<?php

/**
 * TfSearchContent class file.
 * 
 * @copyright   Simon Wilkinson 2013+ (https://tuskfish.biz)
 * @license     https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GNU General Public License (GPL) V2
 * @author      Simon Wilkinson <simon@isengard.biz>
 * @version     Release: 1.0
 * @since       1.1
 * @package     content
 */

// Enable strict type declaration.
declare(strict_types=1);

if (!defined("TFISH_ROOT_PATH")) die("TFISH_ERROR_ROOT_PATH_NOT_DEFINED");

/**
 * Provides search functionality for the content module, returning mixed content objects.
 *
 * @copyright   Simon Wilkinson 2013+ (https://tuskfish.biz)
 * @license     https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GNU General Public License (GPL) V2
 * @author      Simon Wilkinson <simon@isengard.biz>
 * @version     Release: 1.0
 * @since       1.1
 * @package     content
 * @var         TfValidator $validator Instance of the Tuskfish data validator class.
 * @var         TfDatabase $db Instance of the Tuskfish database class.
 * @var         TfPreference $preference Instance of the Tuskfish site preferences class.
 * @var         array $searchTerms Search terms provided by user.
 * @var         array $escapedSearchTerms XSS escaped copies of the search terms, used for display.
 * @var         int $limit Number of records to retrieve in a single page view.
 * @var         int $offset Starting point for reading records from a result set.
 * @var         string $operator Type of search, options are 'AND', 'OR' and 'exact'.
 */
class TfSearchContent
{
    protected $validator;
    protected $db;
    protected $preference;
    protected $searchTerms;
    protected $escapedSearchTerms;
    protected $limit;
    protected $offset;
    protected $operator;
    
    /**
     * Constructor.
     * 
     * @param TfValidator $validator An instance of the Tuskfish data validator class.
     * @param TfDatabase $db An instance of the database class.
     * @param TfPreference $preference An instance of the Tuskfish site preferences class.
     */
    public function __construct(TfValidator $validator,
            TfDatabase $db, TfPreference $preference)
    {
        if (is_a($validator, 'TfValidator')) {
            $this->validator = $validator; 
        } else {
            trigger_error(TFISH_ERROR_NOT_VALIDATOR, E_USER_ERROR);
        }
        
        if (is_a($db, 'TfDatabase')) {
            $this->db = $db; 
        } else {
            trigger_error(TFISH_ERROR_NOT_DATABASE, E_USER_ERROR);
        }
        
        if (is_a($preference, 'TfPreference')) {
            $this->preference = $preference;
        }  else {
            trigger_error(TFISH_ERROR_NOT_PREFERENCE, E_USER_ERROR);
        }
        
        $this->searchTerms = array();
        $this->escapedSearchTerms = array();
        $this->limit = $preference->searchPagination;
        $this->offset = 0;
        $this->operator = 'AND';
    }
    
    /**
     * Provides global search functionality for content objects.
     * 
     * Escaping of search terms is handled through use of a PDO prepared statement with named 
     * placeholders; search terms are inserted indirectly by binding them to the placeholders.
     * Search terms must NEVER be inserted into a query directly (creates an SQL injection
     * vulnerability), otherwise do us all a favour and go shoot yourself now.
     * 
     * Search terms have entity encoding (htmlspecialchars) applied on the teaser and description
     * fields (only) to ensure consistency with the entity encoding treatment that these HTML fields
     * have been subjected to, otherwise searches involving entities will not return results.
     * 
     * @return object|bool Content objects if results found, false if no results or on failure.
     */
    public function searchContent()
    {
        $sql = $count = '';
        $searchTermPlaceholders = $escapedTermPlaceholders = $results = array();
        
        $sqlCount = "SELECT count(*) ";
        $sqlSearch = "SELECT * ";
        $result = array();

        $sql = "FROM `content` ";
        $count = count($this->searchTerms);
        
        if ($count) {
            $sql .= "WHERE ";
            
            for ($i = 0; $i < $count; $i++) {
                $searchTermPlaceholders[$i] = ':searchTerm' . (string) $i;
                $escapedTermPlaceholders[$i] = ':escapedSearchTerm' . (string) $i;
                $sql .= "(";
                $sql .= "`title` LIKE " . $searchTermPlaceholders[$i] . " OR ";
                $sql .= "`teaser` LIKE " . $escapedTermPlaceholders[$i] . " OR ";
                $sql .= "`description` LIKE " . $escapedTermPlaceholders[$i] . " OR ";
                $sql .= "`caption` LIKE " . $searchTermPlaceholders[$i] . " OR ";
                $sql .= "`creator` LIKE " . $searchTermPlaceholders[$i] . " OR ";
                $sql .= "`publisher` LIKE " . $searchTermPlaceholders[$i];
                $sql .= ")";
                
                if ($i != ($count - 1)) {
                    $sql .= $this->operator;
                }
            }
        }
        
        $sql .= " AND `online` = 1 AND `type` != 'TfBlock' ";
        $sql .= "ORDER BY `date` DESC, `submissionTime` DESC ";
        $sqlCount .= $sql;

