<?php

namespace App\Services\Ollama;

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

/**
 * OllamaService
 *
 * Wrapper untuk semua komunikasi dengan Ollama API.
 * Menguruskan: chat completion, embedding generation,
 * timeout, retry, dan error handling.
 *
 * Semua konfigurasi diambil dari config/ollama.php
 */
class OllamaService
{
    private string $baseUrl;
    private string $chatModel;
    private string $embeddingModel;
    private array $timeouts;
    private array $retryConfig;
    private array $chatParams;

    public function __construct()
    {
        $this->baseUrl        = config('ollama.base_url');
        $this->chatModel      = config('ollama.chat_model');
        $this->embeddingModel = config('ollama.embedding_model');
        $this->timeouts       = config('ollama.timeout');
        $this->retryConfig    = config('ollama.retry');
        $this->chatParams     = config('ollama.chat');
    }

    /**
     * Jana embedding vector untuk satu teks.
     *
     * @param  string $text  Teks yang akan di-embed
     * @return float[]       Array vector embedding
     * @throws RuntimeException Jika Ollama tidak boleh dihubungi
     */
    public function embed(string $text): array
    {
        $text = $this->sanitizeText($text);

        if (empty(trim($text))) {
            throw new RuntimeException('Teks untuk embedding tidak boleh kosong.');
        }

        try {
            $response = Http::timeout($this->timeouts['embed'])
                ->retry($this->retryConfig['times'], $this->retryConfig['sleep'])
                ->post("{$this->baseUrl}/api/embed", [
                    'model' => $this->embeddingModel,
                    'input' => $text,
                ]);

            $response->throw();

            $data = $response->json();

            // Qdrant REST API format: {"embeddings": [[...]]}
            if (isset($data['embeddings'][0])) {
                return $data['embeddings'][0];
            }

            // Format lama Ollama: {"embedding": [...]}
            if (isset($data['embedding'])) {
                return $data['embedding'];
            }

            throw new RuntimeException(
                'Format response embedding tidak dijangka: ' . json_encode(array_keys($data))
            );
        } catch (ConnectionException $e) {
            Log::error('Ollama tidak boleh dihubungi (embed)', [
                'url'     => $this->baseUrl,
                'error'   => $e->getMessage(),
            ]);
            throw new RuntimeException(
                'Ollama tidak boleh dihubungi. Pastikan Ollama sedang berjalan.',
                0,
                $e
            );
        } catch (RequestException $e) {
            Log::error('Ollama embed request gagal', [
                'status' => $e->response->status(),
                'body'   => $e->response->body(),
            ]);
            throw new RuntimeException(
                'Embedding gagal: ' . $e->response->body(),
                0,
                $e
            );
        }
    }

    /**
     * Jana embedding untuk banyak teks dalam batch.
     * Lebih efisien berbanding panggil embed() satu per satu.
     *
     * @param  string[] $texts
     * @return array<int, float[]>
     */
    public function embedBatch(array $texts): array
    {
        $results = [];

        foreach ($texts as $index => $text) {
            try {
                $results[$index] = $this->embed($text);
            } catch (RuntimeException $e) {
                Log::warning("Embedding batch gagal untuk index {$index}", [
                    'error' => $e->getMessage(),
                ]);
                throw $e;
            }
        }

        return $results;
    }

    /**
     * Hantar pertanyaan ke Ollama dengan context RAG.
     *
     * @param  string  $question  Soalan pengguna
     * @param  string  $context   Context dari Qdrant (chunk-chunk relevan)
     * @param  ?string $systemPrompt  Override system prompt (optional)
     * @return array{answer: string, model: string, tokens: int|null}
     * @throws RuntimeException
     */
    public function chat(
        string $question,
        string $context,
        ?string $systemPrompt = null
    ): array {
        $systemPrompt ??= config('ollama.rag_system_prompt');

        $userMessage = $this->buildRagUserMessage($question, $context);

        try {
            $response = Http::timeout($this->timeouts['chat'])
                ->retry($this->retryConfig['times'], $this->retryConfig['sleep'])
                ->post("{$this->baseUrl}/api/chat", [
                    'model'  => $this->chatModel,
                    'stream' => false,
                    'options' => [
                        'temperature' => $this->chatParams['temperature'],
                        'top_p'       => $this->chatParams['top_p'],
                        'num_ctx'     => $this->chatParams['num_ctx'],
                    ],
                    'messages' => [
                        [
                            'role'    => 'system',
                            'content' => $systemPrompt,
                        ],
                        [
                            'role'    => 'user',
                            'content' => $userMessage,
                        ],
                    ],
                ]);

            $response->throw();

            $data = $response->json();

            $answer = $data['message']['content']
                ?? $data['response']
                ?? '';

            if (empty(trim($answer))) {
                Log::warning('Ollama mengembalikan jawapan kosong', [
                    'question' => substr($question, 0, 100),
                ]);
            }

            return [
                'answer' => trim($answer),
                'model'  => $data['model'] ?? $this->chatModel,
                'tokens' => $data['eval_count'] ?? null,
            ];
        } catch (ConnectionException $e) {
            Log::error('Ollama tidak boleh dihubungi (chat)', [
                'error' => $e->getMessage(),
            ]);
            throw new RuntimeException(
                'Perkhidmatan AI tidak tersedia pada masa ini.',
                0,
                $e
            );
        } catch (RequestException $e) {
            Log::error('Ollama chat request gagal', [
                'status' => $e->response->status(),
                'body'   => $e->response->body(),
            ]);
            throw new RuntimeException(
                'Permintaan ke model AI gagal.',
                0,
                $e
            );
        }
    }

    /**
     * Semak sama ada Ollama sedang berjalan dan model tersedia.
     *
     * @return array{online: bool, chat_model: bool, embed_model: bool, error: ?string}
     */
    public function healthCheck(): array
    {
        $result = [
            'online'      => false,
            'chat_model'  => false,
            'embed_model' => false,
            'error'       => null,
        ];

        try {
            $response = Http::timeout($this->timeouts['connect'])
                ->get("{$this->baseUrl}/api/tags");

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

            $result['online'] = true;
            $models = collect($response->json('models', []))
                ->pluck('name')
                ->map(fn($m) => explode(':', $m)[0])
                ->unique()
                ->toArray();

            $chatModelBase  = explode(':', $this->chatModel)[0];
            $embedModelBase = explode(':', $this->embeddingModel)[0];

            $result['chat_model']  = in_array($chatModelBase, $models);
            $result['embed_model'] = in_array($embedModelBase, $models);
        } catch (ConnectionException $e) {
            $result['error'] = 'Tidak dapat sambung ke Ollama: ' . $e->getMessage();
        }

        return $result;
    }

    /**
     * Bina mesej user untuk RAG dengan context yang terformat.
     * Teks dari dokumen dibersih untuk elak prompt injection.
     */
    private function buildRagUserMessage(string $question, string $context): string
    {
        return "Konteks Rujukan:\n" .
               "================\n" .
               $context . "\n" .
               "================\n\n" .
               "Soalan: " . $question;
    }

    /**
     * Sanitize teks sebelum dihantar ke Ollama.
     * Elak prompt injection dari kandungan dokumen.
     */
    private function sanitizeText(string $text): string
    {
        // Hadkan panjang
        $text = mb_substr($text, 0, 8000);

        // Buang null bytes dan karakter kawalan berbahaya
        $text = preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/', '', $text);

        return $text;
    }
}