option<u32>,
        children_loaded: bool,
    ) -> NodeId {
        self.push_node(
            parent,
            is_container,
            children_loaded,
            Payload::Json {
                span,
                key,
                child_count,
            },
        )
    }

    /// Attach the input document the JSON spans index into.
    pub(crate) fn set_json_source(&mut self, bytes: Arc<Vec<u8>>) {
        self.json_source = Some(bytes);
    }

    /// Drop every node with id >= `len` (discarding a partially scanned JSONL
    /// record); nodes below `len` and their order are untouched.
    pub(crate) fn truncate(&mut self, len: usize) {
        for node in &self.nodes[len.min(self.nodes.len())..] {
            if !node.children_loaded {
                self.unloaded -= 1;
            }
        }
        self.nodes.truncate(len);
        self.roots.retain(|&id| id < len);
        for node in &mut self.nodes {
            node.children.retain(|&id| id < len);
        }
        self.cursor = self.cursor.min(len);
    }

    fn json_bytes(&self) -> &[u8] {
        self.json_source
            .as_ref()
            .map_or(&[], |bytes| bytes.as_slice())
    }

    /// The shared input document, for materialization to read while pushing.
    pub(crate) fn json_source_arc(&self) -> Option<Arc<Vec<u8>>> {
        self.json_source.clone()
    }

    /// The byte span of a JSON (or error) node.
    pub(crate) fn json_span(&self, id: NodeId) -> Option<Range<u32>> {
        match &self.node(id).payload {
            Payload::Json { span, .. } | Payload::JsonError { span, .. } => Some(span.clone()),
            _ => None,
        }
    }

    fn push_node(
        &mut self,
        parent: Option<NodeId>,
        is_container: bool,
        children_loaded: bool,
        payload: Payload,
    ) -> NodeId {
        let id = self.nodes.len();
        let depth = parent.map_or(0, |id| self.nodes[id].depth + 1);
        self.nodes.push(Node {
            parent,
            children: Vec::new(),
            is_container,
            depth,
            children_loaded,
            payload,
        });
        if !children_loaded {
            self.unloaded += 1;
        }
        match parent {
            Some(parent) => self.nodes[parent].children.push(id),
            None => self.roots.push(id),
        }
        id
    }

    /// Materialize the node's pending children (or validate a pending scalar
    /// record). Returns true when work was actually done.
    pub(crate) fn ensure_children(&mut self, id: NodeId) -> bool {
        if self.nodes[id].children_loaded {
            return false;
        }
        match self.nodes[id].payload {
            Payload::Json { .. } => crate::json_tree::materialize(self, id),
            Payload::Fs { .. } => crate::fstree::materialize(self, id),
            _ => self.mark_children_loaded(id),
        }
        self.revision.advance();
        true
    }

    /// Flip a node to loaded, keeping the pending-work counter accurate.
    pub(crate) fn mark_children_loaded(&mut self, id: NodeId) {
        if !self.nodes[id].children_loaded {
            self.nodes[id].children_loaded = true;
            self.unloaded -= 1;
        }
    }

    /// Convert a node whose span failed to scan into a selectable error leaf
    /// and record the message for the banner and the exit report.
    pub(crate) fn set_json_error(&mut self, id: NodeId, message: String) {
        let (span, key) = match &self.nodes[id].payload {
            Payload::Json { span, key, .. } => (span.clone(), key.clone()),
            _ => return,
        };
        self.nodes[id].payload = Payload::JsonError { span, key };
        self.nodes[id].is_container = false;
        self.mark_children_loaded(id);
        self.errors.push(message);
        self.revision.advance();
    }

    /// Advance the arena-order sweep, loading up to `budget` pending nodes.
    /// Returns true when any work was done. The sweep together with
    /// on-demand loading eventually visits every node, so a fully swept tree
    /// has validated every byte of the input.
    pub(crate) fn index_some(&mut self, budget: usize) -> bool {
        let mut done = 0;
        while done < budget && self.cursor < self.nodes.len() {
            if self.nodes[self.cursor].children_loaded {
                self.cursor += 1;
            } else {
                self.ensure_children(self.cursor);
                done += 1;
            }
        }
        done > 0
    }

    /// Run the sweep to completion (startup `--expand`, and tests).
    pub(crate) fn index_all(&mut self) {
        while self.index_some(usize::MAX) {}
    }

    /// True once every node's children are loaded and every span validated;
    /// the jump picker requires this.
    pub fn fully_indexed(&self) -> bool {
        self.unloaded == 0
    }

