<?php
/**
 * SeekQuarry/Yioop --
 * Open Source Pure PHP Search Engine, Crawler, and Indexer
 *
 * Copyright (C) 2009 - 2026  Chris Pollett chris@pollett.org
 *
 * LICENSE:
 *
 * 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 <https://www.gnu.org/licenses/>.
 *
 * END LICENSE
 *
 * @author Chris Pollett chris@pollett.org
 * @license https://www.gnu.org/licenses/ GPL3
 * @link https://www.seekquarry.com/
 * @copyright 2009 - 2026
 * @filesource
 */
namespace seekquarry\yioop\library\index_bundle_iterators;

use seekquarry\yioop\configs as C;
use seekquarry\yioop\library as L;
use seekquarry\yioop\library\IndexDocumentBundle;

/**
 * This iterator is used to group together documents or document parts
 * which share the same url. For instance, a link document item and
 * the document that it links to will both be stored in the IndexArchiveBundle
 * by the QueueServer. This iterator would combine both these items into
 * a single document result with a sum of their score, and a summary, if
 * returned, containing text from both sources. The iterator's purpose is
 * vaguely analogous to a SQL GROUP BY clause
 *
 * @author Chris Pollett
 * @see IndexArchiveBundle
 */
class GroupIterator extends IndexBundleIterator
{
    /**
     * The number of documents in the current block before filtering
     * by restricted words
     * @var int
     */
    public $count_block_unfiltered;
    /**
     * The number of documents in the current block after filtering
     * by restricted words
     * @var int
     */
    public $count_block;
    /**
     * hashes of document web pages seen in results returned from the
     * most recent call to findDocsWithWord
     * @var array
     */
    public $current_block_hashes;
    /**
     * @var array
     */
    public $current_seen_hashes;
    /**
     * The number of iterated docs before the restriction test
     * @var int
     */
    public $seen_docs_unfiltered;
    /**
     * hashed url keys used to keep track of track of groups seen so far
     * @var array
     */
    public $grouped_keys;
    /**
     * hashed of document web pages used to keep track of track of
     * groups seen so far
     * @var array
     */
    public $grouped_hashes;
    /**
     * Used to keep track and to weight pages based on the number of other
     * pages from the same domain
     * @var array
     */
    public $domain_factors;
    /**
     * Creates a group iterator with the given parameters.
     *
     * @param object $index_bundle_iterator the iterator to use as a
     *      source of documents to iterate over
     * @param int $num_iterators number of word iterators appearing in
     *      sub-iterators -- if larger, reduces the default grouping
     *      number
     * @param int $current_machine if this iterator is being used in a
     *      multi-queue_server setting, this is the id of the current
     *      queue_server (id of queue_server this group_iterator lives
     *      on)
     */
    public function __construct(public $index_bundle_iterator,
        $num_iterators = 1, public $current_machine = 0)
    {
        $this->num_docs = $this->index_bundle_iterator->num_docs;
        $this->results_per_block = max(
            $this->index_bundle_iterator->results_per_block,
            C\p('MIN_RESULTS_TO_GROUP'));
        $this->results_per_block /=  ceil($num_iterators/2);
        $this->reset();
    }
    /**
     * Returns CrawlConstants::ASCENDING or CrawlConstants::DESCENDING
     * depending on the direction in which this iterator ttraverse the
     * underlying index archive bundle.
     *
     * @return int direction traversing underlying archive bundle
     */
    public function getDirection()
    {
        if (!empty($this->index_bundle_iterators)) {
            return $this->index_bundle_iterators->getDirection();
        }
        return self::ASCENDING;
    }
    /**
     * Returns the iterators to the first document block that it could iterate
     * over
     */
    public function reset()
    {
        $this->index_bundle_iterator->reset();
        $this->grouped_keys = [];
         $this->grouped_hashes = [];
            // -1 == never save, so file name not used using time to be safer
        $this->seen_docs = 0;
        $this->seen_docs_unfiltered = 0;
    }
    /**
     * Hook function used by currentDocsWithWord to return the current block
     * of docs if it is not cached
     *
     * @return mixed doc ids and score if there are docs left, -1 otherwise
     */
    public function findDocsWithWord()
    {
        // first get a block of documents on which grouping can be done
        $pages =  $this->getPagesToGroup();
        if (is_array($pages)) {
            $this->count_block_unfiltered = count($pages);
        } else {
            $this->count_block_unfiltered = 0;
            return $pages;
        }
        $this->current_block_hashes = [];
        $this->current_seen_hashes = [];
        if ($this->count_block_unfiltered > 0 ) {
            /* next we group like documents by url and remember
               which urls we've seen this block
            */
            $pre_out_pages = $this->groupByHashUrl($pages);
           /*get doc page for groups of link data if exists and don't have
             also aggregate by hash
           */
           $this->groupByHashAndAggregate($pre_out_pages);
           $this->count_block = count($pre_out_pages);
            /*
                Calculate aggregate values for each field of the groups we
                found
             */
            $pages = $this->computeOutPages($pre_out_pages);
        }
        $this->pages = $pages;
        return $pages;
    }
    /**
     * Gets a sample of a few hundred pages on which to do grouping by URL
     *
     * @return array of pages of document key --> meta data arrays
     */
    public function getPagesToGroup()
    {
        $pages = [];
        $count = 0;
        $done = false;
        do {
            $new_pages = $this->index_bundle_iterator->currentDocsWithWord();
            if (!is_array($new_pages)) {
                $done = true;
                if (count($pages) == 0) {
                    $pages = -1;
                }
            } else if (!empty($new_pages)) {
                $pages = array_merge($pages, $new_pages);
                $count = count($pages);
            }
            if ($count < $this->results_per_block && !$done) {
                $this->index_bundle_iterator->advance();
            } else {
                $done = true;
            }
        } while($done != true);
        return $pages;
    }
    /**
     * Groups documents as well as mini-pages based on links to documents by
     * url to produce an array of arrays of documents with same url. Since
     * this is called in an iterator, documents which were already returned by
     * a previous call to currentDocsWithWord() followed by an advance() will
     * have been remembered in grouped_keys and will be ignored in the return
     * result of this function.
