Add authenticate command

Checks if there is a profile to be loaded, if the ssh agent is running
and if there is a Radicle identity stored in the ssh-agent.

src-tauri/src/auth.rs

@@ -0,0 +1,27 @@
+use anyhow::anyhow;
+use radicle::crypto::ssh;
+
+use crate::{error::Error, AppState};
+
+#[tauri::command]
+pub fn authenticate(ctx: tauri::State<AppState>) -> Result<(), Error> {
+    let profile = &ctx.profile;
+
+    if !profile.keystore.is_encrypted()? {
+        return Ok(());
+    }
+    match ssh::agent::Agent::connect() {
+        Ok(mut agent) => {
+            if agent.request_identities()?.contains(&profile.public_key) {
+                return Ok(());
+            } else {
+                Err(Error::WithHint {
+                    err: anyhow!("Not able to find your keys in the ssh agent"),
+                    hint: "Make sure to run <code>rad auth</code> in your terminal to add your keys to the ssh-agent.",
+                })?
+            }
+        }
+        Err(e) if e.is_not_running() => Err(Error::WithHint { err: anyhow!("SSH Agent is not running"), hint: "For now we require the user to have an ssh agent running, since we don't have passphrase inputs yet." })?, 
+        Err(e) => Err(e)?,
+    }
+}

src-tauri/src/lib.rs

@@ -31,6 +31,7 @@ pub fn run() {
         })
         .plugin(tauri_plugin_shell::init())
         .plugin(tauri_plugin_window_state::Builder::default().build())
+        .invoke_handler(tauri::generate_handler![authenticate])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");
 }