Add shellgen core and backends modules

app/shellgen/backends/factory.py

@@ -0,0 +1,59 @@
+"""Backend factory for easy switching between LLM backends."""
+
+from typing import Optional
+from .base import LLMBackend
+from .ollama import OllamaBackend
+from .llama_cpp import LlamaCppBackend
+
+
+class BackendFactory:
+    """Factory for creating LLM backend instances."""
+
+    @staticmethod
+    def create_backend(
+        backend_type: str = "ollama",
+        host: Optional[str] = None,
+        model: Optional[str] = None,
+        **kwargs,
+    ) -> LLMBackend:
+        """Create an LLM backend instance.
+
+        Args:
+            backend_type: Type of backend ("ollama" or "llama_cpp").
+            host: Backend-specific host/connection info.
+            model: Model name/path.
+            **kwargs: Additional backend-specific arguments.
+
+        Returns:
+            LLMBackend instance.
+        """
+        backend_type = backend_type.lower()
+
+        if backend_type == "ollama":
+            return OllamaBackend(
+                host=host or "localhost:11434",
+                model=model or "codellama",
+                temperature=kwargs.get("temperature", 0.1),
+                max_tokens=kwargs.get("max_tokens", 500),
+            )
+
+        elif backend_type == "llama_cpp":
+            return LlamaCppBackend(
+                model_path=model or "~/.cache/llama-cpp/models/",
+                n_ctx=kwargs.get("n_ctx", 2048),
+                n_threads=kwargs.get("n_threads", 4),
+                temperature=kwargs.get("temperature", 0.1),
+                max_tokens=kwargs.get("max_tokens", 500),
+            )
+
+        else:
+            raise ValueError(f"Unknown backend type: {backend_type}")
+
+    @staticmethod
+    def get_available_backends() -> list[str]:
+        """Get list of available backend types.
+
+        Returns:
+            List of backend type strings.
+        """
+        return ["ollama", "llama_cpp"]