     *
     * @param array &$pages pages to group
     * @return array $pre_out_pages pages after grouping
     */
    public function groupByHashUrl(&$pages)
    {
        $pre_out_pages = [];
        foreach ($pages as $doc_key => $doc_info) {
            if (!is_array($doc_info)) {
                    continue;
            }
            $hash_url = substr($doc_key, 0, WordIterator::KEY_LEN);
            // initial aggregate domain score vector for given domain
            if (!empty($doc_info[self::IS_DOC])) {
                if (!isset($pre_out_pages[$hash_url])) {
                    $pre_out_pages[$hash_url] = [];
                }
                array_unshift($pre_out_pages[$hash_url], $doc_info);
            } else {
                $pre_out_pages[$hash_url][] = $doc_info;
            }
            if (!isset($this->grouped_keys[$hash_url])) {
               /*
                    new urls found in this block
                */
                $this->current_block_hashes[] = $hash_url;
            } else {
                unset($pre_out_pages[$hash_url]);
            }
        }
        return $pre_out_pages;
    }
    /**
     * For documents which had been previously grouped by the hash of their
     * url, groups these groups further by the hash of their pages contents.
     * For each group of groups with the same hash summary, this function
     * then selects the subgroup of with the highest max score for
     * that group as its representative. The function then modifies the
     * supplied argument array to make it an array of group representatives.
     *
     * @param array &$pre_out_pages documents previously grouped by hash of url
     */
    public function groupByHashAndAggregate(&$pre_out_pages)
    {
        foreach ($pre_out_pages as $hash_url => $data) {
            $this->aggregateScores($hash_url, $pre_out_pages[$hash_url]);
            if (isset($pre_out_pages[$hash_url][0][self::HASH])) {
                $hash = $pre_out_pages[$hash_url][0][self::HASH];
                if (IndexDocumentBundle::isType($data[0][self::KEY], "text")) {
                    //in this case the first four bytes is the hash of the title
                    $hash = substr($hash, 0, 4);
                }
                if (isset($this->grouped_hashes[$hash])) {
                    unset($pre_out_pages[$hash_url]);
                } else {
                    if (!isset($this->current_seen_hashes[$hash])) {
                        $this->current_seen_hashes[$hash] = [];
                    }
                    if (!isset($this->current_seen_hashes[$hash][$hash_url])) {
                        $this->current_seen_hashes[$hash][$hash_url] = 0;
                    }
                    $this->current_seen_hashes[$hash][$hash_url] = max(
                        $pre_out_pages[$hash_url][0][self::DOC_RANK],
                        $this->current_seen_hashes[$hash][$hash_url]);
                }
            }
        }
        // delete all except highest scoring group with given hash
        foreach ($this->current_seen_hashes as $hash => $url_data) {
            if (count($url_data) == 1) {
                continue;
            }
            arsort($url_data);
            $first_time = true;
            foreach ($url_data as $hash_url => $value) {
                if ($first_time) {
                    $first_hash_url = $hash_url;
                    $first_time = false;
                } else if ($pre_out_pages[$first_hash_url][0][self::SCORE] <
                    $pre_out_pages[$hash_url][0][self::SCORE]) {
                    $pre_out_pages[$first_hash_url] =
                        $pre_out_pages[$hash_url];
                    unset($pre_out_pages[$hash_url]);
                }
            }
        }
    }
    /**
     * For a collection of grouped pages generates a grouped summary for each
     * group and returns an array of out pages consisting
     * of single summarized documents for each group. These single summarized
     * documents have aggregated scores.
