public function save( $post_id ) {

		if ( ! llms_verify_nonce( 'lifterlms_meta_nonce', 'lifterlms_save_data' ) ) {
			return;
		}

		// Get all defined fields.
		$fields = $this->get_fields();

		if ( ! is_array( $fields ) ) {
			return;
		}

		// Loop through the fields.
		foreach ( $fields as $group => $data ) {

			// Find the fields in each tab.
			if ( isset( $data['fields'] ) && is_array( $data['fields'] ) ) {

				// Loop through the fields.
				foreach ( $data['fields'] as $field ) {

					// Don't save things that don't have an ID.
					if ( isset( $field['id'] ) ) {

						// Skip our faux fields.
						if ( 0 === strpos( $field['id'], '_faux_engagement_trigger_post_' ) ) {
							continue;
						}

						// Get the posted value.
						if ( isset( $_POST[ $field['id'] ] ) ) {

							$val = llms_filter_input_sanitize_string( INPUT_POST, $field['id'] );

						} elseif ( ! isset( $_POST[ $field['id'] ] ) ) {

							$val = '';

						}

						// Update the value if we have one.
						if ( isset( $val ) ) {

							update_post_meta( $post_id, $field['id'], $val );

						}

						unset( $val );

					}
				}
			}
		}

		// Locate and store the trigger post id.
		$type = llms_filter_input( INPUT_POST, $this->prefix . 'trigger_type' );
		switch ( $type ) {

			case 'access_plan_purchased':
				$var = 'access_plan';
				break;

			case 'course_completed':
			case 'course_purchased':
			case 'course_enrollment':
				$var = 'course';
				break;

			case 'lesson_completed':
				$var = 'lesson';
				break;

			case 'membership_purchased':
			case 'membership_enrollment':
				$var = 'membership';
				break;

			case 'quiz_completed':
			case 'quiz_passed':
			case 'quiz_failed':
				$var = 'quiz';
				break;

			case 'section_completed':
				$var = 'section';
				break;

			case 'course_track_completed':
				$var = 'track';
				break;

			default:
				$var = false;

		}

		if ( $var ) {

			$val = llms_filter_input_sanitize_string( INPUT_POST, '_faux_engagement_trigger_post_' . $var );

		} else {

			$val = '';

		}

		update_post_meta( $post_id, $this->prefix . 'engagement_trigger_post', $val );

	}