flow: reformated fsm

[rabikor]

The try to implement cache contract like was described in issue #288

Let's discuss it

[rabikor]

@demget what do you think? is it interesting to Telebot? I need a reason to accomplish all the described changes.

[rabikor]

Below is a minimal working flow example that you can use to see how it works:

testFlow := b.BeginFlow("test", func(c tele.Context) error { return c.Send("Input your firstname:") })

testFlow.OnUpdate(tele.OnText, "test.firstname", func(c tele.Context) error {
	// actions

	return c.Send("Thank you. Input your lastname:")
})

testFlow.OnUpdate(tele.OnText, "test.lastname", func(c tele.Context) error {
	// actions

	return c.Send("Thank you. Input your age:")
})

testFlow.OnUpdate(tele.OnText, "test.age", func(c tele.Context) error {
	age, err := strconv.Atoi(c.Text())
	if err != nil {
		c.Set("flow:state", tele.FlowRepeat)
		return c.Send("Please input a valid number for age:")
	}

	if age < 18 {
		c.Set("flow:state", tele.FlowRepeat)
		defer c.Send("Input your age:")
		return c.Send("You're too young. Let's go back.")
	}

	// actions

	c.Set("flow:state", tele.FlowEnd)
	return c.Send("All set. Thank you!")
})

testFlow.Transite("test", "test.firstname", func(c tele.Context) bool { return true })
testFlow.Transite("test.firstname", "test.lastname", func(c tele.Context) bool { return true })
testFlow.Transite("test.lastname", "test.age", func(c tele.Context) bool { return true })

b.HandleFlow("/test", testFlow)
b.Start()

[rabikor]

more harder example:

Below is a minimal working flow example that you can use to see how it works:

        f := b.BeginFlow("start", func(c tele.Context) error {
		return c.Send(b.Text(c, "welcome.begin", c.Sender().FirstName), b.Markup(c, "start"))
	})

	f.OnUpdate(tele.OnCallback, "lang.choose", func(c tele.Context) error {
		return c.Send(b.Text(c, "lang.choose"), b.Markup(c, "lang"))
	})
	f.OnUpdate(tele.OnCallback, "lang.chosen", func(c tele.Context) error {
		defer b.Markup(c, "currency")

		lang := c.Data()

		if locale, _ := b.Locale(c); locale == lang {
			return c.Respond()
		}

		b.SetLocale(c, lang)

		return c.Respond()
	})
	f.Handle("currency.choose", func(c tele.Context) error {
		return c.Send(b.Text(c, "currency.choose"), b.Markup(c, "currency"))
	})
	f.OnUpdate(tele.OnCallback, "currency.chosen", func(c tele.Context) error {
		return c.Respond()
	})
	f.Handle("configured", func(c tele.Context) error {
		defer c.Send(b.Text(c, "welcome.finish"))
		return c.Send(b.Text(c, "welcome.info"))
	})

	f.Transite("start", "lang.choose", tele.NoConditionTransition)
	f.Transite("lang.choose", "lang.chosen", tele.NoConditionTransition)
	f.Transite("lang.chosen", "currency.choose", tele.NoConditionTransition)
	f.Transite("currency.choose", "currency.chosen", tele.NoConditionTransition)
	f.Transite("currency.chosen", "configured", tele.NoConditionTransition)