Stirling-PDF/.github/workflows/ai_pr_title_review.yml

name: AI - PR Title Review

on:
  pull_request:
    types: [opened, edited]
    branches: [main]

permissions:  # required for secure-repo hardening
  contents: read

jobs:
  ai-title-review:
    permissions:
      contents: read
      pull-requests: write
      models: read

    runs-on: ubuntu-latest

    steps:
      - name: Harden Runner
        uses: step-security/harden-runner@95d9a5deda9de15063e7595e9719c11c38c90ae2 # v2.13.2
        with:
          egress-policy: audit

      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
        with:
          fetch-depth: 0

      - name: Configure Git to suppress detached HEAD warning
        run: git config --global advice.detachedHead false

      - name: Setup GitHub App Bot
        if: github.actor != 'dependabot[bot]'
        id: setup-bot
        uses: ./.github/actions/setup-bot
        continue-on-error: true
        with:
          app-id: ${{ secrets.GH_APP_ID }}
          private-key: ${{ secrets.GH_APP_PRIVATE_KEY }}

      - name: Check if actor is repo developer
        id: actor
        run: |
          if [[ "${{ github.actor }}" == *"[bot]" ]]; then
            echo "PR opened by a bot – skipping AI title review."
            echo "is_repo_dev=false" >> $GITHUB_OUTPUT
            exit 0
          fi
          if [ ! -f .github/config/repo_devs.json ]; then
            echo "Error: .github/config/repo_devs.json not found" >&2
            exit 1
          fi
          # Validate JSON and extract repo_devs
          REPO_DEVS=$(jq -r '.repo_devs[]' .github/config/repo_devs.json 2>/dev/null || { echo "Error: Invalid JSON in repo_devs.json" >&2; exit 1; })
          # Convert developer list into Bash array
          mapfile -t DEVS_ARRAY <<< "$REPO_DEVS"
          if [[ " ${DEVS_ARRAY[*]} " == *" ${{ github.actor }} "* ]]; then
            echo "is_repo_dev=true" >> $GITHUB_OUTPUT
          else
            echo "is_repo_dev=false" >> $GITHUB_OUTPUT
          fi          

      - name: Get PR diff
        if: steps.actor.outputs.is_repo_dev == 'true'
        id: get_diff
        run: |
          git fetch origin ${{ github.base_ref }}
          git diff origin/${{ github.base_ref }}...HEAD | head -n 10000 | grep -vP '[\x00-\x08\x0B\x0C\x0E-\x1F\x7F\x{202E}\x{200B}]' > pr.diff
          echo "diff<<EOF" >> $GITHUB_OUTPUT
          cat pr.diff >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT          

      - name: Check and sanitize PR title
        if: steps.actor.outputs.is_repo_dev == 'true'
        id: sanitize_pr_title
        env:
          PR_TITLE_RAW: ${{ github.event.pull_request.title }}
        run: |
          # Sanitize PR title: max 72 characters, only printable characters
          PR_TITLE=$(echo "$PR_TITLE_RAW" | tr -d '\n\r' | head -c 72 | sed 's/[^[:print:]]//g')
          if [[ ${#PR_TITLE} -lt 5 ]]; then
            echo "PR title is too short. Must be at least 5 characters." >&2
          fi
          echo "pr_title=$PR_TITLE" >> $GITHUB_OUTPUT          

      - name: AI PR Title Analysis
        if: steps.actor.outputs.is_repo_dev == 'true'
        id: ai-title-analysis
        uses: actions/ai-inference@334892bb203895caaed82ec52d23c1ed9385151e # v2.0.4
        with:
          model: openai/gpt-4o
          system-prompt-file: ".github/config/system-prompt.txt"
          prompt: |
            Based on the following input data:

            {
              "diff": "${{ steps.get_diff.outputs.diff }}",
              "pr_title": "${{ steps.sanitize_pr_title.outputs.pr_title }}"
            }

            Respond ONLY with valid JSON in the format:
            {
              "improved_rating": <0-10>,
              "improved_ai_title_rating": <0-10>,
              "improved_title": "<ai generated title>"
            }            

      - name: Validate and set SCRIPT_OUTPUT
        if: steps.actor.outputs.is_repo_dev == 'true'
        run: |
          cat <<EOF > ai_response.json
          ${{ steps.ai-title-analysis.outputs.response }}
          EOF

