name: Changelog Comment

on:
  pull_request_target:
    types: [opened, reopened]
  workflow_dispatch:
    inputs:
      pr_number:
        description: 'PR number to post the changelog comment on (for testing)'
        required: true
        type: number

jobs:
  comment:
    name: Post changelog comment
    runs-on: ubuntu-latest

    steps:
      - name: Post or update changelog comment
        uses: actions/github-script@d746ffe35508b1917358783b479e04febd2b8f71 # v9.0.0
        with:
          github-token: ${{ secrets.CROWDIN_GH_TOKEN }}
          script: |
            const marker = '<!-- changelog -->';
            const mergedMarker = '<!-- changelog-merged -->';

            const sections = ['### Added', '', '### Changed', '', '### Deprecated', '', '### Removed', '', '### Fixed', '', '### Security'].join('\n');
            const productBlock = (name) => `<details>\n<summary>${name}</summary>\n\n${sections}\n\n</details>`;

            const template = [
              marker,
              '## Pull request changelog',
              '',
              '<!-- Fill in the changelog under each product area this PR affects.',
              '     Empty sections are ignored. Leave a product collapsed/empty',
              '     if it doesn\'t apply. -->',
              '',
              productBlock('App'),
              '',
              productBlock('Website'),
              '',
              productBlock('Hosting'),
            ].join('\n');

            // Resolve PR number from event or workflow_dispatch input
            const prNumber = context.payload.pull_request?.number
              ?? parseInt('${{ github.event.inputs.pr_number }}', 10);

            if (!prNumber || isNaN(prNumber)) {
              core.setFailed('Could not determine PR number');
              return;
            }

            // Get PR details (need base ref for child PR detection)
            const { data: pr } = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: prNumber,
            });

            // Check if bot comment already exists
            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
            });

            const existingComment = comments.find(c => c.body.includes(marker));
            if (existingComment) {
              core.info('Changelog comment already exists, skipping');
              return;
            }

            // Post the template comment
            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
              body: template,
            });

            core.info(`Posted changelog comment on PR #${prNumber}`);

            // Detect child PR: check if this PR's base branch is another open PR's head branch
            const baseRef = pr.base.ref;

            if (baseRef === 'main' || baseRef === 'prod') {
              return;
            }

            // Look for a parent PR whose head branch matches our base branch
            const { data: candidatePRs } = await github.rest.pulls.list({
              owner: context.repo.owner,
              repo: context.repo.repo,
              state: 'open',
              head: `${context.repo.owner}:${baseRef}`,
            });

            if (candidatePRs.length === 0) {
              return;
            }

            const parentPR = candidatePRs[0];
            core.info(`Detected parent PR #${parentPR.number} for child PR #${prNumber}`);

            // Add admonition to child PR's changelog comment
            const { data: childComments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
            });

            const childChangelogComment = childComments.find(c => c.body.includes(marker));
            if (childChangelogComment && !childChangelogComment.body.includes(mergedMarker)) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: childChangelogComment.id,
                body: `${mergedMarker}\n> [!NOTE]\n> This changelog has been merged into the changelog for #${parentPR.number}\n\n${childChangelogComment.body}`,
              });
            }