    /// Nodes whose children/validation are still pending (progress display).
    pub fn pending(&self) -> usize {
        self.unloaded
    }

    /// Messages for spans that failed to scan, in discovery order.
    pub fn errors(&self) -> &[String] {
        &self.errors
    }

    /// Record a non-fatal source error (an unreadable directory) for the
    /// banner and the exit report.
    pub(crate) fn record_error(&mut self, message: String) {
        self.errors.push(message);
        self.revision.advance();
    }

    fn node(&self, id: NodeId) -> &Node {
        &self.nodes[id]
    }

    /// The node's display name.
    pub fn name(&self, id: NodeId) -> String {
        let node = self.node(id);
        match &node.payload {
            Payload::Explicit(explicit) => explicit.name.clone(),
            Payload::Fs { file_name } => file_name.to_string_lossy().into_owned(),
            Payload::Json {
                span,
                key,
                child_count,
            } => {
                let bytes = self.json_bytes();
                let prefix = match key {
                    JsonKey::Root | JsonKey::JsonlRoot => "$".to_owned(),
                    JsonKey::Member { key_span } => crate::json_tree::key_text(bytes, key_span),
                    JsonKey::Index(index) => format!("[{index}]"),
                };
                if node.is_container {
                    // Loaded containers count their children; unloaded ones
                    // fall back to the count discovered when their parent was
                    // scanned, and show `…` when even that is pending
                    // (unvalidated JSONL records).
                    let count = if node.children_loaded {
                        Some(node.children.len() as u32)
                    } else {
                        *child_count
                    };
                    // The JSONL root is a virtual array whatever its first
                    // record's first byte happens to be.
                    let object =
                        !matches!(key, JsonKey::JsonlRoot) && bytes[span.start as usize] == b'{';
                    match (object, count) {
                        (true, Some(0)) => format!("{prefix} {{}}"),
                        (true, Some(count)) => format!("{prefix} {{{count}}}"),
                        (true, None) => format!("{prefix} {{…}}"),
                        (false, Some(0)) => format!("{prefix} []"),
                        (false, Some(count)) => format!("{prefix} [{count}]"),
                        (false, None) => format!("{prefix} […]"),
                    }
                } else {
                    format!("{prefix}: {}", crate::json_tree::value_text(bytes, span))
                }
            }
            Payload::JsonError { key, .. } => {
                let prefix = match key {
                    JsonKey::Root | JsonKey::JsonlRoot => "$".to_owned(),
                    JsonKey::Member { key_span } => {
                        crate::json_tree::key_text(self.json_bytes(), key_span)
                    }
                    JsonKey::Index(index) => format!("[{index}]"),
                };
                format!("{prefix} ⚠")
            }
        }
    }

    /// Optional secondary text rendered after the name.
    pub fn detail(&self, id: NodeId) -> Option<String> {
        let node = self.node(id);
        match &node.payload {
            Payload::Explicit(explicit) => explicit.detail.clone(),
            Payload::Fs { .. } => None,
            Payload::Json { span, .. } => {
                let bytes = self.json_bytes();
                if !node.is_container || bytes.get(span.start as usize) != Some(&b'{') {
                    return None;
                }
                let members = node.children.iter().map(|&child| {
                    let child = self.node(child);
                    match &child.payload {
                        Payload::Json {
                            span,
                            key: JsonKey::Member { key_span },
                            ..
                        } if !child.is_container => Some((key_span.clone(), span.clone())),
                        _ => None,
                    }
                });
                crate::json_tree::object_preview(bytes, members)
            }
            Payload::JsonError { span, .. } => {
                let mut text = crate::json_tree::raw_text(self.json_bytes(), span);
                if text.len() > 512 {
                    let mut end = 512;
                    while !text.is_char_boundary(end) {
                        end -= 1;
                    }
                    text.truncate(end);
                }
                Some(text)
            }
        }
    }

    pub fn parent(&self, id: NodeId) -> Option<NodeId> {
        self.node(id).parent
    }

    /// 0 for roots.
    pub fn depth(&self, id: NodeId) -> usize {
        self.node(id).depth
    }

    /// Whether the node represents a container, including an empty one.
    pub fn is_container(&self, id: NodeId) -> bool {
        self.node(id).is_container
    }

    /// The node's children, in display order.
    pub fn children_of(&self, id: NodeId) -> &[NodeId] {
        &self.node(id).children
    }

