<?php

namespace Modules\AI\Services;

use Modules\AI\Models\AIKnowledgeSource;

final class KnowledgeIndexer
{
    public function index(AIKnowledgeSource $source, int $chunkSize = 1800): AIKnowledgeSource
    {
        $content = trim((string) $source->content);
        $source->chunks()->delete();
        $chunks = $content === '' ? [] : $this->split($content, max(500, $chunkSize));
        foreach ($chunks as $position => $chunk) {
            $source->chunks()->create(['position' => $position + 1, 'content' => $chunk]);
        }
        $source->update(['checksum' => hash('sha256', $content), 'status' => 'indexed', 'chunk_count' => count($chunks), 'indexed_at' => now()]);

        return $source->refresh();
    }

    private function split(string $content, int $size): array
    {
        $paragraphs = preg_split('/\R{2,}/', $content) ?: [$content];
        $chunks = [];
        $buffer = '';
        foreach ($paragraphs as $paragraph) {
            if (strlen($buffer) + strlen($paragraph) + 2 > $size && $buffer !== '') {
                $chunks[] = trim($buffer);
                $buffer = '';
            } $buffer .= $paragraph."\n\n";
        }
        if (trim($buffer) !== '') {
            $chunks[] = trim($buffer);
        }

return $chunks;
    }
}