          # Validate JSON structure
          jq -e '
            (keys | sort) == ["improved_ai_title_rating", "improved_rating", "improved_title"] and
            (.improved_rating | type == "number" and . >= 0 and . <= 10) and
            (.improved_ai_title_rating | type == "number" and . >= 0 and . <= 10) and
            (.improved_title | type == "string")
          ' ai_response.json
          if [ $? -ne 0 ]; then
            echo "Invalid AI response format" >&2
            cat ai_response.json >&2
            exit 1
          fi
          # Parse JSON fields
          IMPROVED_RATING=$(jq -r '.improved_rating' ai_response.json)
          IMPROVED_TITLE=$(jq -r '.improved_title' ai_response.json)
          # Limit comment length to 1000 characters
          COMMENT=$(cat <<EOF
          ## 🤖 AI PR Title Suggestion

          **PR-Title Rating**: $IMPROVED_RATING/10

          ### ⬇️ Suggested Title (copy & paste):

          \`\`\`
          $IMPROVED_TITLE
          \`\`\`

          ---
          *Generated by GitHub Models AI*
          EOF
          )
          echo "$COMMENT" > /tmp/ai-title-comment.md
          # Log input and output to the GitHub Step Summary
          echo "### 🤖 AI PR Title Analysis" >> $GITHUB_STEP_SUMMARY
          echo "### Input PR Title" >> $GITHUB_STEP_SUMMARY
          echo '```bash' >> $GITHUB_STEP_SUMMARY
          echo "${{ steps.sanitize_pr_title.outputs.pr_title }}" >> $GITHUB_STEP_SUMMARY
          echo '```' >> $GITHUB_STEP_SUMMARY
          echo '### AI Response (raw JSON)' >> $GITHUB_STEP_SUMMARY
          echo '```json' >> $GITHUB_STEP_SUMMARY
          cat ai_response.json >> $GITHUB_STEP_SUMMARY
          echo '```' >> $GITHUB_STEP_SUMMARY          

      - name: Post comment on PR if needed
        if: steps.actor.outputs.is_repo_dev == 'true'
        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
        continue-on-error: true
        with:
          github-token: ${{ steps.setup-bot.outputs.token }}
          script: |
            const fs = require('fs');
            const body = fs.readFileSync('/tmp/ai-title-comment.md', 'utf8');
            const { GITHUB_REPOSITORY } = process.env;
            const [owner, repo] = GITHUB_REPOSITORY.split('/');
            const issue_number = context.issue.number;

            const ratingMatch = body.match(/\*\*PR-Title Rating\*\*: (\d+)\/10/);
            const rating = ratingMatch ? parseInt(ratingMatch[1], 10) : null;

            const expectedActor = "${{ steps.setup-bot.outputs.app-slug }}[bot]";
            const comments = await github.rest.issues.listComments({ owner, repo, issue_number });

            const existing = comments.data.find(c =>
              c.user?.login === expectedActor &&
              c.body.includes("## 🤖 AI PR Title Suggestion")
            );

            if (rating === null) {
              console.log("No rating found in AI response – skipping.");
              return;
            }

            if (rating <= 5) {
              if (existing) {
                await github.rest.issues.updateComment({
                  owner, repo,
                  comment_id: existing.id,
                  body
                });
                console.log("Updated existing suggestion comment.");
              } else {
                await github.rest.issues.createComment({
                  owner, repo, issue_number,
                  body
                });
                console.log("Created new suggestion comment.");
              }
            } else {
              const praise = `## 🤖 AI PR Title Suggestion\n\nGreat job! The current PR title is clear and well-structured.\n\n✅ No suggestions needed.\n\n---\n*Generated by GitHub Models AI*`;

              if (existing) {
                await github.rest.issues.updateComment({
                  owner, repo,
                  comment_id: existing.id,
                  body: praise
                });
                console.log("Replaced suggestion with praise.");
              } else {
                console.log("Rating > 5 and no existing comment – skipping comment.");
              }
            }            

      - name: is not repo dev
        if: steps.actor.outputs.is_repo_dev != 'true'
        run: |
          exit 0 # Skip the AI title review for non-repo developers          

      - name: Clean up
        if: always()
        run: |
          rm -f pr.diff ai_response.json /tmp/ai-title-comment.md
          echo "Cleaned up temporary files."          
        continue-on-error: true # Ensure cleanup runs even if previous steps fail