class Tribe_Meta_Box {

	protected $_meta_box;
	protected $_fields;

	// Create meta box based on given data
	public function __construct( $meta_box ) {
		// run script only in admin area
		if ( ! is_admin() ) {
			return;
		}

		// assign meta box values to local variables and add it's missed values
		$this->_meta_box = $meta_box;
		// Cast pages to array
		$this->_meta_box['pages'] = (array) $meta_box['pages'];
		$this->_fields = $this->_meta_box['fields'];
		$this->add_missed_values();
		$this->register_scripts_and_styles();

		add_action( 'add_meta_boxes', array( $this, 'add' ) );	// add meta box, using 'add_meta_boxes' for WP 3.0+
		add_action( 'save_post', array( $this, 'save' ) );		// save meta box's data

		// check for some special fields and add needed actions for them
		$this->check_field_upload();
		$this->check_field_color();
		$this->check_field_date();
		$this->check_field_time();

		// load common js, css files
		// must enqueue for all pages as we need js for the media upload, too
		add_action( 'admin_enqueue_scripts', array( __CLASS__, 'js_css' ) );
	}

	public function register_scripts_and_styles() {
		// change '\' to '/' in case using Windows
		$content_dir = str_replace( '\\', '/', WP_CONTENT_DIR );
		$script_dir = str_replace( '\\', '/', dirname( __FILE__ ) );

		// get URL of the directory of current file, this works in both theme or plugin
		$base_url = trailingslashit( str_replace( $content_dir, WP_CONTENT_URL, $script_dir ) );
		$resources_url = apply_filters( 'tribe_apm_resources_url', $base_url . 'resources' );
		$resources_url = trailingslashit( $resources_url );

		wp_register_style( 'tribe-meta-box', $resources_url . 'meta-box.css' );
		wp_register_script( 'tribe-meta-box', $resources_url . 'meta-box.js', array( 'jquery' ), null, true );

		wp_register_style( 'tribe-jquery-ui-css', 'https://ajax.googleapis.com/ajax/libs/jqueryui/' . self::get_jqueryui_ver() . '/themes/base/jquery-ui.css' );
		wp_register_script( 'tribe-jquery-ui', 'https://ajax.googleapis.com/ajax/libs/jqueryui/' . self::get_jqueryui_ver() . '/jquery-ui.min.js', array( 'jquery' ) );
		wp_register_script( 'tribe-timepicker', 'https://github.com/trentrichardson/jQuery-Timepicker-Addon/raw/master/jquery-ui-timepicker-addon.js', array( 'tribe-jquery-ui' ) );
	}

	// Load common js, css files for the script
	public static function js_css() {
		wp_enqueue_script( 'tribe-meta-box' );
		wp_enqueue_style( 'tribe-meta-box' );
	}

	/******************** BEGIN UPLOAD **********************/

	// Check field upload and add needed actions
	public function check_field_upload() {
		if ( ! $this->has_field( 'image' ) && ! $this->has_field( 'file' ) ) {
			return;
		}

		add_action( 'post_edit_form_tag', array( $this, 'add_enctype' ) );				// add data encoding type for file uploading

		// make upload feature works even when custom post type doesn't support 'editor'
		wp_enqueue_script( 'media-upload' );
		add_thickbox();
		wp_enqueue_script( 'jquery-ui-core' );
		wp_enqueue_script( 'jquery-ui-sortable' );

		add_filter( 'media_upload_gallery', array( $this, 'insert_images' ) );			// process adding multiple images to image meta field
		add_filter( 'media_upload_library', array( $this, 'insert_images' ) );
		add_filter( 'media_upload_image', array( $this, 'insert_images' ) );

		add_action( 'wp_ajax_tribe_delete_file', array( $this, 'delete_file' ) );		// ajax delete files
		add_action( 'wp_ajax_tribe_reorder_images', array( $this, 'reorder_images' ) );	// ajax reorder images
	}

	// Add data encoding type for file uploading
	public function add_enctype() {
		echo ' enctype="multipart/form-data"';
	}

