<?php
/**
 * @package WPSEO\Admin
 */

/**
 * Modified (Reduced) TextStatistics Class
 *
 * Mostly removed functionality that isn't needed within the Yoast SEO plugin.
 *
 * @link    http://code.google.com/p/php-text-statistics/
 * @link    https://github.com/DaveChild/Text-Statistics (new repo location)
 * @license http://www.opensource.org/licenses/bsd-license.php New BSD license
 *
 * @todo    [JRF => whomever] Research if a class/library can be found which will offer
 * this functionality to a broader scope of languages/charsets.
 * Now basically limited to English.
 */
class Yoast_TextStatistics {

	/**
	 * @var string $strEncoding Used to hold character encoding to be used by object, if set
	 */
	protected $strEncoding = '';

	/**
	 * @var string $blnMbstring Efficiency: Is the MB String extension loaded ?
	 */
	protected $blnMbstring = true;

	/**
	 * @var bool $normalize Should the result be normalized ?
	 */
	public $normalize = true;


	/**
	 * Constructor.
	 *
	 * @param string $strEncoding Optional character encoding.
	 */
	public function __construct( $strEncoding = '' ) {
		if ( $strEncoding <> '' ) {
			// Encoding is given. Use it!
			$this->strEncoding = $strEncoding;
		}
		$this->blnMbstring = extension_loaded( 'mbstring' );
	}

	/**
	 * Gives the Flesch-Kincaid Reading Ease of text entered rounded to one digit
	 *
	 * @param  string $strText Text to be checked.
	 *
	 * @return int|float
	 */
	public function flesch_kincaid_reading_ease( $strText ) {
		$strText = $this->clean_text( $strText );
		$score   = WPSEO_Utils::calc( WPSEO_Utils::calc( 206.835, '-', WPSEO_Utils::calc( 1.015, '*', $this->average_words_per_sentence( $strText ) ) ), '-', WPSEO_Utils::calc( 84.6, '*', $this->average_syllables_per_word( $strText ) ) );

		return $this->normalize_score( $score, 0, 100 );
	}

	/**
	 * Gives string length.
	 *
	 * @param  string $strText Text to be measured.
	 *
	 * @return int
	 */
	public function text_length( $strText ) {
		if ( ! $this->blnMbstring ) {
			return strlen( $strText );
		}

		try {
			if ( $this->strEncoding == '' ) {
				$intTextLength = mb_strlen( $strText );
			}
			else {
				$intTextLength = mb_strlen( $strText, $this->strEncoding );
			}
		} catch ( Exception $e ) {
			$intTextLength = strlen( $strText );
		}

		return $intTextLength;
	}

	/**
	 * Gives letter count (ignores all non-letters). Tries mb_strlen and if that fails uses regular strlen.
	 *
	 * @param string $strText Text to be measured.
	 *
	 * @return int
	 */
	public function letter_count( $strText ) {
		$strText = $this->clean_text( $strText ); // To clear out newlines etc.
		$strText = preg_replace( '`[^A-Za-z]+`', '', $strText );

		if ( ! $this->blnMbstring ) {
			return strlen( $strText );
		}

		try {
			if ( $this->strEncoding == '' ) {
				$intTextLength = mb_strlen( $strText );
			}
			else {
				$intTextLength = mb_strlen( $strText, $this->strEncoding );
			}
		} catch ( Exception $e ) {
			$intTextLength = strlen( $strText );
		}

		return $intTextLength;
	}

	/**
	 * Trims, removes line breaks, multiple spaces and generally cleans text before processing.
	 *
	 * @param string $strText Text to be transformed.
	 *
	 * @return string
	 */
	protected function clean_text( $strText ) {
		static $clean = array();

		$key = sha1( $strText );

		if ( isset( $clean[ $key ] ) ) {
			return $clean[ $key ];
		}

		// All these tags should be preceeded by a full stop.
		$fullStopTags = array( 'li', 'p', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'dd' );
		foreach ( $fullStopTags as $tag ) {
			$strText = str_ireplace( '</' . $tag . '>', '.', $strText );
		}
		$strText = strip_tags( $strText );
		$strText = preg_replace( '`[",:;\(\)-]`', ' ', $strText ); // Replace commas, hyphens etc (count them as spaces).
		$strText = preg_replace( '`[\.!?]`', '.', $strText ); // Unify terminators.
		$strText = trim( $strText ) . '.'; // Add final terminator, just in case it's missing.
		$strText = preg_replace( '`[ ]*(\n|\r\n|\r)[ ]*`', ' ', $strText ); // Replace new lines with spaces.
		$strText = preg_replace( '`([\.])[\. ]+`', '$1', $strText ); // Check for duplicated terminators.
		$strText = trim( preg_replace( '`[ ]*([\.])`', '$1 ', $strText ) ); // Pad sentence terminators.
		$strText = preg_replace( '` [0-9]+ `', ' ', ' ' . $strText . ' ' ); // Remove "words" comprised only of numbers.
		$strText = preg_replace( '`[ ]+`', ' ', $strText ); // Remove multiple spaces.
		$strText = preg_replace_callback( '`\. [^ ]+?`', create_function( '$matches', 'return strtolower( $matches[0] );' ), $strText ); // Lower case all words following terminators (for gunning fog score).

