Add Rest API Backend

pyproject.toml

@@ -12,6 +12,7 @@ classifiers = [
 description = "Control system agnostic framework for building Device support in Python that will work for both EPICS and Tango"
 dependencies = [
     "aioserial",
+    "fastapi[standard]",
     "numpy",
     "pydantic",
     "pvi~=0.10.0",
@@ -43,6 +44,7 @@ dev = [
     "types-mock",
     "aioca",
     "p4p",
+    "httpx",
 ]
 
 [project.scripts]

src/fastcs/backends/rest/backend.py

@@ -0,0 +1,14 @@
+from fastcs.backend import Backend
+from fastcs.controller import Controller
+
+from .rest import RestServer
+
+
+class RestBackend(Backend):
+    def __init__(self, controller: Controller):
+        super().__init__(controller)
+
+        self._server = RestServer(self._mapping)
+
+    def _run(self):
+        self._server.run()

src/fastcs/backends/rest/rest.py

@@ -0,0 +1,147 @@
+from collections.abc import Awaitable, Callable, Coroutine
+from dataclasses import dataclass
+from types import MethodType
+from typing import Any
+
+import uvicorn
+from fastapi import FastAPI
+from pydantic import create_model
+
+from fastcs.attributes import AttrR, AttrRW, AttrW, T
+from fastcs.controller import BaseController
+from fastcs.mapping import Mapping
+
+
+@dataclass
+class RestServerOptions:
+    host: str = "localhost"
+    port: int = 8080
+    log_level: str = "info"
+
+
+class RestServer:
+    def __init__(self, mapping: Mapping):
+        self._mapping = mapping
+        self._app = self._create_app()
+
+    def _create_app(self):
+        app = FastAPI()
+        _add_dev_attributes(app, self._mapping)
+        _add_dev_commands(app, self._mapping)
+
+        return app
+
+    def run(self, options: RestServerOptions | None = None) -> None:
+        if options is None:
+            options = RestServerOptions()
+
+        uvicorn.run(
+            self._app,
+            host=options.host,
+            port=options.port,
+            log_level=options.log_level,
+        )
+
+
+def _put_request_body(attribute: AttrW[T]):
+    return create_model(
+        f"Put{str(attribute.datatype.dtype)}Value",
+        **{"value": (attribute.datatype.dtype, ...)},  # type: ignore
+    )
+
+
+def _wrap_attr_put(
+    attribute: AttrW[T],
+) -> Callable[[T], Coroutine[Any, Any, None]]:
+    async def attr_set(request):
+        await attribute.process(request.value)
+
+    # Fast api uses type annotations for validation, schema, conversions
+    attr_set.__annotations__["request"] = _put_request_body(attribute)
+
+    return attr_set
+
+
+def _get_response_body(attribute: AttrR[T]):
+    return create_model(
+        f"Get{str(attribute.datatype.dtype)}Value",
+        **{"value": (attribute.datatype.dtype, ...)},  # type: ignore
+    )
+
+
+def _wrap_attr_get(
+    attribute: AttrR[T],
+) -> Callable[[], Coroutine[Any, Any, Any]]:
+    async def attr_get() -> Any:  # Must be any as response_model is set
+        value = attribute.get()  # type: ignore
+        return {"value": value}
+
+    return attr_get
+
+
+def _add_dev_attributes(app: FastAPI, mapping: Mapping) -> None:
+    for single_mapping in mapping.get_controller_mappings():
+        path = single_mapping.controller.path
+
+        for attr_name, attribute in single_mapping.attributes.items():
+            attr_name = attr_name.title().replace("_", "")
+            d_attr_name = f"{'/'.join(path)}/{attr_name}" if path else attr_name
+
+            match attribute:
+                # https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods
+                case AttrRW():
+                    app.add_api_route(
+                        f"/{d_attr_name}",
+                        _wrap_attr_get(attribute),
+                        methods=["GET"],  # Idemponent and safe data retrieval,
+                        status_code=200,  # https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/GET
+                        response_model=_get_response_body(attribute),
+                    )
+                    app.add_api_route(
+                        f"/{d_attr_name}",
+                        _wrap_attr_put(attribute),
+                        methods=["PUT"],  # Idempotent state change
+                        status_code=204,  # https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/PUT
+                    )
+                case AttrR():
+                    app.add_api_route(
+                        f"/{d_attr_name}",
+                        _wrap_attr_get(attribute),
+                        methods=["GET"],
+                        status_code=200,
+                        response_model=_get_response_body(attribute),
+                    )
+                case AttrW():
+                    app.add_api_route(
+                        f"/{d_attr_name}",
+                        _wrap_attr_put(attribute),
+                        methods=["PUT"],
+                        status_code=204,
+                    )
+
+
+def _wrap_command(
+    method: Callable, controller: BaseController
+) -> Callable[..., Awaitable[None]]:
+    async def command() -> None:
+        await getattr(controller, method.__name__)()
+
+    return command
+
+
+def _add_dev_commands(app: FastAPI, mapping: Mapping) -> None:
+    for single_mapping in mapping.get_controller_mappings():
+        path = single_mapping.controller.path
+
+        for name, method in single_mapping.command_methods.items():
+            cmd_name = name.title().replace("_", "")
+            d_cmd_name = f"{'/'.join(path)}/{cmd_name}" if path else cmd_name
+            app.add_api_route(
+                f"/{d_cmd_name}",
+                _wrap_command(
+                    method.fn,
+                    single_mapping.controller,
+                ),
+                methods=["PUT"],
+                status_code=204,
+            )

