name: Bundle Size

on:
  pull_request:
    branches:
      - main

permissions:
  pull-requests: write

jobs:
  size:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout PR
        uses: actions/checkout@v5

      - name: Setup pnpm
        uses: pnpm/action-setup@v4

      - name: Setup Node.js
        uses: actions/setup-node@v5
        with:
          node-version: 22
          cache: pnpm

      - name: Install and build PR
        run: pnpm install && pnpm build:packages

      - name: Measure PR bundle size
        run: pnpm -w exec size-limit --json > /tmp/pr-size.json

      - name: Measure base bundle size
        run: |
          git fetch origin ${{ github.base_ref }} --depth=1
          git checkout -f FETCH_HEAD

          pnpm install

          if [ -f .size-limit.json ]; then
            pnpm build:packages
            pnpm -w exec size-limit --json > /tmp/base-size.json
          else
            echo '[]' > /tmp/base-size.json
          fi

      - name: Report
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');

            const pr = JSON.parse(fs.readFileSync('/tmp/pr-size.json', 'utf8'));
            const base = JSON.parse(fs.readFileSync('/tmp/base-size.json', 'utf8'));

            const baseMap = Object.fromEntries(base.map(e => [e.name, e.size]));

            function formatBytes(bytes) {
              if (bytes < 1024) return `${bytes} B`;
              return `${(bytes / 1024).toFixed(2)} kB`;
            }

            function formatDelta(current, previous) {
              if (previous === undefined) return '—';
              const diff = current - previous;
              if (diff === 0) return '0 B';
              const sign = diff > 0 ? '+' : '';
              const pct = ((diff / previous) * 100).toFixed(1);
              return `${sign}${formatBytes(diff)} (${sign}${pct}%)`;
            }

            function statusIcon(current, previous) {
              if (previous === undefined) return '🆕';
              const diff = current - previous;
              if (diff === 0) return '✅';
              if (diff < 0) return '🔽';
              const pct = (diff / previous) * 100;
              return pct > 10 ? '🔴' : '🔺';
            }

            const rows = pr.map(entry => {
              const prev = baseMap[entry.name];
              return `| ${entry.name} | ${prev !== undefined ? formatBytes(prev) : '—'} | ${formatBytes(entry.size)} | ${formatDelta(entry.size, prev)} | ${statusIcon(entry.size, prev)} |`;
            });

            const total = pr.reduce((sum, e) => sum + e.size, 0);
            const baseTotal = base.reduce((sum, e) => sum + e.size, 0);

            const marker = '<!-- bundle-size-report -->';
            const body = [
              marker,
              '### 📦 Bundle Size Report',
              '',
              '| Package | Base | PR | Delta | |',
              '|---|---|---|---|---|',
              ...rows,
              `| **Total** | **${base.length ? formatBytes(baseTotal) : '—'}** | **${formatBytes(total)}** | **${base.length ? formatDelta(total, baseTotal) : '—'}** | |`,
              '',
              '<details>',
              '<summary>ℹ️ How to interpret</summary>',
              '',
              'Sizes are minified + brotli compressed, measured via [size-limit](https://github.com/ai/size-limit) with esbuild tree-shaking.',
              '',
              '| Icon | Meaning |',
              '|---|---|',
              '| ✅ | No change |',
              '| 🔺 | Size increased ≤ 10% |',
              '| 🔴 | Size increased > 10% |',
              '| 🔽 | Size decreased |',
              '| 🆕 | New entry (no baseline) |',
              '',
              'Run `pnpm size` locally to check current sizes.',
              '</details>',
            ].join('\n');

            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.body?.startsWith(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,
              });
            }