Sindbad~EG File Manager

<?php

/**
 * LP_Meta_Box_Duration_Attribute
 *
 * @author tungnx
 * @version 1.0.0
 * @since 4.0.0
 */
class LP_Meta_Box_Extra_Field extends LP_Meta_Box_Field {

	/**
	 * Constructor.
	 *
	 * @param string $label
	 * @param string $description
	 * @param mixed $default
	 * @param array $extra
	 */
	public function __construct( $label = '', $description = '', $default = '', $extra = array() ) {
		parent::__construct( $label, $description, $default, $extra );
	}

	public function output( $thepostid ) {
		$fields = $this->meta_value( $thepostid );
		?>

		<div class="form-field lp_course_extra_meta_box">
			<label for="<?php echo esc_attr( $this->id ); ?>">
				<?php echo wp_kses_post( $this->label ); ?>
			</label>
			<div class="lp_course_extra_meta_box__content">
				<div class="lp_course_extra_meta_box__fields">
					<?php if ( ! empty( $fields[0][0] ) ) : ?>
						<?php foreach ( $fields as $field ) : ?>
							<div class="lp_course_extra_meta_box__field">
								<span class="sort"></span>
								<input name="<?php echo esc_attr( $this->id ); ?>[]"
									   value="<?php echo esc_attr( $field ); ?>"
									   type="text" class="lp_course_extra_meta_box__input">
								<a href="#" class="delete"></a>
							</div>
						<?php endforeach; ?>
					<?php endif; ?>
				</div>

				<a href="#" class="button button-primary lp_course_extra_meta_box__add"
				   data-add="
				   <?php echo esc_attr(
					'<div class="lp_course_extra_meta_box__field">
						<span class="sort"></span>
						<input name="' . $this->id . '[]" value="" type="text" class="lp_course_extra_meta_box__input">
						<a href="#" class="delete"></a>
					</div>'
					);
				   ?>">
					<?php esc_html_e( '+ Add more', 'learnpress' ); ?>
				</a>
			</div>
		</div>
		<?php
	}

	public function save( $post_id ) {
		$fields = LP_Request::get_param( $this->id, $this->default ?? [], 'html' );

		update_post_meta( $post_id, $this->id, $fields );

		return $fields;
	}
}