wp-contextual-help.php

<?php
/*
Plugin Name: WP Contextual Help
Description: Allows a developer to easily extend the contextual help dropdown content area in WordPress
Version: 1.0.2
Author: kevinlangleyjr
Plugin URI: http://voceplatforms.com
*/

if( !class_exists( 'WP_Contextual_Help' ) ){

	class WP_Contextual_Help {

		static $help_docs_dir = array();
		static $help_docs_img_url = array();
		static $tabs = array();
		static $tabs_by_page = array();

		/**
		 * Initialize plugin
		 * @return void
		 */
		static function init(){
			global $pagenow;

			self::$help_docs_dir[] = get_template_directory() . '/includes/help-docs';
			self::$help_docs_img_url[] = get_template_directory_uri() . '/includes/help-docs/img';
			self::$help_docs_dir = apply_filters( 'wp_contextual_help_docs_dir', self::$help_docs_dir );
			self::$help_docs_img_url = apply_filters( 'wp_contextual_help_docs_url', self::$help_docs_img_url );

			foreach( self::$tabs as $tab ){
				foreach( (array) $tab['page'] as $page ){
					self::$tabs_by_page[ $page ][] = $tab;
					if ( count( self::$tabs_by_page[ $page ] ) < 2 ) {
						add_action( 'load-' . $page, array( __CLASS__, 'add_tab_to_screen' ) );
					}
				}
			}
		}

		/**
		 * Registers new contextual help tab
		 * @param string $page      Page path that is compared to the pagenow global
		 * @param string $id        Help tab id
		 * @param string $title     Help tab title
		 * @param array  $args      Arguments for the tab
		 */
		static function register_tab( $id, $title, $args ) {
			if( empty( $args['page'] ) ){
				_doing_it_wrong( __METHOD__, 'Cannot register help tab without specifying the page or pages to display it on', '0.0.1' );
			}

			$page = $args['page'];
			unset( $args['page'] );

			self::$tabs[$id] = array(
				'page' => $page,
				'id' => $id,
				'title' => $title,
				'args' => $args
			);
		}

		/**
		 * Adds tabs to screen on 'load-' . $tab['page']
		 *
		 * Loops through all tabs and adds them on the appropriate screen
		 */
		static function add_tab_to_screen() {
			$id = substr( current_action(), 5 );
			$tabs = self::$tabs_by_page[ $id ];
			foreach ( ( array ) $tabs as $tab ) {
				// if post type arg is set, check the post type - if not same return
				if ( isset( $tab[ 'args' ][ 'post_type' ] ) ) {
					if ( !self::is_current_post_type( $tab ) ) {
						continue;
					}
				}

				$callback = !empty( $tab[ 'args' ][ 'callback' ] ) ? $tab[ 'args' ][ 'callback' ] : array( __CLASS__, 'echo_tab_html' );

				get_current_screen()->add_help_tab( array(
					'id' => $tab[ 'id' ],
					'title' => $tab[ 'title' ],
					'callback' => $callback
				) );
			}
		}

		/**
		 * Loads the tab html
		 * @param  WP_Screen $screen     Screen that the help tab is being added to
		 * @param  array     $screen_tab Screen tab array
		 * @return void
		 */
		static function echo_tab_html( $screen, $screen_tab ){
			$content = '';
			$tab = self::$tabs[ $screen_tab[ 'id' ] ];
			$file_name = !empty( $tab[ 'file' ] ) ? $tab[ 'file' ] : $tab[ 'id' ] . '.html';
			for( $i = 0; $i < count(self::$help_docs_dir); $i++ ){
				$file = self::$help_docs_dir[$i] . DIRECTORY_SEPARATOR . $file_name;

				if ( file_exists( $file ) ) {
					if ( !empty( $tab[ 'args' ][ 'wpautop' ] ) ) {
						$content = wpautop( file_get_contents( $file ) );
					} else {
						$content = file_get_contents( $file );
					}
					break;
				}
			}
			if ( empty( $content ) ) {
				$content = 'The provided HTML file is invalid or not founded.';
			}

			$content = str_replace( '{WP_HELP_IMG_URL}', self::$help_docs_img_url[$i], $content );

			echo $content;
		}

		/**
		 * Checks to see if the current screen's post type is equivelent to the post type parameter provided when registering help tab
		 * @param  array   $tab
		 * @return boolean
		 */
		static function is_current_post_type( $tab ){
			$screen = get_current_screen();
			$current_post_type = isset( $screen->post_type ) ? $screen->post_type : false;

			if( !empty( $current_post_type ) && isset( $tab['args']['post_type'] ) ){
				if( is_array( $tab['args']['post_type'] ) ){
					return in_array( $current_post_type, $tab['args']['post_type'] );
				} else {
					return (bool) ( $tab['args']['post_type'] == $current_post_type );
				}
			}

			return false;
		}
	}
	add_action( 'init', array( 'WP_Contextual_Help', 'init' ), 99 );

}