1 files changed, 997 insertions, 0 deletions

diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..e2a659b
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,997 @@
+#![feature(try_blocks)]
+pub mod depot {
+    use std::{
+        collections::HashSet,
+        ffi::{OsStr, OsString},
+        ops::Deref,
+        path::{Path, PathBuf},
+    };
+
+    use slotmap::SlotMap;
+
+    pub use disk::{read, write};
+
+    slotmap::new_key_type! {pub struct LinkID;}
+    slotmap::new_key_type! {struct NodeID;}
+
+    #[derive(Debug, Clone, PartialEq, Eq)]
+    pub enum SearchResult {
+        Found(LinkID),
+        Ancestor(LinkID),
+        NotFound,
+    }
+
+    #[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
+        }
+    }
+
+    // wrapper for a path under the depot
+    // this path is relative and does not contain `..` or similar
+    // Deref(Path)
+    struct DepotPath(PathBuf);
+    impl Deref for DepotPath {
+        type Target = Path;
+
+        fn deref(&self) -> &Self::Target {
+            self.0.deref()
+        }
+    }
+
+    #[derive(Debug, Clone)]
+    struct Node {
+        comp: OsString,
+        parent: NodeID,
+        kind: NodeKind,
+    }
+
+    #[derive(Debug, Clone)]
+    enum NodeKind {
+        Link(LinkID),
+        Directory(HashSet<NodeID>),
+    }
+
+    #[derive(Debug, Clone)]
+    struct Link {
+        origin: PathBuf,
+        destination: PathBuf,
+        node_id: NodeID,
+    }
+
+    #[derive(Debug, Clone)]
+    pub struct Depot {
+        links: SlotMap<LinkID, Link>,
+        nodes: SlotMap<NodeID, Node>,
+        root: NodeID,
+    }
+
+    impl Default for Depot {
+        fn default() -> Self {
+            let mut nodes = SlotMap::default();
+            let root = nodes.insert(Node {
+                comp: Default::default(),
+                parent: Default::default(),
+                kind: NodeKind::Directory(Default::default()),
+            });
+            Self {
+                links: Default::default(),
+                nodes,
+                root,
+            }
+        }
+    }
+
+    impl Depot {
+        pub fn create(
+            &mut self,
+            origin: impl AsRef<Path>,
+            destination: impl AsRef<Path>,
+        ) -> anyhow::Result<LinkID> {
+            let origin = origin.as_ref();
+            let destination = destination.as_ref();
+            verify_path(origin)?;
+            verify_path(destination)?;
+
+            // example
+            // origin = fish/config.fish
+            // destination = .config/fish/config.fish
+
+            // search
+            // if ancestor - return error
+            // if found - update destination
+            // if not found - create
+
+            match self.search_unchecked(&origin) {
+                SearchResult::Found(link_id) => {
+                    let link = &mut self.links[link_id];
+                    link.destination = destination.to_owned();
+                    Ok(link_id)
+                }
+                SearchResult::Ancestor(_) => Err(anyhow::anyhow!(
+                    "An ancestor of this path is already linked"
+                )),
+                SearchResult::NotFound => {
+                    let link_id = self.links.insert(Link {
+                        origin: origin.to_owned(),
+                        destination: destination.to_owned(),
+                        node_id: Default::default(),
+                    });
+                    let node_id = self.node_create_link(origin, link_id);
+                    self.links[link_id].node_id = node_id;
+                    Ok(link_id)
+                }
+            }
+        }
+
+        pub fn move_link(
+            &mut self,
+            link_id: LinkID,
+            destination: impl AsRef<Path>,
+        ) -> anyhow::Result<()> {
+            let destination = destination.as_ref();
+            verify_path(destination)?;
+
+            let link_node_id = self.links[link_id].node_id;
+            let link_parent_node_id = self.nodes[link_node_id].parent;
+            let (node_id, found) = self.node_search(destination);
+
+            // the link is already at the destination
+            if found && node_id == link_node_id {
+                return Ok(());
+            }
+
+            if found {
+                let node = &self.nodes[node_id];
+                match &node.kind {
+                    NodeKind::Link(node_link_id) => {
+                        let node_parent_id = node.parent;
+                        let node_link_id = *node_link_id;
+                        assert_ne!(link_id, node_link_id);
+                        self.remove(node_link_id);
