<?php
namespace PHPInsight;

/*
  phpInsight is a Naive Bayes classifier to calculate sentiment. The program
  uses a database of words categorised as positive, negative or neutral

  Copyright (C) 2012  James Hennessey
  Class modifications and improvements by Ismayil Khayredinov (ismayil.khayredinov@gmail.com)

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>

 */

class Sentiment {

	/**
	 * Location of the dictionary files
	 * @var str
	 */
	private $dataFolder = '';

	/**
	 * List of tokens to ignore
	 * @var array
	 */
	private $ignoreList = array();

	/**
	 * List of words with negative prefixes, e.g. isn't, arent't
	 * @var array
	 */
	private $negPrefixList = array();

	/**
	 * Storage of cached dictionaries
	 * @var array
	 */
	private $dictionary = array();

	/**
	 * Min length of a token for it to be taken into consideration
	 * @var int
	 */
	private $minTokenLength = 1;

	/**
	 * Max length of a taken for it be taken into consideration
	 * @var int
	 */
	private $maxTokenLength = 15;

	/**
	 * Classification of opinions
	 * @var array
	 */
	private $classes = array( 'pos', 'neg', 'neu' );

	/**
	 * Token score per class
	 * @var array
	 */
	private $classTokCounts = array(
		'pos' => 0,
		'neg' => 0,
		'neu' => 0
	);

	/**
	 * Analyzed text score per class
	 * @var array
	 */
	private $classDocCounts = array(
		'pos' => 0,
		'neg' => 0,
		'neu' => 0
	);

	/**
	 * Number of tokens in a text
	 * @var int
	 */
	private $tokCount = 0;

	/**
	 * Number of analyzed texts
	 * @var int
	 */
	private $docCount = 0;

	/**
	 * Implication that the analyzed text has 1/3 chance of being in either of the 3 categories
	 * @var array
	 */
	private $prior = array(
		'pos' => 0.333,
		'neg' => 0.333,
		'neu' => 0.334,
	);

	/**
	 * Class constructor
	 *
	 * @param str $dataFolder base folder
	 * Sets defaults and loads/caches dictionaries
	 */
	public function __construct( $dataFolder = false ) {

		//set the base folder for the data models
		$this->setDataFolder( $dataFolder );

		//load and cache directories, get ignore and prefix lists
		$this->loadDefaults();
	}

	/**
	 * Get scores for each class
	 *
	 * @param str $sentence Text to analyze
	 *
	 * @return int Score
	 */
	public function score( $sentence ) {

		//For each negative prefix in the list
		foreach ( $this->negPrefixList as $negPrefix ) {

			//Search if that prefix is in the document
			if ( strpos( $sentence, $negPrefix ) !== false ) {
				//Reove the white space after the negative prefix
				$sentence = str_replace( $negPrefix . ' ', $negPrefix, $sentence );
			}
		}

		//Tokenise Document
		$tokens = $this->_getTokens( $sentence );
		// calculate the score in each category

		$total_score = 0;

		//Empty array for the scores for each of the possible categories
		$scores = array();

		//Loop through all of the different classes set in the $classes variable
		foreach ( $this->classes as $class ) {

			//In the scores array add another dimention for the class and set it's value to 1. EG $scores->neg->1
			$scores[ $class ] = 1;

			//For each of the individual words used loop through to see if they match anything in the $dictionary
			foreach ( $tokens as $token ) {

				//If statement so to ignore tokens which are either too long or too short or in the $ignoreList
				if ( strlen( $token ) > $this->minTokenLength && strlen( $token ) < $this->maxTokenLength && ! in_array( $token, $this->ignoreList ) ) {
					//If dictionary[token][class] is set
					if ( isset( $this->dictionary[ $token ][ $class ] ) ) {
						//Set count equal to it
						$count = $this->dictionary[ $token ][ $class ];
					} else {
						$count = 0;
					}

					//Score[class] is calcumeted by $scores[class] x $count +1 divided by the $classTokCounts[class] + $tokCount
					$scores[ $class ] *= ( $count + 1 );
				}
			}