    /// Text written to stdout when the node is accepted.
    pub fn output(&self, id: NodeId) -> OsString {
        match &self.node(id).payload {
            Payload::Explicit(explicit) => explicit.action.output.clone(),
            Payload::Fs { .. } => self.fs_path(id),
            Payload::Json { .. } | Payload::JsonError { .. } => {
                self.json_pointer_from(id, false).into()
            }
        }
    }

    /// Text written to stdout by the alternate accept action.
    pub fn alternate_output(&self, id: NodeId) -> OsString {
        match &self.node(id).payload {
            Payload::Explicit(explicit) => explicit.action.alternate_output.clone(),
            Payload::Fs { file_name } => file_name.clone(),
            Payload::Json { span, .. } => {
                crate::json_tree::value_text(self.json_bytes(), span).into()
            }
            Payload::JsonError { span, .. } => {
                crate::json_tree::raw_text(self.json_bytes(), span).into()
            }
        }
    }

    /// Value exported to shell bindings as `$path`.
    pub fn path(&self, id: NodeId) -> OsString {
        match &self.node(id).payload {
            Payload::Explicit(explicit) => explicit.action.path.clone(),
            Payload::Fs { .. } => self.fs_path(id),
            Payload::Json { .. } | Payload::JsonError { .. } => {
                self.json_pointer_from(id, false).into()
            }
        }
    }

    /// The node's location in the host filesystem, when it has one. JSON nodes
    /// are addressed by pointer within a document, so nothing outside ite can
    /// open them.
    pub fn filesystem_path(&self, id: NodeId) -> Option<OsString> {
        match &self.node(id).payload {
            Payload::Explicit(explicit) => Some(explicit.action.path.clone()),
            Payload::Fs { .. } => Some(self.fs_path(id)),
            Payload::Json { .. } | Payload::JsonError { .. } => None,
        }
    }

    /// Value exported to shell bindings as `$relpath`: the address within the
    /// source's natural unit — the scan root for directories, the document
    /// for JSON, the containing record for JSONL (the record itself is "").
    pub fn relpath(&self, id: NodeId) -> OsString {
        match &self.node(id).payload {
            Payload::Explicit(explicit) => explicit.action.relpath.clone(),
            Payload::Fs { .. } => self.fs_relpath(id).into_os_string(),
            Payload::Json { .. } | Payload::JsonError { .. } => {
                self.json_pointer_from(id, true).into()
            }
        }
    }

    /// The text the jump picker matches and displays: the node's
    /// document-global address. Coincides with `relpath` for directory scans
    /// and JSON documents; JSONL diverges, since a record-relative `relpath`
    /// repeats across records.
    pub fn jump_key(&self, id: NodeId) -> String {
        match &self.node(id).payload {
            Payload::Json { .. } | Payload::JsonError { .. } => self.json_pointer_from(id, false),
            _ => self.relpath(id).to_string_lossy().into_owned(),
        }
    }

    /// Root-relative path of a filesystem node: ancestor file names joined.
    fn fs_relpath(&self, id: NodeId) -> PathBuf {
        let mut components = Vec::new();
        let mut cursor = Some(id);
        while let Some(current) = cursor {
            let node = self.node(current);
            if let Payload::Fs { file_name } = &node.payload {
                components.push(file_name.as_os_str());
            }
            cursor = node.parent;
        }
        components.iter().rev().collect()
    }

    /// Absolute path of a filesystem node: the scan root plus [`Self::fs_relpath`].
    fn fs_path(&self, id: NodeId) -> OsString {
        let root = self.fs_root.as_deref().unwrap_or(Path::new(""));
        root.join(self.fs_relpath(id)).into_os_string()
    }

    /// Canonical JSON Pointer of a JSON node, assembled from its ancestor
    /// keys. Synthetic roots contribute no token, so a single-rooted
    /// document's root is the empty (whole-document) pointer. With
    /// `within_record` the walk stops at the containing JSONL record, whose
    /// own token is excluded — the record-relative address.
    fn json_pointer_from(&self, id: NodeId, within_record: bool) -> String {
        let mut tokens = Vec::new();
        let mut cursor = Some(id);
        while let Some(current) = cursor {
            let node = self.node(current);
            let (Payload::Json { key, .. } | Payload::JsonError { key, .. }) = &node.payload else {
                break;
            };
            if within_record && self.is_jsonl_record(current) {
                break;
            }
            match key {
                JsonKey::Root | JsonKey::JsonlRoot => {}
                JsonKey::Member { key_span } => {
                    tokens.push(crate::json_tree::key_text(self.json_bytes(), key_span));
                }
                JsonKey::Index(index) => tokens.push(index.to_string()),
            }
            cursor = node.parent;
        }
        let mut pointer = String::new();
        for token in tokens.iter().rev() {
            pointer = crate::json_tree::append_pointer(&pointer, token);
        }
        pointer
    }

