<?php

namespace Box\Spout\Reader\Wrapper;

use Box\Spout\Reader\Exception\XMLProcessingException;

/**
 * Trait XMLInternalErrorsHelper
 *
 * @package Box\Spout\Reader\Wrapper
 */
trait XMLInternalErrorsHelper {

	/** @var bool Stores whether XML errors were initially stored internally - used to reset */
	protected $initialUseInternalErrorsValue;

	/**
	 * To avoid displaying lots of warning/error messages on screen,
	 * stores errors internally instead.
	 *
	 * @return void
	 */
	protected function useXMLInternalErrors() {
		 libxml_clear_errors();
		$this->initialUseInternalErrorsValue = libxml_use_internal_errors( true );
	}

	/**
	 * Throws an XMLProcessingException if an error occured.
	 * It also always resets the "libxml_use_internal_errors" setting back to its initial value.
	 *
	 * @return void
	 * @throws \Box\Spout\Reader\Exception\XMLProcessingException
	 */
	protected function resetXMLInternalErrorsSettingAndThrowIfXMLErrorOccured() {
		if ( $this->hasXMLErrorOccured() ) {
			$this->resetXMLInternalErrorsSetting();
			throw new XMLProcessingException( $this->getLastXMLErrorMessage() );
		}

		$this->resetXMLInternalErrorsSetting();
	}

	/**
	 * Returns whether the a XML error has occured since the last time errors were cleared.
	 *
	 * @return bool TRUE if an error occured, FALSE otherwise
	 */
	private function hasXMLErrorOccured() {
		 return ( libxml_get_last_error() !== false );
	}

	/**
	 * Returns the error message for the last XML error that occured.
	 * @see libxml_get_last_error
	 *
	 * @return String|null Last XML error message or null if no error
	 */
	private function getLastXMLErrorMessage() {
		 $errorMessage = null;
		$error         = libxml_get_last_error();

		if ( $error !== false ) {
			$errorMessage = trim( $error->message );
		}

		return $errorMessage;
	}

	/**
	 * @return void
	 */
	protected function resetXMLInternalErrorsSetting() {
		libxml_use_internal_errors( $this->initialUseInternalErrorsValue );
	}

}