ExpressionEngine extension to prevent members of a specific member group from deleting members in some other member group. http://expressionengine.stackexchange.com/a/18208/22

ext.protected_member_groups.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/**
 * ExpressionEngine - by EllisLab
 *
 * @package		ExpressionEngine
 * @author		ExpressionEngine Dev Team
 * @copyright	Copyright (c) 2003 - 2011, EllisLab, Inc.
 * @license		http://expressionengine.com/user_guide/license.html
 * @link		http://expressionengine.com
 * @since		Version 2.0
 * @filesource
 */
 
// ------------------------------------------------------------------------

/**
 * Protected Member Groups Extension
 *
 * @package		ExpressionEngine
 * @subpackage	Addons
 * @category	Extension
 * @author		Example Only
 * @link		http://example.com
 */

class Protected_member_groups_ext {
	
	public $settings 		= array();
	public $description		= 'Prevent members of a specific member group from deleting members in some other member group.';
	public $docs_url		= '';
	public $name			= 'Protected Member Groups';
	public $settings_exist	= 'n';
	public $version			= '1.0';
	
	private $EE;
	
	/**
	 * Constructor
	 *
	 * @param 	mixed	Settings array or empty string if none exist.
	 */
	public function __construct($settings = '')
	{
		$this->EE =& get_instance();
		$this->settings = $settings;
	}// ----------------------------------------------------------------------
	
	/**
	 * Activate Extension
	 *
	 * This function enters the extension into the exp_extensions table
	 *
	 * @see http://codeigniter.com/user_guide/database/index.html for
	 * more information on the db class.
	 *
	 * @return void
	 */
	public function activate_extension()
	{
		// Setup custom settings in this array.
		$this->settings = array();
		
		$data = array(
			'class'		=> __CLASS__,
			'method'	=> 'member_delete',
			'hook'		=> 'member_delete',
			'settings'	=> serialize($this->settings),
			'version'	=> $this->version,
			'enabled'	=> 'y'
		);

		$this->EE->db->insert('extensions', $data);			
		
	}	

	// ----------------------------------------------------------------------
	
	/**
	 * member_delete
	 *
	 * @param 
	 * @return 
	 */
	public function member_delete($member_ids)
	{

		// Array of member group_ids for which to restrict delete permissions
		$supervised_member_groups = array('7');

		// Array of member group_ids for wich deletion is disallowed
		$protected_member_groups = array('5','6');

		// The group_id of the current admin
		$current_admin_group_id = ee()->session->userdata('group_id');

		// Check if the current admin is in the supervised member group
		if (in_array($current_admin_group_id, $supervised_member_groups))
		{
			// Generate an array of group_ids to which the deleted member(s) belong(s)
			$member_groups = array();
			$query = ee()->db->select('group_id')->where_in('member_id', $member_ids)->get('members');
			foreach ($query->result() as $row) 
			{
				array_push($member_groups, $row->group_id);
			}
			
			// Check if the deleted member belongs to one of the protected member groups 
			// and if so throw an error
			$overlap = count(array_intersect($protected_member_groups, $member_groups));			
			if ($overlap) show_error('You are attempting to delete a member from a protected group. Please adjust your selection.');
		}

		return $member_ids;
	}

	// ----------------------------------------------------------------------

	/**
	 * Disable Extension
	 *
	 * This method removes information from the exp_extensions table
	 *
	 * @return void
	 */
	function disable_extension()
	{
		$this->EE->db->where('class', __CLASS__);
		$this->EE->db->delete('extensions');
	}

	// ----------------------------------------------------------------------

	/**
	 * Update Extension
	 *
	 * This function performs any necessary db updates when the extension
	 * page is visited
	 *
	 * @return 	mixed	void on update / false if none
	 */
	function update_extension($current = '')
	{
		if ($current == '' OR $current == $this->version)
		{
			return FALSE;
		}
	}	
	
	// ----------------------------------------------------------------------
}

/* End of file ext.protected_member_groups.php */
/* Location: /system/expressionengine/third_party/protected_member_groups/ext.protected_member_groups.php */