Add a simple visualisation using graphviz

snippets/test_diff.py

@@ -1,4 +1,8 @@
 from birdvisu import maps
+from pprint import pprint
+import sys
+import subprocess
+from io import StringIO
 
 with open('current.ospf') as actual:
 	act_topo = maps.Topology.from_ospffile(actual)
@@ -8,6 +12,34 @@ with open('reference.ospf') as reference:
 diff = maps.TopologyDifference(act_topo, ref_topo)
 diff.compare()
 
-from pprint import pprint
+def visualize_graphviz(diff):
+	graph = StringIO()
+	
+	# Prologue
+	graph.write('strict graph "OSPF Visualization" {\n')
+
+	for r, n, m in set(diff.reference.links + diff.actual.links):
+		graph.write(f'"{r}" -- "{n}" [label="{m}"];\n')
+	for r in diff.routers_missing | diff.networks_missing:
+		graph.write(f'"{r}" [color=red];\n')
+	for r in diff.routers_extra | diff.networks_extra:
+		graph.write(f'"{r}" [color=green];\n')
+	for r, n, _ in diff.links_missing:
+		graph.write(f'"{r}" -- "{n}" [color=red];\n')
+	for r, n, _ in diff.links_extra:
+		graph.write(f'"{r}" -- "{n}" [color=green];\n')
+	
+
+
+	# Epilogue:
+	graph.write('}\n')
+	
+	# Show:
+	gv = subprocess.Popen(['dot', '-Tgtk', '-Kfdp'], text=True, stdin=subprocess.PIPE)
+	gv.communicate(graph.getvalue())
+	gv.wait()
 
-pprint(vars(diff))
+if len(sys.argv) == 1:
+	pprint(vars(diff))
+elif 'dot' in sys.argv:
+	visualize_graphviz(diff)