<?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

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

 */

/** Zend_Search_Lucene_Search_Query */

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

/**

 * @category   Zend

 * @package    Zend_Search_Lucene

 * @subpackage Search

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

 */

class Zend_Search_Lucene_Search_Query_MultiTerm extends Zend_Search_Lucene_Search_Query

{

    /**

     * Terms to find.

     * Array of Zend_Search_Lucene_Index_Term

     *

     * @var array

     */

    private $_terms = array();

    /**

     * Term signs.

     * If true then term is required.

     * If false then term is prohibited.

     * If null then term is neither prohibited, nor required

     *

     * If array is null then all terms are required

     *

     * @var array

     */

    private $_signs;

    /**

     * Result vector.

     *

     * @var array

     */

    private $_resVector = null;

    /**

     * Terms positions vectors.

     * Array of Arrays:

     * term1Id => (docId => freq, ...)

     * term2Id => (docId => freq, ...)

     *

     * @var array

     */

    private $_termsFreqs = array();

    /**

     * A score factor based on the fraction of all query terms

     * that a document contains.

     * float for conjunction queries

     * array of float for non conjunction queries

     *

     * @var mixed

     */

    private $_coord = null;

    /**

     * Terms weights

     * array of Zend_Search_Lucene_Search_Weight

     *

     * @var array

     */

    private $_weights = array();

    /**

     * Class constructor.  Create a new multi-term query object.

     *

     * if $signs array is omitted then all terms are required

     * it differs from addTerm() behavior, but should never be used

     *

     * @param array $terms    Array of Zend_Search_Lucene_Index_Term objects

     * @param array $signs    Array of signs.  Sign is boolean|null.

     * @throws Zend_Search_Lucene_Exception

     */

    public function __construct($terms = null, $signs = null)

    {

        if (is_array($terms)) {

            require_once 'Zend/Search/Lucene.php';

            if (count($terms) > Zend_Search_Lucene::getTermsPerQueryLimit()) {

                throw new Zend_Search_Lucene_Exception('Terms per query limit is reached.');

            }

            $this->_terms = $terms;

            $this->_signs = null;

            // Check if all terms are required

            if (is_array($signs)) {

                foreach ($signs as $sign ) {

                    if ($sign !== true) {

                        $this->_signs = $signs;

                        break;

                    }

                }

            }

        }

    }

    /**

     * Add a $term (Zend_Search_Lucene_Index_Term) to this query.

     *

     * The sign is specified as:

     *     TRUE  - term is required

     *     FALSE - term is prohibited

     *     NULL  - term is neither prohibited, nor required

     *

     * @param  Zend_Search_Lucene_Index_Term $term

     * @param  boolean|null $sign

     * @return void

     */

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

        if ($sign !== true || $this->_signs !== null) {       // Skip, if all terms are required

            if ($this->_signs === null) {                     // Check, If all previous terms are required

                $this->_signs = array();

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

                    $this->_signs[] = true;

                }

            }

            $this->_signs[] = $sign;

        }

        $this->_terms[] = $term;

    }

    /**

     * 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();

        }

        // Check, that all fields are qualified

        $allQualified = true;

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

            if ($term->field === null) {

                $allQualified = false;

                break;

            }

        }

        if ($allQualified) {

            return $this;

        } else {

            /** transform multiterm query to boolean and apply rewrite() method to subqueries. */

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

            $query = new Zend_Search_Lucene_Search_Query_Boolean();

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

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

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

                $subquery = new Zend_Search_Lucene_Search_Query_Term($term);

                $query->addSubquery($subquery->rewrite($index),

                                    ($this->_signs === null)?  true : $this->_signs[$termId]);

            }

            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)

    {

        $terms = $this->_terms;

        $signs = $this->_signs;

        foreach ($terms as $id => $term) {

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

                if ($signs === null  ||  $signs[$id] === true) {

                    // Term is required

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

                    return new Zend_Search_Lucene_Search_Query_Empty();

                } else {

                    // Term is optional or prohibited

                    // Remove it from terms and signs list

                    unset($terms[$id]);

                    unset($signs[$id]);

                }

            }

        }

        // Check if all presented terms are prohibited

        $allProhibited = true;

        if ($signs === null) {

            $allProhibited = false;

        } else {

            foreach ($signs as $sign) {

                if ($sign !== false) {

                    $allProhibited = false;

                    break;

                }

            }

        }

        if ($allProhibited) {

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

            return new Zend_Search_Lucene_Search_Query_Empty();

        }

        /**

         * @todo make an optimization for repeated terms

         * (they may have different signs)

