<?php

require_once 'core/search/lexer.php';
require_once 'core/functions.php';

/**
 * Поиск в индексе
 */
class Search 
{
    private $lexer;
    private $index;
    function __construct ($index)
    {
        $this->lexer = new Lexer();   
        $this->index = $index;

        $this->op = array ($this, 'Op');    
        $this->binary = array ($this, 'binaryOp');
        $this->union = array ($this, 'union');
        $this->intersection = lcurry($this->op, 'array_uintersect', $this->union);

        $this->notQuery = lcurry ($this->binary, Lexer::TOKEN_NOT, 
            lcurry($this->op, 'array_udiff', 'array_udiff'), array ($this, 'easyQuery'));

        $this->orQuery  = lcurry ($this->binary, Lexer::TOKEN_OR,
            lcurry($this->op, $this->union, $this->union), $this->notQuery);

        $this->andQuery = lcurry ($this->binary, Lexer::TOKEN_AND, $this->intersection, $this->orQuery);
    }

    function union ($a, $b, $callback)
    {
        return array_merge($a, $b);
    }

    function Eq ($a, $b)
    {
        return $a == $b;
    }

    function Op ($files, $words, $a, $b) {
        return array (
            'words' => call_user_func ($words, $a['words'], $b['words'], array ($this, 'eq')), 
            'files' => call_user_func ($files, $a['files'], $b['files'], array ($this, 'eq'))
        );
    }

    public function getQuery ($source)
    {
        $this->lexer->setSource ($source);
        $this->lexer->nextToken();
        return $this->topQuery();
    }

    function topQuery ()
    {
        $result = call_user_func ($this->andQuery); 
        while ($this->lexer->token[0] == Lexer::TOKEN_LPAREN) {
            $result = call_user_func ($this->intersection, $result, call_user_func ($this->andQuery));
        }
        return $result;
    }

    function easyQuery ()
    {
        $result = null;
        if ($this->lexer->token[0] == Lexer::TOKEN_LPAREN) {
            $this->lexer->nextToken ();
            $result = $this->topQuery ();
            if ($this->lexer->token[0] == Lexer::TOKEN_RPAREN) {
                $this->lexer->nextToken ();
            }
            return $result;
        } else {
            $result = call_user_func ($this->index, $this->lexer->token[1]);
            $this->lexer->nextToken ();
            return $result;
        }
    }

    /**
     * @param int $type Тип лексемы  
     * @param function $op Функция при совпадении типа лексемы при запросе  
     * @param function $next Следующий обработчик запроса   
     */
    function binaryOp ($type, $op, $next)
    {
         $result = call_user_func($next);
         while ($this->lexer->token[0] == $type) {
             $this->lexer->nextToken();
             $result = call_user_func($op, $result, call_user_func ($next));
         }
         return $result; 
    }
}