feat: implement AI model API proxy service

backend/app/services/router.py

@@ -0,0 +1,76 @@
+"""Model to provider router."""
+from typing import Optional, Tuple
+from ..database import db_connection
+from ..models import Provider
+from ..config import MODEL_PROVIDER_MAP
+
+
+class ModelRouter:
+    """Routes model names to providers."""
+
+    @staticmethod
+    def get_provider_name(model: str) -> Optional[str]:
+        """Determine provider name from model name.
+
+        Args:
+            model: The model name (e.g., 'gpt-4o', 'claude-3-opus')
+
+        Returns:
+            Provider name or None if unknown
+        """
+        model_lower = model.lower()
+        for prefix, provider in MODEL_PROVIDER_MAP.items():
+            if model_lower.startswith(prefix):
+                return provider
+        return None
+
+    @staticmethod
+    async def get_provider(provider_name: str) -> Optional[Provider]:
+        """Get provider configuration by name.
+
+        Args:
+            provider_name: The provider name (e.g., 'openai', 'anthropic')
+
+        Returns:
+            Provider if found and active, None otherwise
+        """
+        async with db_connection() as db:
+            cursor = await db.execute(
+                """SELECT id, name, base_url, api_type, is_active
+                   FROM providers WHERE name = ? AND is_active = TRUE""",
+                (provider_name,)
+            )
+            row = await cursor.fetchone()
+            if row:
+                return Provider(
+                    id=row["id"],
+                    name=row["name"],
+                    base_url=row["base_url"],
+                    api_type=row["api_type"],
+                    is_active=row["is_active"]
+                )
+            return None
+
+    @staticmethod
+    async def route_model(model: str) -> Tuple[Optional[Provider], Optional[str]]:
+        """Route a model to its provider.
+
+        Args:
+            model: The model name
+
+        Returns:
+            Tuple of (Provider, error_message)
+        """
+        provider_name = ModelRouter.get_provider_name(model)
+        if not provider_name:
+            return None, f"Unsupported model: {model}"
+
+        provider = await ModelRouter.get_provider(provider_name)
+        if not provider:
+            return None, f"Provider not found: {provider_name}"
+
+        return provider, None
+
+
+# Global instance
+model_router = ModelRouter()