tests/backends/rest/test_rest.py

@@ -0,0 +1,90 @@
+import copy
+import re
+from typing import Any
+
+import pytest
+from fastapi.testclient import TestClient
+
+from fastcs.attributes import AttrR
+from fastcs.backends.rest.backend import RestBackend
+from fastcs.datatypes import Bool, Float, Int
+
+
+def pascal_2_snake(input: list[str]) -> list[str]:
+    snake_list = copy.deepcopy(input)
+    snake_list[-1] = re.sub(r"(?<!^)(?=[A-Z])", "_", snake_list[-1]).lower()
+    return snake_list
+
+
+class TestRestServer:
+    @pytest.fixture(scope="class", autouse=True)
+    def setup_class(self, assertable_controller):
+        self.controller = assertable_controller
+
+    @pytest.fixture(scope="class")
+    def client(self):
+        app = RestBackend(self.controller)._server._app
+        return TestClient(app)
+
+    @pytest.fixture(scope="class")
+    def client_read(self, client):
+        def _client_read(path: list[str], expected: Any):
+            route = "/" + "/".join(path)
+            with self.controller.assertPerformed(pascal_2_snake(path), "READ"):
+                response = client.get(route)
+            assert response.status_code == 200
+            assert response.json()["value"] == expected
+
+        return _client_read
+
+    @pytest.fixture(scope="class")
+    def client_write(self, client):
+        def _client_write(path: list[str], value: Any):
+            route = "/" + "/".join(path)
+            with self.controller.assertPerformed(pascal_2_snake(path), "WRITE"):
+                response = client.put(route, json={"value": value})
+            assert response.status_code == 204
+
+        return _client_write
+
+    @pytest.fixture(scope="class")
+    def client_exec(self, client):
+        def _client_exec(path: list[str]):
+            route = "/" + "/".join(path)
+            with self.controller.assertPerformed(pascal_2_snake(path), "EXECUTE"):
+                response = client.put(route)
+            assert response.status_code == 204
+
+        return _client_exec
+
+    def test_read_int(self, client_read):
+        client_read(["ReadInt"], AttrR(Int())._value)
+
+    def test_read_write_int(self, client_read, client_write):
+        client_read(["ReadWriteInt"], AttrR(Int())._value)
+        client_write(["ReadWriteInt"], AttrR(Int())._value)
+
+    def test_read_write_float(self, client_read, client_write):
+        client_read(["ReadWriteFloat"], AttrR(Float())._value)
+        client_write(["ReadWriteFloat"], AttrR(Float())._value)
+
+    def test_read_bool(self, client_read):
+        client_read(["ReadBool"], AttrR(Bool())._value)
+
+    def test_write_bool(self, client_write):
+        client_write(["WriteBool"], AttrR(Bool())._value)
+
+    # # We need to discuss enums
+    # def test_string_enum(self, client_read, client_write):
+
+    def test_big_enum(self, client_read):
+        client_read(["BigEnum"], AttrR(Int(), allowed_values=list(range(1, 18)))._value)
+
+    def test_go(self, client_exec):
+        client_exec(["Go"])
+
+    def test_read_child1(self, client_read):
+        client_read(["SubController01", "ReadInt"], AttrR(Int())._value)
+
+    def test_read_child2(self, client_read):
+        client_read(["SubController02", "ReadInt"], AttrR(Int())._value)

