<?php

declare(strict_types=1);

namespace KTXM\ChronoManager\Import;

use Generator;
use InvalidArgumentException;
use KTXF\Resource\Identifier\CollectionIdentifier;
use KTXM\ChronoManager\Manager;
use KTXM\ChronoManager\Conversion\IcalDecoder;
use Sabre\VObject\Component\VCalendar;
use Sabre\VObject\Component\VEvent;
use Sabre\VObject\Component\VJournal;
use Sabre\VObject\Component\VTodo;
use Sabre\VObject\Parser\MimeDir;
use Sabre\VObject\Reader;
use Throwable;

/** Imports the three RFC 5545 calendar object types into Chrono entities. */
class ImportService {

    public function __construct(
        private readonly Manager $manager,
        private readonly IcalDecoder $decoder,
    ) {}

    /**
     * @param resource $source readable, seekable iCalendar resource
     * @return Generator<int, ImportEvent>
     */
    public function import($source, CollectionIdentifier $target, ImportOptions $options, string $tenantId, string $userId): Generator {
        if (!is_resource($source)) {
            throw new InvalidArgumentException('Invalid import source: must be a file resource');
        }

        try {
            rewind($source);
            $calendar = Reader::read($source, MimeDir::OPTION_FORGIVING | MimeDir::OPTION_IGNORE_INVALID_LINES);
            if (!$calendar instanceof VCalendar) {
                throw new InvalidArgumentException('Supplied input is not an iCalendar document');
            }
        } catch (Throwable $e) {
            if ($options->getCounts()) {
                yield new ImportCountEvent(0);
            }
            yield new ImportObjectEvent(null, ImportDisposition::Error, ['Malformed iCalendar: ' . $e->getMessage()]);
            return;
        }

        $components = array_values(array_filter(
            $calendar->children(),
            static fn($component): bool => $component instanceof VEvent
                || $component instanceof VTodo
                || $component instanceof VJournal,
        ));

        if ($options->getCounts()) {
            yield new ImportCountEvent(count($components));
        }

        foreach ($components as $component) {
            $uid = isset($component->UID) ? (trim((string)$component->UID) ?: null) : null;
            try {
                $this->manager->entityCreate($tenantId, $userId, $target, $this->decoder->fromComponent($component));
                yield new ImportObjectEvent($uid, ImportDisposition::Created);
            } catch (Throwable $e) {
                yield new ImportObjectEvent($uid, ImportDisposition::Error, [$e->getMessage()]);
                if ($options->getErrors() === ImportOptions::ERROR_FAIL) {
                    return;
                }
            }
        }
    }
}