door-alarm/main.go

package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/joho/godotenv"
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	"github.com/labstack/gommon/log"
)

const TimeFormat = "2006-01-02 15:04:05"

var token string

// the condition is: distance >= threshold (is door open)
var opened bool

// is door locked
var locked bool = false

// alert the user when door locked and but open?
var alert bool = false
var gotifyToken string
var gotifyURL string

var mut sync.Mutex

type WriteReq struct {
	Opened bool `json:"opened"`
}

func main() {
	_ = godotenv.Load()
	token = os.Getenv("TOKEN")

	alertRaw := strings.ToLower(os.Getenv("USE_ALERTS"))
	alert = alertRaw == "true" || alertRaw == "t" || alertRaw == "1" || alertRaw == "y" || alertRaw == "yes"

	gotifyToken = os.Getenv("GOTIFY_TOKEN")
	gotifyURL = os.Getenv("GOTIFY_URL")
	if alert && gotifyToken == "" {
		log.Fatal("GOTIFY_TOKEN can't be empty when alerts are enabled")
	}
	if alert && gotifyURL == "" {
		log.Fatal("GOTIFY_URL can't be empty when alerts are enabled")
	}

	app := echo.New()
	app.Logger.SetLevel(log.INFO)

	app.Use(middleware.RecoverWithConfig(middleware.RecoverConfig{
		StackSize: 1 << 10,
		LogLevel:  log.ERROR,
	}))
	app.Use(middleware.Secure())

	app.Use(middleware.LoggerWithConfig(middleware.LoggerConfig{
		Format:           "${time_custom} ${method} ${uri} ---> ${status} in ${latency_human} (${bytes_out} bytes)\n",
		CustomTimeFormat: TimeFormat,
	}))
	app.Use(middleware.RemoveTrailingSlash())

	app.OnAddRouteHandler = func(host string, route echo.Route, handler echo.HandlerFunc, middleware []echo.MiddlewareFunc) {
		now := time.Now()
		fmt.Printf("%s registered %-6s %s\n", now.Format(TimeFormat), route.Method, route.Path)
	}
	app.HTTPErrorHandler = func(err error, c echo.Context) {
		if c.Response().Committed {
			log.Error(err)
			return
		}

		code := http.StatusInternalServerError
		var response any = err.Error()

		var httpErr *echo.HTTPError
		if errors.As(err, &httpErr) {
			code = httpErr.Code
			response = httpErr
		}

		if code >= 500 {
			log.Error(err)
		}

		err2 := c.JSON(code, response)
		if err2 != nil {
			log.Error(err2)
		}
	}

	app.GET("/", func(c echo.Context) error {
		return c.JSON(http.StatusOK, "Hello, World!")
	})

	app.GET("/read", authed(func(c echo.Context) error {
		mut.Lock()
		o := opened
		mut.Unlock()

		return c.JSON(http.StatusOK, o)
	}))

	app.POST("/write", authed(func(c echo.Context) error {
		var data WriteReq
		err := c.Bind(&data)
		if err != nil {
			return c.NoContent(http.StatusBadRequest)
		}

		mut.Lock()
		if data.Opened == opened {
			mut.Unlock()
			return c.NoContent(http.StatusOK)
		}

		opened = data.Opened
		if locked && alert {
			var action string
			if opened {
				action = "opened"
			} else {
				action = "closed"
			}

			go sendAlert(action)
		}

		mut.Unlock()
		return c.NoContent(http.StatusOK)
	}))

	app.POST("/lock", authed(func(c echo.Context) error {
		mut.Lock()
		locked = true
		mut.Unlock()

		return c.NoContent(http.StatusOK)
	}))

	app.POST("/unlock", authed(func(c echo.Context) error {
		mut.Lock()
		locked = false
		mut.Unlock()

		return c.NoContent(http.StatusOK)
	}))

	app.POST("/alerts/pause", authed(func(c echo.Context) error {
		pauseForRaw := c.QueryParam("for")
		if pauseForRaw != "" {
			pauseFor, err := strconv.Atoi(pauseForRaw)
			if err != nil || pauseFor <= 0 {
				return c.JSON(http.StatusBadRequest, "query param 'for' not valid")
			}

			go func() {
				time.Sleep(time.Duration(pauseFor) * time.Second)

				mut.Lock()
				alert = true
				mut.Unlock()
			}()
		}

		mut.Lock()
		alert = false
		mut.Unlock()

		return c.NoContent(http.StatusOK)
	}))

	app.POST("/alerts/resume", authed(func(c echo.Context) error {
		mut.Lock()
		alert = false
		mut.Unlock()

		return c.NoContent(http.StatusOK)
	}))

	log.Fatal(app.Start(":1323"))
}

func authed(next echo.HandlerFunc) echo.HandlerFunc {
	return func(c echo.Context) error {
		if c.Request().Header.Get("Authorization") != token {
			return c.NoContent(http.StatusUnauthorized)
		}

		return next(c)
	}
}

func sendAlert(action string) {
	to := fmt.Sprintf("%s/message?token=%s", gotifyURL, gotifyToken)
	what := echo.Map{
		"title":    fmt.Sprintf("Your door has been %s", action),
		"priority": 1,
		"message":  fmt.Sprintf("Your locked door has been %s at %s", action, time.Now().Format(TimeFormat)),
	}
	b, err := json.Marshal(&what)
	if err != nil {
		log.Error(err)
		return
	}

	res, err := http.Post(to, "application/json", bytes.NewBuffer(b))
	if err != nil {
		log.Error(err)
		return
	}

	body, err := io.ReadAll(res.Body)
	if err != nil {
		log.Error(err)
		return
	}

	if res.StatusCode != 200 {
		log.Errorf("sendAlert response status code is not 200: %d, body:\n%s", res.StatusCode, body)
	} else {
		log.Infof("sent alert (%s) to gotify", action)
	}
}