feat(fls): write the topology of a .fls, loaded by Java as the original

topologyWriter.ts writes konfiguration.xml from Java's view of a project:
the version line, the node items (label position, device with name,
host label flags, interfaces or ports), the cable items and the
documentation items. What a device's constructor makes is changed through
getters, as XMLEncoder does, and more is added; fewer than it makes set the
list anew. Cable ends name the port objects the getters return (the writer
now names a getter's result, <void id="Port0" property="port"/>), and each
cable carries the nodes the editor draws it between.

Checked by Java against Java: every corpus file, read and written again,
loads in Java FILIUS (the oracle's loading method, --sha256 ties its result
to the written bytes) to the same devices, names, positions, interfaces,
cables and documentation as the original; so does a synthetic topology with
what the corpus never sets. The oracle and the reader now also report a
cable's drawing ends (JCablePanel ziel1/ziel2): in the corpus the nodes it
joins, for all 183 cables. Mutation probes rewrite the files and let Java
load each mutant.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/fls/test/beans/beans.java.json

@@ -296,6 +296,47 @@
     ],
     "errors": []
   },
+  "references.xml": {
+    "values": [
+      {
+        "id": 0,
+        "class": "java.util.LinkedList",
+        "items": [
+          {
+            "id": 1,
+            "class": "filius.hardware.NetzwerkInterface",
+            "properties": {
+              "dns": {
+                "string": ""
+              },
+              "gateway": {
+                "string": ""
+              },
+              "ip": {
+                "string": "10.0.0.1"
+              },
+              "mac": {
+                "string": "8E:A8:7E:96:38:62"
+              },
+              "port": {
+                "id": 2,
+                "class": "filius.hardware.Port",
+                "properties": {}
+              },
+              "subnetzMaske": {
+                "string": "255.255.255.0"
+              },
+              "wireless": false
+            }
+          },
+          {
+            "ref": 2
+          }
+        ]
+      }
+    ],
+    "errors": []
+  },
   "shared.xml": {
     "values": [
       {

packages/fls/test/beans/references.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<java version="17" class="java.beans.XMLDecoder">
+ <object class="java.util.LinkedList">
+  <void method="add">
+   <object class="filius.hardware.NetzwerkInterface">
+    <void property="ip">
+     <string>10.0.0.1</string>
+    </void>
+    <void id="Port0" property="port"/>
+   </object>
+  </void>
+  <void method="add">
+   <object idref="Port0"/>
+  </void>
+ </object>
+</java>

packages/fls/test/importProject.test.ts

@@ -1044,9 +1044,9 @@ describe('importProject rules', () => {
       topology({
         nodes: [flsNode('Switch', { portCount: 24 }), flsNode('Rechner', { interfaces: [nic('10.0.0.1')] })],
         links: [
-          { ends: [{ node: 0, port: 0 }, { node: 0, port: 1 }], wireless: false },
-          { ends: [{ node: 1, port: 0 }, { node: 0, port: 2 }], wireless: false },
-          { ends: [{ node: 0, port: 3 }, { node: 1, port: 0 }], wireless: false },
+          { ends: [{ node: 0, port: 0 }, { node: 0, port: 1 }], wireless: false, panel: [null, null] },
+          { ends: [{ node: 1, port: 0 }, { node: 0, port: 2 }], wireless: false, panel: [null, null] },
+          { ends: [{ node: 0, port: 3 }, { node: 1, port: 0 }], wireless: false, panel: [null, null] },
         ],
       }),
       counter(),

packages/fls/test/javaBeansWriter.test.ts

@@ -16,6 +16,7 @@ import {
   int,
   long,
   object,
+  reference,
   type BeanObject,
   type BeanValue,
 } from '../src/javaBeansWriter.js';
@@ -42,7 +43,23 @@ const file = object('filius.software.system.Datei', [
   { set: 'dateiInhalt', value: 'a.de. A 3600 1.2.3.4\n' },
 ]);
 
