godoor/godoor.go

package main

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"github.com/joho/godotenv"
	"io"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"sync"
	"syscall"
)
import "time"

const wiegand_a = 17
const wiegand_b = 18
const wiegand_bit_timeout = time.Millisecond * 8
const solenoid = 21

type card struct {
	UidHash string `json:"uid_hash"`
}

type cardList struct {
	AllowedUids []struct {
		Token card `json:"token"`
	} `json:"allowed_uids"`
}

type simpleUids struct {
	tokens []string
}

type ValidUids map[string]bool // bool has no meaning

type Config struct {
	door     string
	uid_salt string
	mock     string
	api      struct {
		allowed  string
		longpoll string
		swipe    string
		key      string
	}
}

var config Config
var globalLock sync.Mutex
var validUids ValidUids
var wiegand Wiegand

func main() {

	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer cancel()

	godotenv.Load()

	config.door = os.Getenv("KDOORPI_DOOR")
	config.api.allowed = os.Getenv("KDOORPI_API_ALLOWED")
	config.api.longpoll = os.Getenv("KDOORPI_API_LONGPOLL")
	config.api.swipe = os.Getenv("KDOORPI_API_SWIPE")
	config.api.key = os.Getenv("KDOORPI_API_KEY")
	config.uid_salt = os.Getenv("KDOORPI_UID_SALT")
	config.mock = os.Getenv("KDOORPI_MOCK_HW")

	if config.mock == "true" {
		wiegand = &WiegandMock{}
	} else {
		wiegand = WiegandSetup(wiegand_a, wiegand_b, wiegand_bit_timeout, solenoid)
	}

	http.DefaultClient.Timeout = 120 * time.Second

	for {
		err := reloadTokens()
		if err == nil {
			break
		}
		time.Sleep(10 * time.Second)
	}

	go cardRunner(wiegand)

	go func() {
		for {
			waitEvents()
		}
	}()

	fmt.Printf("Sleeping\n")

	<-ctx.Done()
	fmt.Printf("Cleanup\n")

	// cleanup
}

func cardRunner(w Wiegand) {
	for {
		card, err := w.GetCardUid()
		if err != nil {
			continue
		}

		printCardId(card)
		hashedHex := hashCardUid(card)
		fmt.Println(hashedHex)

		globalLock.Lock()
		ok := validUids[hashedHex]
		globalLock.Unlock()
		if ok {
			fmt.Println("Opening door")
			w.OpenDoor()
		} else {
			fmt.Println("Unknown card")
		}

	}
}

func ParseNextMessage(r *bufio.Reader) (string, error) {
	var message string

	for {
		s, err := r.ReadString('\n')
		if err != nil {
			return message, err
		}

		message = message + s
		nextBytes, err := r.ReadByte()
		if err != nil {
			return message, err
		}

		if nextBytes == '\n' {
			return message, nil
		}

		r.UnreadByte()
	}

}

func waitEvents() error {
	req, err := http.NewRequest(http.MethodGet, config.api.longpoll, nil)
	if err != nil {
		return err
	}
	req.Header.Add("KEY", config.api.key)
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	fmt.Printf("%v\n", resp)

	reader := bufio.NewReader(resp.Body)
	for {
		msg, err := ParseNextMessage(reader)
		if err != nil {
			return err
		}

		for _, line := range strings.Split(msg, "\n") {
			data, found_data := strings.CutPrefix(line, "data:")
			if !found_data {
				continue
			}
			fmt.Printf("got server data: %q\n", data)
			if strings.TrimSpace(data) == config.door {
				wiegand.OpenDoor()
			}

			go reloadTokens()
		}

	}

	fmt.Printf("%v\n", resp)
	return nil
}

func reloadTokens() error {
	req, err := http.NewRequest(http.MethodGet, config.api.allowed, nil)
	if err != nil {
		return err
	}
	req.Header.Add("KEY", config.api.key)
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	fmt.Printf("%v\n", resp)

	var cl cardList

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

	err = json.Unmarshal(body, &cl)
	if err != nil {
		return err
	}

	globalLock.Lock()
	defer globalLock.Unlock()
	validUids = make(ValidUids)
	for i, val := range cl.AllowedUids {
		fmt.Printf("%d: %+v\n", i, val.Token.UidHash)
		validUids[val.Token.UidHash] = true
	}

	return nil
}