/.github/workflows/check-pr-size.yml

name: Check PR size

on:
  pull_request_target:
    types: [opened, synchronize, reopened]
  workflow_dispatch:
    inputs:
      pr_number:
        description: 'PR number to check (optional)'
        required: false
        type: string

permissions:
  contents: read
  pull-requests: write
  issues: write

concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.run_id }}
  cancel-in-progress: true

jobs:
  size:
    runs-on: ubuntu-latest
    steps:
      - name: Get PR data for manual trigger
        if: github.event_name == 'workflow_dispatch' && github.event.inputs.pr_number
        id: get_pr
        uses: actions/github-script@v9
        with:
          result-encoding: string
          script: |
            const { data } = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: ${{ github.event.inputs.pr_number }}
            });
            return JSON.stringify(data);

      - name: Evaluate PR size
        if: github.event_name == 'pull_request_target' || (github.event_name == 'workflow_dispatch' && github.event.inputs.pr_number)
        uses: actions/github-script@v9
        env:
          PR_JSON: ${{ steps.get_pr.outputs.result }}
        with:
          script: |
            const pr = context.payload.pull_request || JSON.parse(process.env.PR_JSON || '{}');
            if (!pr || !pr.number) {
              core.setFailed('Unable to resolve PR data. For workflow_dispatch, pass a valid pr_number.');
              return;
            }

            // Check for draft PRs and bots
            const isDraft = !!pr.draft;
            const login = pr.user.login;
            const isBot = pr.user.type === 'Bot' || /\[bot\]$/.test(login);

            if (isDraft || isBot) {
              core.info('Draft or bot PR – skipping size enforcement');
              return;
            }

            const totalChanges = pr.additions + pr.deletions;
            core.info(`PR contains ${pr.additions} additions and ${pr.deletions} deletions (${totalChanges} total)`);

            const sizeLabel =
              totalChanges < 50   ? 'size/XS' :
              totalChanges < 150  ? 'size/S'  :
              totalChanges < 600  ? 'size/M'  :
              totalChanges < 1000 ? 'size/L'  : 'size/XL';

            // Re-fetch labels to avoid acting on stale payload data
            const { data: freshIssue } = await github.rest.issues.get({
              ...context.repo,
              issue_number: pr.number
            });
            const currentLabels = (freshIssue.labels || []).map(l => l.name);

            // Remove old size labels before adding new one
            const allSizeLabels = ['size/XS', 'size/S', 'size/M', 'size/L', 'size/XL'];
            const toRemove = currentLabels.filter(name => allSizeLabels.includes(name) && name !== sizeLabel);

            for (const name of toRemove) {
              try {
                await github.rest.issues.removeLabel({
                  ...context.repo,
                  issue_number: pr.number,
                  name
                });
              } catch (_) {
                // Ignore if already removed
              }
            }

            await github.rest.issues.addLabels({
              ...context.repo,
              issue_number: pr.number,
              labels: [sizeLabel]
            });

            // Check if PR author is a maintainer
            let authorPerm = 'none';
            try {
              const { data } = await github.rest.repos.getCollaboratorPermissionLevel({
                owner: context.repo.owner,
                repo: context.repo.repo,
                username: pr.user.login,
              });
              authorPerm = data.permission || 'none';
            } catch (_) {
              // User might not have any permissions
            }

            core.info(`Author permission: ${authorPerm}`);
            const isMaintainer = ['admin', 'maintain'].includes(authorPerm); // Stricter maintainer definition

            // Check for bypass label (using fresh labels)
            const hasBypass = currentLabels.includes('bypass:size-limit');

            const MAX_LINES = 1000;
            if (totalChanges > MAX_LINES) {
              if (isMaintainer || hasBypass) {
                core.info(`${isMaintainer ? 'Maintainer' : 'Bypass label'} - allowing large PR with ${totalChanges} lines`);
              } else {
                core.setFailed(
                  `This PR contains ${totalChanges} lines of changes, which exceeds the maximum of ${MAX_LINES} lines. ` +
                  `Please split this into smaller, focused pull requests.`
                );
              }
            }