<?php

/**

 * Zend Framework

 *

 * LICENSE

 *

 * This source file is subject to the new BSD license that is bundled

 * with this package in the file LICENSE.txt.

 * It is also available through the world-wide-web at this URL:

 * http://framework.zend.com/license/new-bsd

 * If you did not receive a copy of the license and are unable to

 * obtain it through the world-wide-web, please send an email

 * to license@zend.com so we can send you a copy immediately.

 *

 * @category   Zend

 * @package    Zend_Search_Lucene

 * @subpackage Search

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 * @version    $Id: Phrase.php 20096 2010-01-06 02:05:09Z bkarwin $

 */

/** Zend_Search_Lucene_Search_Query */

require_once 'Zend/Search/Lucene/Search/Query.php';

/**

 * A Query that matches documents containing a particular sequence of terms.

 *

 * @category   Zend

 * @package    Zend_Search_Lucene

 * @subpackage Search

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_Search_Lucene_Search_Query_Phrase extends Zend_Search_Lucene_Search_Query

{

    /**

     * Terms to find.

     * Array of Zend_Search_Lucene_Index_Term objects.

     *

     * @var array

     */

    private $_terms;

    /**

     * Term positions (relative positions of terms within the phrase).

     * Array of integers

     *

     * @var array

     */

    private $_offsets;

    /**

     * Sets the number of other words permitted between words in query phrase.

     * If zero, then this is an exact phrase search.  For larger values this works

     * like a WITHIN or NEAR operator.

     *

     * The slop is in fact an edit-distance, where the units correspond to

     * moves of terms in the query phrase out of position.  For example, to switch

     * the order of two words requires two moves (the first move places the words

     * atop one another), so to permit re-orderings of phrases, the slop must be

     * at least two.

     * More exact matches are scored higher than sloppier matches, thus search

     * results are sorted by exactness.

     *

     * The slop is zero by default, requiring exact matches.

     *

     * @var integer

     */

    private $_slop;

    /**

     * Result vector.

     *

     * @var array

     */

    private $_resVector = null;

    /**

     * Terms positions vectors.

     * Array of Arrays:

     * term1Id => (docId => array( pos1, pos2, ... ), ...)

     * term2Id => (docId => array( pos1, pos2, ... ), ...)

     *

     * @var array

     */

    private $_termsPositions = array();

    /**

     * Class constructor.  Create a new prase query.

     *

     * @param string $field    Field to search.

     * @param array  $terms    Terms to search Array of strings.

     * @param array  $offsets  Relative term positions. Array of integers.

     * @throws Zend_Search_Lucene_Exception

     */

    public function __construct($terms = null, $offsets = null, $field = null)

    {

        $this->_slop = 0;

        if (is_array($terms)) {

            $this->_terms = array();

            require_once 'Zend/Search/Lucene/Index/Term.php';

            foreach ($terms as $termId => $termText) {

                $this->_terms[$termId] = ($field !== null)? new Zend_Search_Lucene_Index_Term($termText, $field):

                                                            new Zend_Search_Lucene_Index_Term($termText);

            }

        } else if ($terms === null) {

            $this->_terms = array();

        } else {

            require_once 'Zend/Search/Lucene/Exception.php';

            throw new Zend_Search_Lucene_Exception('terms argument must be array of strings or null');

        }

        if (is_array($offsets)) {

            if (count($this->_terms) != count($offsets)) {

                require_once 'Zend/Search/Lucene/Exception.php';

                throw new Zend_Search_Lucene_Exception('terms and offsets arguments must have the same size.');

            }

            $this->_offsets = $offsets;

        } else if ($offsets === null) {

            $this->_offsets = array();

            foreach ($this->_terms as $termId => $term) {

                $position = count($this->_offsets);

                $this->_offsets[$termId] = $position;

            }

        } else {

            require_once 'Zend/Search/Lucene/Exception.php';

            throw new Zend_Search_Lucene_Exception('offsets argument must be array of strings or null');

        }

    }

    /**

     * Set slop

     *

     * @param integer $slop

     */

    public function setSlop($slop)

    {

        $this->_slop = $slop;

    }

    /**

     * Get slop

     *

     * @return integer

     */

    public function getSlop()

    {

        return $this->_slop;

    }

    /**

     * Adds a term to the end of the query phrase.

