name: Check file formatting

on:
  push:
    branches:
      - main
  pull_request:
    paths:
      - "**/*.sh"

jobs:
  shfmt:
    name: Shell scripts
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write

    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: ${{ github.event_name == 'pull_request' && 2 || 0 }}

      - name: Set up Go
        uses: actions/setup-go@v5

      - name: Install shfmt
        run: |
          go install mvdan.cc/sh/v3/cmd/shfmt@latest
          echo "$GOPATH/bin" >> $GITHUB_PATH

      - name: Get changed files
        id: changed-files
        run: |
          if ${{ github.event_name == 'pull_request' }}; then
              echo "files=$(git diff --name-only -r HEAD^1 HEAD | grep '\.sh$' | xargs)" >> $GITHUB_OUTPUT
          else
              echo "files=$(git diff --name-only ${{ github.event.before }} ${{ github.event.after }} | grep '\.sh$' | xargs)" >> $GITHUB_OUTPUT
          fi

      - name: Run shfmt
        id: shfmt
        run: |
          set +e

          shfmt_output=$(shfmt -d ${{ steps.changed-files.outputs.files }})
          if [[ $? -eq 0 ]]; then
            exit 0
          else
            echo "diff=\"$(echo -n "$shfmt_output" | base64 -w 0)\"" >> $GITHUB_OUTPUT
            echo -e $shfmt_output
            exit 1
          fi

      - name: Post comment with results
        if: always() && github.event_name == 'pull_request'
        uses: actions/github-script@v6
        with:
          script: |
            const result = '${{ job.status }}' === 'success' ? 'success' : 'failure';
            const diff = Buffer.from('${{ steps.shfmt.outputs.diff }}', 'base64').toString();
            const issueNumber = context.payload.pull_request ? context.payload.pull_request.number : null;
            const commentIdentifier = '<!-- shfmt-comment -->';
            let newCommentBody;
            if (result === 'failure') {
              newCommentBody = `:x: We found issues in the formatting of the following changed files:\n\n\`\`\`diff\n${diff}\n\`\`\`\n${commentIdentifier}`;
            } else {
              newCommentBody = `:rocket: All changed shell scripts are formatted correctly! \n ${commentIdentifier}`;
            }

            if (issueNumber) {
              const { data: comments } = await github.rest.issues.listComments({
                ...context.repo,
                issue_number: issueNumber
              });

              const existingComment = comments.find(comment => comment.body.includes(commentIdentifier));

              if (existingComment) {
                await github.rest.issues.updateComment({
                  ...context.repo,
                  comment_id: existingComment.id,
                  body: newCommentBody
                });
              } else {
                await github.rest.issues.createComment({
                  ...context.repo,
                  issue_number: issueNumber,
                  body: newCommentBody
                });
              }
            }