1 files changed, 850 insertions, 0 deletions

diff --git a/src/depot.rs b/src/depot.rs
new file mode 100644
index 0000000..b2d4e3c
--- /dev/null
+++ b/src/depot.rs
@@ -0,0 +1,850 @@
+use anyhow::Context;
+use std::{
+    collections::HashSet,
+    ffi::{OsStr, OsString},
+    ops::Index,
+    path::{Path, PathBuf},
+};
+use thiserror::Error;
+
+use slotmap::{Key, SlotMap};
+
+//pub type Result<T, E = DepotError> = std::result::Result<T, E>;
+pub use anyhow::Result;
+pub use disk::{read, write};
+
+slotmap::new_key_type! {pub struct LinkID;}
+slotmap::new_key_type! {struct NodeID;}
+
+#[derive(Debug, Error)]
+enum DepotError {
+    #[error("path must be relative")]
+    InvalidPath,
+    #[error("path must be relative and not empty")]
+    InvalidLinkPath,
+}
+
+#[derive(Debug, Clone)]
+struct Node {
+    comp: OsString,
+    parent: NodeID,
+    kind: NodeKind,
+}
+
+#[derive(Debug, Clone)]
+enum NodeKind {
+    Link(LinkID),
+    Directory(HashSet<NodeID>),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+enum NodeSearchResult {
+    Found(NodeID),
+    /// the closest NodeID up the the search point.
+    NotFound(NodeID),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum DirNode {
+    Link(LinkID),
+    Directory(PathBuf),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum SearchResult {
+    Found(LinkID),
+    Ancestor(LinkID),
+    NotFound,
+}
+
+#[derive(Debug, Clone)]
+struct Link {
+    origin: PathBuf,
+    destination: PathBuf,
+    origin_id: NodeID,
+}
+
+#[derive(Debug)]
+pub struct LinkView<'a> {
+    link_id: LinkID,
+    depot: &'a Depot,
+}
+
+impl<'a> LinkView<'a> {
+    pub fn origin(&self) -> &Path {
+        &self.depot.links[self.link_id].origin
+    }
+
+    pub fn destination(&self) -> &Path {
+        &self.depot.links[self.link_id].destination
+    }
+}
+
+#[derive(Debug, Clone)]
+struct DepotTree {
+    root: NodeID,
+    nodes: SlotMap<NodeID, Node>,
+}
+
+impl Default for DepotTree {
+    fn default() -> Self {
+        let mut nodes = SlotMap::<NodeID, Node>::default();
+        let root = nodes.insert(Node {
+            comp: Default::default(),
+            parent: Default::default(),
+            kind: NodeKind::Directory(Default::default()),
+        });
+        Self { root, nodes }
+    }
+}
+
+impl Index<NodeID> for DepotTree {
+    type Output = Node;
+
+    fn index(&self, index: NodeID) -> &Self::Output {
+        self.nodes.index(index)
+    }
+}
+
+impl DepotTree {
+    /// create a node of kind [`NodeKind::Link`].
+    pub fn link_create(&mut self, path: &Path, link_id: LinkID) -> Result<NodeID> {
+        debug_assert!(path_verify_link(path).is_ok());
+
+        let path_search_result = self.search(path);
+
+        // handle the error cases
+        match path_search_result {
+            NodeSearchResult::Found(node_id) => {
+                let node = &self.nodes[node_id];
+                match &node.kind {
+                    NodeKind::Link(_) => Err(anyhow::anyhow!("link already exists")),
+                    NodeKind::Directory(_) => {
+                        Err(anyhow::anyhow!("path already has links under it"))
+                    }
+                }
+            }
+            NodeSearchResult::NotFound(ancestor_node_id) => {
+                let ancestor_node = &self.nodes[ancestor_node_id];
+                match &ancestor_node.kind {
+                    NodeKind::Link(_) => Err(anyhow::anyhow!(
+                        "an ancestor of this path is already linked"
+                    )),
+                    NodeKind::Directory(_) => Ok(()),
+                }
+            }
+        }?;
+
+        // create the node
+        // unwrap: this is a verfied link path, it must have atleast one component
+        let filename = path.file_name().unwrap();
+        let parent_path = path_parent_or_empty(path);
+        let node_id = self.nodes.insert(Node {
+            comp: filename.to_owned(),
+            parent: Default::default(),
+            kind: NodeKind::Link(link_id),
+        });
+        let parent_id = self.directory_get_or_create(parent_path, node_id);
+        self.nodes[node_id].parent = parent_id;
+        Ok(node_id)
+    }
+
+    pub fn link_update_id(&mut self, node_id: NodeID, link_id: LinkID) {
+        let node = &mut self.nodes[node_id];
+        match &mut node.kind {
+            NodeKind::Link(lid) => *lid = link_id,
+            NodeKind::Directory(_) => unreachable!(),
+        }
+    }
+
+    /// attempts to moves a node of kind [`NodeKind::Link`] to `destination`.
