<?php

namespace Box\Spout\Writer\Common;

use Box\Spout\Common\Helper\StringHelper;
use Box\Spout\Writer\Exception\InvalidSheetNameException;

/**
 * Class Sheet
 * External representation of a worksheet
 *
 * @package Box\Spout\Writer\Common
 */
class Sheet {

	const DEFAULT_SHEET_NAME_PREFIX = 'Sheet';

	/** Sheet name should not exceed 31 characters */
	const MAX_LENGTH_SHEET_NAME = 31;

	/** @var array Invalid characters that cannot be contained in the sheet name */
	private static $INVALID_CHARACTERS_IN_SHEET_NAME = array( '\\', '/', '?', '*', ':', '[', ']' );

	/** @var array Associative array [WORKBOOK_ID] => [[SHEET_INDEX] => [SHEET_NAME]] keeping track of sheets' name to enforce uniqueness per workbook */
	protected static $SHEETS_NAME_USED = array();

	/** @var int Index of the sheet, based on order in the workbook (zero-based) */
	protected $index;

	/** @var string ID of the sheet's associated workbook. Used to restrict sheet name uniqueness enforcement to a single workbook */
	protected $associatedWorkbookId;

	/** @var string Name of the sheet */
	protected $name;

	/** @var \Box\Spout\Common\Helper\StringHelper */
	protected $stringHelper;

	/**
	 * @param int $sheetIndex Index of the sheet, based on order in the workbook (zero-based)
	 * @param string $associatedWorkbookId ID of the sheet's associated workbook
	 */
	public function __construct( $sheetIndex, $associatedWorkbookId ) {
		 $this->index               = $sheetIndex;
		$this->associatedWorkbookId = $associatedWorkbookId;
		if ( ! isset( self::$SHEETS_NAME_USED[ $associatedWorkbookId ] ) ) {
			self::$SHEETS_NAME_USED[ $associatedWorkbookId ] = array();
		}

		$this->stringHelper = new StringHelper();
		$this->setName( self::DEFAULT_SHEET_NAME_PREFIX . ( $sheetIndex + 1 ) );
	}

	/**
	 * @api
	 * @return int Index of the sheet, based on order in the workbook (zero-based)
	 */
	public function getIndex() {
		return $this->index;
	}

	/**
	 * @api
	 * @return string Name of the sheet
	 */
	public function getName() {
		 return $this->name;
	}

	/**
	 * Sets the name of the sheet. Note that Excel has some restrictions on the name:
	 *  - it should not be blank
	 *  - it should not exceed 31 characters
	 *  - it should not contain these characters: \ / ? * : [ or ]
	 *  - it should be unique
	 *
	 * @api
	 * @param string $name Name of the sheet
	 * @return Sheet
	 * @throws \Box\Spout\Writer\Exception\InvalidSheetNameException If the sheet's name is invalid.
	 */
	public function setName( $name ) {
		$this->throwIfNameIsInvalid( $name );

		$this->name = $name;
		self::$SHEETS_NAME_USED[ $this->associatedWorkbookId ][ $this->index ] = $name;

		return $this;
	}

	/**
	 * Throws an exception if the given sheet's name is not valid.
	 * @see Sheet::setName for validity rules.
	 *
	 * @param string $name
	 * @return void
	 * @throws \Box\Spout\Writer\Exception\InvalidSheetNameException If the sheet's name is invalid.
	 */
	protected function throwIfNameIsInvalid( $name ) {
		if ( ! is_string( $name ) ) {
			$actualType   = gettype( $name );
			$errorMessage = "The sheet's name is invalid. It must be a string ($actualType given).";
			throw new InvalidSheetNameException( $errorMessage );
		}

		$failedRequirements = array();
		$nameLength         = $this->stringHelper->getStringLength( $name );

		if ( ! $this->isNameUnique( $name ) ) {
			$failedRequirements[] = 'It should be unique';
		} else {
			if ( $nameLength === 0 ) {
				$failedRequirements[] = 'It should not be blank';
			} else {
				if ( $nameLength > self::MAX_LENGTH_SHEET_NAME ) {
					$failedRequirements[] = 'It should not exceed 31 characters';
				}

				if ( $this->doesContainInvalidCharacters( $name ) ) {
					$failedRequirements[] = 'It should not contain these characters: \\ / ? * : [ or ]';
				}

				if ( $this->doesStartOrEndWithSingleQuote( $name ) ) {
					$failedRequirements[] = 'It should not start or end with a single quote';
				}
			}
		}

		if ( count( $failedRequirements ) !== 0 ) {
			$errorMessage  = "The sheet's name (\"$name\") is invalid. It did not respect these rules:\n - ";
			$errorMessage .= implode( "\n - ", $failedRequirements );
			throw new InvalidSheetNameException( $errorMessage );
		}
	}

	/**
	 * Returns whether the given name contains at least one invalid character.
	 * @see Sheet::$INVALID_CHARACTERS_IN_SHEET_NAME for the full list.
	 *
	 * @param string $name
	 * @return bool TRUE if the name contains invalid characters, FALSE otherwise.
	 */
	protected function doesContainInvalidCharacters( $name ) {
		return ( str_replace( self::$INVALID_CHARACTERS_IN_SHEET_NAME, '', $name ) !== $name );
	}

	/**
	 * Returns whether the given name starts or ends with a single quote
	 *
	 * @param string $name
	 * @return bool TRUE if the name starts or ends with a single quote, FALSE otherwise.
	 */
	protected function doesStartOrEndWithSingleQuote( $name ) {
		 $startsWithSingleQuote = ( $this->stringHelper->getCharFirstOccurrencePosition( '\'', $name ) === 0 );
		$endsWithSingleQuote    = ( $this->stringHelper->getCharLastOccurrencePosition( '\'', $name ) === ( $this->stringHelper->getStringLength( $name ) - 1 ) );

		return ( $startsWithSingleQuote || $endsWithSingleQuote );
	}

	/**
	 * Returns whether the given name is unique.
	 *
	 * @param string $name
	 * @return bool TRUE if the name is unique, FALSE otherwise.
	 */
	protected function isNameUnique( $name ) {
		foreach ( self::$SHEETS_NAME_USED[ $this->associatedWorkbookId ] as $sheetIndex => $sheetName ) {
			if ( $sheetIndex !== $this->index && $sheetName === $name ) {
				return false;
			}
		}

		return true;
	}
}