        // Bind the search term values and execute the statement.
        $statement = $this->db->preparedStatement($sqlCount);

        if ($statement) {
            
            for ($i = 0; $i < $count; $i++) {
                $statement->bindValue($searchTermPlaceholders[$i], "%" . $this->searchTerms[$i] . "%",
                        PDO::PARAM_STR);
                $statement->bindValue($escapedTermPlaceholders[$i], "%" . $this->escapedSearchTerms[$i] . "%",
                        PDO::PARAM_STR);
            }
        } else {
            return false;
        }
        
        // Execute the statement.
        $statement->execute();

        $row = $statement->fetch(PDO::FETCH_NUM);
        $result[0] = reset($row);
        unset($statement, $row);

        // Retrieve the subset of objects actually required.
        if (!$this->limit) {
            $limit = $this->preference->searchPagination;
        }
        
        $sql .= "LIMIT :limit ";
        
        if ($this->offset) {
            $sql .= "OFFSET :offset ";
        }

        $sqlSearch .= $sql;
        $statement = $this->db->preparedStatement($sqlSearch);
        if ($statement) {
            for ($i = 0; $i < $count; $i++) {
                $statement->bindValue($searchTermPlaceholders[$i], "%" . $this->searchTerms[$i] . "%",
                        PDO::PARAM_STR);
                $statement->bindValue($escapedTermPlaceholders[$i], "%" . $this->escapedSearchTerms[$i]
                        . "%", PDO::PARAM_STR);
                $statement->bindValue(":limit", (int) $this->limit, PDO::PARAM_INT);
                
                if ($this->offset) {
                    $statement->bindValue(":offset", (int) $this->offset, PDO::PARAM_INT);
                }
            }
        } else {
            return false;
        }

        $statement->execute();

        while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
            $object = new $row['type']($this->validator);
            $object->loadPropertiesFromArray($row, true);
            $result[$object->id] = $object;
            unset($object, $row);
        }
        
        return $result;
    }
    
    /**
     * Set a limit on the number of results to retrieve.
     * 
     * Usually this will be the number of objects you want to display in a single page view, as
     * it is related to pagination, for example a search may return 50 results but you only want
     * to display 10 per page.
     * 
     * @param int $limit Number of objects to retrieve.
     */
    public function setLimit(int $limit)
    {
        $this->limit = $this->validator->isInt($limit, 0) ? (int) $limit : 0;
    }
    
    /**
     * Set a starting point for retrieving objects from a result set.
     * 
     * Related to pagination, for example you have 50 search results and display 10 per page, and
     * are currently viewing the third page of results, you would set this as 29.
     * 
     * @param int $offset Starting point to retrieve objects from a result set.
     */
    public function setOffset(int $offset)
    {
        $this->offset = $this->validator->isInt($offset, 0) ? (int) $offset : 0;
    }
    
    /**
     * Set the search type operator (AND, OR or exact).
     * 
     * Determines whether the search terms will be used inclusively (OR), exclusively (AND) or
     * exactly.
     * 
     * @param string $operator AND, OR or exact.
     */
    public function setOperator(string $operator)
    {
        $cleanOperator = $this->validator->trimString($operator);
        
        if (in_array($cleanOperator, array('AND', 'OR', 'exact'), true)) {
            $this->operator = $cleanOperator;
        } else {
            $this->operator = "AND";
        }
    }
    
    /**
     * Set and escape search terms for use in a query.
     * 
     * As some content fields require entities to be encoded (the HTML fields, ie. teaser,
     * description and icon) and others don't, both encoded and unencoded copies of the terms are
     * required for a comprehensive database search. Terms that do not meet the minimum length
     * preference requirement are discarded.
     * 
     * Note that search operator MUST be set before the search terms are set, otherwise the default
     * AND operator will be used.
     * 
     * @param string $searchTerms Search terms provided by user.
     */
    public function setSearchTerms(string $searchTerms)
    {
        $searchTerms = $this->validator->trimString($searchTerms);
        
        $cleanSearchTerms = $escapedSearchTerms = $cleanEscapedSearchTerms = array();
        
        // Create an escaped copy that will be used to search the HTML teaser and description fields.
        $escapedSearchTerms = htmlspecialchars($searchTerms, ENT_NOQUOTES, "UTF-8");

        if ($this->operator === 'AND' || $this->operator === 'OR') {
            $searchTerms = explode(" ", $searchTerms);
            $escapedSearchTerms = explode(" ", $escapedSearchTerms);
        } else {
            $searchTerms = array($searchTerms);
            $escapedSearchTerms = array($escapedSearchTerms);
        }
        
        // Trim search terms and discard any that are less than the minimum search length characters.
        foreach ($searchTerms as $term) {
            $term = $this->validator->trimString($term);
            
            if (!empty($term) && mb_strlen($term, 'UTF-8') >= $this->preference->minSearchLength) {
                $cleanSearchTerms[] = (string) $term;
            }
        }
        
        $this->searchTerms = $cleanSearchTerms;
        
        foreach ($escapedSearchTerms as $escapedTerm) {
            $escapedTerm = $this->validator->trimString($escapedTerm);
            
            if (!empty($escapedTerm) && mb_strlen($escapedTerm, 'UTF-8')
                    >= $this->preference->minSearchLength) {
                $cleanEscapedSearchTerms[] = (string) $escapedTerm;
            }
        }
        
        $this->escapedSearchTerms = $escapedSearchTerms;
    }
    
}