+    pub fn link_move(&mut self, node_id: NodeID, destination: &Path) -> Result<()> {
+        let parent_id = self.nodes[node_id].parent;
+        let parent = &mut self.nodes[parent_id];
+
+        // remove the node from its parent temporarily so that the search never returns this
+        // link and that way any link will find means an error.
+        // if an error does happen then we re-add this node to its parent to keep the data
+        // consistent.
+        match &mut parent.kind {
+            NodeKind::Link(_) => unreachable!(),
+            NodeKind::Directory(children) => children.remove(&node_id),
+        };
+
+        let search_result = self.search(destination);
+        // handle the error cases
+        match search_result {
+            NodeSearchResult::Found(found_id) => {
+                assert!(found_id != node_id);
+                self.directory_add_child(parent_id, node_id);
+                return Err(anyhow::anyhow!("link already exists at that path"));
+            }
+            NodeSearchResult::NotFound(ancestor_id) => {
+                let ancestor = &self.nodes[ancestor_id];
+                match &ancestor.kind {
+                    NodeKind::Link(_) => {
+                        self.directory_add_child(parent_id, node_id);
+                        return Err(anyhow::anyhow!("ancestor path is already linked"));
+                    }
+                    NodeKind::Directory(_) => {}
+                }
+            }
+        };
+
+        let destination_parent = path_parent_or_empty(destination);
+        let new_parent_id = self.directory_get_or_create(destination_parent, node_id);
+        if new_parent_id != parent_id {
+            self.nodes[node_id].parent = new_parent_id;
+
+            // we have to re-add and call the remove function because it could lead to the removal
+            // of several directories if they become empty after this remove.
+            self.directory_add_child(parent_id, node_id);
+            self.directory_remove_child(parent_id, node_id);
+        }
+
+        // unwrap: destination is a verified link path so it has atleast 1 component
+        let comp = destination.file_name().unwrap();
+        let node = &mut self.nodes[node_id];
+        if node.comp != comp {
+            node.comp = comp.to_owned();
+        }
+
+        Ok(())
+    }
+
+    pub fn link_search(&self, path: &Path) -> SearchResult {
+        match self.search(path) {
+            NodeSearchResult::Found(node_id) => match &self.nodes[node_id].kind {
+                NodeKind::Link(link_id) => SearchResult::Found(*link_id),
+                NodeKind::Directory(_) => SearchResult::NotFound,
+            },
+            NodeSearchResult::NotFound(node_id) => match &self.nodes[node_id].kind {
+                NodeKind::Link(link_id) => SearchResult::Ancestor(*link_id),
+                NodeKind::Directory(_) => SearchResult::NotFound,
+            },
+        }
+    }
+
+    /// remove a node of kind [`NodeKind::Link`].
