graph: Refactor graph item management into new graph_manager object

The graph widgets management (watching a glib receiver, adding and removing
Nodes, Ports and Links) currently done in the `Application` and `GraphView`
objects has been extracted into a new GraphManager object, which watches the
receiver instead, pushes changes directly to the widgets, and reacts to their signals.

This seperates widget logic and management logic cleanly instead of both
being mixed into the GraphView, and also reduces the code size for the
Application object.

src/ui/graph/node.rs

@@ -17,14 +17,15 @@
 use gtk::{glib, prelude::*, subclass::prelude::*};
 use pipewire::spa::Direction;
 
-use std::collections::HashMap;
-
 use super::Port;
 
 mod imp {
     use super::*;
 
-    use std::cell::{Cell, RefCell};
+    use std::{
+        cell::{Cell, RefCell},
+        collections::HashSet,
+    };
 
     #[derive(glib::Properties)]
     #[properties(wrapper_type = super::Node)]
@@ -41,7 +42,7 @@ mod imp {
             }
         )]
         pub(super) label: gtk::Label,
-        pub(super) ports: RefCell<HashMap<u32, Port>>,
+        pub(super) ports: RefCell<HashSet<Port>>,
         pub(super) num_ports_in: Cell<i32>,
         pub(super) num_ports_out: Cell<i32>,
     }
@@ -74,7 +75,7 @@ mod imp {
                 pipewire_id: Cell::new(0),
                 grid,
                 label,
-                ports: RefCell::new(HashMap::new()),
+                ports: RefCell::new(HashSet::new()),
                 num_ports_in: Cell::new(0),
                 num_ports_out: Cell::new(0),
             }
@@ -120,7 +121,7 @@ impl Node {
             .build()
     }
 
-    pub fn add_port(&mut self, id: u32, port: Port) {
+    pub fn add_port(&self, port: Port) {
         let imp = self.imp();
 
         match port.direction() {
@@ -134,22 +135,20 @@ impl Node {
             }
         }
 
-        imp.ports.borrow_mut().insert(id, port);
+        imp.ports.borrow_mut().insert(port);
     }
 
-    pub fn get_port(&self, id: u32) -> Option<Port> {
-        self.imp().ports.borrow_mut().get(&id).cloned()
-    }
-
-    pub fn remove_port(&self, id: u32) {
+    pub fn remove_port(&self, port: &Port) {
         let imp = self.imp();
-        if let Some(port) = imp.ports.borrow_mut().remove(&id) {
+        if imp.ports.borrow_mut().remove(port) {
             match port.direction() {
                 Direction::Input => imp.num_ports_in.set(imp.num_ports_in.get() - 1),
                 Direction::Output => imp.num_ports_in.set(imp.num_ports_out.get() - 1),
             }
 
             port.unparent();
+        } else {
+            log::warn!("Tried to remove non-existant port widget from node");
         }
     }
 }