Restrict users from editing post based on the age of the post

Question

In Wordpress, how can I restrict users (based on Capabilities) from editing their published posts after a custom amount of time.

For instance, a user that can publish_posts (authors) can not edit a their post if it is older than 3 days, and a user that can moderate_comments (editors) can not edit any posts that are older than 20 days. Obviously, admins can edit anytime.

How is such thing possible?

Answer 1

This is the duplicate of a question on wordpress.stackexchange.com. I've copied my answer below.

I took the example code from the Wordpress user_has_cap filter codex page and modified it. Add this code to your theme functions.php:

function restrict_editing_old_posts( $allcaps, $cap, $args ) {

  // Bail out if we're not asking to edit a post ...
  if( 'edit_post' != $args[0]
    // ... or user is admin
    || ! empty( $allcaps['manage_options'] )
    // ... or user already cannot edit the post
    || empty( $allcaps['edit_posts'] ) )
      return $allcaps;

  // Load the post data:  
  $post = get_post( $args[2] );

  // Bail out if the post isn't published:    
  if( 'publish' != $post->post_status )
      return $allcaps;

  $post_date = strtotime( $post->post_date );
  //if post is older than 30 days ... 
  if( $post_date < strtotime( '-30 days' )
    // ... or if older than 4 days and user is not Editor
    || ( empty($allcaps['moderate_comments']) 
    && $post_date < strtotime('-4 days') ) ) {
      $allcaps[$cap[0]] = FALSE;  
  }
  return $allcaps;
}
add_filter( 'user_has_cap', 'restrict_editing_old_posts', 10, 3 );