+    pub fn link_remove(&mut self, node_id: NodeID) {
+        let node = &self.nodes[node_id];
+        assert!(std::matches!(node.kind, NodeKind::Link(_)));
+        let parent_id = node.parent;
+        self.nodes.remove(node_id);
+        self.directory_remove_child(parent_id, node_id);
+    }
+
+    pub fn links_under(&self, path: &Path) -> impl Iterator<Item = LinkID> + '_ {
+        let links = match self.search(path) {
+            NodeSearchResult::Found(node_id) => {
+                let node = &self.nodes[node_id];
+                match &node.kind {
+                    NodeKind::Link(link_id) => vec![*link_id],
+                    NodeKind::Directory(children) => {
+                        let mut links = Vec::new();
+                        let mut node_ids = Vec::from_iter(children.iter().copied());
+                        while let Some(child_id) = node_ids.pop() {
+                            let child = &self.nodes[child_id];
+                            match &child.kind {
+                                NodeKind::Link(link_id) => links.push(*link_id),
+                                NodeKind::Directory(extra_children) => {
+                                    node_ids.extend(extra_children.iter().copied())
+                                }
+                            }
+                        }
+                        links
+                    }
+                }
+            }
+            NodeSearchResult::NotFound(_) => vec![],
+        };
+        links.into_iter()
+    }
+
+    pub fn has_links_under(&self, path: &Path) -> bool {
+        // it does not matter what type of node is found. if a directory exists then there
+        // must be atleast one link under it.
+        match self.search(path) {
+            NodeSearchResult::Found(_) => true,
+            NodeSearchResult::NotFound(_) => false,
+        }
+    }
+
+    pub fn read_dir(&self, path: &Path) -> Result<impl Iterator<Item = DirNode> + '_> {
+        match self.search(path) {
+            NodeSearchResult::Found(node_id) => match &self.nodes[node_id].kind {
+                NodeKind::Link(_) => Err(anyhow::anyhow!("read dir called on a link")),
+                NodeKind::Directory(children) => Ok(children.iter().map(|child_id| {
+                    let child = &self.nodes[*child_id];
+                    match &child.kind {
+                        NodeKind::Link(link_id) => DirNode::Link(*link_id),
+                        NodeKind::Directory(_) => DirNode::Directory(self.build_path(*child_id)),
+                    }
+                })),
+            },
+            NodeSearchResult::NotFound(_) => Err(anyhow::anyhow!("directory not found")),
+        }
+    }
+
+    pub fn build_path(&self, node_id: NodeID) -> PathBuf {
+        fn recursive_helper(nodes: &SlotMap<NodeID, Node>, nid: NodeID, pbuf: &mut PathBuf) {
+            if nid.is_null() {
+                return;
+            }
+            let parent_id = nodes[nid].parent;
+            recursive_helper(nodes, parent_id, pbuf);
+            pbuf.push(&nodes[nid].comp);
+        }
+
+        let mut node_path = PathBuf::default();
+        recursive_helper(&self.nodes, node_id, &mut node_path);
+        node_path
+    }
+
+    fn search(&self, path: &Path) -> NodeSearchResult {
+        debug_assert!(path_verify(path).is_ok());
+
+        let mut curr_node_id = self.root;
+        let mut comp_iter = path_iter_comps(path).peekable();
+        while let Some(comp) = comp_iter.next() {
+            if let Some(child_id) = self.directory_search_children(curr_node_id, comp) {
+                let child = &self.nodes[child_id];
+                match &child.kind {
+                    NodeKind::Link(_) => {
+                        if comp_iter.peek().is_some() {
+                            return NodeSearchResult::NotFound(child_id);
+                        } else {
+                            return NodeSearchResult::Found(child_id);
+                        }
+                    }
+                    NodeKind::Directory(_) => curr_node_id = child_id,
+                }
+            } else {
+                return NodeSearchResult::NotFound(curr_node_id);
+            }
+        }
+        NodeSearchResult::Found(curr_node_id)
+    }
+
+    // creates directories all the way up to and including path.
+    // there cannot be any links up to `path`.
+    fn directory_get_or_create(&mut self, path: &Path, initial_child: NodeID) -> NodeID {
+        // TODO: this could be replaced if the search function also returned the depth of the
+        // node and we skip those components and just start creating directories up to the
+        // path.