+                        self.node_child_remove(link_parent_node_id, link_node_id);
+                        self.node_child_add(node_parent_id, link_node_id);
+                        self.node_set_parent(link_node_id, node_parent_id);
+                        Ok(())
+                    }
+                    NodeKind::Directory(..) => Err(anyhow::anyhow!(
+                        "Cannot move link, other links exist under the destination"
+                    )),
+                }
+            } else {
+                let node = &self.nodes[node_id];
+                match &node.kind {
+                    NodeKind::Link(..) => Err(anyhow::anyhow!(
+                        "Cannot move link, an ancestor is already linked"
+                    )),
+                    NodeKind::Directory(_) => {
+                        let new_node_id = self.node_create_link(destination, link_id);
+                        self.node_remove(link_node_id);
+                        self.links[link_id].node_id = new_node_id;
+                        Ok(())
+                    }
+                }
+            }
+        }
+
+        pub fn remove(&mut self, link_id: LinkID) {
+            let node_id = self.links[link_id].node_id;
+            self.node_remove(node_id);
+            self.links.remove(link_id);
+        }
+
+        pub fn link_view(&self, link_id: LinkID) -> LinkView {
+            LinkView {
+                link_id,
+                depot: self,
+            }
+        }
+
+        /// searchs for the link at `origin`.
+        /// returns SearchResult::Found(..) if there is a link at `origin`.
+        /// returns SearchResult::Ancestor(..) if an ancestor of `origin` is linked.
+        /// returns SearchResult::NotFound otherwise.
+        pub fn search(&self, origin: impl AsRef<Path>) -> anyhow::Result<SearchResult> {
+            let origin = origin.as_ref();
+            verify_path(origin)?;
+            Ok(self.search_unchecked(&origin))
+        }
+
+        /// returns an iterator for all the links at or under the given path.
+        pub fn links_under(
+            &self,
+            path: impl AsRef<Path>,
+        ) -> anyhow::Result<impl Iterator<Item = LinkID> + '_> {
+            let path = path.as_ref();
+            verify_path(path)?;
+
+            let mut link_ids = Vec::new();
+            if let Some(node_id) = self.node_find(path) {
+                let mut node_ids = vec![node_id];
+                while let Some(node_id) = node_ids.pop() {
+                    let node = &self.nodes[node_id];
+                    match &node.kind {
+                        NodeKind::Link(link_id) => link_ids.push(*link_id),
+                        NodeKind::Directory(children) => node_ids.extend(children.iter().copied()),
+                    }
+                }
+            }
+            Ok(link_ids.into_iter())
+        }
+
+        /// returns true if the `path` is a link or contains an ancestor that is linked.
+        /// returns false otherwise.
+        pub fn is_linked(&self, path: impl AsRef<Path>) -> bool {
+            match self.search(path) {
+                Ok(SearchResult::Found(..)) | Ok(SearchResult::Ancestor(..)) => true,
+                _ => false,
+            }
+        }
+
+        fn search_unchecked(&self, origin: &Path) -> SearchResult {
+            debug_assert!(verify_path(origin).is_ok());
+
+            let mut origin_comps = iter_path_comps(&origin);
+            let mut curr_node = self.root;
+            'outer: loop {
+                let node = &self.nodes[curr_node];
+                let curr_comp = origin_comps.next();
+                match &node.kind {
+                    NodeKind::Link(link_id) => match curr_comp {
+                        Some(_) => break SearchResult::Ancestor(*link_id),
+                        None => break SearchResult::Found(*link_id),
+                    },
+                    NodeKind::Directory(children) => match curr_comp {
+                        Some(curr_comp) => {
+                            for &child_id in children.iter() {
+                                let child = &self.nodes[child_id];
+                                if &child.comp == curr_comp {
+                                    curr_node = child_id;
+                                    continue 'outer;
+                                }
+                            }
+                            break SearchResult::NotFound;
+                        }
+                        None => break SearchResult::NotFound,
+                    },
+                }
+            }
+        }
+
+        /// creates a new directory node with no children.
