From 51a3e92980b67b4698a8bc594c3cc8447c44bafe Mon Sep 17 00:00:00 2001
From: Hamza-Ayed <hamzaayedflutter@gmail.com>
Date: Fri, 22 May 2026 15:42:30 +0300
Subject: [PATCH] Add Gemini audio model failover logic to handle HTTP 429 rate
 limits

---
 backend/app/Services/GeminiService.php | 93 ++++++++++++++------------
 1 file changed, 50 insertions(+), 43 deletions(-)

diff --git a/backend/app/Services/GeminiService.php b/backend/app/Services/GeminiService.php
index f79df78..9fb6f8b 100644
--- a/backend/app/Services/GeminiService.php
+++ b/backend/app/Services/GeminiService.php
@@ -218,59 +218,66 @@ class GeminiService
      */
     public static function generateAudioResponse(string $apiKey, string $systemPrompt, string $userMessage, string $voiceName = 'Puck'): ?array
     {
-        $url = 'https://generativelanguage.googleapis.com/v1beta/models/gemini-3.1-flash-tts-preview:generateContent?key=' . $apiKey;
+        $models = [
+            'gemini-3.1-flash-tts-preview',
+            'gemini-2.5-flash-preview-tts'
+        ];
 
-        $parts = [];
-        if (!empty($systemPrompt)) {
-            $parts[] = ['text' => "System instruction: " . $systemPrompt];
-        }
-        $parts[] = ['text' => $userMessage];
+        foreach ($models as $model) {
+            $url = 'https://generativelanguage.googleapis.com/v1beta/models/' . $model . ':generateContent?key=' . $apiKey;
 
-        $payload = json_encode([
-            'contents' => [
-                [
-                    'role' => 'user',
-                    'parts' => $parts
-                ]
-            ],
-            'generationConfig' => [
-                'responseModalities' => ['AUDIO'],
-                'speechConfig' => [
-                    'voiceConfig' => [
-                        'prebuiltVoiceConfig' => [
-                            'voiceName' => $voiceName
+            $parts = [];
+            if (!empty($systemPrompt)) {
+                $parts[] = ['text' => "System instruction: " . $systemPrompt];
+            }
+            $parts[] = ['text' => $userMessage];
+
+            $payload = json_encode([
+                'contents' => [
+                    [
+                        'role' => 'user',
+                        'parts' => $parts
+                    ]
+                ],
+                'generationConfig' => [
+                    'responseModalities' => ['AUDIO'],
+                    'speechConfig' => [
+                        'voiceConfig' => [
+                            'prebuiltVoiceConfig' => [
+                                'voiceName' => $voiceName
+                            ]
                         ]
                     ]
                 ]
-            ]
-        ]);
+            ]);
 
-        $ch = curl_init($url);
-        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
-        curl_setopt($ch, CURLOPT_POST, true);
-        curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
-        curl_setopt($ch, CURLOPT_HTTPHEADER, [
-            'Content-Type: application/json'
-        ]);
-        curl_setopt($ch, CURLOPT_TIMEOUT, 30);
+            $ch = curl_init($url);
+            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+            curl_setopt($ch, CURLOPT_POST, true);
+            curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
+            curl_setopt($ch, CURLOPT_HTTPHEADER, [
+                'Content-Type: application/json'
+            ]);
+            curl_setopt($ch, CURLOPT_TIMEOUT, 30);
 
-        $response = curl_exec($ch);
-        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
-        curl_close($ch);
+            $response = curl_exec($ch);
+            $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+            curl_close($ch);
 
-        if ($httpCode !== 200) {
-            error_log("[Gemini Audio API Error] HTTP " . $httpCode . " | Response: " . $response);
-            return null;
+            if ($httpCode === 200) {
+                $data = json_decode($response, true);
+                $part = $data['candidates'][0]['content']['parts'][0] ?? null;
+                if ($part && isset($part['inlineData'])) {
+                    return [
+                        'audio' => $part['inlineData']['data'],
+                        'mimeType' => $part['inlineData']['mimeType'] ?? 'audio/mp4'
+                    ];
+                }
+            } else {
+                error_log("[Gemini Audio API Error] Model " . $model . " failed with HTTP " . $httpCode . " | Response: " . $response);
+            }
         }
 
-        $data = json_decode($response, true);
-        $part = $data['candidates'][0]['content']['parts'][0] ?? null;
-        if ($part && isset($part['inlineData'])) {
-            return [
-                'audio' => $part['inlineData']['data'],
-                'mimeType' => $part['inlineData']['mimeType'] ?? 'audio/mp4'
-            ];
-        }
         return null;
     }