NOISSUE add GitHub Actions scripts for PR preparation and review management

- Introduced `prepare.js` to validate PR mergeability and branch targeting.
- Added `reviews.js` for automated review dismissal and posting.
- Created `run` script to execute actions with GitHub context.
- Implemented rate limiting in `withRateLimit.js` to manage API requests.
- Added `supportedBranches.js` for branch classification logic.
- Created `update-pinned.sh` for updating pinned dependencies.
- Added `pinned.json` to manage pinned Nix dependencies.
- Updated `libnbtplusplus` version from 2.3 to 3.0 and adjusted README accordingly.

Signed-off-by: Mehmet Samet Duman <yongdohyun@projecttick.org>

1 files changed, 181 insertions, 0 deletions

diff --git a/ci/github-script/prepare.js b/ci/github-script/prepare.js
new file mode 100644
index 0000000000..9f98e8d392
--- /dev/null
+++ b/ci/github-script/prepare.js
@@ -0,0 +1,181 @@
+// @ts-check
+const { classify } = require('../supportedBranches.js')
+const { postReview, dismissReviews } = require('./reviews.js')
+const reviewKey = 'prepare'
+
+/**
+ * Prepares a PR for CI by checking mergeability and branch targeting.
+ *
+ * Outputs:
+ *   - base: base branch classification
+ *   - head: head branch classification
+ *   - mergedSha: the merge commit SHA (or head SHA if conflict)
+ *   - targetSha: the target comparison SHA
+ *
+ * @param {{
+ *  github: InstanceType<import('@actions/github/lib/utils').GitHub>,
+ *  context: import('@actions/github/lib/context').Context,
+ *  core: import('@actions/core'),
+ *  dry?: boolean,
+ * }} PrepareProps
+ */
+module.exports = async ({ github, context, core, dry }) => {
+  const pull_number = context.payload.pull_request.number
+
+  for (const retryInterval of [5, 10, 20, 40, 80]) {
+    core.info('Checking whether the pull request can be merged...')
+    const prInfo = (
+      await github.rest.pulls.get({
+        ...context.repo,
+        pull_number,
+      })
+    ).data
+
+    if (prInfo.state !== 'open') throw new Error('PR is not open anymore.')
+
+    if (prInfo.mergeable == null) {
+      core.info(
+        `GitHub is still computing mergeability, waiting ${retryInterval}s...`,
+      )
+      await new Promise((resolve) => setTimeout(resolve, retryInterval * 1000))
+      continue
+    }
+
+    const { base, head } = prInfo
+
+    const baseClassification = classify(base.ref)
+    core.setOutput('base', baseClassification)
+    console.log('base classification:', baseClassification)
+
+    const headClassification =
+      base.repo.full_name === head.repo.full_name
+        ? classify(head.ref)
+        : { type: ['wip'] }
+    core.setOutput('head', headClassification)
+    console.log('head classification:', headClassification)
+
+    // Warn if targeting a release branch with a non-backport/fix branch
+    if (
+      baseClassification.stable &&
+      baseClassification.type.includes('primary')
+    ) {
+      const headPrefix = head.ref.split('-')[0]
+      if (!['backport', 'fix', 'revert'].includes(headPrefix)) {
+        core.warning(
+          `This PR targets release branch \`${base.ref}\`. ` +
+            'New features should typically target \`master\`.',
+        )
+      }
+    }
+
+    // Check base branch targeting
+    if (headClassification.type.includes('wip')) {
+      // Determine the best base branch candidate
+      const branches = (
+        await github.paginate(github.rest.repos.listBranches, {
+          ...context.repo,
+          per_page: 100,
+        })
+      ).map(({ name }) => classify(name))
+
+      const releases = branches
+        .filter(({ stable, type }) => type.includes('primary') && stable)
+        .sort((a, b) => b.version.localeCompare(a.version))
+
+      async function mergeBase({ branch, order, version }) {
+        const { data } = await github.rest.repos.compareCommitsWithBasehead({
+          ...context.repo,
+          basehead: `${branch}...${head.sha}`,
+          per_page: 1,
+          page: 2,
+        })
+        return {
+          branch,
+          order,
+          version,
+          commits: data.total_commits,
+          sha: data.merge_base_commit.sha,
+        }
+      }
+
+      let candidates = [await mergeBase(classify('master'))]
+      for (const release of releases) {
+        const nextCandidate = await mergeBase(release)
+        if (candidates[0].commits === nextCandidate.commits)
+          candidates.push(nextCandidate)
+        if (candidates[0].commits > nextCandidate.commits)
+          candidates = [nextCandidate]
+        if (candidates[0].commits < 10000) break
+      }
+
+      const best = candidates.sort((a, b) => a.order - b.order).at(0)
+
+      core.info(`Best base branch candidate: ${best.branch}`)
+
+      if (best.branch !== base.ref) {
+        const current = await mergeBase(classify(base.ref))
+        const body = [
+          `This PR targets \`${current.branch}\`, but based on the commit history ` +
+            `\`${best.branch}\` appears to be a better fit ` +
+            `(${current.commits - best.commits} fewer commits ahead).`,
+          '',
+          `If this is intentional, you can ignore this message. Otherwise:`,
+          `- [Change the base branch](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/changing-the-base-branch-of-a-pull-request) to \`${best.branch}\`.`,
+        ].join('\n')
+
+        await postReview({ github, context, core, dry, body, reviewKey })
+        core.warning(`PR may target the wrong base branch.`)
+      } else {
+        await dismissReviews({ github, context, core, dry, reviewKey })
+      }
+    } else {
+      await dismissReviews({ github, context, core, dry, reviewKey })
+    }
+
+    let mergedSha, targetSha
+
+    if (prInfo.mergeable) {
+      core.info('The PR can be merged.')
+      mergedSha = prInfo.merge_commit_sha
+      targetSha = (
+        await github.rest.repos.getCommit({
+          ...context.repo,
+          ref: prInfo.merge_commit_sha,
+        })
+      ).data.parents[0].sha
+    } else {
+      core.warning('The PR has a merge conflict.')
+      mergedSha = head.sha
+      targetSha = (
+        await github.rest.repos.compareCommitsWithBasehead({
+          ...context.repo,
+          basehead: `${base.sha}...${head.sha}`,
+        })
+      ).data.merge_base_commit.sha
+    }
+
+    core.info(`merged: ${mergedSha}\ntarget: ${targetSha}`)
+    core.setOutput('mergedSha', mergedSha)
+    core.setOutput('targetSha', targetSha)
+
+    // Detect touched CI-relevant files
+    const files = (
+      await github.paginate(github.rest.pulls.listFiles, {
+        ...context.repo,
+        pull_number,
+        per_page: 100,
+      })
+    ).map((file) => file.filename)
+
+    const touched = []
+    if (files.some((f) => f.startsWith('ci/'))) touched.push('ci')
+    if (files.includes('ci/pinned.json')) touched.push('pinned')
+    if (files.some((f) => f.startsWith('.github/'))) touched.push('github')
+    core.setOutput('touched', touched)
+
+    return
+  }
+  throw new Error(
+    'Timed out waiting for GitHub to compute mergeability. Check https://www.githubstatus.com.',
+  )
+}