+        /// the node specified by `parent` must be a directory node.
+        fn node_create_dir_empty(&mut self, parent: NodeID, comp: OsString) -> NodeID {
+            let node_id = self.nodes.insert(Node {
+                comp,
+                parent,
+                kind: NodeKind::Directory(Default::default()),
+            });
+            self.node_child_add(parent, node_id);
+            node_id
+        }
+
+        /// all the nodes up to the node to be created have to be directory nodes.
+        /// `path` must be a verified path.
+        fn node_create_link(&mut self, path: &Path, link_id: LinkID) -> NodeID {
+            assert!(verify_path(path).is_ok());
+            let mut curr_node_id = self.root;
+            let mut path_comps = iter_path_comps(path).peekable();
+            // unwrap: a verified path has atleast 1 component
+            let mut curr_path_comp = path_comps.next().unwrap();
+
+            while path_comps.peek().is_some() {
+                let next_node = match self.node_children_search(curr_node_id, curr_path_comp) {
+                    Some(child_id) => child_id,
+                    None => self.node_create_dir_empty(curr_node_id, curr_path_comp.to_owned()),
+                };
+                curr_node_id = next_node;
+                // unwrap: we known next is Some beacause of this loop's condition
+                curr_path_comp = path_comps.next().unwrap();
+            }
+
+            let new_node = self.nodes.insert(Node {
+                comp: curr_path_comp.to_owned(),
+                parent: curr_node_id,
+                kind: NodeKind::Link(link_id),
+            });
+            self.node_child_add(curr_node_id, new_node);
+            new_node
+        }
+
+        /// finds the node at the given path.
+        /// `path` must be a verified path.
+        fn node_find(&self, path: &Path) -> Option<NodeID> {
+            match self.node_search(path) {
+                (node_id, true) => Some(node_id),
+                _ => None,
+            }
+        }
+
+        /// searches for the node at `path`. if that node does not exists then it returns the
+        /// closest node. return (closest_node, found)
+        fn node_search(&self, path: &Path) -> (NodeID, bool) {
+            debug_assert!(verify_path(path).is_ok());
+
+            let mut origin_comps = iter_path_comps(&path).peekable();
+            let mut curr_node = self.root;
+            'outer: loop {
+                let node = &self.nodes[curr_node];
+                match origin_comps.next() {
+                    Some(curr_comp) => match &node.kind {
+                        NodeKind::Link(..) => break (curr_node, false),
+                        NodeKind::Directory(children) => {
+                            for &child_id in children.iter() {
+                                let child = &self.nodes[child_id];
+                                if &child.comp == curr_comp {
+                                    curr_node = child_id;
+                                    continue 'outer;
+                                }
+                            }
+                            break (curr_node, false);
+                        }
+                    },
+                    None => break (curr_node, true),
+                }
+            }
+        }
+
+        /// adds `new_child` to `node_id`'s children.
+        /// the node specified by `node_id` must be a directory node.
+        fn node_child_add(&mut self, node_id: NodeID, new_child: NodeID) {
+            let node = &mut self.nodes[node_id];
+            match node.kind {
+                NodeKind::Directory(ref mut children) => {
+                    children.insert(new_child);
+                }
+                _ => unreachable!(),
+            }
+        }
+
+        /// searchs for a child with the given comp and returns its id.
+        /// the node specified by `node_id` must be a directory node.
+        fn node_children_search(&self, node_id: NodeID, search_comp: &OsStr) -> Option<NodeID> {
+            let child_ids = match &self.nodes[node_id].kind {
+                NodeKind::Directory(c) => c,
+                _ => unreachable!(),
+            };
+            for &child_id in child_ids {
+                let child = &self.nodes[child_id];
+                if child.comp == search_comp {
+                    return Some(child_id);
+                }
+            }
+            None
+        }
+
+        /// removes `child` from `node_id`'s children.
+        /// the node specified by `node_id` must be a directory node and it must contain the node
+        /// `child`.
