<?php
/**
 * Plugin Name.
 *
 * @package   Plugin_Name\Admin
 * @author    Your Name <email@example.com>
 * @license   GPL-2.0+
 * @link      http://example.com
 * @copyright 2013 Your Name or Company Name
 */

/**
 * Plugin Admin class.
 *
 * TODO: Rename this class to a proper name for your plugin.
 *
 * @package Plugin_Name_Admin
 * @author  Your Name <email@example.com>
 */
class Plugin_Name_Admin {

	/**
	 * Instance of this class.
	 *
	 * @since    1.0.0
	 *
	 * @var      object
	 */
	protected static $instance = null;

	/**
	 * Slug of the plugin screen.
	 *
	 * @since    1.0.0
	 *
	 * @var      string
	 */
	protected $plugin_screen_hook_suffix = null;

	/**
	 * Initialize the plugin by loading admin scripts & styles and adding a settings page and menu.
	 *
	 * @since     1.0.0
	 */
	private function __construct() {

		// Call $plugin_slug from initial plugin class. TODO: Rename "Plugin_Name" to the name of your initial plugin class
		$plugin = Plugin_Name::get_instance();
		$this->plugin_slug = $plugin->get_plugin_slug();

		// Load admin style sheet and JavaScript.
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_admin_styles' ) );
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_admin_scripts' ) );

		// Add the options page and menu item.
		add_action( 'admin_menu', array( $this, 'add_plugin_admin_menu' ) );

		// Add an action link pointing to the options page. TODO: Rename "plugin-name.php" to the name your plugin
		$plugin_basename = plugin_basename( plugin_dir_path( __FILE__ ) . 'plugin-name.php' );
		add_filter( 'plugin_action_links_' . $plugin_basename, array( $this, 'add_action_links' ) );

		// Define custom functionality. Read more about actions and filters: http://codex.wordpress.org/Plugin_API#Hooks.2C_Actions_and_Filters
		add_action( 'TODO', array( $this, 'action_method_name' ) );
		add_filter( 'TODO', array( $this, 'filter_method_name' ) );

	}

	/**
	 * Return an instance of this class.
	 *
	 * @since     1.0.0
	 *
	 * @return    object    A single instance of this class.
	 */
	public static function get_instance() {

		// If the single instance hasn't been set, set it now.
		if ( null == self::$instance ) {
			self::$instance = new self;
		}

		return self::$instance;
	}

	/**
	 * Register and enqueue admin-specific style sheet.
	 *
	 * @since     1.0.0
	 *
	 * @return    null    Return early if no settings page is registered.
	 */
	public function enqueue_admin_styles() {

		if ( ! isset( $this->plugin_screen_hook_suffix ) ) {
			return;
		}

		$screen = get_current_screen();
		if ( $screen->id == $this->plugin_screen_hook_suffix ) {
			wp_enqueue_style( $this->plugin_slug .'-admin-styles', plugins_url( 'css/admin.css', __FILE__ ), array(), Plugin_Name::VERSION );
		}

	}

	/**
	 * Register and enqueue admin-specific JavaScript.
	 *
	 * @since     1.0.0
	 *
	 * @return    null    Return early if no settings page is registered.
	 */
	public function enqueue_admin_scripts() {

		if ( ! isset( $this->plugin_screen_hook_suffix ) ) {
			return;
		}

		$screen = get_current_screen();
		if ( $screen->id == $this->plugin_screen_hook_suffix ) {
			wp_enqueue_script( $this->plugin_slug . '-admin-script', plugins_url( 'js/admin.js', __FILE__ ), array( 'jquery' ), Plugin_Name::VERSION );
		}

	}

	/**
	 * Register the administration menu for this plugin into the WordPress Dashboard menu.
	 *
	 * @since    1.0.0
	 */
	public function add_plugin_admin_menu() {

		/*
		 * Add a settings page for this plugin to the Settings menu.
		 *
		 * NOTE:  Alternative menu locations are available via WordPress administration menu functions.
		 *
		 *        Administration Menus: http://codex.wordpress.org/Administration_Menus
		 *
		 * TODO:
		 *
		 * Change 'Page Title' to the title of your plugin admin page
		 * Change 'Menu Text' to the text for menu item for the plugin settings page
		 * Change 'manage_options' to the capability you see fit (http://codex.wordpress.org/Roles_and_Capabilities)
		 */
		$this->plugin_screen_hook_suffix = add_options_page(
			__( 'Page Title', $this->plugin_slug ),
			__( 'Menu Text', $this->plugin_slug ),
			'manage_options',
			$this->plugin_slug,
			array( $this, 'display_plugin_admin_page' )
		);

	}

	/**
	 * Render the settings page for this plugin.
	 *
	 * @since    1.0.0
	 */
	public function display_plugin_admin_page() {
		include_once( 'views/admin.php' );
	}

	/**
	 * Add settings action link to the plugins page.
	 *
	 * @since    1.0.0
	 */
	public function add_action_links( $links ) {

		return array_merge(
			array(
				'settings' => '<a href="' . admin_url( 'options-general.php?page=' . $this->plugin_slug ) . '">' . __( 'Settings', $this->plugin_slug ) . '</a>'
			),
			$links
		);

	}

	/**
	 * NOTE:  Actions are points in the execution of a page or process
	 *        lifecycle that WordPress fires.
	 *
	 *        WordPress Actions: http://codex.wordpress.org/Plugin_API#Actions
	 *        Action Reference:  http://codex.wordpress.org/Plugin_API/Action_Reference
	 *
	 * @since    1.0.0
	 */
	public function action_method_name() {
		// TODO: Define your action hook callback here
	}

	/**
	 * NOTE:  Filters are points of execution in which WordPress modifies data
	 *        before saving it or sending it to the browser.
	 *
	 *        WordPress Filters: http://codex.wordpress.org/Plugin_API#Filters
	 *        Filter Reference:  http://codex.wordpress.org/Plugin_API/Filter_Reference
	 *
	 * @since    1.0.0
	 */
	public function filter_method_name() {
		// TODO: Define your filter hook callback here
	}

}