+        let mut curr_node_id = self.root;
+        for comp in path_iter_comps(path) {
+            if let Some(child_id) = self.directory_search_children(curr_node_id, comp) {
+                debug_assert!(std::matches!(
+                    self.nodes[child_id].kind,
+                    NodeKind::Directory(_)
+                ));
+                curr_node_id = child_id;
+            } else {
+                let new_node_id = self.nodes.insert(Node {
+                    comp: comp.to_owned(),
+                    parent: curr_node_id,
+                    kind: NodeKind::Directory(Default::default()),
+                });
+                self.directory_add_child(curr_node_id, new_node_id);
+                curr_node_id = new_node_id;
+            }
+        }
+        self.directory_add_child(curr_node_id, initial_child);
+        curr_node_id
+    }
+
+    fn directory_search_children(&self, node_id: NodeID, comp: &OsStr) -> Option<NodeID> {
+        let node = &self.nodes[node_id];
+        match &node.kind {
+            NodeKind::Link(_) => unreachable!(),
+            NodeKind::Directory(children) => {
+                for &child_id in children {
+                    let child = &self.nodes[child_id];
+                    if child.comp == comp {
+                        return Some(child_id);
+                    }
+                }
+            }
+        }
+        None
+    }
+
+    fn directory_add_child(&mut self, node_id: NodeID, child_id: NodeID) {
+        let node = &mut self.nodes[node_id];
+        match &mut node.kind {
+            NodeKind::Link(_) => unreachable!(),
+            NodeKind::Directory(children) => children.insert(child_id),
+        };
+    }
+
+    fn directory_remove_child(&mut self, node_id: NodeID, child_id: NodeID) {
+        let node = &mut self.nodes[node_id];
+        match &mut node.kind {
+            NodeKind::Link(_) => unreachable!(),
+            NodeKind::Directory(children) => {
+                children.remove(&child_id);
+                if children.is_empty() && !node.parent.is_null() {
+                    let parent_id = node.parent;
+                    self.directory_remove_child(parent_id, node_id);
+                }
+            }
+        }
+    }
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct Depot {
+    links: SlotMap<LinkID, Link>,
+    origin: DepotTree,
+}
+
+impl Depot {
+    pub fn link_create(
+        &mut self,
+        origin: impl AsRef<Path>,
+        destination: impl AsRef<Path>,
+    ) -> Result<LinkID> {
+        let origin = origin.as_ref();
+        let destination = destination.as_ref();
+        path_verify_link(origin)?;
+        path_verify_link(destination)?;
+        self.link_create_unchecked(origin, destination)
+    }
+
+    pub fn link_remove(&mut self, link_id: LinkID) {
+        let node_id = self.links[link_id].origin_id;
+        self.links.remove(link_id);
+        self.origin.link_remove(node_id);
+    }
+
+    /// moves the link specified by `link_id` to the path at `destination`.
+    /// if the link is already at the destination nothing is done.
+    /// if the destination is another link that that link is removed.
+    /// if the destination is under another link then an error is returned.
+    /// `destination` will be the link's new origin.
+    pub fn link_move(&mut self, link_id: LinkID, destination: impl AsRef<Path>) -> Result<()> {
+        let destination = destination.as_ref();
+        path_verify_link(destination)?;
+        self.link_move_unchecked(link_id, destination)
+    }
+
+    #[allow(unused)]
+    pub fn link_search(&self, path: impl AsRef<Path>) -> Result<SearchResult> {
+        let path = path.as_ref();
+        path_verify(path)?;
+        Ok(self.link_search_unchecked(path))
+    }
+
+    pub fn link_find(&self, path: impl AsRef<Path>) -> Result<Option<LinkID>> {
+        let path = path.as_ref();
+        path_verify(path)?;
+        Ok(self.link_find_unchecked(path))
+    }
+
+    pub fn links_under(&self, path: impl AsRef<Path>) -> Result<impl Iterator<Item = LinkID> + '_> {
+        let path = path.as_ref();
+        path_verify(path)?;
+        Ok(self.links_under_unchecked(path))
+    }
+
+    pub fn has_links_under(&self, path: impl AsRef<Path>) -> Result<bool> {
+        let path = path.as_ref();
+        path_verify(path)?;
+        Ok(self.has_links_under_unchecked(path))
+    }
+
+    pub fn links_verify_install(&self, link_ids: impl Iterator<Item = LinkID>) -> Result<()> {
