More work on pathfinding support

lib/cyberarm_engine/pathfinding/graph.rb

@@ -1,14 +1,47 @@
 module CyberarmEngine
   module Pathfinding
     class Graph
-      Location = Data.define(:x, :y, :z, :cost)
+      class Node
+        KEY_FORMAT = "%s:%s:%s".freeze
 
-      def initialize(edges: {})
-        @edges = edges
+        attr_reader :x, :y, :z, :cost, :key, :edge_nodes
+
+        def initialize(x:, y:, z: 0, cost: 0)
+          @x = x
+          @y = y
+          @z = z
+          @cost = cost
+
+          @key = format(KEY_FORMAT, @x, @y, @z)
+
+          @edge_nodes = []
+        end
+
+        def add_edge_node(node)
+          index = @edge_nodes.find_index { |n| n.key == node.key }
+
+          if index
+            @edge_nodes[index] = node
+          else
+            @edge_nodes.push(node)
+          end
+        end
+
+        def remove_edge_node(node)
+          index = @edge_nodes.find_index { |n| n.key == node.key }
+
+          return unless index
+
+          @edge_nodes.delete(index)
+        end
       end
 
-      def neighbors(location)
-        @edges[location]
+      def initialize(nodes: {})
+        @nodes = nodes
+      end
+
+      def neighbors(node)
+        node.edge_nodes
       end
     end
   end