<?php

namespace mt;

class BlindBox {

    public static function randItem($boxId, $groupId)
    {
        self::mustBeGroupHash();
        $key = $boxId . '_' . $groupId;
        $spaceKey = $key . '_rand_space';

        $spaceVal = getXVal(self::$groupHash, $spaceKey, 0);
        $rndVal = $spaceVal > 0 ? rand() % $spaceVal : 0;

        $groups = getXVal(self::$groupHash, $key);
        foreach ($groups as $group) {
            if ($rndVal <= $group['_weight']) {
                return $group;
            }
        }
        return null;
    }

    protected static function mustBeGroupHash()
    {
        if (is_null(self::$groupHash)) {
            self::$groupHash = array();
            foreach (self::getMetaList() as $meta) {
                $key = $meta['box_id'] . '_' . $meta['group_id'];
                $spaceKey = $key . '_rand_space';

                $spaceVal = getXVal(self::$groupHash, $spaceKey, 0) + $meta['weight'];
                self::$groupHash[$spaceKey] = $spaceVal;

                $meta['_weight'] = $spaceVal;
                if (!getXVal(self::$groupHash, $key)) {
                    self::$groupHash[$key] = array();
                }
                array_push(self::$groupHash[$key], $meta);
            }
        }
    }

    protected static function getMetaList()
    {
        if (!self::$metaList) {
            self::$metaList = getMetaTable('blindBox@blindBox.php');
        }
        return self::$metaList;
    }

    protected static $metaList;
    protected static $groupHash;

};