			//Score for this class is the prior probability multiplyied by the score for this class
			$scores[ $class ] = $this->prior[ $class ] * $scores[ $class ];
		}

		//Makes the scores relative percents
		foreach ( $this->classes as $class ) {
			$total_score += $scores[ $class ];
		}

		foreach ( $this->classes as $class ) {
			$scores[ $class ] = round( $scores[ $class ] / $total_score, 3 );
		}

		//Sort array in reverse order
		arsort( $scores );

		return $scores;
	}

	/**
	 * Get the class of the text based on it's score
	 *
	 * @param str $sentence
	 *
	 * @return str pos|neu|neg
	 */
	public function categorise( $sentence ) {

		$scores = $this->score( $sentence );

		//Classification is the key to the scores array
		$classification = key( $scores );

		return $classification;
	}

	/**
	 * Load and cache dictionary
	 *
	 * @param str $class
	 *
	 * @return boolean
	 */
	public function setDictionary( $class ) {
		/**
		 *  For some people this file extention causes some problems!
		 */
		$fn = "{$this->dataFolder}data.{$class}.php";

		if ( file_exists( $fn ) && is_readable( $fn ) ) {
			$temp  = file_get_contents( $fn );
			$words = unserialize( trim( $temp ) );
		} else {
			echo 'File does not exist: ' . $fn; // phpcs:ignore
			$words = array();
		}

		// Bail early if $words is empty.
		if ( empty( $words ) ) {
			return true;
		}

		//Loop through all of the entries
		foreach ( (array) $words as $word ) {

			$this->docCount ++;
			$this->classDocCounts[ $class ] ++;

			//Trim word
			$word = trim( $word );

			//If this word isn't already in the dictionary with this class
			if ( ! isset( $this->dictionary[ $word ][ $class ] ) ) {

				//Add to this word to the dictionary and set counter value as one. This function ensures that if a word is in the text file more than once it still is only accounted for one in the array
				$this->dictionary[ $word ][ $class ] = 1;
			}//Close If statement

			$this->classTokCounts[ $class ] ++;
			$this->tokCount ++;
		}//Close while loop going through everyline in the text file

		return true;
	}

	/**
	 * Set the base folder for loading data models
	 *
	 * @param str $dataFolder base folder
	 * @param bool $loadDefaults true - load everything by default | false - just change the directory
	 */
	public function setDataFolder( $dataFolder = false, $loadDefaults = false ) {
		//if $dataFolder not provided, load default, else set the provided one
		if ( $dataFolder == false ) {
			$this->dataFolder = __DIR__ . '/data/';
		} else {
			if ( file_exists( $dataFolder ) ) {
				$this->dataFolder = $dataFolder;
			} else {
				echo 'Error: could not find the directory - ' . $dataFolder; // phpcs:ignore
			}
		}

		//load default directories, ignore and prefixe lists
		if ( $loadDefaults !== false ) {
			$this->loadDefaults();
		}
	}

	/**
	 * Load and cache directories, get ignore and prefix lists
	 */
	private function loadDefaults() {
		// Load and cache dictionaries
		foreach ( $this->classes as $class ) {
			if ( ! $this->setDictionary( $class ) ) {
				echo "Error: Dictionary for class '$class' could not be loaded"; // phpcs:ignore
			}
		}

		if ( ! isset( $this->dictionary ) || empty( $this->dictionary ) ) {
			echo 'Error: Dictionaries not set';
		}

		//Run function to get ignore list
		$this->ignoreList = $this->getList( 'ign' );

		//If ingnoreList not get give error message
		if ( ! isset( $this->ignoreList ) ) {
			echo 'Error: Ignore List not set';
		}

		//Get the list of negative prefixes
		$this->negPrefixList = $this->getList( 'prefix' );

		//If neg prefix list not set give error
		if ( ! isset( $this->negPrefixList ) ) {
			echo 'Error: Ignore List not set';
		}
	}