         */

        if (count($terms) == 1) {

            // It's already checked, that it's not a prohibited term

            // It's one term query with one required or optional element

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

            $optimizedQuery = new Zend_Search_Lucene_Search_Query_Term(reset($terms));

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

            return $optimizedQuery;

        }

        if (count($terms) == 0) {

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

            return new Zend_Search_Lucene_Search_Query_Empty();

        }

        $optimizedQuery = new Zend_Search_Lucene_Search_Query_MultiTerm($terms, $signs);

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

        return $optimizedQuery;

    }

    /**

     * Returns query term

     *

     * @return array

     */

    public function getTerms()

    {

        return $this->_terms;

    }

    /**

     * Return terms signs

     *

     * @return array

     */

    public function getSigns()

    {

        return $this->_signs;

    }

    /**

     * 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/MultiTerm.php';

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

        return $this->_weight;

    }

    /**

     * Calculate result vector for Conjunction query

     * (like '+something +another')

     *

     * @param Zend_Search_Lucene_Interface $reader

     */

    private function _calculateConjunctionResult(Zend_Search_Lucene_Interface $reader)

    {

        $this->_resVector = null;

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

            $this->_resVector = array();

        }

        // Order terms by selectivity

        $docFreqs = array();

        $ids      = array();

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

            $docFreqs[] = $reader->docFreq($term);

            $ids[]      = $id; // Used to keep original order for terms with the same selectivity and omit terms comparison

        }

        array_multisort($docFreqs, SORT_ASC, SORT_NUMERIC,

                        $ids,      SORT_ASC, SORT_NUMERIC,

                        $this->_terms);

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

        $docsFilter = new Zend_Search_Lucene_Index_DocsFilter();

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

            $termDocs = $reader->termDocs($term, $docsFilter);

        }

        // Treat last retrieved docs vector as a result set

        // (filter collects data for other terms)

        $this->_resVector = array_flip($termDocs);

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

            $this->_termsFreqs[$termId] = $reader->termFreqs($term, $docsFilter);

        }

        // ksort($this->_resVector, SORT_NUMERIC);

        // Docs are returned ordered. Used algorithms doesn't change elements order.

    }

    /**

     * Calculate result vector for non Conjunction query

     * (like '+something -another')

     *

     * @param Zend_Search_Lucene_Interface $reader

     */

    private function _calculateNonConjunctionResult(Zend_Search_Lucene_Interface $reader)

    {

        $requiredVectors      = array();

        $requiredVectorsSizes = array();

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

        $optional   = array();

        $prohibited = array();

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

            $termDocs = array_flip($reader->termDocs($term));

            if ($this->_signs[$termId] === true) {

                // required

                $requiredVectors[]      = $termDocs;

                $requiredVectorsSizes[] = count($termDocs);

                $requiredVectorsIds[]   = $termId;

            } elseif ($this->_signs[$termId] === false) {

                // prohibited

                // array union

                $prohibited += $termDocs;

            } else {

                // neither required, nor prohibited

                // array union

                $optional += $termDocs;

            }

            $this->_termsFreqs[$termId] = $reader->termFreqs($term);

        }

        // sort resvectors in order of subquery cardinality increasing

        array_multisort($requiredVectorsSizes, SORT_ASC, SORT_NUMERIC,

                        $requiredVectorsIds,   SORT_ASC, SORT_NUMERIC,

                        $requiredVectors);

        $required = null;

        foreach ($requiredVectors as $nextResVector) {

            if($required === null) {

                $required = $nextResVector;

            } else {

                //$required = array_intersect_key($required, $nextResVector);

                /**

                 * This code is used as workaround for array_intersect_key() slowness problem.

                 */

                $updatedVector = array();

                foreach ($required as $id => $value) {

                    if (isset($nextResVector[$id])) {

                        $updatedVector[$id] = $value;

                    }

                }

                $required = $updatedVector;

            }

            if (count($required) == 0) {

                // Empty result set, we don't need to check other terms

                break;

            }

        }

        if ($required !== null) {

            $this->_resVector = $required;

        } else {

            $this->_resVector = $optional;

        }

        if (count($prohibited) != 0) {

            // $this->_resVector = array_diff_key($this->_resVector, $prohibited);

            /**

             * This code is used as workaround for array_diff_key() slowness problem.

             */

            if (count($this->_resVector) < count($prohibited)) {

                $updatedVector = $this->_resVector;

                foreach ($this->_resVector as $id => $value) {

                    if (isset($prohibited[$id])) {

                        unset($updatedVector[$id]);

                    }

                }

                $this->_resVector = $updatedVector;

            } else {