+        let mut destination = DepotTree::default();
+        for link_id in link_ids {
+            let link = &self.links[link_id];
+            destination
+                .link_create(&link.destination, link_id)
+                .context("link destinations overlap")?;
+        }
+        Ok(())
+    }
+
+    pub fn link_view(&self, link_id: LinkID) -> LinkView {
+        LinkView {
+            link_id,
+            depot: self,
+        }
+    }
+
+    pub fn read_dir(&self, path: impl AsRef<Path>) -> Result<impl Iterator<Item = DirNode> + '_> {
+        let path = path.as_ref();
+        path_verify(path)?;
+        self.read_dir_unchecked(path)
+    }
+
+    fn link_create_unchecked(&mut self, origin: &Path, destination: &Path) -> Result<LinkID> {
+        let node_id = self.origin.link_create(origin, Default::default())?;
+        let link_id = self.links.insert(Link {
+            origin: origin.to_owned(),
+            destination: destination.to_owned(),
+            origin_id: node_id,
+        });
+        self.origin.link_update_id(node_id, link_id);
+        Ok(link_id)
+    }
+
+    fn link_move_unchecked(&mut self, link_id: LinkID, destination: &Path) -> Result<()> {
+        let link = &self.links[link_id];
+        if link.origin == destination {
+            return Ok(());
+        }
+        let node_id = link.origin_id;
+        self.origin.link_move(node_id, destination)?;
+        self.links[link_id].origin = destination.to_owned();
+        Ok(())
+    }
+
+    fn link_search_unchecked(&self, path: &Path) -> SearchResult {
+        self.origin.link_search(path)
+    }
+
+    fn link_find_unchecked(&self, path: &Path) -> Option<LinkID> {
+        match self.link_search_unchecked(path) {
+            SearchResult::Found(link_id) => Some(link_id),
+            _ => None,
+        }
+    }
+
+    fn links_under_unchecked(&self, path: &Path) -> impl Iterator<Item = LinkID> + '_ {
+        self.origin.links_under(path)
+    }
+
+    fn has_links_under_unchecked(&self, path: &Path) -> bool {
+        self.origin.has_links_under(path)
+    }
+
+    fn read_dir_unchecked(&self, path: &Path) -> Result<impl Iterator<Item = DirNode> + '_> {
+        self.origin.read_dir(path)
+    }
+}
+
+/// a verified link path is a path that:
+/// + is not empty
+/// + is relative
+/// + does not contain Prefix/RootDir/ParentDir
+fn path_verify_link(path: &Path) -> Result<()> {
+    // make sure the path is not empty
+    if path.components().next().is_none() {
+        return Err(DepotError::InvalidLinkPath.into());
+    }
+    path_verify(path).map_err(|_| DepotError::InvalidLinkPath.into())
+}
+
+/// a verified path is a path that:
+/// + is not empty
+/// + is relative
+/// + does not contain Prefix/RootDir/ParentDir
+fn path_verify(path: &Path) -> Result<()> {
+    // make sure the path is relative
+    // make sure the path does not contain '.' or '..'
+    for component in path.components() {
+        match component {
+            std::path::Component::Prefix(_)
+            | std::path::Component::RootDir
+            | std::path::Component::CurDir
+            | std::path::Component::ParentDir => return Err(DepotError::InvalidPath.into()),
+            std::path::Component::Normal(_) => {}
+        }
+    }
+    Ok(())
+}
+
+fn path_parent_or_empty(path: &Path) -> &Path {
+    path.parent().unwrap_or_else(|| Path::new(""))
+}
+
+/// Iterate over the components of a path.
+/// # Pre
+/// The path can only have "Normal" components.
+fn path_iter_comps(path: &Path) -> impl Iterator<Item = &OsStr> {
+    debug_assert!(path_verify(path).is_ok());
+    path.components().map(|component| match component {
+        std::path::Component::Normal(comp) => comp,
+        _ => unreachable!(),
+    })
+}
+
+mod disk {
+    use std::path::{Path, PathBuf};
+
+    use anyhow::Context;
+    use serde::{Deserialize, Serialize};
+
+    use super::Depot;
+
+    #[derive(Debug, Serialize, Deserialize)]
+    struct DiskLink {
+        origin: PathBuf,
+        destination: PathBuf,
+    }
+
+    #[derive(Debug, Serialize, Deserialize)]
+    struct DiskLinks {
+        links: Vec<DiskLink>,
+    }
+
+    pub fn read(path: &Path) -> anyhow::Result<Depot> {
+        let contents = std::fs::read_to_string(path).context("Failed to read depot file")?;
+        let disk_links = toml::from_str::<DiskLinks>(&contents)
+            .context("Failed to parse depot file")?
