<?php

namespace App\Services\Qdrant;

use Illuminate\Http\Client\ConnectionException;
use Illuminate\Http\Client\RequestException;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;
use RuntimeException;

/**
 * QdrantService
 *
 * Wrapper untuk Qdrant REST API.
 * Menguruskan: buat collection, upsert, cari, update, dan delete point.
 *
 * Reka bentuk: Satu collection 'knowledge_base' untuk semua jenis knowledge.
 * Gunakan payload filtering untuk bezakan kategori, jenis, status.
 */
class QdrantService
{
    private string $baseUrl;
    private ?string $apiKey;
    private string $collection;
    private array $timeouts;
    private int $batchSize;

    public function __construct()
    {
        $this->baseUrl    = config('qdrant.base_url');
        $this->apiKey     = config('qdrant.api_key');
        $this->collection = config('qdrant.collection');
        $this->timeouts   = config('qdrant.timeout');
        $this->batchSize  = config('qdrant.batch_size');
    }

    // =========================================================================
    // COLLECTION MANAGEMENT
    // =========================================================================

    /**
     * Buat collection jika belum wujud.
     * Selamat dipanggil berulang kali (idempotent).
     *
     * @throws RuntimeException
     */
    public function ensureCollectionExists(): void
    {
        try {
            $response = $this->request('GET', "/collections/{$this->collection}");

            if ($response->status() === 200) {
                return; // Collection sudah wujud
            }
        } catch (RequestException $e) {
            if ($e->response->status() !== 404) {
                throw new RuntimeException(
                    'Gagal semak collection Qdrant: ' . $e->response->body()
                );
            }
        }

        // Collection tidak wujud — buat baru
        $this->createCollection();
    }

    /**
     * Buat collection baru dengan konfigurasi dari config/qdrant.php
     */
    public function createCollection(): void
    {
        $vectorSize     = config('qdrant.vector.size');
        $vectorDistance = config('qdrant.vector.distance');

        $response = $this->request('PUT', "/collections/{$this->collection}", [
            'vectors' => [
                'size'     => $vectorSize,
                'distance' => $vectorDistance,
            ],
        ]);

        if (!$response->ok()) {
            throw new RuntimeException(
                "Gagal buat collection Qdrant: " . $response->body()
            );
        }

        Log::info("Qdrant collection '{$this->collection}' berjaya dibuat.", [
            'vector_size'     => $vectorSize,
            'vector_distance' => $vectorDistance,
        ]);
    }

    // =========================================================================
    // POINT OPERATIONS
    // =========================================================================

    /**
     * Upsert satu point ke Qdrant.
     * Jika point dengan ID yang sama sudah wujud, ia akan digantikan.
     *
     * @param  string  $pointId  UUID point
     * @param  float[] $vector   Embedding vector
     * @param  array   $payload  Metadata point
     * @throws RuntimeException
     */
    public function upsertPoint(string $pointId, array $vector, array $payload): void
    {
        $this->upsertPoints([
            [
                'id'      => $pointId,
                'vector'  => $vector,
                'payload' => $payload,
            ],
        ]);
    }

    /**
     * Upsert banyak point sekaligus (lebih efisien).
     *
     * @param  array[] $points  Array of {id, vector, payload}
     * @throws RuntimeException
     */
    public function upsertPoints(array $points): void
    {
        if (empty($points)) {
            return;
        }

        // Hantar dalam batch untuk elak request terlalu besar
        foreach (array_chunk($points, $this->batchSize) as $batch) {
            try {
                $response = $this->request(
                    'PUT',
                    "/collections/{$this->collection}/points",
                    ['points' => $batch]
                );

                if (!$response->ok()) {
                    throw new RuntimeException(
                        "Qdrant upsert gagal: " . $response->body()
                    );
                }
            } catch (ConnectionException $e) {
                throw new RuntimeException(
                    'Tidak dapat sambung ke Qdrant semasa upsert.',
                    0,
                    $e
                );
            }
        }
    }

