screenshot-changes.yml

name: Screenshot change tracker

on:
  pull_request:
    types: [opened, synchronize]
    paths:
      - '**/images/**'
      - 'pages/assets/**'
      - '**/guide.en-gb.md'

permissions:
  pull-requests: write

jobs:
  check:
    runs-on: ubuntu-latest
    steps:
      - name: Detect screenshot changes
        uses: actions/github-script@v8
        with:
          script: |
            const MARKER = '<!-- screenshot-change-tracker -->';
            const IMAGE_EXT = /\.(png|jpe?g|gif|svg|webp)$/i;
            const IMG_LINK = /!\[.*?\]\(|<img\s/;

            // Get all changed files in the PR
            const files = [];
            for (let page = 1; ; page++) {
              const { data } = await github.rest.pulls.listFiles({
                owner: context.repo.owner,
                repo: context.repo.repo,
                pull_number: context.issue.number,
                per_page: 100,
                page
              });
              files.push(...data);
              if (data.length < 100) break;
            }

            // 1. Image files changed (in images/ dirs or pages/assets/)
            const imageFiles = files
              .filter(f => IMAGE_EXT.test(f.filename) &&
                (f.filename.includes('/images/') || f.filename.startsWith('pages/assets/')))
              .map(f => `| \`${f.filename}\` | ${f.status} |`);

            // 2. Image link changes in guide.en-gb.md files
            const guidesWithImgChanges = [];
            for (const f of files) {
              if (!f.filename.endsWith('/guide.en-gb.md') || !f.patch) continue;
              const changedImgLines = f.patch
                .split('\n')
                .filter(line => /^[+-]/.test(line) && !/^[+-]{3}/.test(line))
                .filter(line => IMG_LINK.test(line));
              if (changedImgLines.length > 0) {
                guidesWithImgChanges.push({
                  file: f.filename,
                  lines: changedImgLines.map(l => `\`${l.substring(0, 120)}\``)
                });
              }
            }

            // Nothing to report
            if (imageFiles.length === 0 && guidesWithImgChanges.length === 0) return;

            // Build comment body
            const sections = [MARKER, '## Screenshot Changes Detected\n'];

            if (imageFiles.length > 0) {
              sections.push(
                `### Image files (${imageFiles.length})\n`,
                '| File | Status |',
                '|------|--------|',
                ...imageFiles,
                ''
              );
            }

            if (guidesWithImgChanges.length > 0) {
              sections.push(
                `### Image link changes in guides (${guidesWithImgChanges.length} file(s))\n`
              );
              for (const g of guidesWithImgChanges) {
                sections.push(`**${g.file}**`);
                sections.push(...g.lines.map(l => `- ${l}`), '');
              }
            }

            const body = sections.join('\n');

            // Find existing comment (create once, update thereafter)
            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number
            });
            const existing = comments.find(c =>
              c.user.type === 'Bot' && c.body.includes(MARKER)
            );

            if (existing) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id,
                body
              });
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body
              });
            }