<?php 

/**
 * Wrapper for class method that will check if user is registered member
 *
 * @return	boolean
 */
function is_member(){
	return WP_Members_Only::is_member();
}

class WP_Members_Only {
  var $allowed_post_types = array( 'post', 'page', 'attachment' );

	function __construct($args = null) {
		// do any processing of data here and setup all filters and actions
		if ( is_admin() ) {
			add_filter('wp_get_nav_menu_items', array(&$this, 'nav_item_filter'));
			add_action('get_header', array(&$this, 'is_members_only'));
			add_filter('post_type_link', array(&$this, 'the_download_link'), 10, 2);
			add_filter('the_permalink', array(&$this, 'the_download_link'));
		}		
	}

	/**
	 * Check if user is registered member
	 *
	 * @return	boolean
	 */
	public static function is_member(){
		return current_user_can('is_approved_member');
	}

	/**
	 * Filter nav menu items that are members_only.
	 *
	 * @return	array
	 */
	public function nav_item_filter($items){
		foreach($items as $key => $post) $items[$key]->url = the_download_link($post->url, $post->object_id);
		return $items;
	}

	/**
	 * Check if post if members only content and redirects if necessary.
	 *
	 * @return	bool
	 */
	public function is_members_only() {
		global $post;
	
		$post_check = $this->allowed_post_types; // desired post types to restrict
	
		if ( !in_array(get_post_type(), $post_check) ) return;
		if ( !is_member() && !headers_sent() && (is_single() || is_page())) {
			// not an approved or logged in user
			if ( (boolean)$post->_members_only ) {
				wp_redirect( home_url() );
				exit;
			}
		} else {
			return (boolean)$post->_members_only;
		}
	
	}

	/**
	 * Filter the permalink based on the post type.
	 *
	 * @return	bool
	 */
	function the_download_link($url, $post = null) {
		if ( is_null($post)) {
			global $post;
		}
		$members_only = is_object($post) ? $post->_members_only : get_post_meta($post, "_members_only", true);
		if ($members_only && !is_member()) return "#login";
		$post_type = get_post_type( $post );
		switch( $post_type ) {
			case "attachment": 
				$has_txt_link = ($post->post_mime_type == "text/plain");
				$attachment_link = wp_get_attachment_url($post->ID);
				return $has_txt_link ? get_data($attachment_link) : $attachment_link; 
				break;
			default: return $url;
		}
	}
}

new WP_Members_Only();