package gpio

import (
	"github.com/hybridgroup/gobot"
)

// Represents a digital Button
type ButtonDriver struct {
	gobot.Driver
	Active bool
}

// NewButtonDriver return a new ButtonDriver given a DigitalReader, name and pin
func NewButtonDriver(a DigitalReader, name string, pin string) *ButtonDriver {
	b := &ButtonDriver{
		Driver: *gobot.NewDriver(
			name,
			"ButtonDriver",
			a.(gobot.AdaptorInterface),
			pin,
		),
		Active: false,
	}

	b.AddEvent("push")
	b.AddEvent("release")

	return b
}

func (b *ButtonDriver) adaptor() DigitalReader {
	return b.Adaptor().(DigitalReader)
}

// Starts the ButtonDriver and reads the state of the button at the given Driver.Interval().
// Returns true on successful start of the driver.
//
// Emits the Events:
// 	"push"    int - On button push
//	"release" int - On button release
func (b *ButtonDriver) Start() bool {
	state := 0
	gobot.Every(b.Interval(), func() {
		newValue := b.readState()
		if newValue != state && newValue != -1 {
			state = newValue
			b.update(newValue)
		}
	})
	return true
}

// Halt returns true on a successful halt of the driver
func (b *ButtonDriver) Halt() bool { return true }

func (b *ButtonDriver) readState() int {
	return b.adaptor().DigitalRead(b.Pin())
}

func (b *ButtonDriver) update(newVal int) {
	if newVal == 1 {
		b.Active = true
		gobot.Publish(b.Event("push"), newVal)
	} else {
		b.Active = false
		gobot.Publish(b.Event("release"), newVal)
	}
}