pr-size.yml

name: PR Size

on:
  pull_request_target:
    branches:
      - built-from-scratch
    types: [opened, reopened, synchronize, ready_for_review, converted_to_draft]

permissions:
  contents: read

jobs:
  label:
    name: Label PR size
    runs-on: ubuntu-24.04
    permissions:
      contents: read
      issues: read
      pull-requests: write
    concurrency:
      group: pr-size-${{ github.event.pull_request.number }}
      cancel-in-progress: true
    steps:
      - name: Sync PR size label
        uses: actions/github-script@v8
        with:
          script: |
            const issueNumber = context.payload.pull_request.number;
            const managedLabelNames = new Set([
              "size:XS",
              "size:S",
              "size:M",
              "size:L",
              "size:XL",
              "size:XXL",
            ]);
            // Keep this aligned with the repo's test entrypoints and test-only support files.
            const testFilePatterns = [
              /(^|\/)__tests__(\/|$)/,
              /(^|\/)tests?(\/|$)/,
              /^apps\/server\/integration\//,
              /\.(test|spec|browser|integration)\.[^.\/]+$/,
            ];

            const isTestFile = (filename) =>
              testFilePatterns.some((pattern) => pattern.test(filename));

            const resolveSizeLabel = (totalChangedLines) => {
              if (totalChangedLines < 10) {
                return "size:XS";
              }

              if (totalChangedLines < 30) {
                return "size:S";
              }

              if (totalChangedLines < 100) {
                return "size:M";
              }

              if (totalChangedLines < 500) {
                return "size:L";
              }

              if (totalChangedLines < 1000) {
                return "size:XL";
              }

              return "size:XXL";
            };

            const files = await github.paginate(
              github.rest.pulls.listFiles,
              {
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: issueNumber,
                per_page: 100,
              },
              (response) => response.data,
            );

            if (files.length >= 3000) {
              core.warning(
                "The GitHub pull request files API may truncate results at 3,000 files; PR size may be undercounted.",
              );
            }

            let testChangedLines = 0;
            let nonTestChangedLines = 0;

            for (const file of files) {
              const changedLinesForFile = (file.additions ?? 0) + (file.deletions ?? 0);

              if (changedLinesForFile === 0) {
                continue;
              }

              if (isTestFile(file.filename)) {
                testChangedLines += changedLinesForFile;
                continue;
              }

              nonTestChangedLines += changedLinesForFile;
            }

            const changedLines = nonTestChangedLines === 0 ? testChangedLines : nonTestChangedLines;
            const nextLabelName = resolveSizeLabel(changedLines);

            const { data: currentLabels } = await github.rest.issues.listLabelsOnIssue({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: issueNumber,
              per_page: 100,
            });

            for (const label of currentLabels) {
              if (!managedLabelNames.has(label.name) || label.name === nextLabelName) {
                continue;
              }

              try {
                await github.rest.issues.removeLabel({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  issue_number: issueNumber,
                  name: label.name,
                });
              } catch (removeError) {
                if (removeError.status !== 404) {
                  throw removeError;
                }
              }
            }

            if (!currentLabels.some((label) => label.name === nextLabelName)) {
              await github.rest.issues.addLabels({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: issueNumber,
                labels: [nextLabelName],
              });
            }

            const classification =
              nonTestChangedLines === 0
                ? testChangedLines > 0
                  ? "test-only PR"
                  : "no line changes"
                : testChangedLines > 0
                  ? "test lines excluded"
                  : "all non-test changes";

            core.info(
              `PR #${issueNumber}: ${nonTestChangedLines} non-test lines, ${testChangedLines} test lines, ${changedLines} effective lines -> ${nextLabelName} (${classification})`,
            );