chore: chop fastapi_generator into its module

Decoupled the large script with distinct files and purpose.

Signed-off-by: Sébastien Han <seb@redhat.com>

scripts/openapi_generator/app.py

@@ -0,0 +1,91 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+"""
+FastAPI app creation for OpenAPI generation.
+"""
+
+import inspect
+from typing import Any
+
+from fastapi import FastAPI
+
+from llama_stack.apis.datatypes import Api
+from llama_stack.core.resolver import api_protocol_map
+
+from .state import _protocol_methods_cache
+
+
+def _get_protocol_method(api: Api, method_name: str) -> Any | None:
+    """
+    Get a protocol method function by API and method name.
+    Uses caching to avoid repeated lookups.
+
+    Args:
+        api: The API enum
+        method_name: The method name (function name)
+
+    Returns:
+        The function object, or None if not found
+    """
+    global _protocol_methods_cache
+
+    if _protocol_methods_cache is None:
+        _protocol_methods_cache = {}
+        protocols = api_protocol_map()
+        from llama_stack.apis.tools import SpecialToolGroup, ToolRuntime
+
+        toolgroup_protocols = {
+            SpecialToolGroup.rag_tool: ToolRuntime,
+        }
+
+        for api_key, protocol in protocols.items():
+            method_map: dict[str, Any] = {}
+            protocol_methods = inspect.getmembers(protocol, predicate=inspect.isfunction)
+            for name, method in protocol_methods:
+                method_map[name] = method
+
+            # Handle tool_runtime special case
+            if api_key == Api.tool_runtime:
+                for tool_group, sub_protocol in toolgroup_protocols.items():
+                    sub_protocol_methods = inspect.getmembers(sub_protocol, predicate=inspect.isfunction)
+                    for name, method in sub_protocol_methods:
+                        if hasattr(method, "__webmethod__"):
+                            method_map[f"{tool_group.value}.{name}"] = method
+
+            _protocol_methods_cache[api_key] = method_map
+
+    return _protocol_methods_cache.get(api, {}).get(method_name)
+
+
+def create_llama_stack_app() -> FastAPI:
+    """
+    Create a FastAPI app that represents the Llama Stack API.
+    This uses the existing route discovery system to automatically find all routes.
+    """
+    app = FastAPI(
+        title="Llama Stack API",
+        description="A comprehensive API for building and deploying AI applications",
+        version="1.0.0",
+        servers=[
+            {"url": "http://any-hosted-llama-stack.com"},
+        ],
+    )
+
+    # Get all API routes
+    from llama_stack.core.server.routes import get_all_api_routes
+
+    api_routes = get_all_api_routes()
+
+    # Create FastAPI routes from the discovered routes
+    from . import endpoints
+
+    for api, routes in api_routes.items():
+        for route, webmethod in routes:
+            # Convert the route to a FastAPI endpoint
+            endpoints._create_fastapi_endpoint(app, route, webmethod, api)
+
+    return app