+const port = reference('Port');
+
 const CASES: Record<string, { values: BeanValue[]; expected: unknown[] }> = {
+  references: {
+    values: [
+      object('java.util.LinkedList', [
+        { call: 'add', args: [object('filius.hardware.NetzwerkInterface', [{ set: 'ip', value: '10.0.0.1' }, { get: 'port', statements: [], as: port }])] },
+        { call: 'add', args: [port] },
+      ]),
+    ],
+    expected: [
+      items('java.util.LinkedList', [
+        bean('filius.hardware.NetzwerkInterface', { ip: text('10.0.0.1'), port: { id: 2, class: 'filius.hardware.Port' } }),
+        { ref: 2 },
+      ]),
+    ],
+  },
   strings: {
     values: [list('java.util.LinkedList', STRINGS)],
     expected: [items('java.util.LinkedList', STRINGS.map(text))],

packages/fls/test/topology.test.ts

@@ -190,6 +190,7 @@ function asJavaView(topology: FlsTopology, javaBounds: (number[] | null)[]) {
     cables: topology.links.map((link) => ({
       ends: link.ends.map((end) => [end.node, end.port]),
       wireless: link.wireless,
+      panel: link.panel,
     })),
     documentation: topology.documentation.map((item) => ({
       type: item.type,
@@ -305,7 +306,7 @@ describe('readTopology rules', () => {
       </object>`);
 
     expect(nodes.map((node) => node.javaClass)).toEqual(['Switch']);
-    expect(links).toEqual([{ ends: [{ node: 0, port: 0 }, { node: 0, port: 1 }], wireless: false }]);
+    expect(links).toEqual([{ ends: [{ node: 0, port: 0 }, { node: 0, port: 1 }], wireless: false, panel: [null, null] }]);
     expect(warnings).toEqual([
       'node 1: unknown device class filius.hardware.knoten.Drucker, left out',
       'cable 2: an end is not a port of a device, left out',