		$strText = trim( $strText );

		// Cache it and return.
		$clean[ $key ] = $strText;

		return $strText;
	}

	/**
	 * Converts string to lower case. Tries mb_strtolower and if that fails uses regular strtolower.
	 *
	 * @param string $strText Text to be transformed.
	 *
	 * @return string
	 */
	protected function lower_case( $strText ) {

		if ( ! $this->blnMbstring ) {
			return strtolower( $strText );
		}

		try {
			if ( $this->strEncoding == '' ) {
				$strLowerCaseText = mb_strtolower( $strText );
			}
			else {
				$strLowerCaseText = mb_strtolower( $strText, $this->strEncoding );
			}
		} catch ( Exception $e ) {
			$strLowerCaseText = strtolower( $strText );
		}

		return $strLowerCaseText;
	}

	/**
	 * Converts string to upper case. Tries mb_strtoupper and if that fails uses regular strtoupper.
	 *
	 * @param string $strText Text to be transformed.
	 *
	 * @return string
	 */
	protected function upper_case( $strText ) {
		if ( ! $this->blnMbstring ) {
			return strtoupper( $strText );
		}

		try {
			if ( $this->strEncoding == '' ) {
				$strUpperCaseText = mb_strtoupper( $strText );
			}
			else {
				$strUpperCaseText = mb_strtoupper( $strText, $this->strEncoding );
			}
		} catch ( Exception $e ) {
			$strUpperCaseText = strtoupper( $strText );
		}

		return $strUpperCaseText;
	}

	/**
	 * Returns sentence count for text.
	 *
	 * @param   string $strText Text to be measured.
	 *
	 * @return int
	 */
	public function sentence_count( $strText ) {
		if ( strlen( trim( $strText ) ) == 0 ) {
			return 0;
		}

		$strText = $this->clean_text( $strText );
		// Will be tripped up by "Mr." or "U.K.". Not a major concern at this point.
		// [JRF] Will also be tripped up by ... or ?!
		// @todo [JRF => whomever] May be replace with something along the lines of this - will at least provide better count in ... and ?! situations:
		// $intSentences = max( 1, preg_match_all( '`[^\.!?]+[\.!?]+([\s]+|$)`u', $strText, $matches ) ); [/JRF].
		$intSentences = max( 1, $this->text_length( preg_replace( '`[^\.!?]`', '', $strText ) ) );

		return $intSentences;
	}

	/**
	 * Returns word count for text.
	 *
	 * @param  string $strText Text to be measured.
	 *
	 * @return int
	 */
	public function word_count( $strText ) {
		if ( strlen( trim( $strText ) ) == 0 ) {
			return 0;
		}

		$strText = $this->clean_text( $strText );
		// Will be tripped by em dashes with spaces either side, among other similar characters.
		$intWords = ( 1 + $this->text_length( preg_replace( '`[^ ]`', '', $strText ) ) ); // Space count + 1 is word count.
		return $intWords;
	}

	/**
	 * Returns average words per sentence for text.
	 *
	 * @param string $strText Text to be measured.
	 *
	 * @return int|float
	 */
	public function average_words_per_sentence( $strText ) {
		$strText          = $this->clean_text( $strText );
		$intSentenceCount = $this->sentence_count( $strText );
		$intWordCount     = $this->word_count( $strText );

		return ( WPSEO_Utils::calc( $intWordCount, '/', $intSentenceCount ) );
	}

	/**
	 * Returns average syllables per word for text.
	 *
	 * @param string $strText Text to be measured.
	 *
	 * @return int|float
	 */
	public function average_syllables_per_word( $strText ) {
		$strText          = $this->clean_text( $strText );
		$intSyllableCount = 0;
		$intWordCount     = $this->word_count( $strText );
		$arrWords         = explode( ' ', $strText );
		for ( $i = 0; $i < $intWordCount; $i ++ ) {
			$intSyllableCount += $this->syllable_count( $arrWords[ $i ] );
		}

		return ( WPSEO_Utils::calc( $intSyllableCount, '/', $intWordCount ) );
	}

	/**
	 * Returns the number of syllables in the word.
	 * Based in part on Greg Fast's Perl module Lingua::EN::Syllables
	 *
	 * @param string $strWord Word to be measured.
	 *
	 * @return int
	 */
	public function syllable_count( $strWord ) {
		if ( strlen( trim( $strWord ) ) == 0 ) {
			return 0;
		}