+        fn node_child_remove(&mut self, node_id: NodeID, child: NodeID) {
+            let node = &mut self.nodes[node_id];
+            let remove_node = match &mut node.kind {
+                NodeKind::Directory(children) => {
+                    let contained = children.remove(&child);
+                    assert!(contained);
+                    children.is_empty()
+                }
+                _ => unreachable!(),
+            };
+            if remove_node && node_id != self.root {
+                self.node_remove(node_id);
+            }
+        }
+
+        fn node_set_parent(&mut self, node_id: NodeID, parent: NodeID) {
+            self.nodes[node_id].parent = parent;
+        }
+
+        fn node_remove(&mut self, node_id: NodeID) {
+            debug_assert!(node_id != self.root);
+            debug_assert!(self.nodes.contains_key(node_id));
+
+            let node = self.nodes.remove(node_id).unwrap();
+            match node.kind {
+                NodeKind::Link(..) => {}
+                NodeKind::Directory(children) => {
+                    // Right now directory nodes are only removed from inside this function and
+                    // we do not remove directories with children
+                    assert!(children.is_empty());
+                }
+            }
+            let parent_id = node.parent;
+            self.node_child_remove(parent_id, node_id);
+        }
+    }
+
+    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
+                    .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(())
+        }
+    }
+
+    fn verify_path(path: &Path) -> anyhow::Result<()> {
+        // make sure the path is not empty
+        // make sure the path is relative
+        // make sure the path does not contain '.' or '..'
+        if path.components().next().is_none() {
+            return Err(anyhow::anyhow!("Path cannot be empty"));
+        }
+        for component in path.components() {
+            match component {
+                std::path::Component::Prefix(_) => {
+                    return Err(anyhow::anyhow!("Path cannot have prefix"))
+                }
+                std::path::Component::RootDir => {
+                    return Err(anyhow::anyhow!("Path must be relative"))
+                }
+                std::path::Component::CurDir | std::path::Component::ParentDir => {
+                    return Err(anyhow::anyhow!("Path cannot contain '.' or '..'"))
+                }
+                std::path::Component::Normal(_) => {}
+            }
+        }
+        Ok(())
+    }
+
+    /// Iterate over the components of a path.
+    /// # Pre
+    /// The path can only have "Normal" components.
+    fn iter_path_comps(path: &Path) -> impl Iterator<Item = &OsStr> {
+        debug_assert!(verify_path(path).is_ok());
+        path.components().map(|component| match component {
+            std::path::Component::Normal(comp) => comp,
+            _ => unreachable!(),
+        })
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        #[test]
+        fn test_depot_create() {
+            let mut depot = Depot::default();
+            depot.create("", "dest1.txt").unwrap_err();
+            depot.create("comp1.txt", "").unwrap_err();
+            depot.create("", "").unwrap_err();
+
+            depot.create("comp1.txt", "dest1.txt").unwrap();
+            depot.create("comp1.txt", "dest1_updated.txt").unwrap();
+            depot
+                .create("./comp1.txt", "dest1_updated.txt")
+                .unwrap_err();
+            depot.create("/comp1.txt", "dest1.txt").unwrap_err();
+            depot.create("dir1/", "destdir1/").unwrap();
+            depot.create("dir1/file1.txt", "destfile1.txt").unwrap_err();
+        }
+
+        #[test]
+        fn test_depot_move_link() {
+            let mut depot = Depot::default();
+            let f1 = depot.create("d1/f1", "d1/f1").unwrap();
+            let _f2 = depot.create("d1/f2", "d1/f2").unwrap();
+
+            depot.move_link(f1, "d1/f2/f1").unwrap_err();
