pr-summary-generate.yml

name: Generate PR Summary

on:
  pull_request:
    types: [opened]
  issue_comment:
    types: [created]

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

jobs:
  generate-summary:
    # Run when:
    # 1. A PR is opened without a description, OR
    # 2. Someone comments "/generate-summary" on a PR
    if: |
      (github.event_name == 'pull_request' && (github.event.pull_request.body == '' || github.event.pull_request.body == null)) ||
      (github.event_name == 'issue_comment' && github.event.issue.pull_request && contains(github.event.comment.body, '/generate-summary'))
    runs-on: ubuntu-latest
    outputs:
      pr-number: ${{ steps.pr-number.outputs.number }}
    steps:
      - name: Determine PR number
        id: pr-number
        env:
          EVENT_NAME: ${{ github.event_name }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          ISSUE_NUMBER: ${{ github.event.issue.number }}
        run: |
          if [ "$EVENT_NAME" = "pull_request" ]; then
            echo "number=$PR_NUMBER" >> "$GITHUB_OUTPUT"
          else
            echo "number=$ISSUE_NUMBER" >> "$GITHUB_OUTPUT"
          fi

      - name: Checkout
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: React to comment
        if: github.event_name == 'issue_comment'
        uses: actions/github-script@v7
        with:
          script: |
            await github.rest.reactions.createForIssueComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              comment_id: context.payload.comment.id,
              content: 'rocket',
            });

      - name: Get PR diff summary
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          PR_NUMBER: ${{ steps.pr-number.outputs.number }}
        run: |
          gh pr diff "$PR_NUMBER" --stat > /tmp/diff-stat.txt 2>/dev/null || echo "Unable to retrieve diff" > /tmp/diff-stat.txt
          gh pr diff "$PR_NUMBER" --name-only > /tmp/changed-files.txt 2>/dev/null || echo "" > /tmp/changed-files.txt

      - name: Read format instructions
        run: |
          if [ -f .github/copilot-instructions.md ]; then
            cat .github/copilot-instructions.md > /tmp/format-instructions.txt
          else
            echo "No format instructions found" > /tmp/format-instructions.txt
          fi

      - name: Generate summary with GitHub Models
        id: generate
        uses: actions/github-script@v7
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          script: |
            const fs = require('fs');

            const diffStat = fs.readFileSync('/tmp/diff-stat.txt', 'utf8');
            const changedFiles = fs.readFileSync('/tmp/changed-files.txt', 'utf8');
            const formatInstructions = fs.readFileSync('/tmp/format-instructions.txt', 'utf8');

            const prompt = `You are generating a pull request description for an automated sync from an internal development repository to the public GitHub repository.

            Here are the format instructions to follow:
            ---
            ${formatInstructions}
            ---

            Here are the changed files in this PR:
            ---
            ${changedFiles}
            ---

            Here is the diff stat:
            ---
            ${diffStat}
            ---

            Generate a PR description that follows the format instructions exactly. Categorize files correctly:
            - Files under Samples/ that appear new → New samples
            - Files under Samples/ that are modified → Updated samples (use the sample directory name)
            - Files under Kits/ → Updated kits
            - Everything else (Media/, configs, docs) → General

            Also generate a concise PR title (not the H2 heading) that summarizes the changes in
            a few words (e.g., "Add TriangleWave sample, update ATGTK helpers").

            Output a JSON object with two fields:
            - "title": the PR title string
            - "body": the formatted PR description following the instructions

            Output ONLY valid JSON, nothing else.`;

            const response = await fetch('https://models.github.ai/inference/chat/completions', {
              method: 'POST',
              headers: {
                'Authorization': `Bearer ${process.env.GITHUB_TOKEN}`,
                'Content-Type': 'application/json',
              },
              body: JSON.stringify({
                model: 'openai/gpt-4o-mini',
                messages: [
                  { role: 'user', content: prompt }
                ],
                temperature: 0.3,
                response_format: { type: 'json_object' },
              }),
            });

            if (!response.ok) {
              const error = await response.text();
              core.setFailed(`GitHub Models API error: ${response.status} - ${error}`);
              return;
            }

            const result = await response.json();
            let content = result.choices[0].message.content.trim();

            // Strip markdown code fences if present
            content = content.replace(/^```(?:json)?\s*\n?/i, '').replace(/\n?```\s*$/i, '');

            let parsed;
            try {
              parsed = JSON.parse(content);
            } catch (e) {
              // Fallback: treat entire response as body if JSON parsing fails
              parsed = { title: '', body: content };
            }

            fs.writeFileSync('/tmp/pr-summary.md', parsed.body);
            core.setOutput('summary', parsed.body);
            core.setOutput('title', parsed.title);

      - name: Update PR title and description
        if: steps.generate.outputs.summary != ''
        uses: actions/github-script@v7
        env:
          PR_TITLE: ${{ steps.generate.outputs.title }}
          PR_NUMBER: ${{ steps.pr-number.outputs.number }}
        with:
          script: |
            const fs = require('fs');
            const summary = fs.readFileSync('/tmp/pr-summary.md', 'utf8');
            const title = process.env.PR_TITLE || '';

            const update = {
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: parseInt(process.env.PR_NUMBER, 10),
              body: summary,
            };

            if (title) {
              update.title = title;
            }

            await github.rest.pulls.update(update);

            console.log('PR title and description updated successfully');

  evaluate-summary:
    needs: generate-summary
    uses: ./.github/workflows/pr-summary-eval-reusable.yml
    with:
      pr-number: ${{ fromJSON(needs.generate-summary.outputs.pr-number) }}