	// Process adding images to image meta field, modifiy from 'Faster image insert' plugin
	public function insert_images() {
		if ( ! isset( $_POST['tribe-insert'] ) || empty( $_POST['attachments'] ) ){
			return;
		}

		check_admin_referer( 'media-form' );

		$nonce = wp_create_nonce( 'tribe_ajax_delete' );
		$post_id = $_POST['post_id'];
		$id = $_POST['field_id'];

		// modify the insertion string
		$html = '';
		foreach ( $_POST['attachments'] as $attachment_id => $attachment ) {
			$attachment = stripslashes_deep( $attachment );
			if ( empty( $attachment['selected'] ) || empty( $attachment['url'] ) ) {
				continue;
			}

			$li = "<li id='item_$attachment_id'>";
			$li .= "<img src='{$attachment['url']}' />";
			$li .= "<a title='" . __( 'Delete this image', 'advanced-post-manager' ) . "' class='tribe-delete-file' href='#' rel='$nonce|$post_id|$id|$attachment_id'>" . __( 'Delete', 'advanced-post-manager' ) . '</a>';
			$li .= "<input type='hidden' name='{$id}[]' value='$attachment_id' />";
			$li .= '</li>';
			$html .= $li;
		}

		media_send_to_editor( $html );
	}

	// Delete all attachments when delete post
	public function delete_attachments( $post_id ) {
		$attachments = get_posts( array(
			'numberposts' => -1,
			'post_type' => 'attachment',
			'post_parent' => $post_id,
		) );
		if ( ! empty( $attachments ) ) {
			foreach ( $attachments as $att ) {
				wp_delete_attachment( $att->ID );
			}
		}
	}

	// Ajax callback for deleting files. Modified from a function used by "Verve Meta Boxes" plugin (http://goo.gl/LzYSq)
	public function delete_file() {
		if ( ! isset( $_POST['data'] ) ) {
			die();
		}

		list( $nonce, $post_id, $key, $attach_id ) = explode( '|', $_POST['data'] );

		if ( ! wp_verify_nonce( $nonce, 'tribe_ajax_delete' ) ) {
			die( '1' );
		}

		$post = get_post( $post_id );
		if ( ! $post instanceof WP_Post ) {
			die( '1' );
		}

		$cap = get_post_type_object( $post->post_type )->cap->edit_post;

		// Check if the user can edit the post by ID
		if ( ! current_user_can( $cap, $post->ID ) ) {
			die( '1' );
		}

		delete_post_meta( $post_id, $key, $attach_id );

		die( '0' );
	}

	// Ajax callback for reordering images
	public function reorder_images() {
		if ( ! isset( $_POST['data'] ) ) {
			die();
		}

		list( $order, $post_id, $key, $nonce ) = explode( '|', $_POST['data'] );

		if ( ! wp_verify_nonce( $nonce, 'tribe_ajax_reorder' ) ) {
			die( '1' );
		}

		$post = get_post( $post_id );
		if ( ! $post instanceof WP_Post ) {
			die( '1' );
		}

		$cap = get_post_type_object( $post->post_type )->cap->edit_posts;

		// Check if the user can edit the post by ID
		if ( ! current_user_can( $cap ) ) {
			die( '1' );
		}

		parse_str( $order, $items );
		$items = $items['item'];
		$order = 1;
		foreach ( $items as $item ) {
			wp_update_post( array(
				'ID' => $item,
				'post_parent' => $post_id,
				'menu_order' => $order,
			) );
			$order++;
		}

		die( '0' );
	}

	/******************** END UPLOAD **********************/

	/******************** BEGIN OTHER FIELDS **********************/

	// Check field color
	public function check_field_color() {
		if ( $this->has_field( 'color' ) && self::is_edit_page() ) {
			wp_enqueue_style( 'farbtastic' );		// enqueue built-in script and style for color picker
			wp_enqueue_script( 'farbtastic' );
		}
	}

	// Check field date
	public function check_field_date() {
		if ( $this->has_field( 'date' ) && self::is_edit_page() ) {
			wp_enqueue_style( 'tribe-jquery-ui-css' );
			wp_enqueue_script( 'tribe-jquery-ui' );
		}
	}

