package state

import (
	//"fmt"
	"sync"
)

type StateMachine struct {
	arc map[[2]string]func()
	State chan string
	cur string
	mux sync.Mutex
}

func (s *StateMachine) Arc(a,b string,fs ...func()) {
	var f func()
	if len(fs) == 0 {
		f = func() {}
	} else {
		f = fs[0]
	}
	s.mux.Lock()
	s.arc[[2]string{a,b}] = f
	s.mux.Unlock()
}

func (s *StateMachine) Cur() string {
	s.mux.Lock()
	defer s.mux.Unlock()
	return s.cur
}

func (s *StateMachine) run() {
	laststate := s.cur
	for {
		x := <-s.State
		if f,ok := s.arc[[2]string{"",x}]; ok {
			f()
		}
		if f,ok := s.arc[[2]string{laststate,""}]; ok {
			f()
		}
		if f,ok := s.arc[[2]string{s.cur,x}]; ok {
			f()
		}
		s.mux.Lock()
		laststate = s.cur
		s.cur = x
		s.mux.Unlock()
	}
}

func NewStateMachine(s string) *StateMachine {
	ret := &StateMachine{cur: s}
	ret.arc = make(map[[2]string]func())
	ret.State = make(chan string)
	go ret.run()
	return(ret)
}