    /**
     * Cari point yang paling serupa dengan vector yang diberikan.
     *
     * @param  float[]   $vector         Query vector
     * @param  int       $limit          Bilangan hasil
     * @param  array     $filter         Payload filter (optional)
     * @param  float     $scoreThreshold Min score (optional)
     * @return array[]   Array of {id, score, payload}
     * @throws RuntimeException
     */
    public function searchSimilar(
        array $vector,
        int $limit = 5,
        array $filter = [],
        float $scoreThreshold = 0.0
    ): array {
        $body = [
            'vector'       => $vector,
            'limit'        => $limit,
            'with_payload' => true,
            'with_vector'  => false,
        ];

        if ($scoreThreshold > 0.0) {
            $body['score_threshold'] = $scoreThreshold;
        }

        if (!empty($filter)) {
            $body['filter'] = $filter;
        }

        try {
            $response = $this->request(
                'POST',
                "/collections/{$this->collection}/points/search",
                $body
            );

            $response->throw();

            return $response->json('result', []);
        } catch (ConnectionException $e) {
            throw new RuntimeException(
                'Tidak dapat sambung ke Qdrant semasa carian.',
                0,
                $e
            );
        } catch (RequestException $e) {
            Log::error('Qdrant search gagal', [
                'status' => $e->response->status(),
                'body'   => $e->response->body(),
            ]);
            throw new RuntimeException(
                'Carian dalam Qdrant gagal.',
                0,
                $e
            );
        }
    }

    /**
     * Kemaskini payload point yang sedia ada.
     * Berguna untuk set is_active=false tanpa delete point.
     *
     * @param  string  $pointId
     * @param  array   $payload  Hanya field yang hendak dikemaskini
     * @throws RuntimeException
     */
    public function updatePayload(string $pointId, array $payload): void
    {
        try {
            $response = $this->request(
                'POST',
                "/collections/{$this->collection}/points/payload",
                [
                    'payload' => $payload,
                    'points'  => [$pointId],
                ]
            );

            if (!$response->ok()) {
                throw new RuntimeException(
                    "Qdrant payload update gagal untuk point {$pointId}: " . $response->body()
                );
            }
        } catch (ConnectionException $e) {
            throw new RuntimeException(
                'Tidak dapat sambung ke Qdrant semasa update payload.',
                0,
                $e
            );
        }
    }

    /**
     * Kemaskini payload untuk banyak point sekaligus.
     * Berguna untuk deactivate semua chunk sesuatu dokumen.
     *
     * @param  string[] $pointIds
     * @param  array    $payload
     */
    public function updatePayloadBatch(array $pointIds, array $payload): void
    {
        if (empty($pointIds)) {
            return;
        }

        foreach (array_chunk($pointIds, $this->batchSize) as $batch) {
            $this->request(
                'POST',
                "/collections/{$this->collection}/points/payload",
                [
                    'payload' => $payload,
                    'points'  => $batch,
                ]
            );
        }
    }

    /**
     * Padam point dari Qdrant.
     * Gunakan ini hanya untuk hard delete yang benar-benar diperlukan.
     * Untuk soft delete, gunakan updatePayload({is_active: false}).
     *
     * @param  string|string[] $pointIds
     */
    public function deletePoints(array|string $pointIds): void
    {
        $ids = is_array($pointIds) ? $pointIds : [$pointIds];

        if (empty($ids)) {
            return;
        }

        foreach (array_chunk($ids, $this->batchSize) as $batch) {
            try {
                $this->request(
                    'POST',
                    "/collections/{$this->collection}/points/delete",
                    ['points' => $batch]
                );
            } catch (ConnectionException $e) {
                Log::error('Qdrant delete gagal', ['error' => $e->getMessage()]);
                throw new RuntimeException(
                    'Tidak dapat sambung ke Qdrant semasa delete.',
                    0,
                    $e
                );
            }
        }
    }

