Src, move out of ./rust, add missing wip files

Moves file contents out of ./rust since I'm planning to go with rust for
the backend and the lexicons will be used for codegen soon anyways.

I also added extra files that have been in the works that I have been
accidentally sprinkling into main.rs already. God forbid I need to
cherry-pick anything from so far back in the history.

It will make git blame ugly though.

src/atproto.rs

@@ -0,0 +1,70 @@
+use atrium_api::types::string::{
+  AtIdentifier,
+  RecordKey,
+};
+use regex::Regex;
+
+pub use atrium_api::types::string::{
+  Nsid,
+  Did,
+  Handle,
+};
+
+enum Authority {
+  Did(Did),
+  Handle(Handle),
+}
+
+impl Authority {
+  pub fn new(authority: String) -> Result<Self, &'static str> {
+  }
+}
+
+// This implementation does not support Query or Fragments, and thus follows
+// the following schema: "at://" AUTHORITY [ "/" COLLECTION [ "/" RKEY ] ]
+pub struct Uri {
+  authority: Authority,
+  collection: Option<Nsid>,
+  rkey: Option<RecordKey>,
+}
+
+// TODO: Replace super basic URI regex with real uri parsing
+const URI_REGEX: Regex = Regex::new(
+    r"/^at:\/\/([\w\.\-_~:]+)(?:\/([\w\.\-_~:]+)(?:)\/([\w\.\-_~:]+))?$/i"
+  ).expect("valid regex");
+
+impl Uri {
+  pub fn new(uri: String) -> Result<Self, &'static str> {
+    let Some(captures) = URI_REGEX.captures(&uri) else {
+      return Err("Invalid Uri");
+    };
+    // TODO: Convert authority if its a did or a handle
+    let Some(Ok(authority)) = captures.get(1).map(|mtch| {
+      Authority::new(mtch.as_str().to_string())
+    }) else {
+      return Err("Invalid Authority")
+    };
+    let collection = captures.get(2).map(|mtch| {
+      Nsid::new(mtch.as_str().to_string())
+    });
+    let rkey = captures.get(3).map(|mtch| {
+      RecordKey::new(mtch.as_str().to_string())
+    });
+    Ok(Uri { authority, collection, rkey })
+  }
+
+  pub fn as_string(&self) -> String {
+    let mut uri = String::from("at://");
+    uri.push_str(match &self.authority {
+      Authority::Handle(h) => &*h,
+      Authority::Did(d) => &*d,
+    });
+    if let Some(nsid) = &self.collection {
+      uri.push_str(&*nsid);
+    }
+    if let Some(rkey) = &self.rkey {
+      uri.push_str(&*rkey);
+    }
+    uri
+  }
+}