+            depot.move_link(f1, "d1").unwrap_err();
+
+            depot.move_link(f1, "").unwrap();
+            depot.move_link(f1, "d2/f1").unwrap();
+        }
+
+        #[test]
+        fn test_depot_remove() {
+            let mut depot = Depot::default();
+            let f1 = depot.create("d1/f1", "d1/f1").unwrap();
+            assert_eq!(depot.search("d1/f1").unwrap(), SearchResult::Found(f1));
+            depot.remove(f1);
+            assert_eq!(depot.search("d1/f1").unwrap(), SearchResult::NotFound);
+        }
+
+        #[test]
+        fn test_depot_search() {
+            let mut depot = Depot::default();
+            let f1 = depot.create("d1/f1", "d1/f1").unwrap();
+            let f2 = depot.create("d1/f2", "d1/f2").unwrap();
+            let f3 = depot.create("d1/f3", "d1/f3").unwrap();
+            let f4 = depot.create("d1/d2/f4", "d2/f4").unwrap();
+            let d3 = depot.create("d3", "d3").unwrap();
+
+            assert_eq!(depot.search("d1").unwrap(), SearchResult::NotFound,);
+            assert_eq!(depot.search("d1/f1").unwrap(), SearchResult::Found(f1),);
+            assert_eq!(depot.search("d1/f2").unwrap(), SearchResult::Found(f2),);
+            assert_eq!(depot.search("d1/f3").unwrap(), SearchResult::Found(f3),);
+            assert_eq!(depot.search("d1/d2/f4").unwrap(), SearchResult::Found(f4),);
+            assert_eq!(depot.search("d1/d2/f5").unwrap(), SearchResult::NotFound,);
+            assert_eq!(depot.search("d3/f6").unwrap(), SearchResult::Ancestor(d3),);
+        }
+
+        #[test]
+        fn test_iter_path_comps() {
+            let path = Path::new("comp1/comp2/./comp3/file.txt");
+            let mut iter = iter_path_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);
+        }
+    }
+}
+
+mod dotup {
+    use std::{
+        collections::HashSet,
+        path::{Path, PathBuf},
+    };
+
+    use anyhow::Context;
+
+    use crate::depot::{self, Depot, LinkID};
+
+    #[derive(Debug)]
+    struct CanonicalPair {
+        link_id: LinkID,
+        origin: PathBuf,
+        destination: PathBuf,
+    }
+
+    #[derive(Debug)]
+    pub struct Dotup {
+        depot: Depot,
+        depot_dir: PathBuf,
+        depot_path: PathBuf,
+        install_base: PathBuf,
+    }
+
+    impl Dotup {
+        fn new(depot: Depot, depot_path: PathBuf, install_base: PathBuf) -> anyhow::Result<Self> {
+            assert!(depot_path.is_absolute());
+            assert!(depot_path.is_file());
+            assert!(install_base.is_absolute());
+            assert!(install_base.is_dir());
+            let depot_dir = {
+                let mut d = depot_path.clone();
+                d.pop();
+                d
+            };
+            Ok(Self {
+                depot,
+                depot_dir,
+                depot_path,
+                install_base,
+            })
+        }
+
+        pub fn link(&mut self, origin: impl AsRef<Path>, destination: impl AsRef<Path>) {
+            let link_result: anyhow::Result<()> = try {
+                let origin = self.prepare_origin_path(origin.as_ref())?;
+                let destination = destination.as_ref();
+                self.depot.create(origin, destination)?;
+            };
+            match link_result {
+                Ok(_) => {}
+                Err(e) => println!("Failed to create link : {e}"),
+            }
+        }
+
+        pub fn unlink(&mut self, paths: impl Iterator<Item = impl AsRef<Path>>) {
+            for origin in paths {
+                let unlink_result: anyhow::Result<()> = try {
+                    let origin = self.prepare_origin_path(origin.as_ref())?;
+                    let search_results = self.depot.search(&origin)?;
+                    match search_results {
+                        depot::SearchResult::Found(link_id) => {
+                            self.depot.remove(link_id);
+                            println!("removed link {}", origin.display());
+                        }