	/**
	 * Break text into tokens
	 *
	 * @param str $string String being broken up
	 *
	 * @return array An array of tokens
	 */
	private function _getTokens( $string ) {

		// Replace line endings with spaces
		$string = str_replace( "\r\n", " ", $string );

		//Clean the string so is free from accents
		$string = $this->_cleanString( $string );

		//Make all texts lowercase as the database of words in in lowercase
		$string = strtolower( $string );
		$string = preg_replace( '/[[:punct:]]+/', '', $string );

		//Break string into individual words using explode putting them into an array
		$matches = explode( ' ', $string );

		//Return array with each individual token
		return $matches;
	}

	/**
	 * Load and cache additional word lists
	 *
	 * @param str $type
	 *
	 * @return array
	 */
	public function getList( $type ) {
		//Set up empty word list array
		$wordList = array();

		$fn = "{$this->dataFolder}data.{$type}.php";;
		if ( file_exists( $fn ) ) {
			$temp  = file_get_contents( $fn );
			$words = unserialize( trim( $temp ) );
		} else {
			return 'File does not exist: ' . $fn;
		}

		//Loop through results
		foreach ( $words as $word ) {
			//remove any slashes
			$word = stripcslashes( $word );
			//Trim word
			$trimmed = trim( $word );

			//Push results into $wordList array
			array_push( $wordList, $trimmed );
		}

		//Return $wordList
		return $wordList;
	}

	/**
	 * Function to clean a string so all characters with accents are turned into ASCII characters. EG: ‡ = a
	 *
	 * @param str $string
	 *
	 * @return str
	 */
	private function _cleanString( $string ) {

		$diac =
			/* A */
			chr( 192 ) . chr( 193 ) . chr( 194 ) . chr( 195 ) . chr( 196 ) . chr( 197 ) .
			/* a */
			chr( 224 ) . chr( 225 ) . chr( 226 ) . chr( 227 ) . chr( 228 ) . chr( 229 ) .
			/* O */
			chr( 210 ) . chr( 211 ) . chr( 212 ) . chr( 213 ) . chr( 214 ) . chr( 216 ) .
			/* o */
			chr( 242 ) . chr( 243 ) . chr( 244 ) . chr( 245 ) . chr( 246 ) . chr( 248 ) .
			/* E */
			chr( 200 ) . chr( 201 ) . chr( 202 ) . chr( 203 ) .
			/* e */
			chr( 232 ) . chr( 233 ) . chr( 234 ) . chr( 235 ) .
			/* Cc */
			chr( 199 ) . chr( 231 ) .
			/* I */
			chr( 204 ) . chr( 205 ) . chr( 206 ) . chr( 207 ) .
			/* i */
			chr( 236 ) . chr( 237 ) . chr( 238 ) . chr( 239 ) .
			/* U */
			chr( 217 ) . chr( 218 ) . chr( 219 ) . chr( 220 ) .
			/* u */
			chr( 249 ) . chr( 250 ) . chr( 251 ) . chr( 252 ) .
			/* yNn */
			chr( 255 ) . chr( 209 ) . chr( 241 );

		return strtolower( strtr( $string, $diac, 'AAAAAAaaaaaaOOOOOOooooooEEEEeeeeCcIIIIiiiiUUUUuuuuyNn' ) );
	}

	/**
	 * Deletes old data/data.* files
	 * Creates new files from updated source fi
	 */
	public function reloadDictionaries() {

		foreach ( $this->classes as $class ) {
			$fn = "{$this->dataFolder}data.{$class}.php";
			if ( file_exists( $fn ) ) {
				unlink( $fn );
			}
		}

		$dictionaries = __DIR__ . '/dictionaries/';

		foreach ( $this->classes as $class ) {
			$dict = "{$dictionaries}source.{$class}.php";

			require_once( $dict );

			$data = $class;

			$fn = "{$this->dataFolder}data.{$class}.php";
			file_put_contents( $fn, serialize( $$data ) );
		}


	}

}