fsm: improve and convert to interface

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

fsm/fsm.go

@@ -3,8 +3,6 @@ package fsm // import "go.unistack.org/micro/v3/fsm"
 import (
 	"context"
 	"errors"
-	"fmt"
-	"sync"
 )
 
 var (
@@ -12,170 +10,20 @@ var (
 	StateEnd        = "end"
 )
 
-// Options struct holding fsm options
-type Options struct {
-	// DryRun mode
-	DryRun bool
-	// Initial state
-	Initial string
-	// HooksBefore func slice runs in order before state
-	HooksBefore []HookBeforeFunc
-	// HooksAfter func slice runs in order after state
-	HooksAfter []HookAfterFunc
+type State interface {
+	Name() string
+	Body() interface{}
 }
 
-// HookBeforeFunc func signature
-type HookBeforeFunc func(ctx context.Context, state string, args interface{})
-
-// HookAfterFunc func signature
-type HookAfterFunc func(ctx context.Context, state string, args interface{})
-
-// Option func signature
-type Option func(*Options)
-
-// StateOptions holds state options
-type StateOptions struct {
-	DryRun bool
-}
-
-// StateDryRun says that state executes in dry run mode
-func StateDryRun(b bool) StateOption {
-	return func(o *StateOptions) {
-		o.DryRun = b
-	}
-}
-
-// StateOption func signature
-type StateOption func(*StateOptions)
-
-// InitialState sets init state for state machine
-func InitialState(initial string) Option {
-	return func(o *Options) {
-		o.Initial = initial
-	}
-}
-
-// HookBefore provides hook func slice
-func HookBefore(fns ...HookBeforeFunc) Option {
-	return func(o *Options) {
-		o.HooksBefore = fns
-	}
-}
-
-// HookAfter provides hook func slice
-func HookAfter(fns ...HookAfterFunc) Option {
-	return func(o *Options) {
-		o.HooksAfter = fns
-	}
-}
+// StateWrapper wraps the StateFunc and returns the equivalent
+type StateWrapper func(StateFunc) StateFunc
 
 // StateFunc called on state transition and return next step and error
-type StateFunc func(ctx context.Context, args interface{}, opts ...StateOption) (string, interface{}, error)
+type StateFunc func(ctx context.Context, state State, opts ...StateOption) (State, error)
 
-// FSM is a finite state machine
-type FSM struct {
-	mu          sync.Mutex
-	statesMap   map[string]StateFunc
-	statesOrder []string
-	opts        *Options
-	current     string
-}
-
-// New creates a new finite state machine having the specified initial state
-// with specified options
-func New(opts ...Option) *FSM {
-	options := &Options{}
-
-	for _, opt := range opts {
-		opt(options)
-	}
-
-	return &FSM{
-		statesMap: map[string]StateFunc{},
-		opts:      options,
-	}
-}
-
-// Current returns the current state
-func (f *FSM) Current() string {
-	f.mu.Lock()
-	defer f.mu.Unlock()
-	return f.current
-}
-
-// Current returns the current state
-func (f *FSM) Reset() {
-	f.mu.Lock()
-	f.current = f.opts.Initial
-	f.mu.Unlock()
-}
-
-// State adds state to fsm
-func (f *FSM) State(state string, fn StateFunc) {
-	f.mu.Lock()
-	f.statesMap[state] = fn
-	f.statesOrder = append(f.statesOrder, state)
-	f.mu.Unlock()
-}
-
-// Init initialize fsm and check states
-
-// Start runs state machine with provided data
-func (f *FSM) Start(ctx context.Context, args interface{}, opts ...Option) (interface{}, error) {
-	var err error
-	var ok bool
-	var fn StateFunc
-	var nstate string
-
-	f.mu.Lock()
-	options := f.opts
-
-	for _, opt := range opts {
-		opt(options)
-	}
-
-	sopts := []StateOption{StateDryRun(options.DryRun)}
-
-	cstate := options.Initial
-	states := make(map[string]StateFunc, len(f.statesMap))
-	for k, v := range f.statesMap {
-		states[k] = v
-	}
-	f.current = cstate
-	f.mu.Unlock()
-
-	for {
-		select {
-		case <-ctx.Done():
-			return nil, ctx.Err()
-		default:
-			fn, ok = states[cstate]
-			if !ok {
-				return nil, fmt.Errorf(`state "%s" %w`, cstate, ErrInvalidState)
-			}
-			f.mu.Lock()
-			f.current = cstate
-			f.mu.Unlock()
-			for _, fn := range options.HooksBefore {
-				fn(ctx, cstate, args)
-			}
-			nstate, args, err = fn(ctx, args, sopts...)
-			for _, fn := range options.HooksAfter {
-				fn(ctx, cstate, args)
-			}
-			switch {
-			case err != nil:
-				return args, err
-			case nstate == StateEnd:
-				return args, nil
-			case nstate == "":
-				for idx := range f.statesOrder {
-					if f.statesOrder[idx] == cstate && len(f.statesOrder) > idx+1 {
-						nstate = f.statesOrder[idx+1]
-					}
-				}
-			}
-			cstate = nstate
-		}
-	}
+type FSM interface {
+	Start(context.Context, interface{}, ...Option) (interface{}, error)
+	Current() string
+	Reset()
+	State(string, StateFunc)
 }