<?php declare(strict_types=1);
namespace openvk\Web\Models\Repositories;
use openvk\Web\Models\Entities\User;
use openvk\Web\Models\Entities\Notifications\Notification;
use openvk\Web\Models\Repositories\Users;

class Notifications
{
    private $edbc = NULL;
    private $modelCodes;
    
    function __construct()
    {
        $this->modelCodes = array_flip(json_decode(file_get_contents(__DIR__ . "/../../../data/modelCodes.json"), true));
    }
    
    private function getEDB(bool $throw = true): ?object
    {
        $eax = $this->edbc ?? eventdb();
        if(!$eax && $throw)
            throw new \RuntimeException("Event database err!");
        
        return is_null($eax) ? NULL : $eax->getConnection();
    }
    
    private function getModel(int $code, int $id): object
    {
        $repoClassName = str_replace("Entities", "Repositories", "\\" . $this->modelCodes[$code]) . "s";
        
        return (new $repoClassName)->get($id);
    }
    
    private function getQuery(User $user, bool $count, int $offset, bool $archived = false, int $page = 1, ?int $perPage = NULL): string
    {
        $query    = "SELECT " . ($count ? "COUNT(*) AS cnt" : "*") . " FROM notifications WHERE recipientType=0 ";
        $query   .= "AND timestamp " . ($archived ? "<" : ">") . "$offset AND recipientId=" . $user->getId();
        if(!$count) {
            $query .= " ORDER BY timestamp DESC";
            $query .= " LIMIT " . ($perPage ?? OPENVK_DEFAULT_PER_PAGE);
            $query .= " OFFSET " . (($page - 1) * ($perPage ?? OPENVK_DEFAULT_PER_PAGE));
        }
        
        return $query;
    }
    
    private function assemble(int $act, int $originModelType, int $originModelId, int $targetModelType, int $targetModelId, int $recipientId, int $timestamp, $data, ?string $class = NULL): Notification
    {
        $class ??= 'openvk\Web\Models\Entities\Notifications\Notification';
        
        $originModel = $this->getModel($originModelType, $originModelId);
        $targetModel = $this->getModel($targetModelType, $targetModelId);
        $recipient   = (new Users)->get($recipientId);
        
        $notification = new $class($recipient, $originModel, $targetModel, $timestamp, $data);
        $notification->setActionCode($act);
        return $notification;
    }
    
    function getNotificationCountByUser(User $user, int $offset, bool $archived = false): int
    {
        $db = $this->getEDB(false);
        if(!$db)
            return 0;
        
        $results = $db->query($this->getQuery($user, true, $offset, $archived));
        
        return $results->fetch()->cnt;
    }
    
    function getNotificationsByUser(User $user, int $offset, bool $archived = false, int $page = 1, ?int $perPage = NULL): \Traversable
    {
        $db = $this->getEDB(false);
        if(!$db) {
            yield from [];
            return;
        }
        
        $results  = $this->getEDB()->query($this->getQuery($user, false, $offset, $archived, $page, $perPage));
        foreach($results->fetchAll() as $notif) {
            yield $this->assemble(
                $notif->modelAction,
                $notif->originModelType,
                $notif->originModelId,
                
                $notif->targetModelType,
                $notif->targetModelId,
                
                $notif->recipientId,
                $notif->timestamp,
                $notif->additionalData
            );
        }
    }
    
    function fromDescriptor(string $descriptor, ?object &$parsedData = nullptr)
    {
        [$class, $recv, $data] = explode(",", $descriptor);
        $class = str_replace(".", "\\", $class);
        
        $parsedData = unserialize(base64_decode($data));
        return $this->assemble(
            $parsedData->actionCode,
            $parsedData->originModelType,
            $parsedData->originModelId,
            
            $parsedData->targetModelType,
            $parsedData->targetModelId,
            
            $parsedData->recipient,
            $parsedData->timestamp,
            $parsedData->additionalPayload,
        );
    }
}