tests/conftest.py

@@ -1,16 +1,19 @@
+import copy
 import os
 import random
 import string
 import subprocess
 import time
+from contextlib import contextmanager
 from pathlib import Path
-from typing import Any
+from typing import Any, Literal
 
 import pytest
 from aioca import purge_channel_caches
+from pytest_mock import MockerFixture
 
 from fastcs.attributes import AttrR, AttrRW, AttrW, Handler, Sender, Updater
-from fastcs.controller import Controller
+from fastcs.controller import Controller, SubController
 from fastcs.datatypes import Bool, Float, Int, String
 from fastcs.mapping import Mapping
 from fastcs.wrappers import command, scan
@@ -49,7 +52,20 @@ class TestHandler(Handler, TestUpdater, TestSender):
     pass
 
 
+class TestSubController(SubController):
+    read_int: AttrR = AttrR(Int(), handler=TestUpdater())
+
+
 class TestController(Controller):
+    def __init__(self) -> None:
+        super().__init__()
+
+        self._sub_controllers: list[TestSubController] = []
+        for index in range(1, 3):
+            controller = TestSubController()
+            self._sub_controllers.append(controller)
+            self.register_sub_controller(f"SubController{index:02d}", controller)
+
     read_int: AttrR = AttrR(Int(), handler=TestUpdater())
     read_write_int: AttrRW = AttrRW(Int(), handler=TestHandler())
     read_write_float: AttrRW = AttrRW(Float())
@@ -80,11 +96,58 @@ async def counter(self):
         self.count += 1
 
 
+class AssertableController(TestController):
+    def __init__(self, mocker: MockerFixture) -> None:
+        super().__init__()
+        self.mocker = mocker
+
+    @contextmanager
+    def assertPerformed(
+        self, path: list[str], action: Literal["READ", "WRITE", "EXECUTE"]
+    ):
+        queue = copy.deepcopy(path)
+        match action:
+            case "READ":
+                method = "get"
+            case "WRITE":
+                method = "process"
+            case "EXECUTE":
+                method = ""
+
+        # Navigate to subcontroller
+        controller = self
+        item_name = queue.pop(-1)
+        for item in queue:
+            controllers = controller.get_sub_controllers()
+            controller = controllers[item]
+
+        # create probe
+        if method:
+            attr = getattr(controller, item_name)
+            spy = self.mocker.spy(attr, method)
+        else:
+            spy = self.mocker.spy(controller, item_name)
+        initial = spy.call_count
+        try:
+            yield  # Enter context
+        finally:  # Exit context
+            final = spy.call_count
+            assert final == initial + 1, (
+                f"Expected {'.'.join(path + [method] if method else path)} "
+                f"to be called once, but it was called {final - initial} times."
+            )
+
+
 @pytest.fixture
 def controller():
     return TestController()
 
 
+@pytest.fixture(scope="class")
+def assertable_controller(class_mocker: MockerFixture):
+    return AssertableController(class_mocker)
+
+
 @pytest.fixture
 def mapping(controller):
     return Mapping(controller)