Post duplicator component

post_duplicator.php

<?php
/**
 * Post duplicator component.
 *
 * @author Bhaskar K C
 * @since 24/05/2017
 */
class Component_post_duplicator extends Component {
	
	/**
	 * duplicator version
	 */
	const VERSION = '1.0';
	
	/**
	 * Singleton instance. This is compulsory.
	 *
	 * @var Component
	 */
	protected static $instance = null;

	/**
	 * comma separated list of post types to which duplicator is applied
	 * @var array
	 */
	private $post_types;
	
	/**
	 * whether to skip duplicating taxonomies from original post
	 * @var boolean
	 */
	private $skip_taxonomies;

	/**
	 * whether to skip duplicating postmeta from original post
	 * @var boolean
	 */
	private $skip_postmeta;

	/**
	 * clone nonce string
	 */
	const CLONE_NONCE = 'dm_form_clone_nonce';
	
	/**
	 * clone nonce action
	 */
	const CLONE_ACTION = 'dm_form_clone_action';
	
	/**
	 * duplicate post status
	 */
	const POST_STATUS = 'draft';
	

	function __construct() {
		
		if ( defined( 'DM_DUPLICATOR_POST_TYPES' ) ) {
			$this->post_types = DM_DUPLICATOR_POST_TYPES;
		}

		if ( defined( 'DM_DUPLICATOR_SKIP_TAXONOMIES' ) ) {
			$this->skip_taxonomies = DM_DUPLICATOR_SKIP_TAXONOMIES;
		}

		if ( defined( 'DM_DUPLICATOR_SKIP_POSTMETA' ) ) {
			$this->skip_postmeta = DM_DUPLICATOR_SKIP_POSTMETA;
		}

	}

	public static function get_instance() {
		
		if ( is_null( self::$instance ) ) {
			self::$instance = new self;
			self::$instance->init();
		}

		return self::$instance;
	}

	private function init() {
		
		if ( $this->add_post_types() ) {

			add_filter( 'post_row_actions', array( $this, 'update_post_row_actions' ), 10, 2 );

			add_action( 'admin_action_' . $this::CLONE_ACTION, array( $this, 'clone_the_form_post' ) ) ;
		}
	}

	/**
	 * Post types to have duplicate functionality.
	 * @param string $post_type 
	 */
	protected function add_post_types() {
		
		$post_types = array_map( 'trim', explode( ',', $this->post_types ) );

		foreach( $post_types as $post_type ) {
		
			if ( post_type_exists( $post_type ) ) {
				$this->post_type[] = $post_type;
			}
		}

		return ( ! empty( $this->post_type ) ? true : false );
	}

	/**
	 * Updates post quick edit row options
	 * @param  array $actions list of actions
	 * @param  WP_Post $post   post obj.
	 * @return array
	 */
	function update_post_row_actions( $actions, $post ) {
	    // Check for your post type.
	    if ( in_array( $post->post_type, $this->post_type ) ) {

			$clone_nonce_url = wp_nonce_url( 
				admin_url( 'edit.php?action=' . $this::CLONE_ACTION . '&post='.$post->ID),
				basename( __FILE__ ),
				$this::CLONE_NONCE 
			);

			$actions['clone'] = "<a href='{$clone_nonce_url}'>Duplicate</a>";
	    }

	    return $actions;
	}


	/**
	 * Clones form post id
	 */
	function clone_the_form_post() {

		if ( ! ( isset( $_REQUEST['post'] ) || ( isset( $_REQUEST['action'] ) && $this::CLONE_ACTION == $_REQUEST['action'] ) ) ) {
			wp_die( 'Form post is not supplied.' );
		}

		// nonce verification.
		if ( ! isset( $_REQUEST[ $this::CLONE_NONCE ] ) || ! wp_verify_nonce( $_REQUEST[ $this::CLONE_NONCE ], basename( __FILE__ ) ) ) {
			wp_die( 'nonce failed');
			return;
		}

		$post_id = absint( $_REQUEST['post'] );

		$post = get_post( $post_id );

		if ( ! $post instanceof WP_Post ) {
			wp_die( 'Post does not exist.' );
		}

		$args = array(
			'post_type'      => $post->post_type,
			'post_author'    => $post->post_author,
			'post_title'     => $post->post_title,
			'post_name'      => $post->post_name,
			'post_content'   => $post->post_content,
			'post_excerpt'   => $post->post_excerpt,
			'post_parent'    => $post->post_parent,
			'post_status'    => $this::POST_STATUS,
			'comment_status' => $post->comment_status,
			'ping_status'    => $post->ping_status,
			'post_password'  => $post->post_password,
			'to_ping'        => $post->to_ping,
			'menu_order'     => $post->menu_order
		);

		$cloned_post_id = wp_insert_post( $args );

		if ( false == $cloned_post_id ) {
			wp_die( 'Duplicate post was not created. Try again.' );
		}

		/**
		 * Import taxonomies 
		 */
		if ( false == $this->skip_taxonomies ) {
		
			$taxonomies = get_object_taxonomies( $post->post_type );

			foreach ( $taxonomies as $taxonomy ) {
				$post_terms = wp_get_object_terms( $post_id, $taxonomy, array('fields' => 'slugs') );
				wp_set_object_terms( $cloned_post_id, $post_terms, $taxonomy, false );
			}
		}

		/**
		 * Import postmeta
		 */
		if ( false == $this->skip_postmeta ) {
			
			$postmeta = get_post_custom( $post_id );

			// $skip_meta = array( 'form_fields', 'form_settings' );
			
			foreach( $postmeta as $meta_key=>$value ) {
				
				// if ( in_array( $meta_key, $skip_meta ) ) {
				// 	continue;
				// }

				update_post_meta( $cloned_post_id, $meta_key, maybe_unserialize( $value[0] ) );
			}
		}

		wp_redirect( admin_url( 'edit.php?post_type=' . $post->post_type ) );
		exit;

	}
}