implement to_tls_certificate method

src/profile/identity/gemini/identity.rs

@@ -1,4 +1,18 @@
+mod error;
+use error::Error;
+
+use gtk::gio::TlsCertificate;
+
 pub struct Identity {
     pub pem: String,
     // pub scope: String,
 }
+
+impl Identity {
+    pub fn to_tls_certificate(&self) -> Result<TlsCertificate, Error> {
+        match TlsCertificate::from_pem(&self.pem) {
+            Ok(certificate) => Ok(certificate),
+            Err(reason) => Err(Error::TlsCertificate(reason)),
+        }
+    }
+}

src/profile/identity/gemini/identity/error.rs

@@ -0,0 +1,15 @@
+use gtk::glib;
+use std::fmt::{Display, Formatter, Result};
+
+#[derive(Debug)]
+pub enum Error {
+    TlsCertificate(glib::Error),
+}
+
+impl Display for Error {
+    fn fmt(&self, f: &mut Formatter) -> Result {
+        match self {
+            Self::TlsCertificate(e) => write!(f, "TLS certificate error: {e}"),
+        }
+    }
+}