<?php
declare(strict_types=1);

require_once __DIR__ . '/../includes/LegalTools.php';

dbnToolsRequireMethod('POST');
dbnToolsRequireAuth();

$input    = dbnToolsJsonInput(4000);
$query    = trim(dbnToolsString($input, 'query', 1000));
$rawMode  = $input['mode'] ?? 'hybrid';
$mode     = in_array($rawMode, ['hybrid', 'bm25', 'vector'], true) ? $rawMode : 'hybrid';
$language = dbnToolsNormalizeLanguage($input['language'] ?? 'en');
$limit    = max(1, min(20, (int)($input['limit'] ?? 8)));
$category = isset($input['category']) && $input['category'] !== '' ? trim((string)$input['category']) : null;

const EXCLUDED_DOMAIN = 'dobetternorge.no';

if (mb_strlen($query, 'UTF-8') < 3) {
    dbnToolsError('Query must be at least 3 characters.', 422, 'query_too_short');
}

try {
    // ── HYBRID: delegate to the existing RAG pipeline ──────────────────────
    if ($mode === 'hybrid') {
        $result = (new DbnLegalToolsService())->search($query, $language, $limit, 'disabled', null);
        $hits = array_map(fn($h) => [
            'title'       => $h['title'] ?? '',
            'category'    => $h['category'] ?? '',
            'section'     => $h['section'] ?? null,
            'excerpt'     => $h['excerpt'] ?? ($h['chunk_text'] ?? ''),
            'score'       => $h['score'] ?? null,
            'document_id' => $h['document_id'] ?? null,
            'chunk_id'    => $h['chunk_id'] ?? null,
            'source_url'  => $h['source_url'] ?? null,
            'language'    => null,
        ], $result['hits'] ?? []);
        $hits = array_values(array_filter($hits, fn($h) => !str_contains($h['source_url'] ?? '', EXCLUDED_DOMAIN)));
        dbnToolsRespond(['ok' => true, 'hits' => $hits, 'mode' => 'hybrid', 'query' => $query]);
    }

    $ragDb = dbnToolsRagDb();

    // ── BM25: FULLTEXT with LIKE fallback ───────────────────────────────────
    if ($mode === 'bm25') {
        $catClause = $category !== null ? ' AND d.category = ?' : '';
        $excludeLike = '%' . EXCLUDED_DOMAIN . '%';

        // Try FULLTEXT index first
        try {
            $sql = "SELECT d.id AS document_id, d.title, d.category,
                           d.source_url, c.id AS chunk_id, c.content AS excerpt,
                           c.section_title AS section, d.language,
                           MATCH(c.content) AGAINST (? IN BOOLEAN MODE) AS score
                    FROM chunks c
                    JOIN documents d ON c.document_id = d.id
                    WHERE d.corpus_id = ? AND d.status = 'ready'
                      AND MATCH(c.content) AGAINST (? IN BOOLEAN MODE) > 0
                      AND d.source_url NOT LIKE ?
                    $catClause
                    ORDER BY score DESC
                    LIMIT $limit";
            $params = [$query, 1, $query, $excludeLike];
            if ($category !== null) $params[] = $category;
            $stmt = $ragDb->prepare($sql);
            $stmt->execute($params);
            $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
        } catch (Throwable $e) {
            // FULLTEXT index absent — use LIKE
            $like = '%' . str_replace(['%', '_'], ['\\%', '\\_'], $query) . '%';
            $sql = "SELECT d.id AS document_id, d.title, d.category,
                           d.source_url, c.id AS chunk_id, c.content AS excerpt,
                           c.section_title AS section, d.language,
                           0.25 AS score
                    FROM chunks c
                    JOIN documents d ON c.document_id = d.id
                    WHERE d.corpus_id = ? AND d.status = 'ready'
                      AND (c.content LIKE ? OR d.title LIKE ?)
                      AND d.source_url NOT LIKE ?
                    $catClause
                    ORDER BY (d.title LIKE ?) DESC
                    LIMIT $limit";
            $params = [1, $like, $like, $excludeLike];
            if ($category !== null) $params[] = $category;
            $params[] = $like;
            $stmt = $ragDb->prepare($sql);
            $stmt->execute($params);
            $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
        }

