Controlling BuddyPress Private Messages

plugin.php

<?php

/**
 * Plugin Name: Control Private Messages in BuddyPress
 * Author: Igor Benic
 * Author URI: http://www.ibenic.com
 * Version: 1.0
 */

if( ! defined( 'ABSPATH' ) ) {
	return;
}

if( class_exists( 'BuddyPress' ) ) {
	// We are sure that BuddyPress has been activated.	
}

plugin2.php

<?php

// ...

add_filter( 'bp_get_send_message_button', 'control_private_message_button' );
/**
 * Returns HTML for the Private Message Button or false
 * @param  string $html 
 * @return mixed       
 */
function control_private_message_button( $html ) {

	if( ! this_user_can_create_private_messages() ) {
		return false;
	}

	return $html;
}

plugin3.php

<?php

// ...

add_filter( 'messages_template_compose', 'control_display_of_message_form' );

/**
 * Removes the Form if can't use it
 * @param  string $template 
 * @return mixed           
 */
function control_display_of_message_form( $template ) {

	if( ! this_user_can_create_private_messages() ) {
		return false;
	}

	return $template;
}

plugin4.php

<?php

// ...

add_action( 'messages_message_before_save', 'control_sending_of_private_message' );

/**
 * Control the message from Private Messages before beign saved/sent
 * @param  BP_Messages_Message $message_object 
 * @return void
 */
function control_sending_of_private_message( $message_object ) {

	$sender_id = $message_object->sender_id;

	if( ! user_can_create_private_messages( $sender_id ) ) {
		$message_object->recipients = false;
	}
}

plugin5.php

<?php

// ...

add_action( 'bp_messages_setup_nav', 'control_parts_of_private_messages' );

/**
 * Control Parts of Private Messages
 * @return void 
 */
function control_parts_of_private_messages() {

	if( ! this_user_can_create_private_messages() ) {
		// Remove Compose
		bp_core_remove_subnav_item( 'messages', 'compose' );
	}

	if( ! this_user_can_see_sent_private_messages() ) {
		// Remove Sent
		bp_core_remove_subnav_item( 'messages', 'sent' );
	}

	if( ! this_user_can_see_sent_private_messages() ) {
		// Remove Sent
		bp_core_remove_subnav_item( 'messages', 'sent' );
	}

	if( ! this_user_can_see_starred_private_messages() ) {
		// Remove Starred
		bp_core_remove_subnav_item( 'messages', bp_get_messages_starred_slug() );
	}

	if( ! this_user_can_use_messages() ) {
		bp_core_remove_nav_item( bp_get_messages_slug() );
	}

}