web.go

package main

import (
	"encoding/json"
	"fmt"
	"github.com/gorilla/mux"
	"github.com/mrmorphic/hwio"
	"golang.org/x/net/websocket"
	"html/template"
	"math"
	"net/http"
	"os"
	"strconv"
	"time"
)

var (
	in string
)

type Response map[string]interface{}

func (r Response) String() (s string) {
	b, err := json.Marshal(r)
	if err != nil {
		s = ""
		return
	}
	s = string(b)
	return
}

func handler(w http.ResponseWriter, r *http.Request) {
	t, _ := template.ParseFiles("index.html")
	t.Execute(w, nil)
}

func writeblaster(pin string, value string) {
	f, err := os.Create("/dev/pi-blaster")
	if err != nil {
		panic(err)
	}
	_, err = f.WriteString(fmt.Sprintf("%s=%s\n", pin, value))
	if err != nil {
		panic(err)
	}
	f.Sync()
}

func on(w http.ResponseWriter, r *http.Request) {
	myPin1, err := hwio.GetPinWithMode("gpio18", hwio.INPUT)
	if err != nil {
		panic(err)
	}
	w.Header().Set("Content-Type", "application/json")
	r.ParseForm()

	if r.FormValue("turnon") == "true" {
		writeblaster("17", "1")
		time.Sleep(100 * time.Millisecond)
		val, _ := hwio.DigitalRead(myPin1)
		if val == hwio.HIGH {
			fmt.Fprint(w, Response{"success": true})
		} else {
			fmt.Fprint(w, Response{"success": false})
		}
	} else {
		writeblaster("17", "0")
		time.Sleep(100 * time.Millisecond)
		val, _ := hwio.DigitalRead(myPin1)
		if val == hwio.LOW {
			fmt.Fprint(w, Response{"success": true})
		} else {
			fmt.Fprint(w, Response{"success": false})
		}
	}
	hwio.ClosePin(myPin1)
}

func socketHandler(ws *websocket.Conn) {
	for {
		if err := websocket.Message.Receive(ws, &in); err != nil {
			return
		}
		writeblaster("17", in)
	}
}

func currentHandler(ws *websocket.Conn) {
	m, e := hwio.GetModule("i2c")
	if e != nil {
		fmt.Printf("could not get i2c module: %s\n", e)
		return
	}
	i2c := m.(hwio.I2CModule)

	i2c.Enable()
	defer i2c.Disable()
	device := i2c.GetDevice(0x48)

	for {
		a, _ := device.Read(0x48, 1)
		s := fmt.Sprintf("%d", a[0])
		i, _ := strconv.ParseFloat(s, 64)
		val := math.Abs(i-124) * 0.039215
		websocket.Message.Send(ws, fmt.Sprintf("%v", val))
		time.Sleep(1 * time.Second)
	}
}

func init() {
	defer hwio.CloseAll()
}

func main() {
	r := mux.NewRouter()
	r.HandleFunc("/", handler)
	r.HandleFunc("/control/on", on).Methods("POST")
	r.Handle("/ws/slide", websocket.Handler(socketHandler))
	r.Handle("/ws/current", websocket.Handler(currentHandler))
	fmt.Println("listen and server at port: 8080")
	http.ListenAndServe(":8080", r)
}