+            .links;
+        let mut depot = Depot::default();
+        for disk_link in disk_links {
+            depot
+                .link_create(disk_link.origin, disk_link.destination)
+                .context("Failed to build depot from file. File is in an invalid state")?;
+        }
+        Ok(depot)
+    }
+
+    pub fn write(path: &Path, depot: &Depot) -> anyhow::Result<()> {
+        let mut links = Vec::with_capacity(depot.links.len());
+        for (_, link) in depot.links.iter() {
+            links.push(DiskLink {
+                origin: link.origin.clone(),
+                destination: link.destination.clone(),
+            });
+        }
+        let contents =
+            toml::to_string_pretty(&DiskLinks { links }).context("Failed to serialize depot")?;
+        std::fs::write(path, contents).context("Failed to write depot to file")?;
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_depot_link_create() {
+        let mut depot = Depot::default();
+        let f1 = depot.link_create("f1", "f1").unwrap();
+        let f2 = depot.link_create("f2", "f2").unwrap();
+        let f3 = depot.link_create("d1/f3", "d1/f3").unwrap();
+        let f4 = depot.link_create("d1/d2/f4", "d1/d2/d4").unwrap();
+
+        assert_eq!(depot.link_find("f1").unwrap(), Some(f1));
+        assert_eq!(depot.link_find("f2").unwrap(), Some(f2));
+        assert_eq!(depot.link_find("d1/f3").unwrap(), Some(f3));
+        assert_eq!(depot.link_find("d1/d2/f4").unwrap(), Some(f4));
+
+        depot.link_create("f2", "").unwrap_err();
+        depot.link_create("", "d4").unwrap_err();
+        depot.link_create("f1/f3", "f3").unwrap_err();
+    }
+
+    #[test]
+    fn test_depot_link_remove() {
+        let mut depot = Depot::default();
+        let f1 = depot.link_create("d1/f1", "d1/f1").unwrap();
+        let f2 = depot.link_create("d1/f2", "d1/f2").unwrap();
+        let _f3 = depot.link_create("d1/f3", "d1/f3").unwrap();
+        let f4 = depot.link_create("d1/d2/f4", "d2/f4").unwrap();
+        let d3 = depot.link_create("d3", "d3").unwrap();
+
+        depot.link_remove(f2);
+        assert_eq!(depot.link_find("d1/f1").unwrap(), Some(f1));
+        assert_eq!(depot.link_find("d1/f2").unwrap(), None);
+        depot.link_remove(f4);
+        assert_eq!(depot.link_find("d1/d2/f4").unwrap(), None);
+        depot.link_remove(d3);
+        assert_eq!(depot.link_find("d3").unwrap(), None);
+    }
+
+    #[test]
+    fn test_depot_link_move() {
+        let mut depot = Depot::default();
+        let f1 = depot.link_create("d1/f1", "d1/f1").unwrap();
+        let _f2 = depot.link_create("d1/f2", "d1/f2").unwrap();
+
+        depot.link_move(f1, "").unwrap_err();
+        depot.link_move(f1, "d1/f2/f1").unwrap_err();
+        depot.link_move(f1, "d1/f2").unwrap_err();
+
+        depot.link_move(f1, "f1").unwrap();
+        assert_eq!(depot.link_view(f1).origin(), Path::new("f1"));
+        depot.link_move(f1, "f2").unwrap();
+        assert_eq!(depot.link_view(f1).origin(), Path::new("f2"));
+        assert_eq!(depot.link_find("f2").unwrap(), Some(f1));
+    }
+
+    #[test]
+    fn test_depot_link_search() {
+        let mut depot = Depot::default();
+        let f1 = depot.link_create("d1/f1", "d1/f1").unwrap();
+        let _f2 = depot.link_create("d1/f2", "d1/f2").unwrap();
+        let _f3 = depot.link_create("d1/f3", "d1/f3").unwrap();
+        let _f4 = depot.link_create("d1/d2/f4", "d2/f4").unwrap();
