ci: update danger to do more stuff

dangerfile.ts

@@ -1,13 +1,57 @@
-import { danger } from 'danger';
+import { parse } from 'path';
+import { danger, warn } from 'danger';
 
 // Ensure that people include a description on their PRs
 if (danger.github.pr.body.length === 0) {
   fail('Please include a body for your PR');
 }
 
-if (
-  danger.git.created_files.find(filename => filename.startsWith('rules/')) &&
-  !danger.git.modified_files.includes('README.md')
-) {
-  fail('Please update the README when new rules are added');
-}
+const createOrAddLabelSafely = async (name: string, color: string) => {
+  try {
+    await danger.github.utils.createOrAddLabel({
+      name,
+      color,
+      description: '',
+    });
+  } catch (error) {
+    console.warn(error);
+    warn(`Was unable to create or add label "${name}"`);
+  }
+};
+
+const labelBasedOnRules = async () => {
+  const affectedRules = [
+    ...danger.git.created_files,
+    ...danger.git.modified_files,
+    ...danger.git.deleted_files,
+  ]
+    .filter(filename => {
+      const { dir, ext } = parse(filename);
+
+      return dir === 'src/rules' && ext === '.ts';
+    })
+    .map(filename => parse(filename).name);
+
+  await Promise.all(
+    affectedRules.map(rule =>
+      createOrAddLabelSafely(`rule: ${rule}`, '#7d3abc'),
+    ),
+  );
+};
+
+const labelBasedOnCommits = async () => {
+  const commits = danger.github.commits.map(commits => commits.commit.message);
+
+  if (commits.some(commit => commit.startsWith('fix'))) {
+    await createOrAddLabelSafely('bug', '#ee0701');
+  }
+
+  if (commits.some(commit => commit.startsWith('feat'))) {
+    await createOrAddLabelSafely('enhancement', '#84b6eb');
+  }
+};
+
+Promise.all([labelBasedOnRules(), labelBasedOnCommits()]).catch(error => {
+  console.error(error);
+  fail(`Something went very wrong: ${error}`);
+});