name: PR Labeler

on:
  pull_request:
    types: [opened, synchronize, reopened]

permissions:
  pull-requests: write
  contents: read

jobs:
  label-pr:
    runs-on: ubuntu-latest
    steps:
      - name: Analyze PR and apply labels
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const { data: files } = await github.rest.pulls.listFiles({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.issue.number,
              per_page: 100,
            });

            let goFiles = 0, jsFiles = 0, tsFiles = 0, mdFiles = 0, otherFiles = 0;
            let additions = 0, deletions = 0;

            for (const file of files) {
              const name = file.filename.toLowerCase();
              additions += file.additions || 0;
              deletions += file.deletions || 0;
              if (name.endsWith('.go')) goFiles++;
              else if (name.endsWith('.js') || name.endsWith('.jsx')) jsFiles++;
              else if (name.endsWith('.ts') || name.endsWith('.tsx') || name.endsWith('.vue')) tsFiles++;
              else if (name.endsWith('.md')) mdFiles++;
              else otherFiles++;
            }

            const totalFiles = goFiles + jsFiles + tsFiles + mdFiles + otherFiles;
            if (totalFiles === 0) return;

            // --- Scope label ---
            const labels = [];
            if (goFiles / totalFiles > 0.5) labels.push('backend');
            else if ((jsFiles + tsFiles) / totalFiles > 0.5) labels.push('frontend');
            else if (mdFiles / totalFiles > 0.7) labels.push('documentation');
            else labels.push('fullstack');

            // --- Size label (like OpenClaw) ---
            const totalChanged = additions + deletions;
            const sizeLabels = ['size: XS', 'size: S', 'size: M', 'size: L', 'size: XL'];
            let sizeLabel = 'size: XL';
            if (totalChanged < 50) sizeLabel = 'size: XS';
            else if (totalChanged < 200) sizeLabel = 'size: S';
            else if (totalChanged < 500) sizeLabel = 'size: M';
            else if (totalChanged < 1000) sizeLabel = 'size: L';
            labels.push(sizeLabel);

            // Ensure size labels exist
            for (const sl of sizeLabels) {
              try {
                await github.rest.issues.getLabel({ owner: context.repo.owner, repo: context.repo.repo, name: sl });
              } catch (e) {
                if (e.status === 404) {
                  await github.rest.issues.createLabel({ owner: context.repo.owner, repo: context.repo.repo, name: sl, color: 'b76e79' });
                }
              }
            }

            // Remove stale size labels
            const { data: currentLabels } = await github.rest.issues.listLabelsOnIssue({
              owner: context.repo.owner, repo: context.repo.repo, issue_number: context.issue.number,
            });
            for (const cl of currentLabels) {
              if (sizeLabels.includes(cl.name) && cl.name !== sizeLabel) {
                await github.rest.issues.removeLabel({
                  owner: context.repo.owner, repo: context.repo.repo, issue_number: context.issue.number, name: cl.name,
                }).catch(() => {});
              }
            }

            // Apply labels
            await github.rest.issues.addLabels({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              labels: labels,
            });

            console.log(`Applied labels: ${labels.join(', ')} (${totalChanged} lines changed)`);