name: Comment with Pyrefly Diff

on:
  workflow_run:
    workflows:
      - Pyrefly Diff Check
    types:
      - completed

permissions: {}

jobs:
  comment:
    name: Comment PR with pyrefly diff
    runs-on: ubuntu-latest
    permissions:
      actions: read
      contents: read
      issues: write
      pull-requests: write
    if: ${{ github.event.workflow_run.conclusion == 'success' && github.event.workflow_run.pull_requests[0].head.repo.full_name != github.repository }}
    steps:
      - name: Download pyrefly diff artifact
        uses: actions/github-script@v8
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const fs = require('fs');
            const artifacts = await github.rest.actions.listWorkflowRunArtifacts({
              owner: context.repo.owner,
              repo: context.repo.repo,
              run_id: ${{ github.event.workflow_run.id }},
            });
            const match = artifacts.data.artifacts.find((artifact) =>
              artifact.name === 'pyrefly_diff'
            );
            if (!match) {
              throw new Error('pyrefly_diff artifact not found');
            }
            const download = await github.rest.actions.downloadArtifact({
              owner: context.repo.owner,
              repo: context.repo.repo,
              artifact_id: match.id,
              archive_format: 'zip',
            });
            fs.writeFileSync('pyrefly_diff.zip', Buffer.from(download.data));

      - name: Unzip artifact
        run: unzip -o pyrefly_diff.zip

      - name: Post comment
        uses: actions/github-script@v8
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const fs = require('fs');
            let diff = fs.readFileSync('pyrefly_diff.txt', { encoding: 'utf8' });
            let prNumber = null;
            try {
              prNumber = parseInt(fs.readFileSync('pr_number.txt', { encoding: 'utf8' }), 10);
            } catch (err) {
              // Fallback to workflow_run payload if artifact is missing or incomplete.
              const prs = context.payload.workflow_run.pull_requests || [];
              if (prs.length > 0 && prs[0].number) {
                prNumber = prs[0].number;
              }
            }
            if (!prNumber) {
              throw new Error('PR number not found in artifact or workflow_run payload');
            }

            const MAX_CHARS = 65000;
            if (diff.length > MAX_CHARS) {
              diff = diff.slice(0, MAX_CHARS);
              diff = diff.slice(0, diff.lastIndexOf('\\n'));
              diff += '\\n\\n... (truncated) ...';
            }

            const body = diff.trim()
              ? `### Pyrefly Diff
<details>
<summary>base → PR</summary>

\`\`\`diff
${diff}
\`\`\`
</details>`
              : '### Pyrefly Diff\nNo changes detected.';

            await github.rest.issues.createComment({
              issue_number: prNumber,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body,
            });