		// Should be no non-alpha characters.
		$strWord = preg_replace( '`[^A-Za-z]`', '', $strWord );

		$intSyllableCount = 0;
		$strWord          = $this->lower_case( $strWord );

		// Specific common exceptions that don't follow the rule set below are handled individually.
		// Array of problem words (with word as key, syllable count as value).
		$arrProblemWords = array(
			'simile'    => 3,
			'forever'   => 3,
			'shoreline' => 2,
		);
		if ( isset( $arrProblemWords[ $strWord ] ) ) {
			$intSyllableCount = $arrProblemWords[ $strWord ];
		}
		if ( $intSyllableCount > 0 ) {
			return $intSyllableCount;
		}

		// These syllables would be counted as two but should be one.
		$arrSubSyllables = array(
			'cial',
			'tia',
			'cius',
			'cious',
			'giu',
			'ion',
			'iou',
			'sia$',
			'[^aeiuoyt]{2,}ed$',
			'.ely$',
			'[cg]h?e[rsd]?$',
			'rved?$',
			'[aeiouy][dt]es?$',
			'[aeiouy][^aeiouydt]e[rsd]?$',
			// Sorts out deal, deign etc.
			'^[dr]e[aeiou][^aeiou]+$',
			// Purse, hearse.
			'[aeiouy]rse$',
		);

		// These syllables would be counted as one but should be two.
		$arrAddSyllables = array(
			'ia',
			'riet',
			'dien',
			'iu',
			'io',
			'ii',
			'[aeiouym]bl$',
			'[aeiou]{3}',
			'^mc',
			'ism$',
			'([^aeiouy])\1l$',
			'[^l]lien',
			'^coa[dglx].',
			'[^gq]ua[^auieo]',
			'dnt$',
			'uity$',
			'ie(r|st)$',
		);

		// Single syllable prefixes and suffixes.
		$arrPrefixSuffix = array(
			'`^un`',
			'`^fore`',
			'`ly$`',
			'`less$`',
			'`ful$`',
			'`ers?$`',
			'`ings?$`',
		);

		// Remove prefixes and suffixes and count how many were taken.
		$strWord = preg_replace( $arrPrefixSuffix, '', $strWord, - 1, $intPrefixSuffixCount );

		// Removed non-word characters from word.
		$strWord          = preg_replace( '`[^a-z]`is', '', $strWord );
		$arrWordParts     = preg_split( '`[^aeiouy]+`', $strWord );
		$intWordPartCount = 0;
		foreach ( $arrWordParts as $strWordPart ) {
			if ( $strWordPart <> '' ) {
				$intWordPartCount ++;
			}
		}

		// Some syllables do not follow normal rules - check for them.
		// Thanks to Joe Kovar for correcting a bug in the following lines.
		$intSyllableCount = ( $intWordPartCount + $intPrefixSuffixCount );
		foreach ( $arrSubSyllables as $strSyllable ) {
			$intSyllableCount -= preg_match( '`' . $strSyllable . '`', $strWord );
		}
		foreach ( $arrAddSyllables as $strSyllable ) {
			$intSyllableCount += preg_match( '`' . $strSyllable . '`', $strWord );
		}
		$intSyllableCount = ( $intSyllableCount == 0 ) ? 1 : $intSyllableCount;

		return $intSyllableCount;
	}

	/**
	 * Normalizes score according to min & max allowed. If score larger
	 * than max, max is returned. If score less than min, min is returned.
	 * Also rounds result to specified precision.
	 * Thanks to github.com/lvil.
	 *
	 * @param    int|float $score Initial score.
	 * @param    int       $min   Minimum score allowed.
	 * @param    int       $max   Maximum score allowed.
	 * @param    int       $dps   Round to # decimals.
	 *
	 * @return    int|float
	 */
	public function normalize_score( $score, $min, $max, $dps = 1 ) {
		$score = WPSEO_Utils::calc( $score, '+', 0, true, $dps ); // Round.
		if ( ! $this->normalize ) {
			return $score;
		}

		if ( $score > $max ) {
			$score = $max;
		}
		elseif ( $score < $min ) {
			$score = $min;
		}

		return $score;
	}

} /* End of class */