1 files changed, 147 insertions, 0 deletions
diff --git a/crates/atuin-common/src/shell.rs b/crates/atuin-common/src/shell.rs
new file mode 100644
index 00000000..42e32f72
--- /dev/null
+++ b/crates/atuin-common/src/shell.rs
@@ -0,0 +1,147 @@
+use std::{ffi::OsStr, path::Path, process::Command};
+
+use serde::Serialize;
+use sysinfo::{get_current_pid, Process, System};
+use thiserror::Error;
+
+pub enum Shell {
+    Sh,
+    Bash,
+    Fish,
+    Zsh,
+    Xonsh,
+    Nu,
+
+    Unknown,
+}
+
+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,
+
+    #[error("failed to execute shell command: {0}")]
+    ExecError(String),
+}
+
+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");
+
+        let parent = sys
+            .process(process.parent().expect("Atuin running with no parent!"))
+            .expect("Process with parent pid does not exist");
+
+        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,
+        }
+    }
+
+    /// 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 {
+    let sys = System::new_all();
+
+    let parent = if let Some(parent) = parent {
+        parent
+    } else {
+        let process = sys
+            .process(get_current_pid().expect("Failed to get current PID"))
+            .expect("Process with current pid does not exist");
+
+        sys.process(process.parent().expect("Atuin running with no parent!"))
+            .expect("Process with parent pid does not exist")
+    };
+
+    let shell = parent.name().trim().to_lowercase();
+    let shell = shell.strip_prefix('-').unwrap_or(&shell);
+
+    shell.to_string()
+}