	// Check field time
	public function check_field_time() {
		if ( $this->has_field( 'time' ) && self::is_edit_page() ) {
			// add style and script, use proper jQuery UI version
			wp_enqueue_style( 'tribe-jquery-ui-css' );
			wp_enqueue_script( 'tribe-jquery-ui' );
			wp_enqueue_script( 'tribe-timepicker' );
		}
	}

	/******************** END OTHER FIELDS **********************/

	/******************** BEGIN META BOX PAGE **********************/

	// Add meta box for multiple post types
	public function add() {
		foreach ( (array) $this->_meta_box['pages'] as $page ) {
			add_meta_box( $this->_meta_box['id'], $this->_meta_box['title'], array( $this, 'show' ), $page, $this->_meta_box['context'], $this->_meta_box['priority'] );
		}
	}

	// Callback function to show fields in meta box
	public function show() {
		global $post;

		wp_nonce_field( basename( __FILE__ ), 'tribe_meta_box_nonce' );
		echo '<table class="form-table tribe-meta">';

		foreach ( $this->_fields as $field ) {
			$meta = $this->retrieve_meta_for_field( $field, $post );
			echo '<tr>';
			// call separated methods for displaying each type of field
			call_user_func( array( $this, 'show_field_' . $field['type'] ), $field, $meta );
			echo '</tr>';
		}
		echo '</table>';
	}

	public function retrieve_meta_for_field( $field, $post ) {
		$meta = get_post_meta( $post->ID, $field['meta'], ! $field['multiple'] );
		$meta = ! empty( $meta ) ? $meta : $field['std'];
		$meta = ( is_array( $meta ) ) ? self::array_map_deep( 'esc_attr', $meta ) : esc_attr( $meta );
		return $meta;
	}

	public function array_map_deep( $callback, $data ) {
		$results =	array();
		$args = array();
		if ( func_num_args() > 2 ) {
			$args =	(array) array_shift( array_slice( func_get_args(), 2 ) );
		}

		foreach ( $data as $key => $value ) {
			if ( is_array( $value ) ) {
				array_unshift( $args, $value );
				array_unshift( $args, $callback );
				$results[ $key ] = call_user_func_array( array( 'self', 'array_map_deep' ), $args );
			}
			else {
				array_unshift( $args, $value );
				$results[ $key ] = call_user_func_array( $callback, $args );
			}
		}
		return $results;
	}

	/******************** END META BOX PAGE **********************/

	/******************** BEGIN META BOX FIELDS **********************/

	public function show_field_begin( $field, $meta ) {
		if ( isset( $field['span'] ) && 'full' === $field['span'] ) {
			echo "<td colspan='2' class='full-span {$field['type']}'><label for='{$field['meta']}'>{$field['name']}</label>";
		} else {
			echo "<th scope='row' class='label-row'><label for='{$field['meta']}'>{$field['name']}</label></th><td class='{$field['type']}'>";
		}
	}

	public function show_field_end( $field, $meta ) {
		if ( isset( $field['desc'] ) ) {
			echo "<p class='description'>{$field['desc']}</p>";
		}
		echo '</td>';
	}

	public function show_field_text( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		echo "<input type='text' class='tribe-text' name='{$field['meta']}' id='{$field['meta']}' value='$meta' size='30' />";
		$this->show_field_end( $field, $meta );
	}

	public function show_field_textarea( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		echo "<textarea class='tribe-textarea large-text' name='{$field['meta']}' id='{$field['meta']}' cols='60' rows='10'>$meta</textarea>";
		$this->show_field_end( $field, $meta );
	}

	public function show_field_select( $field, $meta ) {
		if ( ! is_array( $meta ) ) {
			$meta = (array) $meta;
		}

