<?php
// SPDX-License-Identifier: GPL-3.0-or-later
declare(strict_types=1);

namespace Aiwend\Knowledge;

use Aiwend\Support\OptionStore;

/**
 * Reads and writes a site's EmbeddingConfig in one option ("aiwend_embedding"; WordPress options are per site, so a multisite
 * network never shares it). Reading never throws: a missing, malformed, unsupported or foreign (wrong site id) value yields the
 * lexical default, flagged corrupt when something was stored but could not be trusted. Writing validates, bumps the
 * configuration version and stores no secret. Nothing here activates an index or contacts a provider.
 */
final class EmbeddingConfigStore
{
    public const OPTION = 'aiwend_embedding';

    public function __construct(private OptionStore $options)
    {
    }

    public function get(int $siteId): EmbeddingConfig
    {
        $raw = $this->options->get(self::OPTION, null);
        if ($raw === null || $raw === false || $raw === '') {
            return EmbeddingConfig::lexical($siteId);
        }
        if (!is_array($raw) || ($raw['v'] ?? null) !== EmbeddingConfig::SCHEMA || (int) ($raw['site_id'] ?? 0) !== $siteId) {
            return EmbeddingConfig::lexical($siteId, 0, true);
        }
        $version = is_int($raw['version'] ?? null) ? $raw['version'] : 0;
        if (($raw['mode'] ?? null) === EmbeddingConfig::MODE_LEXICAL) {
            return EmbeddingConfig::lexical($siteId, $version);
        }
        try {
            return EmbeddingConfig::semantic(
                $siteId,
                is_string($raw['provider'] ?? null) ? $raw['provider'] : '',
                is_string($raw['model'] ?? null) ? $raw['model'] : '',
                is_int($raw['dimension'] ?? null) ? $raw['dimension'] : 0,
                is_int($raw['connection_id'] ?? null) ? $raw['connection_id'] : null,
                $version
            );
        } catch (InvalidEmbeddingConfig) {
            return EmbeddingConfig::lexical($siteId, $version, true);
        }
    }

    /**
     * @param (callable(int, int): bool)|null $connectionBelongsToSite checks that a referenced connection exists on this site
     * @throws InvalidEmbeddingConfig
     */
    public function save(EmbeddingConfig $config, ?callable $connectionBelongsToSite = null): EmbeddingConfig
    {
        if ($config->connectionId !== null && ($connectionBelongsToSite === null || !$connectionBelongsToSite($config->siteId, $config->connectionId))) {
            throw new InvalidEmbeddingConfig('connection_not_found');
        }
        $next = $this->get($config->siteId)->version + 1;
        $saved = $config->isSemantic()
            ? EmbeddingConfig::semantic($config->siteId, (string) $config->provider, (string) $config->model, (int) $config->dimension, $config->connectionId, $next)
            : EmbeddingConfig::lexical($config->siteId, $next);
        $this->options->set(self::OPTION, $saved->toArray());
        return $saved;
    }
}