feat: add local repository scanning (#8)

Reviewed-on: https://git.reya.su/reya/signed/pulls/8

crates/signed_core/src/addr.rs

@@ -2,12 +2,38 @@ use nostr::prelude::*;
 
 /// Address of a NIP-34 repository announcement: `30617:<owner-pubkey>:<repo-id>`.
 ///
-/// The Rust Nostr SDK's [`Coordinate`] already provides parsing, formatting
-/// and hashing for this; the alias keeps the repository-specific vocabulary
-/// while reusing the SDK type.
+/// The Rust Nostr SDK's [`Coordinate`] already provides parsing, formatting and hashing for this.
+/// The alias keeps the repository-specific vocabulary while reusing the SDK type.
 pub type RepoAddr = Coordinate;
 
 /// Build the address of a NIP-34 repository announcement.
 pub fn repo_addr(owner: PublicKey, id: impl Into<String>) -> RepoAddr {
     Coordinate::new(Kind::GitRepoAnnouncement, owner).identifier(id)
 }
+
+/// Derive a repository identifier from a display name
+pub fn identifier_from_name(name: &str) -> String {
+    name.chars()
+        .map(|c| {
+            if c.is_ascii_alphanumeric() || c == '/' {
+                c
+            } else {
+                '-'
+            }
+        })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn identifier_from_name_slugs_like_gitworkshop() {
+        assert_eq!(identifier_from_name("My Repo"), "My-Repo");
+        assert_eq!(identifier_from_name("my-repo"), "my-repo");
+        assert_eq!(identifier_from_name("Foo_Bar!"), "Foo-Bar-");
+        assert_eq!(identifier_from_name("a/b"), "a/b");
+        assert_eq!(identifier_from_name("Café"), "Caf-");
+    }
+}