unused-imports.yml

name: CI / Unused Imports Check

on:
  pull_request:
    branches: [main]
  workflow_dispatch:

jobs:
  check-unused-imports:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: write

    steps:
      - name: Checkout PR code
        uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - name: Setup Zig
        uses: mlugg/setup-zig@v2
        with:
          version: 0.15.1

      - name: Build zigimports
        run: |
          git clone --depth 1 https://github.com/tusharsadhwani/zigimports.git /tmp/zigimports
          cd /tmp/zigimports
          zig build --release=safe
          # Binary is named zigimports-<arch>-<os>, find and symlink it
          ln -s /tmp/zigimports/zig-out/bin/zigimports-* /tmp/zigimports/zig-out/bin/zigimports

      - name: Get changed Zig files
        id: changed-files
        run: |
          FILES=$(git diff --name-only --diff-filter=d ${{ github.event.pull_request.base.sha }} ${{ github.event.pull_request.head.sha }} | grep '\.zig$' || true)
          echo "files<<EOF" >> $GITHUB_OUTPUT
          echo "$FILES" >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT

      - name: Check for unused imports
        id: check
        run: |
          RESULTS=""
          echo "${{ steps.changed-files.outputs.files }}" | while read file; do
            if [ -n "$file" ] && [ -f "$file" ]; then
              /tmp/zigimports/zig-out/bin/zigimports "$file" 2>&1 || true
            fi
          done | tee unused_imports.txt

          # Set output for later steps
          if grep -q "is unused" unused_imports.txt 2>/dev/null; then
            echo "has_issues=true" >> $GITHUB_OUTPUT
          else
            echo "has_issues=false" >> $GITHUB_OUTPUT
          fi

      - name: Post PR comment
        if: steps.check.outputs.has_issues == 'true'
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');

            const content = fs.readFileSync('unused_imports.txt', 'utf8').trim();
            const lines = content.split('\n').filter(l => l.includes('is unused'));

            if (lines.length === 0) return;

            // Check for existing comment and update it
            const marker = '<!-- unused-imports-check -->';
            const comments = await github.paginate(
              github.rest.issues.listComments,
              {
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number
              }
            );

            const existing = comments.find(c =>
              c.user.login === 'github-actions[bot]' &&
              c.body.includes(marker)
            );

            let body = '## ⚠️ Unused Imports Found\n\n';
            body += '```\n' + lines.join('\n') + '\n```\n\n';
            body += 'Run `zigimports --fix <file>` locally to automatically remove unused imports.\n\n';
            body += marker;

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

      - name: Remove comment if no issues
        if: steps.check.outputs.has_issues == 'false'
        uses: actions/github-script@v7
        with:
          script: |
            const marker = '<!-- unused-imports-check -->';
            const comments = await github.paginate(
              github.rest.issues.listComments,
              {
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number
              }
            );

            const existing = comments.find(c =>
              c.user.login === 'github-actions[bot]' &&
              c.body.includes(marker)
            );

            if (existing) {
              await github.rest.issues.deleteComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id
              });
            }