laravel-llm-gateway/laravel-app/app/Services/LLM/Providers/GeminiProvider.php

<?php

namespace App\Services\LLM\Providers;

use App\Models\ModelPricing;
use Illuminate\Support\Facades\Cache;

class GeminiProvider extends AbstractProvider
{
    protected string $baseUrl = 'https://generativelanguage.googleapis.com/v1beta';

    protected function buildRequest(array $messages, array $options): array
    {
        // Gemini uses a different message format
        $contents = [];
        
        foreach ($messages as $message) {
            $role = $message['role'];
            
            // Gemini uses 'model' instead of 'assistant' and doesn't support 'system'
            if ($role === 'assistant') {
                $role = 'model';
            } elseif ($role === 'system') {
                // Convert system messages to user messages with context
                $role = 'user';
            }
            
            $contents[] = [
                'role' => $role,
                'parts' => [
                    ['text' => $message['content']]
                ]
            ];
        }

        $request = [
            'contents' => $contents,
        ];

        // Add generation config if options provided
        $generationConfig = array_filter([
            'temperature' => $options['temperature'] ?? null,
            'maxOutputTokens' => $options['max_tokens'] ?? null,
            'topP' => $options['top_p'] ?? null,
            'stopSequences' => $options['stop'] ?? null,
        ], fn($value) => $value !== null);

        if (!empty($generationConfig)) {
            $request['generationConfig'] = $generationConfig;
        }

        return $request;
    }

    protected function getAuthHeaders(): array
    {
        return [
            'Content-Type' => 'application/json',
        ];
    }

    public function chatCompletion(array $messages, array $options = []): array
    {
        $model = $options['model'] ?? 'gemini-pro';
        $data = $this->buildRequest($messages, $options);
        
        // Gemini uses API key as query parameter
        $endpoint = "/models/{$model}:generateContent?key={$this->apiKey}";
        
        return $this->makeRequest($endpoint, $data);
    }

    public function normalizeResponse(array $response): array
    {
        $candidate = $response['candidates'][0] ?? [];
        $content = $candidate['content'] ?? [];
        $parts = $content['parts'] ?? [];
        
        $textContent = '';
        foreach ($parts as $part) {
            $textContent .= $part['text'] ?? '';
        }

        $usageMetadata = $response['usageMetadata'] ?? [];

        return [
            'id' => null, // Gemini doesn't provide an ID
            'model' => $response['modelVersion'] ?? null,
            'content' => $textContent,
            'role' => 'assistant',
            'finish_reason' => $candidate['finishReason'] ?? null,
            'usage' => [
                'prompt_tokens' => $usageMetadata['promptTokenCount'] ?? 0,
                'completion_tokens' => $usageMetadata['candidatesTokenCount'] ?? 0,
                'total_tokens' => $usageMetadata['totalTokenCount'] ?? 0,
            ],
            'raw_response' => $response,
        ];
    }

    public function calculateCost(int $promptTokens, int $completionTokens, string $model): float
    {
        $cacheKey = "pricing:gemini:{$model}";

        $pricing = Cache::remember($cacheKey, 3600, function () use ($model) {
            return ModelPricing::where('provider', 'gemini')
                ->where('model', $model)
                ->where('is_active', true)
                ->first();
        });

        if (!$pricing) {
            return 0.0;
        }

        $promptCost = ($promptTokens / 1_000_000) * $pricing->input_price_per_million;
        $completionCost = ($completionTokens / 1_000_000) * $pricing->output_price_per_million;

        return round($promptCost + $completionCost, 6);
    }

    public function getSupportedModels(): array
    {
        return [
            'gemini-pro',
            'gemini-pro-vision',
            'gemini-1.5-pro',
            'gemini-1.5-flash',
            'gemini-ultra',
        ];
    }
}