<?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', 'azure'], 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'] ?? ''),
            'full_text'   => $h['full_text'] ?? $h['chunk_text'] ?? $h['excerpt'] ?? '',
            '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 . '%';

        // Exact-identifier routing: the FULLTEXT tokenizer drops "§ 4-12" / "Art. 8"
        // to stopword fragments, so a citation query never matches. Route those to a
        // verbatim LIKE lookup and pin the hits ahead of the fuzzy BM25 results.
        $exactHits = [];
        $exactChunkIds = [];
        $citationAtoms = DbnLegalToolsService::citationAtoms($query);
        if (!empty($citationAtoms)) {
            $atomClauses = [];
            $atomParams  = [1];
            foreach ($citationAtoms as $atom) {
                $like = '%' . str_replace(['%', '_'], ['\\%', '\\_'], $atom) . '%';
                $atomClauses[] = '(c.content LIKE ? OR c.section_title LIKE ?)';
                $atomParams[]  = $like;
                $atomParams[]  = $like;
            }
            $atomParams[] = $excludeLike;
            $exactSql = "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, 1.0 AS score
                         FROM chunks c
                         JOIN documents d ON c.document_id = d.id
                         WHERE d.corpus_id = ? AND d.status = 'ready'
                           AND (" . implode(' OR ', $atomClauses) . ")
                           AND d.source_url NOT LIKE ?
                         $catClause
                         LIMIT $limit";
            $exactParams = $atomParams;
            if ($category !== null) $exactParams[] = $category;
            try {
                $stmt = $ragDb->prepare($exactSql);
                $stmt->execute($exactParams);
                foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $r) {
                    $exactHits[] = $r;
                    if (isset($r['chunk_id'])) $exactChunkIds[(int)$r['chunk_id']] = true;
                }
            } catch (Throwable $e) {
                // Non-fatal — fall through to fuzzy BM25.
            }
        }

        // 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);
        }

        // Exact identifier hits lead; drop fuzzy rows that duplicate them.
        if (!empty($exactChunkIds)) {
            $rows = array_values(array_filter($rows, fn($r) => empty($exactChunkIds[(int)($r['chunk_id'] ?? 0)])));
        }
        $rows = array_slice(array_merge($exactHits, $rows), 0, $limit);

        $hits = array_map(fn($r) => [
            'title'       => $r['title'] ?? '',
            'category'    => $r['category'] ?? '',
            'section'     => $r['section'] ?? null,
            'excerpt'     => mb_substr((string)($r['excerpt'] ?? ''), 0, 600, 'UTF-8'),
            'full_text'   => (string)($r['excerpt'] ?? ''),
            'score'       => isset($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'    => $r['language'] ?? null,
            'exact_match' => !empty($exactChunkIds[(int)($r['chunk_id'] ?? 0)]),
        ], $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'),
                'full_text'   => (string)($p['content'] ?? ''),
                'score'       => round((float)($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]);
    }

    // ── AZURE AI SEARCH: semantic + vector via Azure AI Search ────────────────
    if ($mode === 'azure') {
        $searchEndpoint = rtrim((string)dbnToolsEnv('DBN_AZURE_SEARCH_ENDPOINT', ''), '/');
        $searchKey      = (string)dbnToolsEnv('DBN_AZURE_SEARCH_KEY', '');
        $searchIndex    = (string)dbnToolsEnv('DBN_AZURE_SEARCH_INDEX', 'bnl-legal-v2');

        if (!$searchEndpoint || !$searchKey) {
            dbnToolsError('Azure AI Search is not configured on this server.', 503, 'azure_search_not_configured');
        }

        // Try to embed the query for hybrid (semantic + vector) search
        $vector = null;
        $embeddings = dbnToolsLiteLLMEmbedBatch([$query]);
        if (!empty($embeddings) && is_array($embeddings[0])) {
            $vector = $embeddings[0];
        }

        // Expanded keep-list: original 11 + government-policy, health-law,
        // social-services, labour-law, immigration (unblocked after contamination cleanup)
        $keepCats = [
            'child-welfare', 'echr-case-law', 'child-abduction', 'legislation',
            'anti-discrimination', 'legal', 'children-rights', 'family-law',
            'civil-litigation', 'patient-rights', 'parliamentary',
            'government-policy', 'health-law', 'social-services', 'labour-law', 'immigration',
        ];
        $catFilter = implode(' or ', array_map(fn($c) => "category eq '$c'", $keepCats));
        if ($category !== null) {
            $catFilter = "category eq '$category'";
        }

        $payload = [
            'search'                => $query,
            'top'                   => $limit,
            'select'                => 'id,chunk_id,content,title,section_title,category,source_url',
            'queryType'             => 'semantic',
            'semanticConfiguration' => 'bnl-semantic',
            'filter'                => $catFilter,
        ];
        if ($vector) {
            $payload['vectorQueries'] = [[
                'kind'   => 'vector',
                'vector' => $vector,
                'fields' => 'content_vector',
                'k'      => $limit,
            ]];
        }

        $url = "$searchEndpoint/indexes/" . rawurlencode($searchIndex) . '/docs/search?api-version=2024-05-01-preview';
        $ch  = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_POST           => true,
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => 15,
            CURLOPT_HTTPHEADER     => ['Content-Type: application/json', "api-key: $searchKey"],
            CURLOPT_POSTFIELDS     => json_encode($payload, JSON_UNESCAPED_SLASHES),
        ]);
        $resp = curl_exec($ch);
        $code = (int)curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
        $curlErr = curl_error($ch);
        curl_close($ch);

        if ($curlErr) dbnToolsError("Azure Search unreachable: $curlErr", 502, 'azure_search_error');
        if ($code !== 200) {
            $errBody = json_decode((string)$resp, true);
            $errMsg  = $errBody['error']['message'] ?? "HTTP $code";
            dbnToolsError("Azure AI Search error: $errMsg", 502, 'azure_search_error');
        }

        $data = json_decode((string)$resp, true);
        $hits = array_map(fn($d) => [
            'title'       => trim(implode(' — ', array_filter([$d['title'] ?? '', $d['section_title'] ?? '']))),
            'category'    => $d['category'] ?? '',
            'section'     => $d['section_title'] ?? null,
            'excerpt'     => mb_substr((string)($d['content'] ?? ''), 0, 600, 'UTF-8'),
            'full_text'   => (string)($d['content'] ?? ''),
            'score'       => round((float)($d['@search.rerankerScore'] ?? $d['@search.score'] ?? 0), 4),
            'document_id' => null,
            'chunk_id'    => $d['chunk_id'] ?? $d['id'] ?? null,
            'source_url'  => $d['source_url'] ?? null,
            'language'    => null,
        ], $data['value'] ?? []);

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