<?php

declare(strict_types=1);

namespace App\Knowledge\Retrieval;

use App\Entity\ModelGenerationConfig;
use App\Knowledge\ChunkManager;
use App\Knowledge\QueryCleaner;
use App\Repository\ModelGenerationConfigRepository;
use App\Tag\TagRoutingService;
use App\Vector\VectorSearchClient;

final class NdjsonHybridRetriever implements RetrieverInterface
{
    private const VECTOR_SCORE_THRESHOLD = 0.22;
    private const VECTOR_TOPK_MULTIPLIER_WHEN_ROUTED = 3;

    private const HARD_MAX_CHUNKS = 200;
    private const HARD_MAX_VECTORK = 200;

    public function __construct(
        private readonly ChunkManager $chunkManager,
        private readonly NdjsonChunkLookup $lookup,
        private readonly VectorSearchClient $vectorClient,
        private readonly TagRoutingService $tagRouting,
        private readonly ModelGenerationConfigRepository $configRepository,
        private readonly QueryCleaner $queryCleaner,
    ) {}

    public function retrieve(string $prompt): array
    {
        $config = $this->configRepository->findActiveForModel();

        if ($config === null) {
            throw new \RuntimeException('No active ModelGenerationConfig found.');
        }

        return $this->retrieveInternal($prompt, $config);
    }

    public function retrieveForConfig(string $prompt, ModelGenerationConfig $config): array
    {
        return $this->retrieveInternal($prompt, $config);
    }

    private function retrieveInternal(string $prompt, ModelGenerationConfig $config): array
    {
        $limit = max(1, min($config->getRetrievalMaxChunks(), self::HARD_MAX_CHUNKS));
        $vectorTopKBase = max(1, min($config->getRetrievalVectorTopK(), self::HARD_MAX_VECTORK));

        // Wichtig: List-Detection bleibt auf Originalprompt (sonst entfernst du "zeige/liste" etc.)
        $isListQuery = $this->isListQuery($prompt);

        // -------------------------------------------------
        // CLEAN QUERY (nur für Retrieval: Tags + Vector)
        // -------------------------------------------------
        $cleanQuery = $this->queryCleaner->clean($prompt);
        if ($cleanQuery === '') {
            $cleanQuery = $prompt;
        }

        // -------------------------------------------------
        // 1) Tag Routing (bereinigte Query)
        // -------------------------------------------------
        $candidateDocIds = $this->tagRouting->route($cleanQuery);
        $candidateSet = null;

        if (is_array($candidateDocIds) && $candidateDocIds !== []) {
            $candidateSet = array_fill_keys($candidateDocIds, true);
        }

        // -------------------------------------------------
        // 2) TopK bestimmen
        // -------------------------------------------------
        $topK = $vectorTopKBase;

        if ($isListQuery) {
            $topK = max($vectorTopKBase * 3, 80);
        }

        if ($candidateSet !== null) {
            $topK = min(
                max($topK * self::VECTOR_TOPK_MULTIPLIER_WHEN_ROUTED, $topK),
                self::HARD_MAX_VECTORK
            );
        }

        // -------------------------------------------------
        // 3) Vector Search (bereinigte Query; scoped wenn möglich)
        // -------------------------------------------------
        if ($candidateSet !== null) {
            $hits = $this->vectorClient->searchScoped(
                $cleanQuery,
                $topK,
                array_keys($candidateSet)
            );

            // Wenn scoped nichts liefert → global fallback
            if ($hits === []) {
                $hits = $this->vectorClient->search($cleanQuery, $vectorTopKBase);
            }

        } else {
            $hits = $this->vectorClient->search($cleanQuery, $topK);
        }

        if ($hits === []) {
            return $candidateSet !== null
                ? $this->fallbackChunksFromCandidateDocs($candidateSet, $limit)
                : [];
        }

        // -------------------------------------------------
        // 4) ChunkIds + Lookup
        // -------------------------------------------------
        $chunkIds = [];

        foreach ($hits as $hit) {
            if (!isset($hit['chunk_id'], $hit['score'])) {
                continue;
            }

            if ((float)$hit['score'] < self::VECTOR_SCORE_THRESHOLD) {
                continue;
            }

            $chunkIds[] = (string)$hit['chunk_id'];
        }

        if ($chunkIds === []) {
            return $candidateSet !== null
                ? $this->fallbackChunksFromCandidateDocs($candidateSet, $limit)
                : [];
        }