+        let _d3 = depot.link_create("d3", "d3").unwrap();
+
+        assert_eq!(depot.link_search("d1/f1").unwrap(), SearchResult::Found(f1));
+        assert_eq!(
+            depot.link_search("d1/f1/f5").unwrap(),
+            SearchResult::Ancestor(f1)
+        );
+        assert_eq!(depot.link_search("d1").unwrap(), SearchResult::NotFound);
+        assert_eq!(
+            depot.link_search("d1/d2/f5").unwrap(),
+            SearchResult::NotFound
+        );
+    }
+
+    #[test]
+    fn test_depot_link_find() {
+        let mut depot = Depot::default();
+        let f1 = depot.link_create("d1/f1", "d1/f1").unwrap();
+        let _f2 = depot.link_create("d1/f2", "d1/f2").unwrap();
+        let f3 = depot.link_create("d1/f3", "d1/f3").unwrap();
+        let f4 = depot.link_create("d1/d2/f4", "d2/f4").unwrap();
+        let d3 = depot.link_create("d3", "d3").unwrap();
+
+        assert_eq!(depot.link_find("d1/f1").unwrap(), Some(f1));
+        assert_eq!(depot.link_find("d1/f3").unwrap(), Some(f3));
+        assert_eq!(depot.link_find("d1/d2/f4").unwrap(), Some(f4));
+        assert_eq!(depot.link_find("d3").unwrap(), Some(d3));
+
+        assert_eq!(depot.link_find("d5").unwrap(), None);
+        assert_eq!(depot.link_find("d3/d5").unwrap(), None);
+        assert_eq!(depot.link_find("d1/d2/f5").unwrap(), None);
+    }
+
+    #[test]
+    fn test_depot_links_under() {
+        let mut depot = Depot::default();
+        let f1 = depot.link_create("d1/f1", "d1/f1").unwrap();
+        let f2 = depot.link_create("d1/f2", "d1/f2").unwrap();
+        let f3 = depot.link_create("d1/f3", "d1/f3").unwrap();
+        let f4 = depot.link_create("d1/d2/f4", "d2/f4").unwrap();
+        let d3 = depot.link_create("d3", "d3").unwrap();
+
+        let under_f1 = depot.links_under("d1/f1").unwrap().collect::<Vec<_>>();
+        assert_eq!(under_f1, vec![f1]);
+
+        let under_d1 = depot.links_under("d1").unwrap().collect::<Vec<_>>();
+        let expected_under_d1 = vec![f1, f2, f3, f4];
+        assert!(
+            under_d1.len() == expected_under_d1.len()
+                && expected_under_d1.iter().all(|x| under_d1.contains(x))
+        );
+
+        let under_d2 = depot.links_under("d2").unwrap().collect::<Vec<_>>();
+        assert_eq!(under_d2, vec![]);
+
+        let under_d3 = depot.links_under("d3").unwrap().collect::<Vec<_>>();
+        assert_eq!(under_d3, vec![d3]);
+
+        let under_root = depot.links_under("").unwrap().collect::<Vec<_>>();
+        let expected_under_root = vec![f1, f2, f3, f4, d3];
+        assert!(
+            under_root.len() == expected_under_root.len()
+                && expected_under_root.iter().all(|x| under_root.contains(x))
+        );
+    }
+
+    #[test]
+    fn test_depot_has_links_under() {
+        let mut depot = Depot::default();
+        let _f1 = depot.link_create("d1/f1", "d1/f1").unwrap();
+        let _f2 = depot.link_create("d1/f2", "d1/f2").unwrap();
+        let _f3 = depot.link_create("d1/f3", "d1/f3").unwrap();
+        let _f4 = depot.link_create("d1/d2/f4", "d2/f4").unwrap();
+        let _d3 = depot.link_create("d3", "d3").unwrap();
+
+        assert!(depot.has_links_under("").unwrap());
+        assert!(depot.has_links_under("d1").unwrap());
+        assert!(depot.has_links_under("d3").unwrap());
+        assert!(depot.has_links_under("d1/f1").unwrap());
+        assert!(depot.has_links_under("d1/d2").unwrap());