		$this->show_field_begin( $field, $meta );
		echo "<select class='tribe-select' name='{$field['meta']}" . ( $field['multiple'] ? "[]' id='{$field['meta']}' multiple='multiple'" : "'" ) . '>';
		foreach ( $field['options'] as $key => $value ) {
			echo "<option value='$key'" . selected( in_array( $key, $meta ), true, false ) . ">$value</option>";
		}
		echo '</select>';
		$this->show_field_end( $field, $meta );
	}

	public function show_field_radio( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		foreach ( $field['options'] as $key => $value ) {
			echo "<input type='radio' class='tribe-radio' name='{$field['meta']}' value='$key'" . checked( $meta, $key, false ) . " /> $value ";
		}
		$this->show_field_end( $field, $meta );
	}

	public function show_field_checkbox( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		echo "<label><input type='checkbox' class='tribe-checkbox' name='{$field['meta']}' id='{$field['meta']}'" . checked( ! empty( $meta ), true, false ) . " /> {$field['desc']}</label></td>";
	}

	public function show_field_wysiwyg( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		$content  = get_post_meta( get_the_ID(), $field['meta'], true );
		$content  = empty( $content ) || ! is_string( $content ) ? '' : $content;
		$settings = array(
			'media_buttons' => isset( $field['media_buttons'] ) ? (bool) $field['meta_buttons'] : false,
		);
		wp_editor( $content, $field['meta'], $settings );
		$this->show_field_end( $field, $meta );
	}

	public function show_field_file( $field, $meta ) {
		global $post;

		if ( ! is_array( $meta ) ) {
			$meta = (array) $meta;
		}

		$this->show_field_begin( $field, $meta );
		if ( isset( $field['desc'] ) ) {
			echo "<p class='description'>{$field['desc']}</p>";
		}

		if ( ! empty( $meta ) ) {
			$nonce = wp_create_nonce( 'tribe_ajax_delete' );
			echo '<div style="margin-bottom: 10px"><strong>' . esc_html__( 'Uploaded files', 'advanced-post-manager' ) . '</strong></div>';
			echo '<ol class="tribe-upload">';
			foreach ( $meta as $att ) {
				echo '<li>' . wp_get_attachment_link( $att, '', false, false, ' ' ) . " (<a class='tribe-delete-file' href='#' rel='$nonce|{$post->ID}|{$field['meta']}|$att'>" . esc_html__( 'Delete', 'advanced-post-manager' ) . '</a>)</li>';
			}
			echo '</ol>';
		}

		// show form upload
		echo '<div style="clear: both"><strong>' . esc_html__( 'Upload new files', 'advanced-post-manager' ) . "</strong></div>
			<div class='new-files'>
				<div class='file-input'><input type='file' name='{$field['meta']}[]' /></div>
				<a class='tribe-add-file' href='#'>" . esc_html__( 'Add another file', 'advanced-post-manager' ) . '</a>
			</div>
		</td>';
	}

	public function show_field_image( $field, $meta ) {
		global $wpdb, $post;

		if ( ! is_array( $meta ) ) {
			$meta = (array) $meta;
		}

		$this->show_field_begin( $field, $meta );
		if ( isset( $field['desc'] ) ) {
			echo "<p class='description'>{$field['desc']}</p>";
		}

		$nonce_delete = wp_create_nonce( 'tribe_ajax_delete' );
		$nonce_sort = wp_create_nonce( 'tribe_ajax_reorder' );

		echo "<input type='hidden' class='tribe-images-data' value='{$post->ID}|{$field['meta']}|$nonce_sort' />
				<ul class='tribe-images tribe-upload' id='tribe-images-{$field['meta']}'>";

		// re-arrange images with 'menu_order', thanks Onur
		if ( ! empty( $meta ) ) {
			$meta = implode( ',', $meta );
			$images = $wpdb->get_col( "
				SELECT ID FROM $wpdb->posts
				WHERE post_type = 'attachment'
				AND ID in ($meta)
				ORDER BY menu_order ASC
			" );
			foreach ( $images as $image ) {
				$src = wp_get_attachment_image_src( $image );
				$src = $src[0];

