From 894cbe4a0bf3ec571f46a365c5fe3182cd590ded Mon Sep 17 00:00:00 2001
From: Ben Bierens <thatbenbierens@gmail.com>
Date: Wed, 8 Feb 2023 14:54:29 +0100
Subject: [PATCH] implements minimal state switching

---
 codex/utils/asyncstatemachine.nim           |  9 +++++++-
 tests/codex/utils/testasyncstatemachine.nim | 24 +++++++++++++++++++--
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/codex/utils/asyncstatemachine.nim b/codex/utils/asyncstatemachine.nim
index 004deda4..e861ed7c 100644
--- a/codex/utils/asyncstatemachine.nim
+++ b/codex/utils/asyncstatemachine.nim
@@ -5,6 +5,13 @@ type
   AsyncStateMachine* = ref object of RootObj
   AsyncState* = ref object of RootObj
 
-method start*(stateMachine: AsyncStateMachine, initialState: AsyncState) =
+method run*(state: AsyncState): Future[?AsyncState] {.base.} = 
   discard
 
+proc runState(state: AsyncState): Future[void] {.async.} =
+  if next =? await state.run():
+    await runState(next)
+
+proc start*(stateMachine: AsyncStateMachine, initialState: AsyncState) =
+  asyncSpawn runState(initialState)
+
diff --git a/tests/codex/utils/testasyncstatemachine.nim b/tests/codex/utils/testasyncstatemachine.nim
index c0d1f884..d5c49f34 100644
--- a/tests/codex/utils/testasyncstatemachine.nim
+++ b/tests/codex/utils/testasyncstatemachine.nim
@@ -4,16 +4,27 @@ import pkg/chronos
 import codex/utils/asyncstatemachine
 import ../helpers/eventually
 
-type TestState = ref object of AsyncState
+type 
+  TestState = ref object of AsyncState
+  State1 = ref object of AsyncState
+  State2 = ref object of AsyncState
 
 var runInvoked = 0
+var state2runInvoked = 0
 
-method run(state: TestState): Future[?AsyncState] = 
+method run(state: TestState): Future[?AsyncState] {.async.} = 
   inc runInvoked
 
+method run(state: State1): Future[?AsyncState] {.async.} = 
+  return some AsyncState(State2.new())
+
+method run(state: State2): Future[?AsyncState] {.async.} = 
+  inc state2runInvoked
+
 suite "async state machines":
   setup:
     runInvoked = 0
+    state2runInvoked = 0
 
   test "creates async state machine":
     let sm = AsyncStateMachine.new()
@@ -27,3 +38,12 @@ suite "async state machines":
 
     check eventually runInvoked == 1
 
+  test "moves to next state when run completes":
+    let sm = AsyncStateMachine.new()
+    let state1 = State1.new()
+    let state2 = State2.new()
+
+    sm.start(state1)
+
+    check eventually state2runInvoked == 1
+