        $rows = $this->lookup->findByChunkIds($chunkIds);

        // -------------------------------------------------
        // 5) Listenmodus → Dokument-Ranking
        // -------------------------------------------------
        if ($isListQuery && $candidateSet !== null) {

            $rankedDocIds = $this->rankDocumentsFromHits($hits, $rows, $candidateSet);

            if ($rankedDocIds === []) {
                return $this->fallbackChunksFromCandidateDocs($candidateSet, $limit);
            }

            $topDocIds = array_slice($rankedDocIds, 0, $limit);

            return $this->collectBestChunkPerDocument($topDocIds, $hits, $rows);
        }

        // -------------------------------------------------
        // 6) Normaler Chunk-Modus
        // -------------------------------------------------
        return $this->collectTexts($chunkIds, $rows, $limit);
    }

    // =========================================================
    // LIST QUERY DETECTION
    // =========================================================

    private function isListQuery(string $prompt): bool
    {
        $prompt = mb_strtolower($prompt);

        return str_contains($prompt, 'liste')
            || str_contains($prompt, 'zeige')
            || str_contains($prompt, 'nenn')
            || str_contains($prompt, 'welche')
            || preg_match('/\b\d+\b/', $prompt) === 1;
    }

    // =========================================================
    // DOCUMENT RANKING
    // =========================================================

    private function rankDocumentsFromHits(
        array $hits,
        array $rows,
        array $candidateSet
    ): array {
        $documentScores = [];

        foreach ($hits as $hit) {
            $chunkId = (string)($hit['chunk_id'] ?? '');

            if (!isset($rows[$chunkId])) {
                continue;
            }

            $docId = $rows[$chunkId]['document_id'] ?? null;

            if (!is_string($docId) || !isset($candidateSet[$docId])) {
                continue;
            }

            $documentScores[$docId][] = (float)$hit['score'];
        }

        if ($documentScores === []) {
            return [];
        }

        $ranked = [];

        foreach ($documentScores as $docId => $scores) {
            rsort($scores);
            $topScores = array_slice($scores, 0, 3);
            $ranked[$docId] = array_sum($topScores) / count($topScores);
        }

        arsort($ranked);

        return array_keys($ranked);
    }

    private function collectBestChunkPerDocument(
        array $docIds,
        array $hits,
        array $rows
    ): array {
        $result = [];

        foreach ($docIds as $docId) {

            $bestScore = -INF;
            $bestText = null;

            foreach ($hits as $hit) {
                $chunkId = (string)($hit['chunk_id'] ?? '');

                if (!isset($rows[$chunkId])) {
                    continue;
                }

                if (($rows[$chunkId]['document_id'] ?? null) !== $docId) {
                    continue;
                }

                if ((float)$hit['score'] > $bestScore) {
                    $bestScore = (float)$hit['score'];
                    $bestText = $rows[$chunkId]['text'] ?? null;
                }
            }

            if (is_string($bestText) && $bestText !== '') {
                $result[] = trim($bestText);
            }
        }

        return $result;
    }

    // =========================================================
    // FALLBACK + NORMAL MODE
    // =========================================================

    private function fallbackChunksFromCandidateDocs(array $candidateSet, int $limit): array
    {
        $seen = [];
        $out = [];

        foreach ($this->chunkManager->streamAll() as $row) {
            $docId = $row['document_id'] ?? null;

            if (!is_string($docId) || !isset($candidateSet[$docId])) {
                continue;
            }

            $text = $row['text'] ?? null;

            if (!is_string($text) || $text === '') {
                continue;
            }

            $chunk = trim($text);
            $key = mb_strtolower((string)preg_replace('/\s+/u', ' ', $chunk));

            if (isset($seen[$key])) {
                continue;
            }

            $seen[$key] = true;
            $out[] = $chunk;

            if (\count($out) >= $limit) {
                break;
            }
        }

        return $out;
    }

    private function collectTexts(array $chunkIds, array $rows, int $limit): array
    {
        $seen = [];
        $out = [];

        foreach ($chunkIds as $id) {
            if (!isset($rows[$id]['text'])) {
                continue;
            }

            $chunk = trim($rows[$id]['text']);
            $key = mb_strtolower((string)preg_replace('/\s+/u', ' ', $chunk));

            if (isset($seen[$key])) {
                continue;
            }

            $seen[$key] = true;
            $out[] = $chunk;

            if (\count($out) >= $limit) {
                break;
            }
        }

        return $out;
    }
}