				echo "<li id='item_$image'>
						<img src='$src' />
						<a title='" . esc_attr__( 'Delete this image', 'advanced-post-manager' ) . "' class='tribe-delete-file' href='#' rel='$nonce_delete|{$post->ID}|{$field['meta']}|$image'>" . esc_html__( 'Delete', 'advanced-post-manager' ) . "</a>
						<input type='hidden' name='{$field['meta']}[]' value='$image' />
					</li>";
			}
		}
		echo '</ul>';

		echo "<a href='#' class='tribe-upload-button button' rel='{$post->ID}|{$field['meta']}'>" . esc_html__( 'Add more images', 'advanced-post-manager' ) . '</a>';
		echo '</td>';
	}

	public function show_field_color( $field, $meta ) {
		if ( empty( $meta ) ) {
			$meta = '#';
		}

		$this->show_field_begin( $field, $meta );
		echo "<input class='tribe-color' type='text' name='{$field['meta']}' id='{$field['meta']}' value='$meta' size='8' />
				<a href='#' class='tribe-color-select' rel='{$field['meta']}'>" . esc_html__( 'Select a color', 'advanced-post-manager' ) . "</a>
				<div style='display:none' class='tribe-color-picker' rel='{$field['meta']}'></div>";
		$this->show_field_end( $field, $meta );
	}

	public function show_field_checkbox_list( $field, $meta ) {
		if ( ! is_array( $meta ) ) {
			$meta = (array) $meta;
		}

		$this->show_field_begin( $field, $meta );
		$html = array();
		foreach ( $field['options'] as $key => $value ) {
			$html[] = "<input type='checkbox' class='tribe-checkbox_list' name='{$field['meta']}[]' value='$key'" . checked( in_array( $key, $meta ), true, false ) . " /> $value";
		}
		echo implode( '<br />', $html );
		$this->show_field_end( $field, $meta );
	}

	public function show_field_date( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		echo "<input type='text' class='tribe-date' name='{$field['meta']}' id='{$field['meta']}' rel='{$field['format']}' value='$meta' size='30' />";
		$this->show_field_end( $field, $meta );
	}

	public function show_field_time( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		echo "<input type='text' class='tribe-time' name='{$field['meta']}' id='{$field['meta']}' rel='{$field['format']}' value='$meta' size='30' />";
		$this->show_field_end( $field, $meta );
	}

	public function show_field_text_multi( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		$meta = (array) $meta;
		$hide_remove = ( count( $meta ) < 2 ) ? ' hide-remove' : '';
		$size = floor( 36 / count( $field['ids'] ) );

		echo '<div class="tribe-multi-text-wrap' . esc_attr( $hide_remove ) . '">';
		foreach ( $meta as $k => $v ) {
			echo '<div class="tribe-multi-text">';
			foreach ( $field['ids'] as $key => $id ) {
				$val = ( isset( $v[ $id ] ) ) ? $v[ $id ] : '';
				$name = "{$field['meta']}[{$id}][]";
				$ph = $field['placeholders'][ $key ];
				echo "<input type='text' name='{$name}' value='{$val}' size='{$size}' placeholder='{$ph}' /> ";
			}
			echo "<a class='tribe-add'>+</a><a class='tribe-remove'>-</a></div>";
		}
		echo '</div>';
		$this->show_field_end( $field, $meta );
	}

	public function show_field_html( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		echo $field['html'];
		$this->show_field_end( $field, $meta );
	}

	public function show_field_post2post( $field, $meta ) {
		$this->show_field_begin( $field, $meta );
		if ( ! isset( $field['dropdown_title'] ) ) {
			$post_type_object = get_post_type_object( $field['post_type'] );
			$field['dropdown_title'] = sprintf( 'Select %s', $post_type_object->labels->singular_name );
		}

		$this->dropdown_posts( array(
			'post_type' => $field['post_type'],
			'show_option_none' => $field['dropdown_title'],
			'name' => $field['meta'],
			'class' => 'p2p-drop',
		) );

		$list_items = '';
		$list_item_template = '<li><label><input type="checkbox" name="'.$field['meta'].'[]" value="%s" checked="checked" /> %s</label></li>';
		if ( ! empty( $meta ) ) {
			foreach ( (array) $meta as $post_id ) {
				$p = get_post( $post_id );
				$list_items .= sprintf( $list_item_template, $p->ID, $p->post_title );
			}
		}

		echo '<ul class="p2p-connected">' . $list_items . '</ul>';
		$this->show_field_end( $field, $meta );
	}

