<?php
declare(strict_types=1);

/** Validates untrusted semantic output. Does not call a model or publish content. */
final class TheDotDevAgenticBridge_Question_Assessment
{
    public static function fingerprint(string $question, array $sources): string
    {
        return hash('sha256', json_encode([$question, $sources], JSON_THROW_ON_ERROR));
    }

    public static function validate(array $output, string $question, array $sources): array
    {
        $fail = static fn(string $reason): array => ['ok'=>false, 'error'=>$reason];
        if (!is_string($output['fingerprint'] ?? null) || !hash_equals(self::fingerprint($question, $sources), $output['fingerprint'])) return $fail('stale_or_wrong_evidence');
        if (!in_array($output['status'] ?? null, ['supported','partial','not_found','conflicting','uncertain'], true)) return $fail('invalid_status');
        if (!is_string($output['explanation'] ?? null) || trim($output['explanation']) === '' || mb_strlen($output['explanation']) > 1500) return $fail('invalid_explanation');
        if (!is_array($output['evidence'] ?? null) || count($output['evidence']) > 10) return $fail('invalid_evidence');
        $lookup = [];
        foreach ($sources as $source) {
            if (!is_int($source['id'] ?? null) || !is_string($source['text'] ?? null) || isset($lookup[$source['id']])) return $fail('invalid_sources');
            $lookup[$source['id']] = $source['text'];
        }
        $evidence = [];
        foreach ($output['evidence'] as $item) {
            if (!is_array($item) || !is_int($item['sourceId'] ?? null) || !is_string($item['quote'] ?? null)) return $fail('invalid_quote');
            $quote = $item['quote'];
            if (trim($quote) === '' || mb_strlen($quote) > 1000 || !isset($lookup[$item['sourceId']]) || !str_contains($lookup[$item['sourceId']], $quote)) return $fail('quote_not_in_source');
            $evidence[] = ['sourceId'=>$item['sourceId'], 'quote'=>$quote];
        }
        if (in_array($output['status'], ['supported','partial'], true) && $evidence === []) return $fail('evidence_required');
        if ($output['status'] === 'conflicting' && count(array_unique(array_column($evidence, 'quote'))) < 2) return $fail('two_distinct_passages_required');
        return ['ok'=>true, 'assessment'=>[
            'status'=>$output['status'], 'explanation'=>$output['explanation'], 'evidence'=>$evidence,
            'fingerprint'=>$output['fingerprint'], 'provenance'=>'model_assessment',
            'requiresHumanReview'=>true, 'citationTestPerformed'=>false,
        ]];
    }
}