    /// Whether the node is a JSONL record: a direct child of the virtual
    /// array root.
    fn is_jsonl_record(&self, id: NodeId) -> bool {
        self.node(id).parent.is_some_and(|parent| {
            matches!(
                &self.node(parent).payload,
                Payload::Json {
                    key: JsonKey::JsonlRoot,
                    ..
                }
            )
        })
    }

    pub fn len(&self) -> usize {
        self.nodes.len()
    }

    pub fn is_empty(&self) -> bool {
        self.nodes.is_empty()
    }

    pub fn root_ids(&self) -> &[NodeId] {
        &self.roots
    }

    /// The temporary root used by the tree view, if it has been narrowed.
    pub(crate) fn view_root(&self) -> Option<NodeId> {
        self.view_root
    }

    /// Narrow the tree model to one subtree, or restore the original forest.
    pub(crate) fn set_view_root(&mut self, root: Option<NodeId>) {
        if self.view_root != root {
            self.view_root = root;
            self.revision.advance();
        }
    }

    /// The node's parent in the current view. A temporary root has no parent.
    pub(crate) fn view_parent(&self, id: NodeId) -> Option<NodeId> {
        if self.view_root == Some(id) {
            None
        } else {
            self.nodes[id].parent
        }
    }

    /// Whether a node belongs to the subtree exposed by the current view.
    pub(crate) fn is_in_view(&self, id: NodeId) -> bool {
        let Some(root) = self.view_root else {
            return true;
        };
        let mut cursor = Some(id);
        while let Some(current) = cursor {
            if current == root {
                return true;
            }
            cursor = self.nodes[current].parent;
        }
        false
    }

    /// True when the node cannot be expanded. Containers are never leaves:
    /// an empty directory is still a directory and `{}`/`[]` are still
    /// containers — they simply open to nothing.
    pub fn is_leaf(&self, id: NodeId) -> bool {
        !self.node(id).is_container
    }

    /// All expandable nodes as `(id, parent)` pairs, in tree order.
    pub fn branches(&self) -> impl Iterator<Item = (NodeId, Option<NodeId>)> + '_ {
        self.nodes
            .iter()
            .enumerate()
            .filter(|(id, _)| !self.is_leaf(*id))
            .map(|(id, node)| (id, node.parent))
    }

    /// Reorder every sibling list (roots included) to put containers first,
    /// keeping the existing relative order within each group.
    pub(crate) fn containers_first(&mut self) {
        let containers_first = |nodes: &[Node], ids: &mut Vec<NodeId>| {
            ids.sort_by_key(|&id| !nodes[id].is_container);
        };
        let mut roots = std::mem::take(&mut self.roots);
        containers_first(&self.nodes, &mut roots);
        self.roots = roots;
        for id in 0..self.nodes.len() {
            let mut children = std::mem::take(&mut self.nodes[id].children);
            containers_first(&self.nodes, &mut children);
            self.nodes[id].children = children;
        }
    }

    /// Reorder one node's children to put containers first (lazy directory
    /// walks sort each sibling list as it materializes).
    pub(crate) fn containers_first_children(&mut self, id: NodeId) {
        let mut children = std::mem::take(&mut self.nodes[id].children);
        children.sort_by_key(|&child| !self.nodes[child].is_container);
        self.nodes[id].children = children;
    }
}

impl TreeModel for Tree {
    type Id = NodeId;

    fn roots(&self) -> impl Iterator<Item = NodeId> + '_ {
        self.roots
            .iter()
            .copied()
            .filter(|_| self.view_root.is_none())
            .chain(self.view_root)
    }

    fn children(&self, id: NodeId) -> TreeChildren<'_, NodeId> {
        let node = &self.nodes[id];
        if node.is_container && node.children.is_empty() {
            // `Unloaded` rather than an empty slice (which the widget
            // normalizes to `Leaf`): a childless container — unwalked,
            // unvalidated, or genuinely empty — must stay a branch.
            TreeChildren::Unloaded
        } else {
            TreeChildren::loaded(&node.children)
        }
    }

    fn revision(&self) -> TreeRevision {
        self.revision
    }

    fn size_hint(&self) -> usize {
        self.nodes.len()
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::ffi::OsStr;

    fn sample() -> (Tree, NodeId, NodeId, NodeId) {
        let mut tree = Tree::new();
        let dir = tree.push(
            None,
            "dir",
            true,
            ActionValues::new("dir", "/abs/dir", "dir"),
        );
        let file = tree.push_with_detail(
            Some(dir),
            "file",
            Some("hint".to_owned()),
            false,
            ActionValues::new("dir/file", "/abs/dir/file", "dir/file")
                .with_alternate_output("file"),
        );
        let leaf = tree.push(
            None,
            "leaf",
            false,
            ActionValues::new("leaf", "/abs/leaf", "leaf"),
        );
        (tree, dir, file, leaf)
    }

