1 files changed, 94 insertions, 13 deletions

diff --git a/atuin-common/src/shell.rs b/atuin-common/src/shell.rs
index 2c0f3534..42e32f72 100644
--- a/atuin-common/src/shell.rs
+++ b/atuin-common/src/shell.rs
@@ -1,3 +1,6 @@
+use std::{ffi::OsStr, path::Path, process::Command};
+
+use serde::Serialize;
 use sysinfo::{get_current_pid, Process, System};
 use thiserror::Error;
 
@@ -12,7 +15,24 @@ pub enum Shell {
     Unknown,
 }
 
-#[derive(Debug, Error)]
+impl std::fmt::Display for Shell {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let shell = match self {
+            Shell::Bash => "bash",
+            Shell::Fish => "fish",
+            Shell::Zsh => "zsh",
+            Shell::Nu => "nu",
+            Shell::Xonsh => "xonsh",
+            Shell::Sh => "sh",
+
+            Shell::Unknown => "unknown",
+        };
+
+        write!(f, "{}", shell)
+    }
+}
+
+#[derive(Debug, Error, Serialize)]
 pub enum ShellError {
     #[error("shell not supported")]
     NotSupported,
@@ -21,28 +41,89 @@ pub enum ShellError {
     ExecError(String),
 }
 
-pub fn shell() -> Shell {
-    let name = shell_name(None);
+impl Shell {
+    pub fn current() -> Shell {
+        let sys = System::new_all();
+
+        let process = sys
+            .process(get_current_pid().expect("Failed to get current PID"))
+            .expect("Process with current pid does not exist");
 
-    match name.as_str() {
-        "bash" => Shell::Bash,
-        "fish" => Shell::Fish,
-        "zsh" => Shell::Zsh,
-        "xonsh" => Shell::Xonsh,
-        "nu" => Shell::Nu,
-        "sh" => Shell::Sh,
+        let parent = sys
+            .process(process.parent().expect("Atuin running with no parent!"))
+            .expect("Process with parent pid does not exist");
 
-        _ => Shell::Unknown,
+        let shell = parent.name().trim().to_lowercase();
+        let shell = shell.strip_prefix('-').unwrap_or(&shell);
+
+        Shell::from_string(shell.to_string())
+    }
+
+    /// Best-effort attempt to determine the default shell
+    /// This implementation will be different across different platforms
+    /// Caller should ensure to handle Shell::Unknown correctly
+    pub fn default_shell() -> Result<Shell, ShellError> {
+        let sys = System::name().unwrap_or("".to_string()).to_lowercase();
+
+        // TODO: Support Linux
+        // I'm pretty sure we can use /etc/passwd there, though there will probably be some issues
+        if sys.contains("darwin") {
+            // This works in my testing so far
+            let path = Shell::Sh.run_interactive([
+                "dscl localhost -read \"/Local/Default/Users/$USER\" shell | awk '{print $2}'",
+            ])?;
+
+            let path = Path::new(path.trim());
+
+            let shell = path.file_name();
+
+            if shell.is_none() {
+                return Err(ShellError::NotSupported);
+            }
+
+            Ok(Shell::from_string(
+                shell.unwrap().to_string_lossy().to_string(),
+            ))
+        } else {
+            Err(ShellError::NotSupported)
+        }
+    }
+
+    pub fn from_string(name: String) -> Shell {
+        match name.as_str() {
+            "bash" => Shell::Bash,
+            "fish" => Shell::Fish,
+            "zsh" => Shell::Zsh,
+            "xonsh" => Shell::Xonsh,
+            "nu" => Shell::Nu,
+            "sh" => Shell::Sh,
+
+            _ => Shell::Unknown,
+        }
     }
-}
 
-impl Shell {
     /// Returns true if the shell is posix-like
     /// Note that while fish is not posix compliant, it behaves well enough for our current
     /// featureset that this does not matter.
     pub fn is_posixish(&self) -> bool {
         matches!(self, Shell::Bash | Shell::Fish | Shell::Zsh)
     }
+
+    pub fn run_interactive<I, S>(&self, args: I) -> Result<String, ShellError>
+    where
+        I: IntoIterator<Item = S>,
+        S: AsRef<OsStr>,
+    {
+        let shell = self.to_string();
+
+        let output = Command::new(shell)
+            .arg("-ic")
+            .args(args)
+            .output()
+            .map_err(|e| ShellError::ExecError(e.to_string()))?;
+
+        Ok(String::from_utf8(output.stdout).unwrap())
+    }
 }
 
 pub fn shell_name(parent: Option<&Process>) -> String {