Adding ~user tilde recognition in file paths (#5251)

* Added search terms to math commands

* Attempts to add ~user.

From: // Extend this to work with "~user" style of home paths

* Clippy recommendation

* clippy suggestions, again.

* fixing non-compilation on windows and macos

* fmt apparently does not like my imports

* even more clippy issues.

* less expect(), single conversion, match. Should work for MacOS too.

* Attempted to add functionality for windows: all it does is take the home path of current user, and replace the username.

* silly mistake in Windows version of user_home_dir()

* Update tilde.rs

* user_home_dir now returns a path instead of a string - should be smoother with no conversions to string

* clippy warnings

* clippy warnings 2

* Changed user_home_dir to return PathBuf now.

* Changed user_home_dir to return PathBuf now.

* forgot to fmt

* fixed windows build errors from modifying pathbuf but not returning it

* fixed windows clippy errors from returning () instead of pathbuf

* forgot to fmt

* borrowed path did not live long enough.

* previously, path.push did not work because rest_of_path started with "/" - it was not relative. Removing the / makes it a relative path again.

* Issue fixed.

* Update tilde.rs

* fmt.

* There is now a zero chance of panic. All expect()s have been removed.

crates/nu-path/Cargo.toml

@@ -9,3 +9,6 @@ version = "0.61.1"
 [dependencies]
 dirs-next = "2.0.0"
 dunce = "1.0.1"
+
+[target.'cfg(target_os = "linux")'.dependencies]
+pwd = "1.3.1"

crates/nu-path/src/tilde.rs

@@ -1,10 +1,17 @@
+#[cfg(target_os = "linux")]
+use pwd::Passwd;
 use std::path::{Path, PathBuf};
 
 fn expand_tilde_with_home(path: impl AsRef<Path>, home: Option<PathBuf>) -> PathBuf {
     let path = path.as_ref();
 
     if !path.starts_with("~") {
-        return path.into();
+        let string = path.to_string_lossy();
+        let mut path_as_string = string.as_ref().chars();
+        return match path_as_string.next() {
+            Some('~') => expand_tilde_with_another_user_home(path),
+            _ => path.into(),
+        };
     }
 
     match home {
@@ -31,6 +38,104 @@ fn expand_tilde_with_home(path: impl AsRef<Path>, home: Option<PathBuf>) -> Path
     }
 }
 
+#[cfg(target_os = "linux")]
+fn user_home_dir(username: &str) -> PathBuf {
+    let passwd = Passwd::from_name(username);
+    match &passwd.ok() {
+        Some(Some(dir)) => PathBuf::from(&dir.dir),
+        _ => {
+            let mut file = String::from("/home/");
+            file.push_str(username);
+            PathBuf::from(file)
+        }
+    }
+    // PathBuf::from(concat!("/home/", username)),
+    // Returns home dir of user.
+}
+
+#[cfg(target_os = "macos")]
+fn user_home_dir(username: &str) -> PathBuf {
+    match dirs_next::home_dir() {
+        None => {
+            let mut expected_path = String::from("/Users/");
+            expected_path.push_str(username);
+            let path = Path::new(&expected_path);
+            let mut home = PathBuf::new();
+            home.push(path);
+            home
+        }
+        Some(user) => {
+            let mut expected_path = user;
+            expected_path.pop();
+            expected_path.push(Path::new(username));
+            if expected_path.is_dir() {
+                expected_path
+            } else {
+                let mut expected_path_as_string = String::from("/Users/");
+                expected_path_as_string.push_str(username);
+                let path = Path::new(&expected_path_as_string);
+                let mut home = PathBuf::new();
+                home.push(path);
+                home
+            }
+        }
+    }
+}
+
+#[cfg(target_os = "windows")]
+fn user_home_dir(username: &str) -> PathBuf {
+    match dirs_next::home_dir() {
+        None => {
+            let mut expected_path = String::from("C:\\Users\\");
+            expected_path.push_str(username);
+            let path = Path::new(&expected_path);
+            let mut home = PathBuf::new();
+            home.push(path);
+            home
+        }
+        Some(user) => {
+            let mut expected_path = user;
+            expected_path.pop();
+            expected_path.push(Path::new(username));
+            if expected_path.is_dir() {
+                expected_path
+            } else {
+                let mut expected_path_as_string = String::from("C:\\Users\\");
+                expected_path_as_string.push_str(username);
+                let path = Path::new(&expected_path_as_string);
+                let mut home = PathBuf::new();
+                home.push(path);
+                home
+            }
+        }
+    }
+}
+
+fn expand_tilde_with_another_user_home(path: &Path) -> PathBuf {
+    return match path.to_str() {
+        Some(file_path) => {
+            let mut file = file_path.to_string();
+            match file_path.chars().position(|c| c == '/' || c == '\\') {
+                None => {
+                    file.remove(0);
+                    user_home_dir(&file)
+                }
+                Some(i) => {
+                    let (pre_name, rest_of_path) = file.split_at(i);
+                    let mut name = pre_name.to_string();
+                    let mut rest_path = rest_of_path.to_string();
+                    rest_path.remove(0);
+                    name.remove(0);
+                    let mut path = user_home_dir(&name);
+                    path.push(Path::new(&rest_path));
+                    path
+                }
+            }
+        }
+        None => path.to_path_buf(),
+    };
+}
+
 /// Expand tilde ("~") into a home directory if it is the first path component
 pub fn expand_tilde(path: impl AsRef<Path>) -> PathBuf {
     // TODO: Extend this to work with "~user" style of home paths