package main

import "fmt"

// Go does not have a native enum type, but you can achieve similar functionality using constants and iota.
type ServerState int

// iota is a special identifier that is reset to 0 whenever the word const appears in the source and
// increments by one after each const specification. It is often used to create enumerated constants.
const (
	StateIdle ServerState = iota
	StateConnected
	StateError
	StateRetrying
)

// We can use a map to associate the ServerState values with their string representations.
var stateName = map[ServerState]string{
	StateIdle:      "idle",
	StateConnected: "connected",
	StateError:     "error",
	StateRetrying:  "retrying",
}

// By implementing the Stringer interface, we can define how our ServerState values are printed.
func (ss ServerState) String() string {
	return stateName[ss]
}

func main() {
	ns := transition(StateIdle)
	fmt.Println(ns)

	ns2 := transition(ns)
	fmt.Println(ns2)
}

func transition(s ServerState) ServerState {
	// A simple state machine that transitions between states based on the current state.
	switch s {
	case StateIdle:
		return StateConnected
	case StateConnected, StateRetrying:
		return StateIdle
	case StateError:
		return StateError
	default:
		panic(fmt.Errorf("unknown state: %s", s))
	}
}