	/******************** END META BOX FIELDS **********************/

	/******************** BEGIN META BOX SAVE **********************/

	// Save data from meta box
	public function save( $post_id ) {
		global $post_type;
		$post_type_object = get_post_type_object( $post_type );

		if ( ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )						// check autosave
		|| ( ! isset( $_POST['post_ID'] ) || $post_id != $_POST['post_ID'] )			// check revision
		|| ( ! in_array( $post_type, $this->_meta_box['pages'] ) )					// check if current post type is supported
		|| ( ! check_admin_referer( basename( __FILE__ ), 'tribe_meta_box_nonce' ) )		// verify nonce
		|| ( ! current_user_can( $post_type_object->cap->edit_post, $post_id ) ) ) {	// check permission
			return $post_id;
		}

		foreach ( $this->_fields as $field ) {
			$name = $field['meta'];
			$type = $field['type'];
			$old = get_post_meta( $post_id, $name, ! $field['multiple'] );
			$new = isset( $_POST[ $name ] ) ? $_POST[ $name ] : ( $field['multiple'] ? array() : '' );

			// validate meta value
			if ( class_exists( 'Tribe_Meta_Box_Validate' ) && method_exists( 'Tribe_Meta_Box_Validate', $field['validate_func'] ) ) {
				$new = call_user_func( array( 'Tribe_Meta_Box_Validate', $field['validate_func'] ), $new );
			}

			// call defined method to save meta value, if there's no methods, call common one
			$save_func = 'save_field_' . $type;
			if ( method_exists( $this, $save_func ) ) {
				call_user_func( array( $this, 'save_field_' . $type ), $post_id, $field, $old, $new );
			} else {
				$this->save_field( $post_id, $field, $old, $new );
			}
		}
	}

	// Common functions for saving field
	public function save_field( $post_id, $field, $old, $new ) {
		$name = $field['meta'];

		delete_post_meta( $post_id, $name );
		if ( $new === '' || $new === array() ) {
			return;
		}

		if ( $field['multiple'] ) {
			foreach ( $new as $add_new ) {
				add_post_meta( $post_id, $name, $add_new, false );
			}
		} else {
			update_post_meta( $post_id, $name, $new );
		}
	}

	public function save_field_wysiwyg( $post_id, $field, $old, $new ) {
		$new = wpautop( $new );
		$this->save_field( $post_id, $field, $old, $new );
	}

	public function save_field_file( $post_id, $field, $old, $new ) {
		$name = $field['meta'];
		if ( empty( $_FILES[ $name ] ) ) {
			return;
		}

		self::fix_file_array( $_FILES[ $name ] );

		foreach ( $_FILES[ $name ] as $position => $fileitem ) {
			$file = wp_handle_upload( $fileitem, array( 'test_form' => false ) );

			if ( empty( $file['file'] ) ){
				continue;
			}

			$filename = $file['file'];

			$attachment = array(
				'post_mime_type' => $file['type'],
				'guid' => $file['url'],
				'post_parent' => $post_id,
				'post_title' => preg_replace( '/\.[^.]+$/', '', basename( $filename ) ),
				'post_content' => '',
			);
			$id = wp_insert_attachment( $attachment, $filename, $post_id );
			if ( ! is_wp_error( $id ) ) {
				wp_update_attachment_metadata( $id, wp_generate_attachment_metadata( $id, $filename ) );
				add_post_meta( $post_id, $name, $id, false );	// save file's url in meta fields
			}
		}
	}

	public function save_field_text_multi( $post_id, $field, $old, $new ) {
		$data = array();
		$new = (array) $new;
		foreach ( $field['ids'] as $id ) {
			foreach ( $new[ $id ] as $key => $value ) {
				$data[ $key ][ $id ] = $value;
			}
		}
		if ( ! empty( $data ) ) {
			update_post_meta( $post_id, $field['meta'], $data );
		}
	}

	public function save_field_html() {
		// do nothing
	}

	public function save_field_post2post( $post_id, $field, $old, $new ) {
		delete_post_meta( $post_id, $field['meta'] );
		$new = (array) $new;
		$new = array_unique( $new );
		foreach ( $new as $id ) {
			add_post_meta( $post_id, $field['meta'], $id );
		}
	}

