refactor: build dep-graph

Build a Snyk dep-graph from a MavenGraph.

Implement graph pruning. Will be unused today as 'mvn dependency:tree'
already hides repeat branches, but if we ever want to move to -Dverbose
and parse larger graphs this will help prune away repeat dependency sub
graphs.

Test describes the modules behaviour.

lib/parse/dep-graph.ts

@@ -0,0 +1,55 @@
+import type { MavenGraph, MavenGraphNode } from './types';
+
+import { DepGraph, DepGraphBuilder, PkgInfo } from '@snyk/dep-graph';
+import { parseDependency } from './dependency';
+
+export function buildDepGraph(mavenGraph: MavenGraph): DepGraph {
+  const { rootId, nodes } = mavenGraph;
+  const root = getPkgInfo(rootId);
+  const builder = new DepGraphBuilder({ name: 'maven' }, root);
+  const visited: string[] = [];
+  const queue: QueueItem[] = [];
+  queue.push(...getItems(rootId, nodes[rootId]));
+
+  // breadth first search
+  while (queue.length > 0) {
+    const item = queue.shift();
+    if (!item) continue;
+    const { id, parentId } = item;
+    const pkgInfo = getPkgInfo(id);
+    if (visited.includes(id)) {
+      const prunedId = id + ':pruned';
+      builder.addPkgNode(pkgInfo, prunedId, { labels: { pruned: 'true' } });
+      builder.connectDep(parentId, prunedId);
+      continue; // don't queue any more children
+    }
+    const parentNodeId = parentId === rootId ? builder.rootNodeId : parentId;
+    builder.addPkgNode(pkgInfo, id);
+    builder.connectDep(parentNodeId, id);
+    queue.push(...getItems(id, nodes[id]));
+    visited.push(id);
+  }
+
+  return builder.build();
+}
+
+interface QueueItem {
+  id: string;
+  parentId: string;
+}
+
+function getItems(parentId: string, node?: MavenGraphNode): QueueItem[] {
+  const items: QueueItem[] = [];
+  for (const id of node?.dependsOn || []) {
+    items.push({ id, parentId });
+  }
+  return items;
+}
+
+function getPkgInfo(value: string): PkgInfo {
+  const { groupId, artifactId, version } = parseDependency(value);
+  return {
+    name: `${groupId}:${artifactId}`,
+    version,
+  };
+}

tests/functional/parse/dep-graph.test.ts

@@ -0,0 +1,144 @@
+import { test } from 'tap';
+import { buildDepGraph } from '../../../lib/parse/dep-graph';
+
+test('buildDepGraph', async (t) => {
+  const depGraph = buildDepGraph({
+    rootId: 'test:root:jar:1.2.3',
+    nodes: {
+      'test:root:jar:1.2.3': {
+        dependsOn: ['test:a:jar:1.0.0', 'test:c:jar:1.0.0', 'test:d:jar:1.0.0'],
+      },
+      'test:a:jar:1.0.0': {
+        dependsOn: ['test:b:jar:1.0.0'],
+      },
+      'test:b:jar:1.0.0': {
+        dependsOn: ['test:a:jar:1.0.0'], // pruned (cyclic)
+      },
+      'test:c:jar:1.0.0': {
+        dependsOn: ['test:d:jar:1.0.0'], // pruned (first seen at top level)
+      },
+      'test:d:jar:1.0.0': {
+        dependsOn: [],
+      },
+    },
+  });
+  t.same(
+    depGraph.toJSON(),
+    {
+      schemaVersion: '1.2.0',
+      pkgManager: {
+        name: 'maven',
+      },
+      pkgs: [
+        {
+          id: 'test:root@1.2.3',
+          info: {
+            name: 'test:root',
+            version: '1.2.3',
+          },
+        },
+        {
+          id: 'test:a@1.0.0',
+          info: {
+            name: 'test:a',
+            version: '1.0.0',
+          },
+        },
+        {
+          id: 'test:c@1.0.0',
+          info: {
+            name: 'test:c',
+            version: '1.0.0',
+          },
+        },
+        {
+          id: 'test:d@1.0.0',
+          info: {
+            name: 'test:d',
+            version: '1.0.0',
+          },
+        },
+        {
+          id: 'test:b@1.0.0',
+          info: {
+            name: 'test:b',
+            version: '1.0.0',
+          },
+        },
+      ],
+      graph: {
+        rootNodeId: 'root-node',
+        nodes: [
+          {
+            nodeId: 'root-node',
+            pkgId: 'test:root@1.2.3',
+            deps: [
+              {
+                nodeId: 'test:a:jar:1.0.0',
+              },
+              {
+                nodeId: 'test:c:jar:1.0.0',
+              },
+              {
+                nodeId: 'test:d:jar:1.0.0',
+              },
+            ],
+          },
+          {
+            nodeId: 'test:a:jar:1.0.0',
+            pkgId: 'test:a@1.0.0',
+            deps: [
+              {
+                nodeId: 'test:b:jar:1.0.0',
+              },
+            ],
+          },
+          {
+            nodeId: 'test:c:jar:1.0.0',
+            pkgId: 'test:c@1.0.0',
+            deps: [
+              {
+                nodeId: 'test:d:jar:1.0.0:pruned',
+              },
+            ],
+          },
+          {
+            nodeId: 'test:d:jar:1.0.0',
+            pkgId: 'test:d@1.0.0',
+            deps: [],
+          },
+          {
+            nodeId: 'test:b:jar:1.0.0',
+            pkgId: 'test:b@1.0.0',
+            deps: [
+              {
+                nodeId: 'test:a:jar:1.0.0:pruned',
+              },
+            ],
+          },
+          {
+            nodeId: 'test:d:jar:1.0.0:pruned',
+            pkgId: 'test:d@1.0.0',
+            deps: [],
+            info: {
+              labels: {
+                pruned: 'true',
+              },
+            },
+          },
+          {
+            nodeId: 'test:a:jar:1.0.0:pruned',
+            pkgId: 'test:a@1.0.0',
+            deps: [],
+            info: {
+              labels: {
+                pruned: 'true',
+              },
+            },
+          },
+        ],
+      },
+    },
+    'contains expected dep-graph',
+  );
+});