From 79bc82828ff1e1ff0ce9c855d8a1a48caeb46555 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Tue, 13 Dec 2022 23:23:11 +0100
Subject: [PATCH] cli: add ability to analyze lockfile changes when listing
 changed packages

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 packages/cli/src/lib/monorepo/PackageGraph.ts | 70 ++++++++++++++++++-
 1 file changed, 68 insertions(+), 2 deletions(-)

diff --git a/packages/cli/src/lib/monorepo/PackageGraph.ts b/packages/cli/src/lib/monorepo/PackageGraph.ts
index c65f5c003c..8aa7fc9416 100644
--- a/packages/cli/src/lib/monorepo/PackageGraph.ts
+++ b/packages/cli/src/lib/monorepo/PackageGraph.ts
@@ -18,7 +18,8 @@ import path from 'path';
 import { getPackages, Package } from '@manypkg/get-packages';
 import { paths } from '../paths';
 import { PackageRole } from '../role';
-import { listChangedFiles } from '../git';
+import { listChangedFiles, readFileAtRef } from '../git';
+import { Lockfile } from '../versioning';
 
 type PackageJSON = Package['packageJson'];
 
@@ -191,7 +192,10 @@ export class PackageGraph extends Map<string, PackageGraphNode> {
     return targets;
   }
 
-  async listChangedPackages(options: { ref: string }) {
+  async listChangedPackages(options: {
+    ref: string;
+    analyzeLockfile?: boolean;
+  }) {
     const changedFiles = await listChangedFiles(options.ref);
 
     const dirMap = new Map(
@@ -234,6 +238,68 @@ export class PackageGraph extends Map<string, PackageGraphNode> {
       }
     }
 
+    if (changedFiles.includes('yarn.lock') && options.analyzeLockfile) {
+      // Load the lockfile in the working tree and the one at the ref and diff them
+      const thisLockfile = await Lockfile.load(
+        paths.resolveTargetRoot('yarn.lock'),
+      );
+      const otherLockfile = Lockfile.parse(
+        await readFileAtRef('yarn.lock', options.ref),
+      );
+      const diff = thisLockfile.diff(otherLockfile);
+
+      // Create a simplified dependency graph only keeps track of package names
+      const graph = thisLockfile.createSimplifiedDependencyGraph();
+
+      // Merge the dependency graph from the other lockfile into this one in
+      // order to be able to detect removals accurately.
+      {
+        const otherGraph = thisLockfile.createSimplifiedDependencyGraph();
+        for (const [name, dependencies] of otherGraph) {
+          const node = graph.get(name);
+          if (node) {
+            dependencies.forEach(d => node.add(d));
+          } else {
+            graph.set(name, dependencies);
+          }
+        }
+      }
+
+      // The check is simplified by only considering the package names rather
+      // than the exact version range queries that were changed.
+      // TODO(Rugvip): Use a more exact check
+      const changedPackages = new Set(
+        [...diff.added, ...diff.changed, ...diff.removed].map(e => e.name),
+      );
+
+      // Starting with our set of changed packages from the diff, we loop through
+      // the full graph and add any package that has a dependency on a changed package.
+      // We keep looping until all transitive dependencies have been detected.
+      let changed = false;
+      do {
+        changed = false;
+        for (const [name, dependencies] of graph) {
+          if (changedPackages.has(name)) {
+            continue;
+          }
+          for (const dep of dependencies) {
+            if (changedPackages.has(dep)) {
+              changed = true;
+              changedPackages.add(name);
+              break;
+            }
+          }
+        }
+      } while (changed);
+
+      // Add all local packages that had a transitive dependency change to the result set
+      for (const node of this.values()) {
+        if (changedPackages.has(node.name) && !result.includes(node)) {
+          result.push(node);
+        }
+      }
+    }
+
     return result;
   }
 }