packages/fls/test/topologyWriter.test.ts

@@ -0,0 +1,154 @@
+// Every corpus file, read and written again: Java FILIUS loads the written
+// file (tools/java-oracle, written.java.json) to the same topology as the
+// original (corpus.java.json) — devices, names, positions, interfaces,
+// cables and documentation. Java against Java: no mapping of this package
+// stands between the two.
+//
+// UPDATE_WRITTEN=1 writes the files to test/written/ (not checked in); the
+// Java oracle then loads them and records each file's SHA-256, which must
+// match what the writer makes now.
+
+import { createHash } from 'node:crypto';
+import { mkdirSync, readdirSync, readFileSync, statSync, writeFileSync } from 'node:fs';
+import { dirname, join, relative } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { describe, expect, it } from 'vitest';
+import { decodeJavaBeans, readFlsArchive, readTopology, writeFlsArchive } from '../src/index.js';
+import { writeTopologyXml, type TopologyToWrite } from '../src/topologyWriter.js';
+
+const here = dirname(fileURLToPath(import.meta.url));
+const corpusRoot = join(here, '../../../corpus');
+const writtenRoot = join(here, 'written');
+
+function flsFiles(directory: string): string[] {
+  return readdirSync(directory).flatMap((name) => {
+    const path = join(directory, name);
+    if (statSync(path).isDirectory()) return flsFiles(path);
+    return name.endsWith('.fls') ? [path] : [];
+  });
+}
+
+type JavaNode = { class: string; name: string | null; bounds: number[]; useIpAsName: boolean; useMacAsName: boolean; ports: unknown };
+type JavaFile = { success: boolean; nodes: JavaNode[]; cables: unknown[]; documentation: unknown[]; sha256?: string };
+
+const original = JSON.parse(readFileSync(join(corpusRoot, 'corpus.java.json'), 'utf8')) as Record<string, JavaFile>;
+const written = JSON.parse(readFileSync(join(here, 'written.java.json'), 'utf8')) as Record<string, JavaFile>;
+
+/** The topology of Java's view: the label's position, not its size, which Java works out itself. */
+function topologyOf(view: JavaFile) {
+  return {
+    success: view.success,
+    nodes: view.nodes.map((node) => ({
+      class: node.class,
+      name: node.name,
+      position: node.bounds.slice(0, 2),
+      useIpAsName: node.useIpAsName,
+      useMacAsName: node.useMacAsName,
+      ports: node.ports,
+    })),
+    cables: view.cables,
+    documentation: view.documentation,
+  };
+}
+
+describe('the topology written again, as Java loads it', () => {
+  for (const file of flsFiles(corpusRoot)) {
+    const name = relative(corpusRoot, file);
+    it(name, () => {
+      const topology = readTopology(decodeJavaBeans(readFlsArchive(new Uint8Array(readFileSync(file))).configurationXml));
+      const archive = writeFlsArchive(new TextEncoder().encode(writeTopologyXml(topology)));
+      if (process.env.UPDATE_WRITTEN === '1') {
+        mkdirSync(dirname(join(writtenRoot, name)), { recursive: true });
+        writeFileSync(join(writtenRoot, name), archive);
+      }
+      const java = written[name];
+      expect(java?.sha256, 'written.java.json is not about this output: UPDATE_WRITTEN=1, then npm run oracle:java').toBe(
+        createHash('sha256').update(archive).digest('hex'),
+      );
+      expect(topologyOf(java!)).toEqual(topologyOf(original[name]!));
+    });
+  }
+});
+
+/** What the corpus does not have: a name set to null, useMACAsName, fewer ports than the constructor makes, more interfaces. */
+const SYNTHETIC: TopologyToWrite = {
+  nodes: [
+    {
+      javaClass: 'Rechner',
+      name: null,
+      x: 10,
+      y: 20,
+      useIpAsName: false,
+      useMacAsName: true,
+      interfaces: [{ ip: '10.0.0.1', mask: '255.0.0.0', mac: 'AA:BB:CC:DD:EE:01', gateway: null, dns: '10.0.0.53' }],
+      portCount: 1,
+    },
+    { javaClass: 'Switch', name: 'S', x: 100, y: 20, useIpAsName: false, useMacAsName: false, interfaces: [], portCount: 3 },
+    {
+      javaClass: 'Vermittlungsrechner',
+      name: 'R',
+      x: 200,
+      y: 20,
+      useIpAsName: false,
+      useMacAsName: false,
+      interfaces: ['1', '2', '3'].map((octet) => ({
+        ip: `10.0.${octet}.1`,
+        mask: '255.255.255.0',
+        mac: `AA:BB:CC:DD:EE:1${octet}`,
+        gateway: '',
+        dns: '',
+      })),
+      portCount: 3,
+    },
+    { javaClass: 'Modem', name: 'M', x: 300, y: 20, useIpAsName: false, useMacAsName: false, interfaces: [], portCount: 1 },
+  ],
+  links: [
+    { ends: [{ node: 0, port: 0 }, { node: 1, port: 2 }], wireless: false, panel: [0, 1] },
+    { ends: [{ node: 2, port: 2 }, { node: 1, port: 0 }], wireless: true, panel: [2, 1] },
+  ],
+  documentation: [{ type: 1, text: null, x: 5, y: 6, width: 70, height: 80, color: null, font: null }],
+};
+
+describe('a topology beyond the corpus, as Java loads it', () => {
+  it('keeps what the corpus never sets', () => {
+    const name = 'synthetic/synthetic.fls';
+    const archive = writeFlsArchive(new TextEncoder().encode(writeTopologyXml(SYNTHETIC)));
+    if (process.env.UPDATE_WRITTEN === '1') {
+      mkdirSync(join(writtenRoot, 'synthetic'), { recursive: true });
+      writeFileSync(join(writtenRoot, name), archive);
+    }
+    const java = written[name];
+    expect(java?.sha256, 'written.java.json is not about this output: UPDATE_WRITTEN=1, then npm run oracle:java').toBe(
+      createHash('sha256').update(archive).digest('hex'),
+    );
+    const plainInterface = (octet: string) => ({ ip: `10.0.${octet}.1`, mask: '255.255.255.0', mac: `AA:BB:CC:DD:EE:1${octet}`, gateway: '', dns: '' });
+    expect(topologyOf(java!)).toEqual({
+      success: true,
+      nodes: [
+        {
+          class: 'Rechner',
+          name: null,
+          position: [10, 20],
+          useIpAsName: false,
+          useMacAsName: true,
+          ports: [{ ip: '10.0.0.1', mask: '255.0.0.0', mac: 'AA:BB:CC:DD:EE:01', gateway: null, dns: '10.0.0.53' }],
+        },
+        { class: 'Switch', name: 'S', position: [100, 20], useIpAsName: undefined, useMacAsName: undefined, ports: [{}, {}, {}] },
+        {
+          class: 'Vermittlungsrechner',
+          name: 'R',
+          position: [200, 20],
+          useIpAsName: undefined,
+          useMacAsName: undefined,
+          ports: ['1', '2', '3'].map(plainInterface),
+        },
+        { class: 'Modem', name: 'M', position: [300, 20], useIpAsName: undefined, useMacAsName: undefined, ports: [{}] },
+      ],
+      cables: [
+        { ends: [[0, 0], [1, 2]], wireless: false, panel: [0, 1] },
+        { ends: [[2, 2], [1, 0]], wireless: true, panel: [2, 1] },
+      ],
+      documentation: [{ type: 1, text: null, bounds: [5, 6, 70, 80], color: null, font: null }],
+    });
+  });
+});