feat: implement image generation service

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

imagecreator/backend/app/services/image.py

@@ -1 +1,79 @@
-"""Image service placeholder."""
+import base64
+import os
+import uuid
+from typing import Optional
+from google.genai import Client
+from app.config import settings
+
+class ImageGenerationService:
+    def __init__(self):
+        self._client = None
+
+    @property
+    def client(self) -> Client:
+        if self._client is None:
+            self._client = Client(api_key=settings.GEMINI_API_KEY)
+        return self._client
+
+    async def generate_text2image(
+        self,
+        prompt: str,
+        model: str = "gemini-2.5-flash"
+    ) -> dict:
+        response = self.client.models.generate_content(
+            model=model,
+            contents=prompt,
+            config={"response_modalities": ["TEXT", "IMAGE"]}
+        )
+
+        image_data = None
+        for part in response.parts:
+            if hasattr(part, 'inline_data') and part.inline_data:
+                image_data = base64.b64encode(part.inline_data.data).decode('utf-8')
+                break
+
+        return {
+            "image_b64": image_data,
+            "model": model,
+            "finish_reason": response.candidates[0].finish_reason if hasattr(response, 'candidates') and response.candidates else None
+        }
+
+    async def generate_image2image(
+        self,
+        prompt: str,
+        input_image_b64: str,
+        input_mime_type: str = "image/png",
+        model: str = "gemini-2.5-flash"
+    ) -> dict:
+        response = self.client.models.generate_content(
+            model=model,
+            contents=[
+                {"text": prompt},
+                {"inline_data": {"mime_type": input_mime_type, "data": input_image_b64}}
+            ],
+            config={"response_modalities": ["TEXT", "IMAGE"]}
+        )
+
+        image_data = None
+        for part in response.parts:
+            if hasattr(part, 'inline_data') and part.inline_data:
+                image_data = base64.b64encode(part.inline_data.data).decode('utf-8')
+                break
+
+        return {
+            "image_b64": image_data,
+            "model": model,
+            "finish_reason": response.candidates[0].finish_reason if hasattr(response, 'candidates') and response.candidates else None
+        }
+
+    def save_image(self, image_b64: str, user_id: str) -> str:
+        os.makedirs(settings.IMAGE_STORAGE_PATH, exist_ok=True)
+        filename = f"{user_id}/{uuid.uuid4()}.png"
+        filepath = os.path.join(settings.IMAGE_STORAGE_PATH, filename)
+        os.makedirs(os.path.dirname(filepath), exist_ok=True)
+
+        image_data = base64.b64decode(image_b64)
+        with open(filepath, "wb") as f:
+            f.write(image_data)
+
+        return f"/uploads/{filename}"

imagecreator/backend/tests/test_image_service.py

@@ -0,0 +1,9 @@
+import pytest
+from app.services.image import ImageGenerationService
+
+def test_generate_text2image_request_structure():
+    # Test that the service creates proper request structure
+    # This is a unit test - actual generation would require API key
+    service = ImageGenerationService()
+    # Just verify service initializes
+    assert service is not None