laracan

class Ability implements AbilityContract {

    public function initialize($user, Closure $can)
    {
        $user = $user ?: new App\User;

        // NOTE: Laracan does not provide any roles behavior! Assume that some
        // package already installed for this, like Entrust
        if ($user->hasRole('admin')) {

            // Admin can edit posts and comments unconditionally
            $can('edit', 'Post');
            $can('edit', 'Comment');

            return;
        }

        // User can edit a post only if he is its author
        $can('edit', 'Post', ['author_id' => $user->getKey()]);

        $can('edit', 'Comment', function($comment) use ($user)
        {
            // User can edit a comment only if he is its author
            // and comment is not older than 15 minutes
            return (
                $comment->author_id == $user->getKey() &&
                $comment->created_at >= Carbon::now()->subMinutes(15)
            );
        });

    }
}

class EditPostRequest {

    public function rules()
    {
        // ...
    }

    public function authorize()
    {
        $post = Post::find( $this->route('post') );

        return can('edit', $post);
    }

}

@foreach($post->comments as $comment)

<div class="comment">

    <div class="comment-body">{{ $comment->body }}</div>

    @can('edit', $comment)

        <div class="comment-footer">
            <a href="{{ route('comment.edit', $comment) }}">Edit</a>
        </div>

    @endcan

    </div>

</div>

@endforeach

@foreach($post->comments as $comment)

<div class="comment">

    <div class="comment-body">{{ $comment->body }}</div>

    @if( can('edit', $comment) )

        <div class="comment-footer">
            <a href="{{ route('comment.edit', $comment) }}">Edit</a>
        </div>

    @endif

    </div>

</div>

@endforeach