<?php

declare(strict_types=1);

namespace KTXM\ProviderImap\Client\Command;

use Generator;
use KTXM\ProviderImap\Client\ImapException;
use KTXM\ProviderImap\Client\Message;
use KTXM\ProviderImap\Client\MessageParser;
use KTXM\ProviderImap\Client\Protocol\Response\TaggedResponse;
use KTXM\ProviderImap\Client\Protocol\Response\UntaggedResponse;
use KTXM\ProviderImap\Client\Protocol\ResponseStream;

final class FetchResponseParser
{
    public function parseOne(ResponseStream $responses): Message
    {
        $message = null;

        foreach ($this->parseMany($responses) as $summary) {
            if ($message !== null) {
                throw new ImapException('FETCH returned multiple messages for a single-message request.');
            }

            $message = $summary;
        }

        if ($message === null) {
            throw new ImapException('FETCH did not return a message summary.');
        }

        return $message;
    }

    /**
     * @return Generator<int, Message>
     */
    public function parseMany(ResponseStream $responses): Generator
    {
        foreach ($responses as $response) {
            if ($response instanceof UntaggedResponse && MessageParser::isFetchMessage($response->payload())) {
                yield MessageParser::parse($response->raw());
                continue;
            }

            if ($response instanceof TaggedResponse) {
                if (!$response->isOk()) {
                    throw new ImapException('FETCH failed: ' . $response->text());
                }

                return;
            }
        }

        throw new ImapException('FETCH did not receive a tagged completion response.');
    }
}