+                        depot::SearchResult::Ancestor(_) | depot::SearchResult::NotFound => {
+                            println!("{} is not linked", origin.display())
+                        }
+                    }
+                };
+                match unlink_result {
+                    Ok(_) => {}
+                    Err(e) => println!("Failed to unlink {} : {e}", origin.as_ref().display()),
+                }
+            }
+        }
+
+        pub fn install(&self, paths: impl Iterator<Item = impl AsRef<Path>>) {
+            let mut already_linked: HashSet<LinkID> = Default::default();
+            for origin in paths {
+                let install_result: anyhow::Result<()> = try {
+                    let origin = self.prepare_origin_path(origin.as_ref())?;
+                    let canonical_pairs = self.canonical_pairs_under(&origin)?;
+                    for pair in canonical_pairs {
+                        if already_linked.contains(&pair.link_id) {
+                            continue;
+                        }
+                        self.install_symlink(&pair.origin, &pair.destination)?;
+                        already_linked.insert(pair.link_id);
+                    }
+                };
+                if let Err(e) = install_result {
+                    println!("error while installing {} : {e}", origin.as_ref().display());
+                }
+            }
+        }
+
+        pub fn uninstall(&self, paths: impl Iterator<Item = impl AsRef<Path>>) {
+            for origin in paths {
+                let uninstall_result: anyhow::Result<()> = try {
+                    let origin = self.prepare_origin_path(origin.as_ref())?;
+                    let canonical_pairs = self.canonical_pairs_under(&origin)?;
+                    for pair in canonical_pairs {
+                        self.uninstall_symlink(&pair.origin, &pair.destination)?;
+                    }
+                };
+                if let Err(e) = uninstall_result {
+                    println!(
+                        "error while uninstalling {} : {e}",
+                        origin.as_ref().display()
+                    );
+                }
+            }
+        }
+
+        pub fn mv(&mut self, from: impl Iterator<Item = impl AsRef<Path>>, to: impl AsRef<Path>) {
+            let to = to.as_ref();
+            let from: Vec<_> = from.map(|p| p.as_ref().to_owned()).collect();
+            match from.as_slice() {
+                [] => unreachable!(),
+                [from] => self.mv_one(from, to),
+                [from @ ..] => self.mv_many(from, to),
+            }
+        }
+
+        fn mv_one(&mut self, from: &Path, to: &Path) {}
+
+        fn mv_many(&mut self, from: &[PathBuf], to: &Path) {}
+
+        fn prepare_origin_path(&self, origin: &Path) -> anyhow::Result<PathBuf> {
+            let canonical = origin
+                .canonicalize()
+                .context("Failed to canonicalize origin path")?;
+            let relative = canonical
+                .strip_prefix(&self.depot_dir)
+                .context("Invalid origin path, not under depot directory")?;
+            Ok(relative.to_owned())
+        }
+
+        // returns the canonical pairs (origin, destination) for all links under `path`.
+        fn canonical_pairs_under(&self, path: &Path) -> anyhow::Result<Vec<CanonicalPair>> {
+            let origin = self.prepare_origin_path(path)?;
+            let mut paths = Vec::new();
+            for link_id in self.depot.links_under(origin)? {
+                let link_view = self.depot.link_view(link_id);
+                let relative_origin = link_view.origin();
+                let relative_destination = link_view.destination();
+                let canonical_origin = self.depot_dir.join(relative_origin);
+                let canonical_destination = self.install_base.join(relative_destination);
+                paths.push(CanonicalPair {
+                    link_id,
+                    origin: canonical_origin,
+                    destination: canonical_destination,
