name: PR Size Check

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

permissions:
  contents: read
  pull-requests: write

jobs:
  check-pr-size:
    runs-on: ubuntu-latest
    timeout-minutes: 10
    
    steps:
      - name: Harden the runner
        uses: step-security/harden-runner@ec9f2d5744a09debf3a187a3f4f675c53b671911 # v2.13.0
        with:
          egress-policy: audit
      
      - name: Checkout code
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          fetch-depth: 0
      
      - name: Check PR size
        id: check-size
        run: |
          set -euo pipefail
          
          # Fetch the base branch
          git fetch origin "${{ github.base_ref }}"
          
          # Get diff stats
          diff_output=$(git diff --numstat "origin/${{ github.base_ref }}"...HEAD)
          
          # Count lines, excluding:
          # - Test files (*.test.ts, *.spec.tsx, etc.)
          # - Locale files (locales/*.json, i18n/*.json)
          # - Lock files (pnpm-lock.yaml, package-lock.json, yarn.lock)
          # - Generated files (dist/, coverage/, build/, .next/)
          # - Storybook stories (*.stories.tsx)
          
          total_additions=0
          total_deletions=0
          counted_files=0
          excluded_files=0
          
          while IFS=$'\t' read -r additions deletions file; do
            # Skip if additions or deletions are "-" (binary files)
            if [ "$additions" = "-" ] || [ "$deletions" = "-" ]; then
              continue
            fi
            
            # Check if file should be excluded
            case "$file" in
              *.test.ts|*.test.tsx|*.spec.ts|*.spec.tsx|*.test.js|*.test.jsx|*.spec.js|*.spec.jsx)
                excluded_files=$((excluded_files + 1))
                continue
                ;;
              */locales/*.json|*/i18n/*.json)
                excluded_files=$((excluded_files + 1))
                continue
                ;;
              pnpm-lock.yaml|package-lock.json|yarn.lock)
                excluded_files=$((excluded_files + 1))
                continue
                ;;
              dist/*|coverage/*|build/*|node_modules/*|test-results/*|playwright-report/*|.next/*|*.tsbuildinfo)
                excluded_files=$((excluded_files + 1))
                continue
                ;;
              *.stories.ts|*.stories.tsx|*.stories.js|*.stories.jsx)
                excluded_files=$((excluded_files + 1))
                continue
                ;;
            esac
            
            total_additions=$((total_additions + additions))
            total_deletions=$((total_deletions + deletions))
            counted_files=$((counted_files + 1))
          done <<EOF
          ${diff_output}
          EOF
          
          total_changes=$((total_additions + total_deletions))
          
          echo "counted_files=${counted_files}" >> "${GITHUB_OUTPUT}"
          echo "excluded_files=${excluded_files}" >> "${GITHUB_OUTPUT}"
          echo "total_additions=${total_additions}" >> "${GITHUB_OUTPUT}"
          echo "total_deletions=${total_deletions}" >> "${GITHUB_OUTPUT}"
          echo "total_changes=${total_changes}" >> "${GITHUB_OUTPUT}"
          
          # Set flag if PR is too large (> 800 lines)
          if [ ${total_changes} -gt 800 ]; then
            echo "is_too_large=true" >> "${GITHUB_OUTPUT}"
          else
            echo "is_too_large=false" >> "${GITHUB_OUTPUT}"
          fi
      
      - name: Comment on PR if too large
        if: steps.check-size.outputs.is_too_large == 'true'
        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const totalChanges = ${{ steps.check-size.outputs.total_changes }};
            const countedFiles = ${{ steps.check-size.outputs.counted_files }};
            const excludedFiles = ${{ steps.check-size.outputs.excluded_files }};
            const additions = ${{ steps.check-size.outputs.total_additions }};
            const deletions = ${{ steps.check-size.outputs.total_deletions }};
            
            const body = '## 🚨 PR Size Warning\n\n' +
              'This PR has approximately **' + totalChanges + ' lines** of changes (' + additions + ' additions, ' + deletions + ' deletions across ' + countedFiles + ' files).\n\n' +
              'Large PRs (>800 lines) are significantly harder to review and increase the chance of merge conflicts. Consider splitting this into smaller, self-contained PRs.\n\n' +
              '### 💡 Suggestions:\n' +
              '- **Split by feature or module** - Break down into logical, independent pieces\n' +
              '- **Create a sequence of PRs** - Each building on the previous one\n' +
              '- **Branch off PR branches** - Don\'t wait for reviews to continue dependent work\n\n' +
              '### 📊 What was counted:\n' +
              '- ✅ Source files, stylesheets, configuration files\n' +
              '- ❌ Excluded ' + excludedFiles + ' files (tests, locales, locks, generated files)\n\n' +
              '### 📚 Guidelines:\n' +
              '- **Ideal:** 300-500 lines per PR\n' +
              '- **Warning:** 500-800 lines\n' +
              '- **Critical:** 800+ lines ⚠️\n\n' +
              'If this large PR is unavoidable (e.g., migration, dependency update, major refactor), please explain in the PR description why it couldn\'t be split.';
            
            // Check if we already commented
            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });
            
            const botComment = comments.find(comment => 
              comment.user.type === 'Bot' && 
              comment.body.includes('🚨 PR Size Warning')
            );
            
            if (botComment) {
              // Update existing comment
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: botComment.id,
                body: body
              });
            } else {
              // Create new comment
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body: body
              });
            }