+        assert!(depot.has_links_under("d1/d2/f4").unwrap());
+
+        assert!(!depot.has_links_under("d2").unwrap());
+        assert!(!depot.has_links_under("d4").unwrap());
+        assert!(!depot.has_links_under("d1/d2/f4/f5").unwrap());
+    }
+
+    #[test]
+    fn test_depot_links_verify_install() {
+        let mut depot = Depot::default();
+        let f1 = depot.link_create("nvim", ".config/nvim").unwrap();
+        let f2 = depot.link_create("alacritty", ".config/alacritty").unwrap();
+        let f3 = depot.link_create("bash/.bashrc", ".bashrc").unwrap();
+        let f4 = depot.link_create("bash_laptop/.bashrc", ".bashrc").unwrap();
+
+        depot
+            .links_verify_install(vec![f1, f2, f3].into_iter())
+            .unwrap();
+        depot
+            .links_verify_install(vec![f1, f2, f3, f4].into_iter())
+            .unwrap_err();
+    }
+
+    #[test]
+    fn test_depot_read_dir() {
+        let mut depot = Depot::default();
+        let f1 = depot.link_create("d1/f1", "d1/f1").unwrap();
+        let f2 = depot.link_create("d1/f2", "d1/f2").unwrap();
+        let f3 = depot.link_create("d1/f3", "d1/f3").unwrap();
+        let _f4 = depot.link_create("d1/d2/f4", "d2/f4").unwrap();
+        let _d3 = depot.link_create("d3", "d3").unwrap();
+
+        let read_dir = depot.read_dir("d1").unwrap().collect::<Vec<_>>();
+        let expected_read_dir = vec![
+            DirNode::Link(f1),
+            DirNode::Link(f2),
+            DirNode::Link(f3),
+            DirNode::Directory(PathBuf::from("d1/d2")),
+        ];
+        assert!(
+            read_dir.len() == expected_read_dir.len()
+                && expected_read_dir.iter().all(|x| read_dir.contains(x))
+        );
+    }
+
+    #[test]
+    fn test_path_verify() {
+        path_verify(Path::new("")).unwrap();
+        path_verify(Path::new("f1")).unwrap();
+        path_verify(Path::new("d1/f1")).unwrap();
+        path_verify(Path::new("d1/f1.txt")).unwrap();
+        path_verify(Path::new("d1/./f1.txt")).unwrap();
+
+        path_verify(Path::new("/")).unwrap_err();
+        path_verify(Path::new("./f1")).unwrap_err();
+        path_verify(Path::new("/d1/f1")).unwrap_err();
+        path_verify(Path::new("d1/../f1.txt")).unwrap_err();
+        path_verify(Path::new("/d1/../f1.txt")).unwrap_err();
+    }
+
+    #[test]
+    fn test_path_verify_link() {
+        path_verify_link(Path::new("f1")).unwrap();
+        path_verify_link(Path::new("d1/f1")).unwrap();
+        path_verify_link(Path::new("d1/f1.txt")).unwrap();
+        path_verify_link(Path::new("d1/./f1.txt")).unwrap();
+
+        path_verify_link(Path::new("")).unwrap_err();
+        path_verify_link(Path::new("/")).unwrap_err();
+        path_verify_link(Path::new("./f1")).unwrap_err();
+        path_verify_link(Path::new("/d1/f1")).unwrap_err();
+        path_verify_link(Path::new("d1/../f1.txt")).unwrap_err();
+        path_verify_link(Path::new("/d1/../f1.txt")).unwrap_err();
+    }
+
+    #[test]
+    fn test_path_iter_comps() {
+        let path = Path::new("comp1/comp2/./comp3/file.txt");
+        let mut iter = path_iter_comps(path);
+        assert_eq!(iter.next(), Some(OsStr::new("comp1")));
+        assert_eq!(iter.next(), Some(OsStr::new("comp2")));
+        assert_eq!(iter.next(), Some(OsStr::new("comp3")));
+        assert_eq!(iter.next(), Some(OsStr::new("file.txt")));
+        assert_eq!(iter.next(), None);
+    }
+}