     * The relative position of the term is specified explicitly or the one immediately

     * after the last term added.

     *

     * @param Zend_Search_Lucene_Index_Term $term

     * @param integer $position

     */

    public function addTerm(Zend_Search_Lucene_Index_Term $term, $position = null) {

        if ((count($this->_terms) != 0)&&(end($this->_terms)->field != $term->field)) {

            require_once 'Zend/Search/Lucene/Exception.php';

            throw new Zend_Search_Lucene_Exception('All phrase terms must be in the same field: ' .

                                                   $term->field . ':' . $term->text);

        }

        $this->_terms[] = $term;

        if ($position !== null) {

            $this->_offsets[] = $position;

        } else if (count($this->_offsets) != 0) {

            $this->_offsets[] = end($this->_offsets) + 1;

        } else {

            $this->_offsets[] = 0;

        }

    }

    /**

     * Re-write query into primitive queries in the context of specified index

     *

     * @param Zend_Search_Lucene_Interface $index

     * @return Zend_Search_Lucene_Search_Query

     */

    public function rewrite(Zend_Search_Lucene_Interface $index)

    {

        if (count($this->_terms) == 0) {

            require_once 'Zend/Search/Lucene/Search/Query/Empty.php';

            return new Zend_Search_Lucene_Search_Query_Empty();

        } else if ($this->_terms[0]->field !== null) {

            return $this;

        } else {

            require_once 'Zend/Search/Lucene/Search/Query/Boolean.php';

            $query = new Zend_Search_Lucene_Search_Query_Boolean();

            $query->setBoost($this->getBoost());

            foreach ($index->getFieldNames(true) as $fieldName) {

                $subquery = new Zend_Search_Lucene_Search_Query_Phrase();

                $subquery->setSlop($this->getSlop());

                require_once 'Zend/Search/Lucene/Index/Term.php';

                foreach ($this->_terms as $termId => $term) {

                    $qualifiedTerm = new Zend_Search_Lucene_Index_Term($term->text, $fieldName);

                    $subquery->addTerm($qualifiedTerm, $this->_offsets[$termId]);

                }

                $query->addSubquery($subquery);

            }

            return $query;

        }

    }

    /**

     * Optimize query in the context of specified index

     *

     * @param Zend_Search_Lucene_Interface $index

     * @return Zend_Search_Lucene_Search_Query

     */

    public function optimize(Zend_Search_Lucene_Interface $index)

    {

        // Check, that index contains all phrase terms

        foreach ($this->_terms as $term) {

            if (!$index->hasTerm($term)) {

                require_once 'Zend/Search/Lucene/Search/Query/Empty.php';

                return new Zend_Search_Lucene_Search_Query_Empty();

            }

        }

        if (count($this->_terms) == 1) {

            // It's one term query

            require_once 'Zend/Search/Lucene/Search/Query/Term.php';

            $optimizedQuery = new Zend_Search_Lucene_Search_Query_Term(reset($this->_terms));

            $optimizedQuery->setBoost($this->getBoost());

            return $optimizedQuery;

        }

        if (count($this->_terms) == 0) {

            require_once 'Zend/Search/Lucene/Search/Query/Empty.php';

            return new Zend_Search_Lucene_Search_Query_Empty();

        }

        return $this;

    }

    /**

     * Returns query term

     *

     * @return array

     */

    public function getTerms()

    {

        return $this->_terms;

    }

    /**

     * Set weight for specified term

     *

     * @param integer $num

     * @param Zend_Search_Lucene_Search_Weight_Term $weight

     */

    public function setWeight($num, $weight)

    {

        $this->_weights[$num] = $weight;

    }

    /**

     * Constructs an appropriate Weight implementation for this query.