    #[test]
    fn accessors_expose_hierarchy_and_display_data() {
        let (tree, dir, file, leaf) = sample();
        assert_eq!(tree.name(dir), "dir");
        assert_eq!(tree.detail(dir), None);
        assert_eq!(tree.detail(file).as_deref(), Some("hint"));
        assert_eq!(tree.parent(dir), None);
        assert_eq!(tree.parent(file), Some(dir));
        assert_eq!(tree.depth(dir), 0);
        assert_eq!(tree.depth(file), 1);
        assert!(tree.is_container(dir));
        assert!(!tree.is_container(leaf));
        assert_eq!(tree.children_of(dir), [file]);
        assert!(tree.children_of(leaf).is_empty());
    }

    #[test]
    fn accessors_expose_action_values() {
        let (tree, _, file, _) = sample();
        assert_eq!(tree.output(file), OsStr::new("dir/file"));
        assert_eq!(tree.alternate_output(file), OsStr::new("file"));
        assert_eq!(tree.path(file), OsStr::new("/abs/dir/file"));
        assert_eq!(tree.relpath(file), OsStr::new("dir/file"));
    }

    #[test]
    fn jump_key_is_the_relpath_text_today() {
        let (tree, dir, file, _) = sample();
        assert_eq!(tree.jump_key(dir), "dir");
        assert_eq!(tree.jump_key(file), "dir/file");
    }

    #[test]
    fn fs_nodes_derive_action_values_from_the_hierarchy() {
        let mut tree = Tree::new_fs("/scan/root".into(), false);
        let dir = tree.push_fs(None, "b-dir", true);
        let file = tree.push_fs(Some(dir), "inner.txt", false);

        assert_eq!(tree.name(file), "inner.txt");
        assert_eq!(tree.detail(file), None);
        assert_eq!(tree.path(dir), OsStr::new("/scan/root/b-dir"));
        assert_eq!(tree.path(file), OsStr::new("/scan/root/b-dir/inner.txt"));
        assert_eq!(tree.relpath(file), OsStr::new("b-dir/inner.txt"));
        assert_eq!(tree.output(file), tree.path(file));
        assert_eq!(tree.alternate_output(file), OsStr::new("inner.txt"));
        assert_eq!(tree.jump_key(file), "b-dir/inner.txt");
        assert!(tree.is_container(dir));
        assert!(!tree.is_container(file));
    }

    #[test]
    fn only_filesystem_backed_nodes_have_a_filesystem_path() {
        let mut tree = Tree::new_fs("/scan/root".into(), false);
        let dir = tree.push_fs(None, "b-dir", true);
        let file = tree.push_fs(Some(dir), "inner.txt", false);
        assert_eq!(
            tree.filesystem_path(file),
            Some(OsString::from("/scan/root/b-dir/inner.txt"))
        );

        let json = crate::json_tree::from_reader(r#"{"a": 1}"#.as_bytes()).unwrap();
        let member = json.root_ids()[0];
        // A JSON node is addressed by pointer, not by a path anything can open.
        assert!(!json.path(member).is_empty());
        assert_eq!(json.filesystem_path(member), None);
    }

    #[test]
    fn containers_first_reorders_every_sibling_list_stably() {
        let mut tree = Tree::new();
        let a = tree.push(None, "a-file", false, ActionValues::new("", "", ""));
        let b = tree.push(None, "b-dir", true, ActionValues::new("", "", ""));
        let c = tree.push(None, "c-file", false, ActionValues::new("", "", ""));
        let d = tree.push(None, "d-dir", true, ActionValues::new("", "", ""));
        let inner_file = tree.push(Some(b), "x-file", false, ActionValues::new("", "", ""));
        let inner_dir = tree.push(Some(b), "y-dir", true, ActionValues::new("", "", ""));

        tree.containers_first();

        assert_eq!(tree.root_ids(), [b, d, a, c]);
        assert_eq!(tree.children_of(b), [inner_dir, inner_file]);
    }
}