<?php

namespace Box\Spout\Reader\XLSX\Helper;

use Box\Spout\Reader\Wrapper\XMLReader;
use Box\Spout\Reader\XLSX\Sheet;

/**
 * Class SheetHelper
 * This class provides helper functions related to XLSX sheets
 *
 * @package Box\Spout\Reader\XLSX\Helper
 */
class SheetHelper {

	/** Paths of XML files relative to the XLSX file root */
	const WORKBOOK_XML_RELS_FILE_PATH = 'xl/_rels/workbook.xml.rels';
	const WORKBOOK_XML_FILE_PATH      = 'xl/workbook.xml';

	/** Definition of XML node names used to parse data */
	const XML_NODE_WORKBOOK_VIEW = 'workbookView';
	const XML_NODE_SHEET         = 'sheet';
	const XML_NODE_SHEETS        = 'sheets';
	const XML_NODE_RELATIONSHIP  = 'Relationship';

	/** Definition of XML attributes used to parse data */
	const XML_ATTRIBUTE_ACTIVE_TAB = 'activeTab';
	const XML_ATTRIBUTE_R_ID       = 'r:id';
	const XML_ATTRIBUTE_NAME       = 'name';
	const XML_ATTRIBUTE_ID         = 'Id';
	const XML_ATTRIBUTE_TARGET     = 'Target';

	/** @var string Path of the XLSX file being read */
	protected $filePath;

	/** @var \Box\Spout\Reader\XLSX\ReaderOptions Reader's current options */
	protected $options;

	/** @var \Box\Spout\Reader\XLSX\Helper\SharedStringsHelper Helper to work with shared strings */
	protected $sharedStringsHelper;

	/** @var \Box\Spout\Common\Helper\GlobalFunctionsHelper Helper to work with global functions */
	protected $globalFunctionsHelper;

	/**
	 * @param string $filePath Path of the XLSX file being read
	 * @param \Box\Spout\Reader\XLSX\ReaderOptions $options Reader's current options
	 * @param \Box\Spout\Reader\XLSX\Helper\SharedStringsHelper Helper to work with shared strings
	 * @param \Box\Spout\Common\Helper\GlobalFunctionsHelper $globalFunctionsHelper
	 */
	public function __construct( $filePath, $options, $sharedStringsHelper, $globalFunctionsHelper ) {
		$this->filePath              = $filePath;
		$this->options               = $options;
		$this->sharedStringsHelper   = $sharedStringsHelper;
		$this->globalFunctionsHelper = $globalFunctionsHelper;
	}

	/**
	 * Returns the sheets metadata of the file located at the previously given file path.
	 * The paths to the sheets' data are read from the [Content_Types].xml file.
	 *
	 * @return Sheet[] Sheets within the XLSX file
	 */
	public function getSheets() {
		$sheets           = array();
		$sheetIndex       = 0;
		$activeSheetIndex = 0; // By default, the first sheet is active

		$xmlReader = new XMLReader();
		if ( $xmlReader->openFileInZip( $this->filePath, self::WORKBOOK_XML_FILE_PATH ) ) {
			while ( $xmlReader->read() ) {
				if ( $xmlReader->isPositionedOnStartingNode( self::XML_NODE_WORKBOOK_VIEW ) ) {
					// The "workbookView" node is located before "sheet" nodes, ensuring that
					// the active sheet is known before parsing sheets data.
					$activeSheetIndex = (int) $xmlReader->getAttribute( self::XML_ATTRIBUTE_ACTIVE_TAB );
				} elseif ( $xmlReader->isPositionedOnStartingNode( self::XML_NODE_SHEET ) ) {
					$isSheetActive = ( $sheetIndex === $activeSheetIndex );
					$sheets[]      = $this->getSheetFromSheetXMLNode( $xmlReader, $sheetIndex, $isSheetActive );
					$sheetIndex++;
				} elseif ( $xmlReader->isPositionedOnEndingNode( self::XML_NODE_SHEETS ) ) {
					// stop reading once all sheets have been read
					break;
				}
			}

			$xmlReader->close();
		}

		return $sheets;
	}

	/**
	 * Returns an instance of a sheet, given the XML node describing the sheet - from "workbook.xml".
	 * We can find the XML file path describing the sheet inside "workbook.xml.res", by mapping with the sheet ID
	 * ("r:id" in "workbook.xml", "Id" in "workbook.xml.res").
	 *
	 * @param \Box\Spout\Reader\Wrapper\XMLReader $xmlReaderOnSheetNode XML Reader instance, pointing on the node describing the sheet, as defined in "workbook.xml"
	 * @param int $sheetIndexZeroBased Index of the sheet, based on order of appearance in the workbook (zero-based)
	 * @param bool $isSheetActive Whether this sheet was defined as active
	 * @return \Box\Spout\Reader\XLSX\Sheet Sheet instance
	 */
	protected function getSheetFromSheetXMLNode( $xmlReaderOnSheetNode, $sheetIndexZeroBased, $isSheetActive ) {
		$sheetId          = $xmlReaderOnSheetNode->getAttribute( self::XML_ATTRIBUTE_R_ID );
		$escapedSheetName = $xmlReaderOnSheetNode->getAttribute( self::XML_ATTRIBUTE_NAME );

		/** @noinspection PhpUnnecessaryFullyQualifiedNameInspection */
		$escaper   = \Box\Spout\Common\Escaper\XLSX::getInstance();
		$sheetName = $escaper->unescape( $escapedSheetName );

		$sheetDataXMLFilePath = $this->getSheetDataXMLFilePathForSheetId( $sheetId );

		return new Sheet(
			$this->filePath,
			$sheetDataXMLFilePath,
			$sheetIndexZeroBased,
			$sheetName,
			$isSheetActive,
			$this->options,
			$this->sharedStringsHelper
		);
	}

	/**
	 * @param string $sheetId The sheet ID, as defined in "workbook.xml"
	 * @return string The XML file path describing the sheet inside "workbook.xml.res", for the given sheet ID
	 */
	protected function getSheetDataXMLFilePathForSheetId( $sheetId ) {
		$sheetDataXMLFilePath = '';

		// find the file path of the sheet, by looking at the "workbook.xml.res" file
		$xmlReader = new XMLReader();
		if ( $xmlReader->openFileInZip( $this->filePath, self::WORKBOOK_XML_RELS_FILE_PATH ) ) {
			while ( $xmlReader->read() ) {
				if ( $xmlReader->isPositionedOnStartingNode( self::XML_NODE_RELATIONSHIP ) ) {
					$relationshipSheetId = $xmlReader->getAttribute( self::XML_ATTRIBUTE_ID );

					if ( $relationshipSheetId === $sheetId ) {
						// In workbook.xml.rels, it is only "worksheets/sheet1.xml"
						// In [Content_Types].xml, the path is "/xl/worksheets/sheet1.xml"
						$sheetDataXMLFilePath = $xmlReader->getAttribute( self::XML_ATTRIBUTE_TARGET );

						// sometimes, the sheet data file path already contains "/xl/"...
						if ( strpos( $sheetDataXMLFilePath, '/xl/' ) !== 0 ) {
							$sheetDataXMLFilePath = '/xl/' . $sheetDataXMLFilePath;
							break;
						}
					}
				}
			}

			$xmlReader->close();
		}

		return $sheetDataXMLFilePath;
	}
}