Replace OpenAI integration with Google Gemini API

README.md

@@ -1,6 +1,6 @@
 # PromptSQL
 
-PromptSQL is a secure PHP 8.2+ library that converts natural language questions into read-only SQL queries using OpenAI, and executes them safely against MySQL or PostgreSQL databases via PDO.
+PromptSQL is a secure PHP 8.2+ library that converts natural language questions into read-only SQL queries using Google Gemini API, and executes them safely against MySQL or PostgreSQL databases via PDO.
 
 - Only SELECT queries allowed
 - Prepared statements with named parameters
@@ -21,7 +21,7 @@ composer require jona-odoh/promptsql
 - PHP 8.2+
 - ext-pdo, ext-json
 - MySQL or PostgreSQL
-- OpenAI API key
+- Google Gemini API key
 
 ## Quick Start
 
@@ -31,7 +31,7 @@ composer require jona-odoh/promptsql
 use PromptSQL\Config\PromptSQLConfig;
 use PromptSQL\Database\PdoDatabaseAdapter;
 use PromptSQL\Enums\DatabaseDriver;
-use PromptSQL\OpenAI\GuzzleOpenAIClient;
+use PromptSQL\OpenAI\GuzzleGeminiClient;
 use PromptSQL\OpenAI\OpenAIBasedSqlGenerator;
 use PromptSQL\PromptSQL;
 use PromptSQL\Validation\SqlValidator;
@@ -44,8 +44,8 @@ $config = new PromptSQLConfig(
     dsn: 'pgsql:host=127.0.0.1;port=5432;dbname=app_db',
     username: 'readonly_user',
     password: 'readonly_password',
-    openAiApiKey: getenv('OPENAI_API_KEY') ?: '',
-    openAiModel: 'gpt-4o-mini',
+    geminiApiKey: getenv('GEMINI_API_KEY') ?: '',
+    geminiModel: 'gemini-1.5-flash',
     pdoOptions: [],
     allowList: [
         // Table => allowed columns (empty array means all columns allowed)
@@ -69,8 +69,8 @@ $config = new PromptSQLConfig(
 );
 
 // 2) Wire dependencies (constructor DI)
-$openAI = new GuzzleOpenAIClient($config->openAiApiKey);
-$generator = new OpenAIBasedSqlGenerator($openAI, $config->openAiModel);
+$gemini = new GuzzleGeminiClient($config->geminiApiKey);
+$generator = new OpenAIBasedSqlGenerator($gemini, $config->geminiModel);
 $validator = new SqlValidator();
 $db = new PdoDatabaseAdapter(
     driver: $config->driver,

src/Config/PromptSQLConfig.php

@@ -10,8 +10,8 @@ final class PromptSQLConfig
 {
     /**
      * @param DatabaseDriver $driver
-     * @param string $openAiApiKey
-     * @param string $openAiModel
+     * @param string $geminiApiKey
+     * @param string $geminiModel
      * @param array<string, mixed> $pdoOptions
      * @param array<string, array<int, string>> $allowList table => columns (empty list means all columns allowed)
      * @param bool $allowSelectStar Whether SELECT * is allowed
@@ -23,8 +23,8 @@ public function __construct(
         public readonly string $dsn,
         public readonly string $username,
         public readonly string $password,
-        public readonly string $openAiApiKey,
-        public readonly string $openAiModel = 'gpt-4o-mini',
+        public readonly string $geminiApiKey,
+        public readonly string $geminiModel = 'gemini-1.5-flash',
         public readonly array $pdoOptions = [],
         public readonly array $allowList = [],
         public readonly bool $allowSelectStar = false,

src/OpenAI/GuzzleGeminiClient.php

@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PromptSQL\OpenAI;
+
+use GuzzleHttp\Client;
+use GuzzleHttp\Exception\GuzzleException;
+use PromptSQL\Contracts\OpenAIClientInterface;
+use PromptSQL\Exceptions\GenerationException;
+use Psr\Log\LoggerInterface;
+
+final class GuzzleGeminiClient implements OpenAIClientInterface
+{
+    private readonly Client $http;
+
+    public function __construct(
+        private readonly string $apiKey,
+        private readonly ?LoggerInterface $logger = null,
+        ?Client $httpClient = null
+    ) {
+        $this->http = $httpClient ?? new Client([
+            'base_uri' => 'https://generativelanguage.googleapis.com/v1beta/',
+            'timeout' => 30,
+        ]);
+    }
+
+    public function chat(array $messages, string $model, float $temperature = 0.0): string
+    {
+        try {
+            // Convert OpenAI-style messages to Gemini format
+            $contents = $this->convertMessagesToGeminiFormat($messages);
+
+            $response = $this->http->post("models/{$model}:generateContent", [
+                'query' => ['key' => $this->apiKey],
+                'json' => [
+                    'contents' => $contents,
+                    'generationConfig' => [
+                        'temperature' => $temperature,
+                        'responseMimeType' => 'application/json',
+                    ],
+                ],
+            ]);
+
+            $payload = json_decode((string) $response->getBody(), true, 512, JSON_THROW_ON_ERROR);
+
+            // Extract content from Gemini response format
+            $content = $payload['candidates'][0]['content']['parts'][0]['text'] ?? '';
+            if (!is_string($content) || $content === '') {
+                throw new GenerationException('Empty response content from Gemini.');
+            }
+
+            return $content;
+        } catch (GuzzleException $e) {
+            $this->logger?->error('Gemini request failed', ['exception' => $e]);
+            throw new GenerationException('Gemini request failed: ' . $e->getMessage());
+        } catch (\JsonException $e) {
+            $this->logger?->error('Failed to parse Gemini response JSON', ['exception' => $e]);
+            throw new GenerationException('Failed to parse Gemini response JSON: ' . $e->getMessage());
+        }
+    }
+
+    /**
+     * Convert OpenAI-style messages to Gemini format
+     * 
+     * @param array<array{role:string, content:string}> $messages
+     * @return array<array{role:string, parts:array<array{text:string}>}>
+     */
+    private function convertMessagesToGeminiFormat(array $messages): array
+    {
+        $contents = [];
+
+        foreach ($messages as $message) {
+            $role = $message['role'] === 'system' || $message['role'] === 'user' ? 'user' : 'model';
+            $contents[] = [
+                'role' => $role,
+                'parts' => [
+                    ['text' => $message['content']],
+                ],
+            ];
+        }
+
+        return $contents;
+    }
+}