<?php

declare(strict_types=1);

namespace app\adminapi\service;

use app\common\service\NihaixiaClinicalSkill;
use app\common\service\TcmAncientBooksReference;
use think\facade\Cache;

/** Short-lived evidence only. The caller must re-authorize and aggregate before lookup. */
final class AiContextCompactionCache
{
    public static function remember(string $scope, string $profile, string $source, callable $produce, ?callable $shouldAbort = null): array
    {
        $config = config('prescription_ai') ?: [];
        $ttl = max(0, min(600, (int) ($config['context_compaction_cache_ttl'] ?? 300)));
        $key = self::key($scope, $profile, $source, $config);
        if ($scope !== '' && $ttl > 0) {
            try {
                $cached = Cache::get($key);
                if (self::valid($cached, strlen($source))) {
                    $cached['cache_hit'] = true;
                    return $cached;
                }
            } catch (\Throwable $ignored) {
                // An unavailable cache must not prevent a complete fresh analysis.
            }
        }
        $result = $produce();
        if ($shouldAbort !== null && $shouldAbort()) throw new \RuntimeException('Context operation cancelled');
        if ($scope !== '' && $ttl > 0 && self::valid($result, strlen($source))) {
            try {
                Cache::set($key, $result, $ttl);
            } catch (\Throwable $ignored) {
            }
        }
        return $result + ['cache_hit' => false];
    }

    private static function key(string $scope, string $profile, string $source, array $config): string
    {
        return 'ai-context-evidence:' . hash('sha256', serialize([
            'evidence-extraction-v2', $scope, $profile, hash('sha256', $source),
            $config['base_url'] ?? '', $config['models'][$profile] ?? [],
            NihaixiaClinicalSkill::VERSION, TcmAncientBooksReference::COMMIT,
        ]));
    }

    private static function valid($value, int $sourceBytes): bool
    {
        return is_array($value) && is_string($value['text'] ?? null)
            && trim($value['text']) !== '' && strlen($value['text']) <= 240000
            && ($value['source_bytes'] ?? null) === $sourceBytes
            && is_int($value['chunk_count'] ?? null) && $value['chunk_count'] > 0
            && is_int($value['reduction_rounds'] ?? null) && $value['reduction_rounds'] >= 0
            && ($value['compacted'] ?? null) === true;
    }
}