saveme.go

package main

import (
	"github.com/gorilla/mux"
	rpio "github.com/stianeikeland/go-rpio"
	"log"
	"net/http"
	"os"
	"os/signal"
	"time"
)

const (
	gameTime        = 4
	startBlinkDelay = 50
)

func main() {
	log.Print("Starting up...")

	err := rpio.Open()
	if err != nil {
		panic(err)
	}
	defer func() {
		log.Print("Cleaning up...")
		rpio.Close()
	}()

	pin := rpio.Pin(10)
	pin.Output()

	defer func() {
		log.Print("Setting pin 10 to low")
		pin.Low()
	}()

	r := mux.NewRouter()

	r.HandleFunc("/current", func(resp http.ResponseWriter, req *http.Request) {
		defer pin.Output()
		pin.Input()
		state := pin.Read()
		var output string
		if state == rpio.Low {
			output = "Low"
		} else {
			output = "High"
		}
		resp.Write([]byte(output))
	}).
		Methods("GET")

	saved := make(chan bool)

	r.HandleFunc("/save", func(resp http.ResponseWriter, req *http.Request) {
		saved <- true
	}).
		Methods("POST")

	go func() {
		log.Print("Starting web server")
		http.ListenAndServe(":8080", r)
	}()

	resetBlinking, stopBlinking := blinker(pin)

	timeout := time.After(gameTime * time.Second)
	quit := make(chan bool, 1)
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt, os.Kill)
	go func() {
		<-c
		quit <- true
	}()

	for {
		select {
		case <-saved:
			log.Print("Saved by the bell")
			timeout = time.After(gameTime * time.Second)
			resetBlinking <- true
			log.Printf("You got another %v seconds", gameTime)
		case <-timeout:
			log.Print("You couldnt save the LED")
			quit <- true
		case <-quit:
			stoppedBlinking := make(chan bool)
			stopBlinking <- stoppedBlinking
			<-stoppedBlinking
			return
		}
	}
}

func blinker(pin rpio.Pin) (chan<- bool, chan<- chan bool) {
	resetBlinking := make(chan bool)
	stopBlinking := make(chan chan bool)

	go func() {
		var everySecond <-chan time.Time
		resetTimer := func() { everySecond = time.Tick(1 * time.Second) }
		resetTimer()

		blinkDelay := startBlinkDelay
		printBlinkDelay := func() { log.Printf("Blink delay now %v", blinkDelay) }

		for {
			select {
			case <-resetBlinking:
				blinkDelay = startBlinkDelay
				printBlinkDelay()
				resetTimer()
			case <-everySecond:
				blinkDelay *= 2
				printBlinkDelay()
			case stoppedBlinking := <-stopBlinking:
				everySecond = nil
				stoppedBlinking <- true
			default:
				time.Sleep(time.Duration(blinkDelay) * time.Millisecond)
				pin.High()
				time.Sleep(10 * time.Millisecond)
				pin.Low()
			}
		}
	}()

	return resetBlinking, stopBlinking
}