<?php

namespace App\Services;

class ArticleChunkerService
{
    /** @return array<int, string> */
    public function chunk(string $text, int $targetTokens = 100, int $overlapTokens = 20): array
    {
        $text = trim(preg_replace('/\s+/', ' ', $text) ?? $text);
        if ($text === '') {
            return [];
        }

        // Approximate tokenization by words for deterministic local chunking.
        $words = preg_split('/\s+/', $text) ?: [];
        $count = count($words);
        if ($count === 0) {
            return [];
        }

        $step = max(1, $targetTokens - $overlapTokens);
        $chunks = [];

        for ($start = 0; $start < $count; $start += $step) {
            $slice = array_slice($words, $start, $targetTokens);
            if ($slice === []) {
                continue;
            }
            $chunks[] = implode(' ', $slice);

            if (($start + $targetTokens) >= $count) {
                break;
            }
        }

        return $chunks;
    }
}