fsm: run steps in order

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

fsm/fsm.go

@@ -23,10 +23,10 @@ type Options struct {
 }
 
 // HookBeforeFunc func signature
-type HookBeforeFunc func(ctx context.Context, state string, args map[string]interface{})
+type HookBeforeFunc func(ctx context.Context, state string, args interface{})
 
 // HookAfterFunc func signature
-type HookAfterFunc func(ctx context.Context, state string, args map[string]interface{})
+type HookAfterFunc func(ctx context.Context, state string, args interface{})
 
 // Option func signature
 type Option func(*Options)
@@ -53,12 +53,13 @@ func StateHookAfter(fns ...HookAfterFunc) Option {
 }
 
 // StateFunc called on state transition and return next step and error
-type StateFunc func(ctx context.Context, args map[string]interface{}) (string, map[string]interface{}, error)
+type StateFunc func(ctx context.Context, args interface{}) (string, interface{}, error)
 
 // FSM is a finite state machine
 type FSM struct {
 	mu          sync.Mutex
-	states  map[string]StateFunc
+	statesMap   map[string]StateFunc
+	statesOrder []string
 	opts        *Options
 	current     string
 }
@@ -73,7 +74,7 @@ func New(opts ...Option) *FSM {
 	}
 
 	return &FSM{
-		states: map[string]StateFunc{},
+		statesMap: map[string]StateFunc{},
 		opts:      options,
 	}
 }
@@ -95,12 +96,13 @@ func (f *FSM) Reset() {
 // State adds state to fsm
 func (f *FSM) State(state string, fn StateFunc) {
 	f.mu.Lock()
-	f.states[state] = fn
+	f.statesMap[state] = fn
+	f.statesOrder = append(f.statesOrder, state)
 	f.mu.Unlock()
 }
 
 // Start runs state machine with provided data
-func (f *FSM) Start(ctx context.Context, args map[string]interface{}, opts ...Option) (map[string]interface{}, error) {
+func (f *FSM) Start(ctx context.Context, args interface{}, opts ...Option) (interface{}, error) {
 	var err error
 	var ok bool
 	var fn StateFunc
@@ -114,8 +116,8 @@ func (f *FSM) Start(ctx context.Context, args map[string]interface{}, opts ...Op
 	}
 
 	cstate := options.Initial
-	states := make(map[string]StateFunc, len(f.states))
+	states := make(map[string]StateFunc, len(f.statesMap))
-	for k, v := range f.states {
+	for k, v := range f.statesMap {
 		states[k] = v
 	}
 	f.current = cstate
@@ -142,8 +144,14 @@ func (f *FSM) Start(ctx context.Context, args map[string]interface{}, opts ...Op
 			}
 			if err != nil {
 				return args, err
-			} else if nstate == "" || nstate == StateEnd {
+			} else if nstate == StateEnd {
 				return args, nil
+			} else if nstate == "" {
+				for idx := range f.statesOrder {
+					if f.statesOrder[idx] == cstate && len(f.statesOrder) > idx+1 {
+						nstate = f.statesOrder[idx+1]
+					}
+				}
 			}
 			cstate = nstate
 		}

fsm/fsm_test.go

@@ -10,40 +10,54 @@ import (
 func TestFSMStart(t *testing.T) {
 	ctx := context.TODO()
 	buf := bytes.NewBuffer(nil)
-	pfb := func(_ context.Context, state string, _ map[string]interface{}) {
+	pfb := func(_ context.Context, state string, _ interface{}) {
 		fmt.Fprintf(buf, "before state %s\n", state)
 	}
-	pfa := func(_ context.Context, state string, _ map[string]interface{}) {
+	pfa := func(_ context.Context, state string, _ interface{}) {
 		fmt.Fprintf(buf, "after state %s\n", state)
 	}
 	f := New(StateInitial("1"), StateHookBefore(pfb), StateHookAfter(pfa))
-	f1 := func(_ context.Context, args map[string]interface{}) (string, map[string]interface{}, error) {
+	f1 := func(_ context.Context, req interface{}) (string, interface{}, error) {
+		args := req.(map[string]interface{})
 		if v, ok := args["request"].(string); !ok || v == "" {
 			return "", nil, fmt.Errorf("empty request")
 		}
 		return "2", map[string]interface{}{"response": "test2"}, nil
 	}
-	f2 := func(_ context.Context, args map[string]interface{}) (string, map[string]interface{}, error) {
+	f2 := func(_ context.Context, req interface{}) (string, interface{}, error) {
+		args := req.(map[string]interface{})
 		if v, ok := args["response"].(string); !ok || v == "" {
 			return "", nil, fmt.Errorf("empty response")
 		}
 		return "", map[string]interface{}{"response": "test"}, nil
 	}
+	f3 := func(_ context.Context, req interface{}) (string, interface{}, error) {
+		args := req.(map[string]interface{})
+		if v, ok := args["response"].(string); !ok || v == "" {
+			return "", nil, fmt.Errorf("empty response")
+		}
+		return StateEnd, map[string]interface{}{"response": "test_last"}, nil
+	}
 	f.State("1", f1)
 	f.State("2", f2)
-	args, err := f.Start(ctx, map[string]interface{}{"request": "test1"})
+	f.State("3", f3)
+	rsp, err := f.Start(ctx, map[string]interface{}{"request": "test1"})
 	if err != nil {
 		t.Fatal(err)
-	} else if v, ok := args["response"].(string); !ok || v == "" {
+	}
+	args := rsp.(map[string]interface{})
+	if v, ok := args["response"].(string); !ok || v == "" {
 		t.Fatalf("nil rsp: %#+v", args)
-	} else if v != "test" {
+	} else if v != "test_last" {
 		t.Fatalf("invalid rsp %#+v", args)
 	}
 
 	if !bytes.Contains(buf.Bytes(), []byte(`before state 1`)) ||
 		!bytes.Contains(buf.Bytes(), []byte(`before state 2`)) ||
 		!bytes.Contains(buf.Bytes(), []byte(`after state 1`)) ||
-		!bytes.Contains(buf.Bytes(), []byte(`after state 2`)) {
+		!bytes.Contains(buf.Bytes(), []byte(`after state 2`)) ||
+		!bytes.Contains(buf.Bytes(), []byte(`after state 3`)) ||
+		!bytes.Contains(buf.Bytes(), []byte(`after state 3`)) {
 		t.Fatalf("fsm not works properly or hooks error, buf: %s", buf.Bytes())
 	}
 }