	/******************** END META BOX SAVE **********************/

	/******************** BEGIN HELPER FUNCTIONS **********************/

	public function dropdown_posts( $args = '' ) {
		$defaults = array(
			'numberposts' => -1,
			'post_type' => 'post',
			'depth' => 0,
			'selected' => 0,
			'echo' => 1,
			'name' => 'page_id',
			'id' => '',
			'class' => '',
			'show_option_none' => '',
			'show_option_no_change' => '',
			'option_none_value' => '',
		);

		$r = wp_parse_args( $args, $defaults );
		extract( $r, EXTR_SKIP );
		$get_posts_args = compact( 'post_type', 'numberposts' );
		$pages = get_posts( $get_posts_args );
		$output = '';
		$name = esc_attr( $name );
		// Back-compat with old system where both id and name were based on $name argument
		if ( empty( $id ) )
			$id = $name;

		if ( ! empty( $pages ) ) {
			$output = "<select name=\"$name\" id=\"$id\" class=\"$class\">\n";
			if ( $show_option_no_change )
				$output .= "\t<option value=\"-1\">$show_option_no_change</option>";
			if ( $show_option_none ) {
				$output .= "\t<option value=\"" . esc_attr( $option_none_value ) . "\">$show_option_none</option>\n";
			}
			$output .= walk_page_dropdown_tree( $pages, $depth, $r );
			$output .= "</select>\n";
		}

		$output = apply_filters( 'dropdown_posts-' . $post_type, $output );

		if ( $echo ) {
			echo $output;
		}

		return $output;
	}

	// Add missed values for meta box
	public function add_missed_values() {
		// default values for meta box
		$this->_meta_box = array_merge( array(
			'context' => 'normal',
			'priority' => 'high',
			'pages' => array( 'post' ),
		), $this->_meta_box );

		// default values for fields
		foreach ( $this->_fields as &$field ) {
			$multiple = in_array( $field['type'], array( 'checkbox_list', 'file', 'image' ) );
			$std = $multiple ? array() : '';
			$format = 'date' == $field['type'] ? 'yy-mm-dd' : ( 'time' == $field['type'] ? 'hh:mm' : '' );

			$field = array_merge( array(
				'multiple' => $multiple,
				'std' => $std,
				'desc' => '',
				'format' => $format,
				'validate_func' => '',
			), $field );
		}
	}

	// Check if field with $type exists
	public function has_field( $type ) {
		foreach ( $this->_fields as $field ) {
			if ( $type == $field['type'] ) {
				return true;
			}
		}
		return false;
	}

	// Check if current page is edit page
	public static function is_edit_page() {
		global $pagenow;
		return in_array( $pagenow, array( 'post.php', 'post-new.php' ) );
	}

	/**
	 * Fixes the odd indexing of multiple file uploads from the format:
	 *	 $_FILES['field']['key']['index']
	 * To the more standard and appropriate:
	 *	 $_FILES['field']['index']['key']
	 */
	public static function fix_file_array( &$files ) {
		$output = array();
		foreach ( $files as $key => $list ) {
			foreach ( $list as $index => $value ) {
				$output[ $index ][ $key ] = $value;
			}
		}
		$files = $output;
	}

	// Get proper jQuery UI version to not conflict with WP admin scripts
	public static function get_jqueryui_ver() {
		global $wp_version;
		if ( version_compare( $wp_version, '3.5', '>=' ) ) {
			return '1.9.2';
		}

		if ( version_compare( $wp_version, '3.1', '>=' ) ) {
			return '1.8.10';
		}

		return '1.7.3';
	}
	/******************** END HELPER FUNCTIONS **********************/
}