<?php

namespace App\Services;

class LlmJsonDecoder
{
    public function decode(string $raw): ?array
    {
        $raw = trim($raw);
        $decoded = json_decode($raw, true);
        if (is_array($decoded)) {
            return $decoded;
        }

        // Handles responses wrapped as ```json ... ```
        if (preg_match('/```(?:json)?\s*(\{.*\})\s*```/is', $raw, $matches) === 1) {
            $decoded = json_decode(trim($matches[1]), true);
            if (is_array($decoded)) {
                return $decoded;
            }
        }

        // Last-resort: extract first JSON object from mixed text.
        $start = strpos($raw, '{');
        $end = strrpos($raw, '}');
        if ($start !== false && $end !== false && $end > $start) {
            $candidate = substr($raw, $start, $end - $start + 1);
            $decoded = json_decode($candidate, true);
            if (is_array($decoded)) {
                return $decoded;
            }
        }

        return null;
    }
}