    /**
     * Scroll — dapatkan semua point yang memenuhi filter.
     * Berguna untuk audit atau bulk operations.
     *
     * @param  array   $filter
     * @param  int     $limit
     * @param  ?string $offset  Point ID untuk paginasi
     * @return array{points: array[], next_page_offset: ?string}
     */
    public function scroll(array $filter = [], int $limit = 100, ?string $offset = null): array
    {
        $body = [
            'limit'        => $limit,
            'with_payload' => true,
            'with_vector'  => false,
        ];

        if (!empty($filter)) {
            $body['filter'] = $filter;
        }

        if ($offset !== null) {
            $body['offset'] = $offset;
        }

        try {
            $response = $this->request(
                'POST',
                "/collections/{$this->collection}/points/scroll",
                $body
            );

            $response->throw();

            return [
                'points'           => $response->json('result.points', []),
                'next_page_offset' => $response->json('result.next_page_offset'),
            ];
        } catch (ConnectionException $e) {
            throw new RuntimeException(
                'Tidak dapat sambung ke Qdrant semasa scroll.',
                0,
                $e
            );
        }
    }

    /**
     * Semak kesihatan Qdrant.
     *
     * @return array{online: bool, collection_exists: bool, points_count: int|null, error: ?string}
     */
    public function healthCheck(): array
    {
        $result = [
            'online'           => false,
            'collection_exists' => false,
            'points_count'     => null,
            'error'            => null,
        ];

        try {
            $response = Http::timeout($this->timeouts['connect'])
                ->when($this->apiKey, fn($h) => $h->withToken($this->apiKey))
                ->get("{$this->baseUrl}/healthz");

            if (!$response->ok()) {
                $result['error'] = 'Qdrant tidak responsif';
                return $result;
            }

            $result['online'] = true;

            // Semak collection
            $collResponse = $this->request('GET', "/collections/{$this->collection}");
            if ($collResponse->ok()) {
                $result['collection_exists'] = true;
                $result['points_count'] = $collResponse->json(
                    'result.points_count'
                );
            }
        } catch (ConnectionException $e) {
            $result['error'] = 'Tidak dapat sambung ke Qdrant: ' . $e->getMessage();
        } catch (\Exception $e) {
            $result['error'] = $e->getMessage();
        }

        return $result;
    }

    // =========================================================================
    // FILTER BUILDERS
    // =========================================================================

    /**
     * Bina filter Qdrant untuk carian berdasarkan kategori dan jenis.
     *
     * Gunakan: QdrantService::buildFilter(category_id: 1, is_active: true)
     */
    public function buildFilter(
        ?int $categoryId = null,
        ?bool $isActive = true,
        ?string $sourceType = null,
        ?string $knowledgeType = null,
    ): array {
        $must = [];

        // Sentiasa tapis yang aktif sahaja (default)
        if ($isActive !== null) {
            $must[] = [
                'key'   => 'is_active',
                'match' => ['value' => $isActive],
            ];
        }

        if ($categoryId !== null) {
            $must[] = [
                'key'   => 'category_id',
                'match' => ['value' => $categoryId],
            ];
        }

        if ($sourceType !== null) {
            $must[] = [
                'key'   => 'source_type',
                'match' => ['value' => $sourceType],
            ];
        }

        if ($knowledgeType !== null) {
            $must[] = [
                'key'   => 'knowledge_type',
                'match' => ['value' => $knowledgeType],
            ];
        }

        if (empty($must)) {
            return [];
        }

        return ['must' => $must];
    }

    // =========================================================================
    // PRIVATE HELPERS
    // =========================================================================

    private function request(string $method, string $path, array $body = [])
    {
        $http = Http::timeout($this->timeouts['request'])
            ->when($this->apiKey, fn($h) => $h->withHeaders(['api-key' => $this->apiKey]));

        return match (strtoupper($method)) {
            'GET'    => $http->get("{$this->baseUrl}{$path}"),
            'POST'   => $http->post("{$this->baseUrl}{$path}", $body),
            'PUT'    => $http->put("{$this->baseUrl}{$path}", $body),
            'DELETE' => $http->delete("{$this->baseUrl}{$path}", $body),
            default  => throw new \InvalidArgumentException("Method tidak disokong: {$method}"),
        };
    }
}