<?php

namespace TFGraphics\SmartImport\Search;

use TFGraphics\SmartImport\Domain\Contracts\SearchEngineInterface;
use TFGraphics\SmartImport\Domain\Search\MediaType;
use TFGraphics\SmartImport\Domain\Search\SearchRequest;
use TFGraphics\SmartImport\Domain\Search\SearchResult;
use TFGraphics\SmartImport\Inspector\Pipeline\FieldPipelineInspector;

final class SearchEngine implements SearchEngineInterface
{
    private ProviderManager $providerManager;
    private SearchResponseMerger $responseMerger;
    private SearchCache $cache;

    public function __construct(
        ProviderManager $providerManager,
        SearchResponseMerger $responseMerger,
        SearchCache $cache,
        private ?FieldPipelineInspector $inspector = null
    ) {
        $this->providerManager = $providerManager;
        $this->responseMerger = $responseMerger;
        $this->cache = $cache;
    }

    public function search(SearchRequest $request): SearchResult
    {
        if ($this->shouldSkipBrandIncompatibleDomain($request)) {
            $domain = MediaType::normalize($request->getMediaType());
            return new SearchResult(
                [],
                0,
                null,
                null,
                0,
                0.0,
                [[
                    'provider' => 'DomainEngine',
                    'domain' => $domain,
                    'search_type' => $request->getSearchType(),
                    'execution_mode' => $request->getExecutionMode(),
                    'brand' => $request->getBrand(),
                    'status' => 'SKIPPED_BRAND_DOMAIN',
                    'reason' => sprintf('Marchio/Azienda is not a search input for domain %s; provider calls skipped.', $domain),
                    'result_count' => 0,
                    'response_time_ms' => 0.0,
                ]]
            );
        }

        $engineStart = microtime(true);
        $phaseStart = $engineStart;
        $cacheKey = $this->cache->createCacheKey($request);

        if ($this->cache->has($cacheKey)) {
            $cached = $this->cache->get($cacheKey);
            $cacheReadMs = (microtime(true) - $phaseStart) * 1000;
            $phaseStart = microtime(true);
            // Cache reuse must remain observable on the current UAS trace.
            // Without this hand-off, a valid cached identifier card reaches
            // Preview with no ProductDTO/PDI linkage at all.
            try { $this->inspector?->observeCachedResult($cached); } catch (\Throwable) {}
            return $this->withTimings($cached, 'SearchCache', [
                'cache_read_ms' => $cacheReadMs,
                'cache_inspector_ms' => (microtime(true) - $phaseStart) * 1000,
                'engine_ms' => (microtime(true) - $engineStart) * 1000,
            ]);
        }

        $cacheReadMs = (microtime(true) - $phaseStart) * 1000;
        $phaseStart = microtime(true);
        $context = new SearchContext($request);
        $providerResults = $this->providerManager->search($context);

        $providerMs = (microtime(true) - $phaseStart) * 1000;
        $phaseStart = microtime(true);
        // A physical barcode identifies one retail identity. Results returned by
        // different providers for the same exact code are merged before the
        // optional specialist enrichment pass, preventing duplicate cards and
        // repeated RAWG/IGDB/etc. title lookups for the same product.
        $result = $this->responseMerger->merge(
            $providerResults,
            $request->getLimit(),
            $request->getOffset(),
            true,
            $request->getQuery(),
            $request->isIdentifierSearch(),
            $request->isTitleSearch(),
            $request->getMediaType()
        );

        $mergeMs = (microtime(true) - $phaseStart) * 1000;
        $phaseStart = microtime(true);
        if ($this->isCacheable($result)) {
            $this->cache->store($cacheKey, $result);
        }

        return $this->withTimings($result, 'SearchMerger', [
            'cache_read_ms' => $cacheReadMs,
            'providers_ms' => $providerMs,
            'merge_ms' => $mergeMs,
            'cache_write_ms' => (microtime(true) - $phaseStart) * 1000,
            'engine_ms' => (microtime(true) - $engineStart) * 1000,
        ]);
    }

    private function withTimings(SearchResult $result, string $target, array $timings): SearchResult
    {
        $trace = $result->getProviderTrace();
        foreach ($trace as &$attempt) {
            if (! is_array($attempt) || ($attempt['provider'] ?? '') !== $target) { continue; }
            $parts = [];
            foreach ($timings as $key => $value) { $parts[] = $key . '=' . round(max(0.0, $value), 2); }
            $attempt['reason'] = trim((string) ($attempt['reason'] ?? '') . ' current_engine{' . implode(', ', $parts) . '}');
        }
        unset($attempt);
        return new SearchResult(
            $result->getItems(), $result->getTotal(), $result->getProviderUsed(),
            $result->getProviderFallbackFrom(), $result->getProviderAttempts(),
            $result->getProviderResponseTimeMs(), $trace, $result->getAppliedOffset(),
            $result->getRemoteTotal(), $result->getKnownQualifiedTotal(),
            $result->hasRemoteContinuation(), $result->getProviderContinuations()
        );
    }

    private function shouldSkipBrandIncompatibleDomain(SearchRequest $request): bool
    {
        if (! $request->isTitleSearch() || trim($request->getBrand()) === '') {
            return false;
        }

        return in_array(MediaType::normalize($request->getMediaType()), [
            MediaType::BOOK,
            MediaType::MOVIE,
            MediaType::MUSIC,
            MediaType::GAME,
        ], true);
    }

    private function isCacheable(SearchResult $result): bool
    {
        // Never cache an empty response: an intermittent 503/timeout from the
        // only matching provider must not become a persistent "not found".
        // A positive partial response is valuable even when another provider
        // timed out, and stabilises repeated operator searches.
        return $result->getTotal() > 0 && $result->getItems() !== [];
    }
}