export async function assertActiveLtsBranch()

in ng-dev/pr/common/targeting/lts-branch.ts [31:83]
39 lines of code
10 McCabe index (conditional complexity)

export async function assertActiveLtsBranch(
  repo: ReleaseRepoWithApi,
  releaseConfig: ReleaseConfig,
  branchName: string,
) {
  const version = await getVersionOfBranch(repo, branchName);
  const {'dist-tags': distTags, time} = await fetchProjectNpmPackageInfo(releaseConfig);

  // LTS versions should be tagged in NPM in the following format: `v{major}-lts`.
  const ltsNpmTag = getLtsNpmDistTagOfMajor(version.major);
  const ltsVersion = semver.parse(distTags[ltsNpmTag]);

  // Ensure that there is an LTS version tagged for the given version-branch major. e.g.
  // if the version branch is `9.2.x` then we want to make sure that there is an LTS
  // version tagged in NPM for `v9`, following the `v{major}-lts` tag convention.
  if (ltsVersion === null) {
    throw new InvalidTargetBranchError(`No LTS version tagged for v${version.major} in NPM.`);
  }

  // Ensure that the correct branch is used for the LTS version. We do not want to merge
  // changes to older minor version branches that do not reflect the current LTS version.
  if (branchName !== `${ltsVersion.major}.${ltsVersion.minor}.x`) {
    throw new InvalidTargetBranchError(
      `Not using last-minor branch for v${version.major} LTS version. PR ` +
        `should be updated to target: ${ltsVersion.major}.${ltsVersion.minor}.x`,
    );
  }

  const today = new Date();
  const majorReleaseDate = new Date(time[`${version.major}.0.0`]);
  const ltsEndDate = computeLtsEndDateOfMajor(majorReleaseDate);

  // Check if LTS has already expired for the targeted major version. If so, we do not
  // allow the merge as per our LTS guarantees. Can be forcibly overridden if desired.
  // See: https://angular.io/guide/releases#support-policy-and-schedule.
  if (today > ltsEndDate) {
    const ltsEndDateText = ltsEndDate.toLocaleDateString(defaultLocale);
    warn(red(`Long-term support ended for v${version.major} on ${ltsEndDateText}.`));
    warn(
      yellow(
        `Merging of pull requests for this major is generally not ` +
          `desired, but can be forcibly ignored.`,
      ),
    );
    if (await promptConfirm('Do you want to forcibly proceed with merging?')) {
      return;
    }
    throw new InvalidTargetBranchError(
      `Long-term supported ended for v${version.major} on ${ltsEndDateText}. ` +
        `Pull request cannot be merged into the ${branchName} branch.`,
    );
  }
}