     *

     * @param Zend_Search_Lucene_Interface $reader

     * @return Zend_Search_Lucene_Search_Weight

     */

    public function createWeight(Zend_Search_Lucene_Interface $reader)

    {

        require_once 'Zend/Search/Lucene/Search/Weight/Phrase.php';

        $this->_weight = new Zend_Search_Lucene_Search_Weight_Phrase($this, $reader);

        return $this->_weight;

    }

    /**

     * Score calculator for exact phrase queries (terms sequence is fixed)

     *

     * @param integer $docId

     * @return float

     */

    public function _exactPhraseFreq($docId)

    {

        $freq = 0;

        // Term Id with lowest cardinality

        $lowCardTermId = null;

        // Calculate $lowCardTermId

        foreach ($this->_terms as $termId => $term) {

            if ($lowCardTermId === null ||

                count($this->_termsPositions[$termId][$docId]) <

                count($this->_termsPositions[$lowCardTermId][$docId]) ) {

                    $lowCardTermId = $termId;

                }

        }

        // Walk through positions of the term with lowest cardinality

        foreach ($this->_termsPositions[$lowCardTermId][$docId] as $lowCardPos) {

            // We expect phrase to be found

            $freq++;

            // Walk through other terms

            foreach ($this->_terms as $termId => $term) {

                if ($termId != $lowCardTermId) {

                    $expectedPosition = $lowCardPos +

                                            ($this->_offsets[$termId] -

                                             $this->_offsets[$lowCardTermId]);

                    if (!in_array($expectedPosition, $this->_termsPositions[$termId][$docId])) {

                        $freq--;  // Phrase wasn't found.

                        break;

                    }

                }

            }

        }

        return $freq;

    }

    /**

     * Score calculator for sloppy phrase queries (terms sequence is fixed)

     *

     * @param integer $docId

     * @param Zend_Search_Lucene_Interface $reader

     * @return float

     */

    public function _sloppyPhraseFreq($docId, Zend_Search_Lucene_Interface $reader)

    {

        $freq = 0;

        $phraseQueue = array();

        $phraseQueue[0] = array(); // empty phrase

        $lastTerm = null;

        // Walk through the terms to create phrases.

        foreach ($this->_terms as $termId => $term) {

            $queueSize = count($phraseQueue);

            $firstPass = true;

            // Walk through the term positions.

            // Each term position produces a set of phrases.

            foreach ($this->_termsPositions[$termId][$docId] as $termPosition ) {

                if ($firstPass) {

                    for ($count = 0; $count < $queueSize; $count++) {

                        $phraseQueue[$count][$termId] = $termPosition;

                    }

                } else {

                    for ($count = 0; $count < $queueSize; $count++) {

                        if ($lastTerm !== null &&

                            abs( $termPosition - $phraseQueue[$count][$lastTerm] -

                                 ($this->_offsets[$termId] - $this->_offsets[$lastTerm])) > $this->_slop) {

                            continue;

                        }

                        $newPhraseId = count($phraseQueue);

                        $phraseQueue[$newPhraseId]          = $phraseQueue[$count];

                        $phraseQueue[$newPhraseId][$termId] = $termPosition;

                    }

                }

                $firstPass = false;

            }

            $lastTerm = $termId;

        }

        foreach ($phraseQueue as $phrasePos) {

            $minDistance = null;

            for ($shift = -$this->_slop; $shift <= $this->_slop; $shift++) {

                $distance = 0;

                $start = reset($phrasePos) - reset($this->_offsets) + $shift;

                foreach ($this->_terms as $termId => $term) {

                    $distance += abs($phrasePos[$termId] - $this->_offsets[$termId] - $start);

                    if($distance > $this->_slop) {

                        break;

                    }

                }

                if ($minDistance === null || $distance < $minDistance) {

                    $minDistance = $distance;

                }

            }

            if ($minDistance <= $this->_slop) {

                $freq += $reader->getSimilarity()->sloppyFreq($minDistance);

            }

        }

        return $freq;

    }

    /**

     * Execute query in context of index reader

     * It also initializes necessary internal structures

     *

     * @param Zend_Search_Lucene_Interface $reader

     * @param Zend_Search_Lucene_Index_DocsFilter|null $docsFilter

     */

    public function execute(Zend_Search_Lucene_Interface $reader, $docsFilter = null)

    {

        $this->_resVector = null;

        if (count($this->_terms) == 0) {

            $this->_resVector = array();

        }

        $resVectors      = array();

        $resVectorsSizes = array();

        $resVectorsIds   = array(); // is used to prevent arrays comparison

        foreach ($this->_terms as $termId => $term) {

            $resVectors[]      = array_flip($reader->termDocs($term));

            $resVectorsSizes[] = count(end($resVectors));

            $resVectorsIds[]   = $termId;

            $this->_termsPositions[$termId] = $reader->termPositions($term);

        }

        // sort resvectors in order of subquery cardinality increasing