disconnect existing incoming connection when connecting another and refuse duplicate connections (#22)

fixes #17

Reviewed-on: https://codeberg.org/Eroax/StreamGraph/pulls/22
Co-authored-by: Lera Elvoé <yagich@poto.cafe>
Co-committed-by: Lera Elvoé <yagich@poto.cafe>

classes/deck/deck.gd

@@ -42,6 +42,8 @@ var emit_node_added_signal: bool = true
 signal node_added(node: DeckNode)
 ## Emitted when a node has been removed from this deck.
 signal node_removed(node: DeckNode)
+## Emitted when nodes have been disconnected
+signal nodes_disconnected(from_node_id: String, to_node_id: String, from_output_port: int, to_input_port: int)
 
 #region group signals
 signal node_added_to_group(node: DeckNode, assign_id: String, assign_to_self: bool, deck: Deck)
@@ -124,7 +126,17 @@ func connect_nodes(from_node_id: String, to_node_id: String, from_output_port: i
 		)
 		return false
 
-	# TODO: prevent duplicate connections
+	# refuse duplicate connections
+	if from_node.has_outgoing_connection_exact(from_output_port, to_node_id, to_input_port):
+		print("no duplicates")
+		return false
+
+	if to_node.has_incoming_connection(to_input_port):
+		var connection: Dictionary = to_node.incoming_connections[to_input_port]
+		var node_id: String = connection.keys()[0]
+		var node_out_port: int = connection.values()[0]
+		disconnect_nodes(node_id, to_node_id, node_out_port, to_input_port)
+
 
 	if is_group && emit_group_signals:
 		nodes_connected_in_group.emit(from_node_id, to_node_id, from_output_port, to_input_port, self)
@@ -141,6 +153,8 @@ func disconnect_nodes(from_node_id: String, to_node_id: String, from_output_port
 	to_node.remove_incoming_connection(to_input_port)
 	if is_group && emit_group_signals:
 		nodes_disconnected_in_group.emit(from_node_id, to_node_id, from_output_port, to_input_port, self)
+	
+	nodes_disconnected.emit(from_node_id, to_node_id, from_output_port, to_input_port)
 
 
 ## Returns true if this deck has no nodes and no variables.

classes/deck/deck_node.gd

@@ -202,6 +202,27 @@ func remove_incoming_connection(to_port: int) -> void:
 	incoming_connection_removed.emit(to_port)
 
 
+## Returns [code]true[/code] if the exact connection from this node exists.
+func has_outgoing_connection_exact(from_port: int, to_node: String, to_port: int) -> bool:
+	if !outgoing_connections.has(from_port):
+		return false
+	
+	var connection: Dictionary = outgoing_connections[from_port]
+	if !connection.has(to_node):
+		return false
+	
+	var connections_to_node: Array = connection[to_node]
+	if !(to_port in connections_to_node):
+		return false
+	
+	return true
+
+
+## Returns [code]true[/code] if the node has an incoming connection at input port [param on_port].
+func has_incoming_connection(on_port: int) -> bool:
+	return incoming_connections.has(on_port)
+
+
 func rename(new_name: String) -> void:
 	name = new_name
 	renamed.emit(new_name)

graph_node_renderer/deck_renderer_graph_edit.gd

@@ -29,6 +29,7 @@ var deck: Deck:
 		deck = v
 		deck.node_added.connect(_on_deck_node_added)
 		deck.node_removed.connect(_on_deck_node_removed)
+		deck.nodes_disconnected.connect(_on_deck_nodes_disconnected)
 
 ## Emits when Group creation is requested.  Ex. Hitting the "group_nodes" Hotkey.
 signal group_enter_requested(group_id: String)
@@ -125,7 +126,6 @@ func initialize_from_deck() -> void:
 		i.queue_free()
 
 	scroll_offset = deck.get_meta("offset", Vector2())
-
 	is_group = deck.is_group
 	for node_id in deck.nodes:
 		var node_renderer: DeckNodeRendererGraphNode = NODE_SCENE.instantiate()
@@ -263,6 +263,21 @@ func _on_add_node_menu_node_selected(type: String) -> void:
 	search_popup_panel.hide()
 
 
+func _on_deck_nodes_disconnected(from_node_id: String, to_node_id: String, from_output_port: int, to_input_port: int) -> void:
+	print("1")
+	var from_node: DeckNodeRendererGraphNode = get_children().filter(
+		func(x: DeckNodeRendererGraphNode):
+			return x.node._id == from_node_id
+	)[0]
+	var to_node: DeckNodeRendererGraphNode = get_children().filter(
+		func(x: DeckNodeRendererGraphNode):
+			return x.node._id == to_node_id
+	)[0]
+	
+	print(is_node_connected(from_node.name, from_output_port, to_node.name, to_input_port))
+	disconnect_node(from_node.name, from_output_port, to_node.name, to_input_port)
+
+
 func _on_delete_nodes_request(nodes: Array[StringName]) -> void:
 	var node_ids := nodes.map(
 		func(n: StringName):