Fix expansion of `~` (#284)

* Fix expansion of `~`, dont use directory relative to cwd.

* Add `expand_tilde`

* Bring back `canonicalize_path`, use `expand_tilde` to `normalize`

* Make `:open ~` completion work

* Fix clippy

* Fold home dir into tilde in Document `realitve_path`

4 files changed, 71 insertions, 16 deletions

diff --git a/helix-core/src/lib.rs b/helix-core/src/lib.rs
index b11faeab..03741719 100644
--- a/helix-core/src/lib.rs
+++ b/helix-core/src/lib.rs
@@ -89,6 +89,8 @@ pub fn cache_dir() -> std::path::PathBuf {
     path
 }
 
+pub use etcetera::home_dir;
+
 use etcetera::base_strategy::{choose_base_strategy, BaseStrategy};
 
 pub use ropey::{Rope, RopeSlice};
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index dc4805a5..b2dd0d11 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -1188,8 +1188,8 @@ mod cmd {
             .filter(|doc| doc.is_modified())
             .map(|doc| {
                 doc.relative_path()
-                    .and_then(|path| path.to_str())
-                    .unwrap_or("[scratch]")
+                    .map(|path| path.to_string_lossy().to_string())
+                    .unwrap_or_else(|| "[scratch]".into())
             })
             .collect();
         if !modified.is_empty() {
@@ -1487,7 +1487,7 @@ fn buffer_picker(cx: &mut Context) {
         cx.editor
             .documents
             .iter()
-            .map(|(id, doc)| (id, doc.relative_path().map(Path::to_path_buf)))
+            .map(|(id, doc)| (id, doc.relative_path()))
             .collect(),
         move |(id, path): &(DocumentId, Option<PathBuf>)| {
             // format_fn
diff --git a/helix-term/src/ui/mod.rs b/helix-term/src/ui/mod.rs
index b2274d06..39e11cd6 100644
--- a/helix-term/src/ui/mod.rs
+++ b/helix-term/src/ui/mod.rs
@@ -126,10 +126,11 @@ pub mod completers {
         use ignore::WalkBuilder;
         use std::path::{Path, PathBuf};
 
-        let path = Path::new(input);
+        let is_tilde = input.starts_with('~') && input.len() == 1;
+        let path = helix_view::document::expand_tilde(Path::new(input));
 
         let (dir, file_name) = if input.ends_with('/') {
-            (path.into(), None)
+            (path, None)
         } else {
             let file_name = path
                 .file_name()
@@ -154,7 +155,16 @@ pub mod completers {
                     let is_dir = entry.file_type().map_or(false, |entry| entry.is_dir());
 
                     let path = entry.path();
-                    let mut path = path.strip_prefix(&dir).unwrap_or(path).to_path_buf();
+                    let mut path = if is_tilde {
+                        // if it's a single tilde an absolute path is displayed so that when `TAB` is pressed on
+                        // one of the directories the tilde will be replaced with a valid path not with a relative
+                        // home directory name.
+                        // ~ -> <TAB> -> /home/user
+                        // ~/ -> <TAB> -> ~/first_entry
+                        path.to_path_buf()
+                    } else {
+                        path.strip_prefix(&dir).unwrap_or(path).to_path_buf()
+                    };
 
                     if is_dir {
                         path.push("");
@@ -184,7 +194,7 @@ pub mod completers {
                 })
                 .collect();
 
-            let range = ((input.len() - file_name.len())..);
+            let range = ((input.len().saturating_sub(file_name.len()))..);
 
             matches.sort_unstable_by_key(|(_file, score)| Reverse(*score));
             files = matches
diff --git a/helix-view/src/document.rs b/helix-view/src/document.rs
index 254e01b0..fe9c87f7 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -127,6 +127,36 @@ where
     }
 }
 
+/// Expands tilde `~` into users home directory if avilable, otherwise returns the path
+/// unchanged. The tilde will only be expanded when present as the first component of the path
+/// and only slash follows it.
+pub fn expand_tilde(path: &Path) -> PathBuf {
+    let mut components = path.components().peekable();
+    if let Some(Component::Normal(c)) = components.peek() {
+        if c == &"~" {
+            if let Ok(home) = helix_core::home_dir() {
+                // it's ok to unwrap, the path starts with `~`
+                return home.join(path.strip_prefix("~").unwrap());
+            }
+        }
+    }
+
+    path.to_path_buf()
+}
+
+/// Replaces users home directory from `path` with tilde `~` if the directory
+/// is available, otherwise returns the path unchanged.
+pub fn fold_home_dir(path: &Path) -> PathBuf {
+    if let Ok(home) = helix_core::home_dir() {
+        if path.starts_with(&home) {
+            // it's ok to unwrap, the path starts with home dir
+            return PathBuf::from("~").join(path.strip_prefix(&home).unwrap());
+        }
+    }
+
+    path.to_path_buf()
+}
+
 /// Normalize a path, removing things like `.` and `..`.
 ///
 /// CAUTION: This does not resolve symlinks (unlike
@@ -137,6 +167,7 @@ where
 /// needs to improve on.
 /// Copied from cargo: https://github.com/rust-lang/cargo/blob/070e459c2d8b79c5b2ac5218064e7603329c92ae/crates/cargo-util/src/paths.rs#L81
 pub fn normalize_path(path: &Path) -> PathBuf {
+    let path = expand_tilde(path);
     let mut components = path.components().peekable();
     let mut ret = if let Some(c @ Component::Prefix(..)) = components.peek().cloned() {
         components.next();
@@ -163,12 +194,17 @@ pub fn normalize_path(path: &Path) -> PathBuf {
     ret
 }
 
-// Returns the canonical, absolute form of a path with all intermediate components normalized.
-//
-// This function is used instead of `std::fs::canonicalize` because we don't want to verify
-// here if the path exists, just normalize it's components.
+/// Returns the canonical, absolute form of a path with all intermediate components normalized.
+///
+/// This function is used instead of `std::fs::canonicalize` because we don't want to verify
+/// here if the path exists, just normalize it's components.
 pub fn canonicalize_path(path: &Path) -> std::io::Result<PathBuf> {
-    std::env::current_dir().map(|current_dir| normalize_path(&current_dir.join(path)))
+    let normalized = normalize_path(path);
+    if normalized.is_absolute() {
+        Ok(normalized)
+    } else {
+        std::env::current_dir().map(|current_dir| current_dir.join(normalized))
+    }
 }
 
 use helix_lsp::lsp;
@@ -709,12 +745,19 @@ impl Document {
         &self.selections[&view_id]
     }
 
-    pub fn relative_path(&self) -> Option<&Path> {
+    pub fn relative_path(&self) -> Option<PathBuf> {
         let cwdir = std::env::current_dir().expect("couldn't determine current directory");
 
-        self.path
-            .as_ref()
-            .map(|path| path.strip_prefix(cwdir).unwrap_or(path))
+        self.path.as_ref().map(|path| {
+            let path = fold_home_dir(path);
+            if path.is_relative() {
+                path
+            } else {
+                path.strip_prefix(cwdir)
+                    .map(|p| p.to_path_buf())
+                    .unwrap_or(path)
+            }
+        })
     }
 
     // pub fn slice<R>(&self, range: R) -> RopeSlice where R: RangeBounds {