<?php

namespace App\Services\Providers;

class OpenAIProvider
{
    public static function stream(string $model, array $messages, array $options, callable $onChunk): void
    {
        $provider = $options['provider'];
        $apiUrl = rtrim($provider['apiUrl'] ?? 'https://api.openai.com', '/');
        $apiKey = $provider['apiKey'] ?? '';
        $systemPrompt = $options['systemPrompt'] ?? '';

        $url = $apiUrl . '/v1/chat/completions';

        if (!empty($systemPrompt)) {
            array_unshift($messages, ['role' => 'system', 'content' => $systemPrompt]);
        }

        $body = json_encode([
            'model' => $model,
            'messages' => $messages,
            'stream' => true
        ]);

        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_POST => true,
            CURLOPT_POSTFIELDS => $body,
            CURLOPT_HTTPHEADER => [
                'Authorization: Bearer ' . $apiKey,
                'Content-Type: application/json',
                'Accept: text/event-stream'
            ],
            CURLOPT_TIMEOUT => 120,
            CURLOPT_RETURNTRANSFER => false,
            CURLOPT_SSL_VERIFYPEER => true,
            CURLOPT_WRITEFUNCTION => function ($ch, $data) use ($onChunk) {
                $lines = explode("\n", $data);
                foreach ($lines as $line) {
                    $line = trim($line);
                    if ($line === '') {
                        continue;
                    }
                    if (str_starts_with($line, 'data: ')) {
                        $payload = substr($line, 6);
                        if ($payload === '[DONE]') {
                            return strlen($data);
                        }
                        $json = json_decode($payload, true);
                        if ($json && isset($json['choices'][0]['delta']['content'])) {
                            $content = $json['choices'][0]['delta']['content'];
                            if ($content !== '') {
                                $onChunk($content);
                            }
                        }
                    }
                }
                return strlen($data);
            }
        ]);

        $result = curl_exec($ch);
        if ($result === false) {
            $error = curl_error($ch);
            curl_close($ch);
            throw new \RuntimeException('API请求失败: ' . $error);
        }

        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        if ($httpCode >= 400) {
            throw new \RuntimeException('API返回错误，状态码: ' . $httpCode);
        }
    }
}