+                });
+            }
+            Ok(paths)
+        }
+
+        fn install_symlink(&self, origin: &Path, destination: &Path) -> anyhow::Result<()> {
+            debug_assert!(origin.is_absolute());
+            debug_assert!(destination.is_absolute());
+
+            if let Some(destination_parent) = destination.parent() {
+                std::fs::create_dir_all(destination_parent)
+                    .context("Failed to create directories")?;
+            }
+
+            let destination_exists = destination.exists();
+            let destination_is_symlink = destination.is_symlink();
+
+            if destination_exists && !destination_is_symlink {
+                return Err(anyhow::anyhow!("destination already exists"));
+            }
+
+            if destination_is_symlink {
+                std::fs::remove_file(&destination)?;
+            }
+            std::os::unix::fs::symlink(origin, destination).context("Failed to create symlink")?;
+
+            Ok(())
+        }
+
+        fn uninstall_symlink(&self, origin: &Path, destination: &Path) -> anyhow::Result<()> {
+            debug_assert!(origin.is_absolute());
+            debug_assert!(destination.is_absolute());
+
+            if destination.is_symlink() {
+                let symlink_destination = destination.read_link()?.canonicalize()?;
+                if symlink_destination == origin {
+                    std::fs::remove_file(&destination)?;
+                }
+            }
+
+            Ok(())
+        }
+    }
+
+    pub fn read(depot_path: PathBuf, install_base: PathBuf) -> anyhow::Result<Dotup> {
+        let depot_path = depot_path
+            .canonicalize()
+            .context("Failed to canonicalize depot path")?;
+        let install_base = install_base
+            .canonicalize()
+            .context("Failed to canonicalize install base")?;
+        if !install_base.is_dir() {
+            return Err(anyhow::anyhow!("Install base must be a directory"));
+        }
+        let depot = depot::read(&depot_path)?;
+        Dotup::new(depot, depot_path, install_base)
+    }
+
+    pub fn write(dotup: &Dotup) -> anyhow::Result<()> {
+        depot::write(&dotup.depot_path, &dotup.depot)?;
+        Ok(())
+    }
+}
+
+mod utils {
+    use std::path::PathBuf;
+
+    use crate::{
+        depot::{self, Depot},
+        dotup::{self, Dotup},
+        Flags,
+    };
+
+    pub const DEFAULT_DEPOT_FILE_NAME: &str = ".depot";
+
+    pub fn read_dotup(flags: &Flags) -> anyhow::Result<Dotup> {
+        let depot_path = depot_path_from_flags(flags)?;
+        let install_base = install_base_from_flags(flags);
+        dotup::read(depot_path, install_base)
+    }
+
+    pub fn write_dotup(dotup: &Dotup) -> anyhow::Result<()> {
+        dotup::write(dotup)
+    }
+
+    pub fn read_depot(flags: &Flags) -> anyhow::Result<Depot> {
+        let depot_path = depot_path_from_flags(flags)?;
+        let depot = depot::read(&depot_path)?;
+        Ok(depot)
+    }
+
+    pub fn write_depot(flags: &Flags, depot: &Depot) -> anyhow::Result<()> {
+        let depot_path = depot_path_from_flags(flags)?;
+        depot::write(&depot_path, depot)?;
+        Ok(())
+    }
+
+    pub fn depot_path_from_flags(flags: &Flags) -> anyhow::Result<PathBuf> {
+        match flags.depot {
+            Some(ref path) => Ok(path.clone()),
+            None => find_depot_path().ok_or_else(|| anyhow::anyhow!("Failed to find depot path")),
+        }
+    }
+
+    pub fn default_depot_path() -> PathBuf {
+        current_working_directory().join(DEFAULT_DEPOT_FILE_NAME)
+    }
+
+    pub fn find_depot_path() -> Option<PathBuf> {
+        let mut cwd = current_working_directory();
+        loop {
+            let path = cwd.join(DEFAULT_DEPOT_FILE_NAME);
+            if path.exists() {
+                break Some(path);
+            }
+            if !cwd.pop() {
+                break None;
+            }
+        }
+    }
+
+    pub fn install_base_from_flags(flags: &Flags) -> PathBuf {