        $hits = array_map(fn($r) => [
            'title'       => $r['title'] ?? '',
            'category'    => $r['category'] ?? '',
            'section'     => $r['section'] ?? null,
            'excerpt'     => mb_substr((string)($r['excerpt'] ?? ''), 0, 600, 'UTF-8'),
            'score'       => isset($r['score']) ? round((float)$r['score'], 4) : null,
            'document_id' => (int)$r['document_id'],
            'chunk_id'    => isset($r['chunk_id']) ? (int)$r['chunk_id'] : null,
            'source_url'  => $r['source_url'] ?? null,
            'language'    => $r['language'] ?? null,
        ], $rows);
        dbnToolsRespond(['ok' => true, 'hits' => $hits, 'mode' => 'bm25', 'query' => $query]);
    }

    // ── VECTOR: embed → Qdrant ─────────────────────────────────────────────
    if ($mode === 'vector') {
        $embeddings = dbnToolsLiteLLMEmbedBatch([$query]);
        if (empty($embeddings) || !is_array($embeddings[0])) {
            dbnToolsError('Embedding failed — vector search unavailable.', 502, 'embed_error');
        }

        $filter = ['must' => [['key' => 'corpus_id', 'match' => ['value' => 1]]]];
        if ($category !== null) {
            $filter['must'][] = ['key' => 'category', 'match' => ['value' => $category]];
        }

        $qdrantPayload = json_encode([
            'vector'       => $embeddings[0],
            'limit'        => $limit,
            'with_payload' => true,
            'filter'       => $filter,
        ]);

        $ch = curl_init('http://10.0.2.10:6333/collections/bnl_chunks/points/search');
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_POST           => true,
            CURLOPT_POSTFIELDS     => $qdrantPayload,
            CURLOPT_HTTPHEADER     => ['Content-Type: application/json'],
            CURLOPT_TIMEOUT        => 15,
        ]);
        $resp    = curl_exec($ch);
        $curlErr = curl_error($ch);
        curl_close($ch);

        if ($resp === false) {
            dbnToolsError('Qdrant unreachable: ' . $curlErr, 502, 'qdrant_error');
        }

        $qdrantResult = json_decode($resp, true);
        $points = $qdrantResult['result'] ?? [];

        $hits = [];
        foreach ($points as $pt) {
            $p = $pt['payload'] ?? [];
            $hits[] = [
                'title'       => $p['title'] ?? $p['document_title'] ?? '',
                'category'    => $p['category'] ?? '',
                'section'     => $p['section_title'] ?? null,
                'excerpt'     => mb_substr((string)($p['content'] ?? ''), 0, 600, 'UTF-8'),
                'score'       => round((float)($pt['score'] ?? 0), 4),
                'document_id' => isset($p['document_id']) ? (int)$p['document_id'] : null,
                'chunk_id'    => $pt['id'] ?? null,
                'source_url'  => $p['source_url'] ?? null,
                'language'    => $p['language'] ?? null,
            ];
        }

        $hits = array_values(array_filter($hits, fn($h) => !str_contains($h['source_url'] ?? '', EXCLUDED_DOMAIN)));
        dbnToolsRespond(['ok' => true, 'hits' => $hits, 'mode' => 'vector', 'query' => $query]);
    }

    dbnToolsError('Unknown search mode.', 422, 'invalid_mode');
} catch (DbnToolsHttpException $e) {
    throw $e;
} catch (Throwable $e) {
    dbnToolsError('Corpus search failed: ' . $e->getMessage(), 500, 'search_error');
}