     *
     * @param array &$pre_out_pages array of groups of pages for which out pages
     *     are to be generated.
     * @return array $out_pages array of single summarized documents
     */
    public function computeOutPages(&$pre_out_pages)
    {
        $out_pages = [];
        foreach ($pre_out_pages as $hash_url => $group_infos) {
            $out_pages[$hash_url] = $pre_out_pages[$hash_url][0];
            $add_lookup = false;
            $hash = $out_pages[$hash_url][self::HASH];
            $is_location =
                (L\crawlHash($hash_url . "LOCATION", true) == $hash);
            if (empty($out_pages[$hash_url][self::IS_DOC]) || $is_location) {
                $add_lookup = true;
            }
            $out_pages[$hash_url][self::SUMMARY_OFFSET] = [];
            unset($out_pages[$hash_url][self::GENERATION]);
            $hash_count = $out_pages[$hash_url][self::HASH_URL_COUNT];
            for ($i = 0; $i < $hash_count; $i++) {
                $doc_info = $group_infos[$i];
                if (isset($doc_info[self::GENERATION])) {
                    $machine_id = (isset($doc_info[self::MACHINE_ID])) ?
                        $doc_info[self::MACHINE_ID] :$this->current_machine;
                    $out_pages[$hash_url][self::SUMMARY_OFFSET][] =
                        [$machine_id, $doc_info[self::KEY],
                            $doc_info[self::CRAWL_TIME],
                            $doc_info[self::GENERATION],
                            "PDB"];
                }
            }
            if ($add_lookup) {
                $prefix = ($is_location) ? "location:" : "info:";
                $word_key = $prefix . L\base64Hash($hash_url);
                array_unshift($out_pages[$hash_url][self::SUMMARY_OFFSET],
                    [$word_key, $group_infos[0][self::CRAWL_TIME]]);
            }
        }
        return $out_pages;
    }
    /**
     * For a collection of pages each with the same url, computes the page
     * with the max score, as well as the max of the ranks and
     * relevance scores.
     * Stores this information in the first element of the array of pages.
     * This process is described in detail at:
     * https://www.seekquarry.com/?c=main&p=ranking#search
     *
     * @param string $hash_url the crawlHash of the url of the page we are
     *      scoring which will be compared with that of the host to see if
     *      the current page has the url of a hostname.
     * @param array &$pre_hash_page pages to compute scores for
     */
    public function aggregateScores($hash_url, &$pre_hash_page)
    {
        $max_rank = 0;
        $max_relevance = 0;
        $domain_weights = [];
        foreach ($pre_hash_page as $hash_page) {
            if (isset($hash_page[self::SCORE])) {
                $max_rank = max($max_rank, $hash_page[self::DOC_RANK]);
                $max_relevance = max($max_relevance,
                    $hash_page[self::RELEVANCE]);
            }
        }
        $pre_hash_page[0][self::SCORE] = $max_rank + $max_relevance;
        $pre_hash_page[0][self::DOC_RANK] = $max_rank;
        $pre_hash_page[0][self::HASH_URL_COUNT] = count($pre_hash_page);
        $pre_hash_page[0][self::RELEVANCE] = $max_relevance;
    }
    /**
     * Forwards the iterator one group of docs
     * @param array $gen_doc_offset a generation, doc_offset pair. If set,
     *     the must be of greater than or equal generation, and if equal the
     *     next block must all have $doc_offsets larger than or equal to
     *     this value
     */
    public function advance($gen_doc_offset = null)
    {
        $this->advanceSeenDocs();
        $this->seen_docs_unfiltered += $this->count_block_unfiltered;
        if ($this->seen_docs_unfiltered > 0) {
            if ( $this->count_block_unfiltered < $this->results_per_block) {
                $this->num_docs = $this->seen_docs;
            } else {
                $this->num_docs =
                    floor(
                    ($this->seen_docs * $this->index_bundle_iterator->num_docs)/
                    $this->seen_docs_unfiltered);
            }
        } else {
            $this->num_docs = 0;
        }
        foreach ($this->current_block_hashes as $hash_url) {
            $this->grouped_keys[$hash_url] = true;
        }
        foreach ($this->current_seen_hashes as $hash => $url_data) {
            $this->grouped_hashes[$hash] = true;
        }
        $this->index_bundle_iterator->advance($gen_doc_offset);
    }
    /**
     * Gets the doc_offset and generation for the next document that
     * would be return by this iterator
     *
     * @return mixed an array with the desired document offset
     * and generation; -1 on fail
     */
    public function currentGenDocOffsetWithWord() {
        $this->index_bundle_iterator->currentGenDocOffsetWithWord();
    }
}
