<?php

declare(strict_types=1);

/**
 * SPDX-FileCopyrightText: Sebastian Krupinski <krupinski01@gmail.com>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */

namespace KTXM\ProviderImap\Stores;

use KTXC\Db\DataStore;
use KTXM\ProviderImap\Providers\EntityResource;

/**
 * IMAP Message Meta Store
 *
 * One MongoDB document per cached message in `provider_imap_mail_messages`,
 * keyed by (sid, mailbox, uidValidity, uid). Holds only what list, filter and
 * sort need; message content lives in the content store (message.json).
 */
class MessageStore
{
    protected const COLLECTION_NAME = 'provider_imap_mail_messages';

    public function __construct(
        protected readonly DataStore $dataStore,
    ) {}

    /**
     * Create the collection indexes.
     *
     * MongoDB createIndex is idempotent when the name and specification match.
     *
     * @return string[]
     */
    public function ensureIndexes(): array
    {
        $collection = $this->dataStore->selectCollection(self::COLLECTION_NAME);

        return [
            $collection->createIndex(
                ['sid' => 1, 'mailbox' => 1, 'uidValidity' => 1, 'uid' => 1],
                ['name' => 'messages_key', 'unique' => true]
            ),
            $collection->createIndex(
                ['sid' => 1, 'mailbox' => 1, 'received' => -1],
                ['name' => 'messages_by_received']
            ),
            $collection->createIndex(
                ['sid' => 1, 'mailbox' => 1, 'sent' => -1],
                ['name' => 'messages_by_sent']
            ),
            $collection->createIndex(
                ['sid' => 1, 'mailbox' => 1, 'flags' => 1],
                ['name' => 'messages_by_flags']
            ),
            $collection->createIndex(
                ['sid' => 1, 'urid' => 1],
                ['name' => 'messages_by_urid']
            ),
            $collection->createIndex(
                ['tid' => 1, 'sid' => 1],
                ['name' => 'messages_by_tenant_service']
            ),
        ];
    }

    /**
     * Insert or replace the meta document of a message.
     *
     * Fields owned by other writers (e.g. blobs) are left untouched.
     */
    public function upsert(string $tenantId, string $serviceId, int $uidValidity, EntityResource $entity): void
    {
        $document = $entity->toCacheMeta();
        $key = [
            'sid'         => $serviceId,
            'mailbox'     => $document['mailbox'],
            'uidValidity' => $uidValidity,
            'uid'         => $document['uid'],
        ];

        $this->dataStore->selectCollection(self::COLLECTION_NAME)->updateOne(
            $key,
            ['$set' => ['tid' => $tenantId, ...$key, ...$document]],
            ['upsert' => true],
        );
    }

    /**
     * Retrieve the meta document of a message.
     */
    public function fetch(string $serviceId, string $mailbox, int $uidValidity, int $uid): ?array
    {
        return $this->dataStore->selectCollection(self::COLLECTION_NAME)->findOne([
            'sid'         => $serviceId,
            'mailbox'     => $mailbox,
            'uidValidity' => $uidValidity,
            'uid'         => $uid,
        ]);
    }

    /**
     * Retrieve the meta documents of several messages.
     *
     * @return array<int, array> keyed by UID; UIDs that are not cached are absent
     */
    public function fetchMany(string $serviceId, string $mailbox, int $uidValidity, int ...$uids): array
    {
        if ($uids === []) {
            return [];
        }

        $cursor = $this->dataStore->selectCollection(self::COLLECTION_NAME)->find([
            'sid'         => $serviceId,
            'mailbox'     => $mailbox,
            'uidValidity' => $uidValidity,
            'uid'         => ['$in' => array_values($uids)],
        ]);

        $list = [];
        foreach ($cursor as $document) {
            $list[(int) $document['uid']] = $document;
        }
        return $list;
    }

    /**
     * List the UIDs cached for a mailbox.
     *
     * @return int[]
     */
    public function uids(string $serviceId, string $mailbox, int $uidValidity): array
    {
        $cursor = $this->dataStore->selectCollection(self::COLLECTION_NAME)->find(
            ['sid' => $serviceId, 'mailbox' => $mailbox, 'uidValidity' => $uidValidity],
            ['projection' => ['uid' => 1]],
        );

        $uids = [];
        foreach ($cursor as $document) {
            $uids[] = (int) $document['uid'];
        }
        return $uids;
    }

    /**
     * List the flags of every message cached for a mailbox.
     *
     * @return array<int, list<string>> set flags keyed by UID
     */
    public function flags(string $serviceId, string $mailbox, int $uidValidity): array
    {
        $cursor = $this->dataStore->selectCollection(self::COLLECTION_NAME)->find(
            ['sid' => $serviceId, 'mailbox' => $mailbox, 'uidValidity' => $uidValidity],
            ['projection' => ['uid' => 1, 'flags' => 1]],
        );

        $flags = [];
        foreach ($cursor as $document) {
            $flags[(int) $document['uid']] = array_values(array_map('strval', (array) ($document['flags'] ?? [])));
        }
        return $flags;
    }

    /**
     * Replace the flags of a message.
     *
     * @param string[] $flags set flags, e.g. ['seen', 'flagged']
     */
    public function updateFlags(string $serviceId, string $mailbox, int $uidValidity, int $uid, array $flags): void
    {
        $this->dataStore->selectCollection(self::COLLECTION_NAME)->updateOne(
            ['sid' => $serviceId, 'mailbox' => $mailbox, 'uidValidity' => $uidValidity, 'uid' => $uid],
            ['$set' => ['flags' => array_values($flags)]],
        );
    }

    /**
     * Delete the meta documents of messages.
     */
    public function delete(string $serviceId, string $mailbox, int $uidValidity, int ...$uids): void
    {
        if ($uids === []) {
            return;
        }

        $this->dataStore->selectCollection(self::COLLECTION_NAME)->deleteMany([
            'sid'         => $serviceId,
            'mailbox'     => $mailbox,
            'uidValidity' => $uidValidity,
            'uid'         => ['$in' => array_values($uids)],
        ]);
    }

    /**
     * Delete all meta documents of a mailbox (any UIDVALIDITY).
     */
    public function deleteByMailbox(string $serviceId, string $mailbox): void
    {
        $this->dataStore->selectCollection(self::COLLECTION_NAME)->deleteMany([
            'sid'     => $serviceId,
            'mailbox' => $mailbox,
        ]);
    }

    /**
     * Delete all meta documents of a service.
     */
    public function deleteByService(string $serviceId): void
    {
        $this->dataStore->selectCollection(self::COLLECTION_NAME)->deleteMany(['sid' => $serviceId]);
    }
}