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.github/scripts/compute-backport-targets.mjs

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+// Creates backport PR's according to labels on merged PR
+
+import { readPrLabels, resolveRcBranchForTrack, writeGithubOutput } from './github-helpers.mjs';
+
+/** @type { Record<string, import('./github-helpers.mjs').ReleaseTrack> } */
+const BACKPORT_BY_TAG_MAP = {
+	'Backport to Beta': 'beta',
+	'Backport to Stable': 'stable',
+};
+
+const BACKPORT_BY_BRANCH_MAP = {
+	'Backport to v1': '1.x',
+};
+
+/**
+ * @param {Set<string>} labels
+ *
+ * @returns { Set<string> }
+ */
+export function labelsToReleaseCandidateBranches(labels) {
+	const targets = new Set();
+
+	// Backport by tag map includes mapping of label to git tag to resolve
+	for (const [label, tag] of Object.entries(BACKPORT_BY_TAG_MAP)) {
+		// Check if backport label is present
+		if (!labels.has(label)) {
+			continue;
+		}
+
+		const branch = resolveRcBranchForTrack(tag);
+		// Make sure our backport branch exists
+		if (!branch) {
+			continue;
+		}
+
+		targets.add(branch);
+	}
+
+	// Backport by branch map includes mapping of label to git branch. This is used for
+	// older versions of n8n. v1, etc.
+	for (const [label, branch] of Object.entries(BACKPORT_BY_BRANCH_MAP)) {
+		// Check if backport label is present
+		if (!labels.has(label)) {
+			continue;
+		}
+
+		targets.add(branch);
+	}
+
+	return targets;
+}
+
+async function main() {
+	const labels = new Set(readPrLabels());
+	if (!labels || labels.size === 0) {
+		console.log('No labels on PR. Exiting...');
+		return;
+	}
+
+	const backportBranches = labelsToReleaseCandidateBranches(labels);
+
+	if (backportBranches.size === 0) {
+		console.log('No backports needed. Exiting...');
+		return;
+	}
+
+	const target_branches = [...backportBranches].join(' '); // korthout/backport-action@v4 uses space-delimited branch list
+	writeGithubOutput({ target_branches });
+}
+
+// only run when executed directly, not when imported by tests
+if (import.meta.url === `file://${process.argv[1]}`) {
+	await main();
+}