+        match flags.install_base {
+            Some(ref path) => path.clone(),
+            None => default_install_base(),
+        }
+    }
+
+    pub fn default_install_base() -> PathBuf {
+        PathBuf::from(std::env::var("HOME").expect("Failed to obtain HOME environment variable"))
+    }
+
+    fn current_working_directory() -> PathBuf {
+        std::env::current_dir().expect("Failed to obtain current working directory")
+    }
+}
+
+use std::path::PathBuf;
+
+use clap::Parser;
+use utils::DEFAULT_DEPOT_FILE_NAME;
+
+#[derive(Parser, Debug)]
+pub struct Flags {
+    #[clap(long)]
+    depot: Option<PathBuf>,
+    #[clap(long)]
+    install_base: Option<PathBuf>,
+}
+
+#[derive(Parser, Debug)]
+#[clap(author, version, about, long_about = None)]
+struct Args {
+    #[clap(flatten)]
+    flags: Flags,
+    #[clap(subcommand)]
+    command: SubCommand,
+}
+
+#[derive(Parser, Debug)]
+enum SubCommand {
+    Init(InitArgs),
+    Link(LinkArgs),
+    Unlink(UnlinkArgs),
+    Install(InstallArgs),
+    Uninstall(UninstallArgs),
+    Mv(MvArgs),
+}
+
+fn main() -> anyhow::Result<()> {
+    let args = Args::parse();
+    match args.command {
+        SubCommand::Init(cmd_args) => command_init(args.flags, cmd_args),
+        SubCommand::Link(cmd_args) => command_link(args.flags, cmd_args),
+        SubCommand::Unlink(cmd_args) => command_unlink(args.flags, cmd_args),
+        SubCommand::Install(cmd_args) => command_install(args.flags, cmd_args),
+        SubCommand::Uninstall(cmd_args) => command_uninstall(args.flags, cmd_args),
+        SubCommand::Mv(cmd_args) => command_mv(args.flags, cmd_args),
+    }
+}
+
+#[derive(Parser, Debug)]
+struct InitArgs {
+    path: Option<PathBuf>,
+}
+
+fn command_init(_global_flags: Flags, args: InitArgs) -> anyhow::Result<()> {
+    let depot_path = {
+        let mut path = args.path.unwrap_or_else(utils::default_depot_path);
+        if path.is_dir() {
+            path = path.join(DEFAULT_DEPOT_FILE_NAME);
+        }
+        path
+    };
+
+    if depot_path.exists() {
+        println!("Depot at {} already exists", depot_path.display());
+    } else {
+        depot::write(&depot_path, &Default::default())?;
+        println!("Depot initialized at {}", depot_path.display());
+    }
+
+    Ok(())
+}
+
+#[derive(Parser, Debug)]
+struct LinkArgs {
+    origin: PathBuf,
+    destination: PathBuf,
+}
+
+fn command_link(global_flags: Flags, args: LinkArgs) -> anyhow::Result<()> {
+    let mut dotup = utils::read_dotup(&global_flags)?;
+    dotup.link(args.origin, args.destination);
+    utils::write_dotup(&dotup)?;
+    Ok(())
+}
+
+#[derive(Parser, Debug)]
+struct UnlinkArgs {
+    paths: Vec<PathBuf>,
+}
+
+fn command_unlink(global_flags: Flags, args: UnlinkArgs) -> anyhow::Result<()> {
+    let mut dotup = utils::read_dotup(&global_flags)?;
+    dotup.unlink(args.paths.into_iter());
+    utils::write_dotup(&dotup)?;
+    Ok(())
+}
+
+#[derive(Parser, Debug)]
+struct InstallArgs {
+    paths: Vec<PathBuf>,
+}
+
+fn command_install(global_flags: Flags, args: InstallArgs) -> anyhow::Result<()> {
+    let dotup = utils::read_dotup(&global_flags)?;
+    dotup.install(args.paths.into_iter());
+    utils::write_dotup(&dotup)?;
+    Ok(())
+}
+
+#[derive(Parser, Debug)]
+struct UninstallArgs {
+    paths: Vec<PathBuf>,
+}
+
+fn command_uninstall(global_flags: Flags, args: UninstallArgs) -> anyhow::Result<()> {
+    let dotup = utils::read_dotup(&global_flags)?;
+    dotup.uninstall(args.paths.into_iter());
+    utils::write_dotup(&dotup)?;
+    Ok(())
+}
+
+#[derive(Parser, Debug)]
+struct MvArgs {
+    paths: Vec<PathBuf>,
+}
+
+fn command_mv(global_flags: Flags, args: MvArgs) -> anyhow::Result<()> {
+    let mut dotup = utils::read_dotup(&global_flags)?;
+    let mut paths = args.paths;
+    if paths.len() < 2 {
+        return Err(anyhow::anyhow!("mv requires atleast 2 arguments"));
+    }
+    let to = paths.pop().unwrap();
+    let from = paths;
+    dotup.mv(from.iter(), &to);
+    utils::write_dotup(&dotup)?;
+    Ok(())
+}