package main

import (
	"flag"
	"fmt"
	"math"
	"net"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"

	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
	"github.com/probakowski/go-satel"
)

const (
	MaximumMessagesPerMinute = 2
	NanosecondsPerMinute     = 6e10
)

type TgEvent struct {
	msg tgbotapi.MessageConfig
}

type SecurityEvent interface {
	Execute(chat_ids []int64, tg_events chan TgEvent)
}

type SatelEvent struct {
	ev satel.Event
}

func (s SatelEvent) Execute(chat_ids []int64, tg_events chan TgEvent) {
	fmt.Println("Change from SATEL: ", "type", s.ev.Type, "index", s.ev.Index, "value", s.ev.Value)
	for _, chat_id := range chat_ids {
		msg := tgbotapi.NewMessage(chat_id, fmt.Sprintf("Change from SATEL: Zone: %d Type: %s Value: %t",
			s.ev.Index, s.ev.Type, s.ev.Value))

		send_tg_message(tg_events, msg)
	}
}

type EmptyEvent struct{}

func (s EmptyEvent) Execute(chat_ids []int64, tg_events chan TgEvent) {}

func tg_sender_worker(tg_events <-chan TgEvent, bot *tgbotapi.BotAPI, wg *sync.WaitGroup) {
	wg.Add(1)
	defer wg.Done()
	lastExecutionTime := time.Now()
	minimumTimeBetweenEachExecution := time.Duration(math.Ceil(NanosecondsPerMinute / MaximumMessagesPerMinute))
	_, shouldOmitTg := os.LookupEnv("OMIT_TG")

	for ev := range tg_events {
		defer func() { lastExecutionTime = time.Now() }()

		time.Sleep(minimumTimeBetweenEachExecution - time.Since(lastExecutionTime))
		fmt.Println("Will send to TG: ", ev.msg.Text)
		if shouldOmitTg {
			continue
		}
		_, err := bot.Send(ev.msg)
		if err != nil {
			// TODO: handle it better
			panic(err)
		}
	}
}

func send_tg_message(tg_events chan TgEvent, msg tgbotapi.MessageConfig) {
	tg_events <- TgEvent{msg}
}

func main() {
	var (
		wg         sync.WaitGroup
		tg_events  = make(chan TgEvent)
		sec_events = make(chan SecurityEvent)
	)
	satel_api_addr := flag.String("satel-addr", "", "Address that should be used to connect to the SATEL device")
	satel_api_port := flag.String("satel-port", "7094", "Port that should be used to connect to the SATEL device")
	chat_id_raw := flag.String("tg-chat-id", "", "Telegram Chat ID where to send updates. Use \",\" to specify multiple IDs.")
	flag.Parse()

	if len(*satel_api_addr) == 0 || len(*satel_api_port) == 0 || len(*chat_id_raw) == 0 {
		fmt.Println("Use --satel-addr=ADDR, --satel-port=PORT and --tg-chat-id=CHAT_ID command line flags to continue.")
		os.Exit(1)
	}
	chat_ids_strings := strings.Split(*chat_id_raw, ",")
	var chat_ids []int64
	for _, chat_id_str := range chat_ids_strings {
		chat_id, err := strconv.ParseInt(chat_id_str, 10, 64)
		if err != nil {
			fmt.Printf("Tried to use a non-int value for one of tg_chat_ids: %s. That's bad.", chat_id_str)
			os.Exit(1)
		}
		chat_ids = append(chat_ids, chat_id)
	}

	satel_addr := fmt.Sprintf("%s:%s", *satel_api_addr, *satel_api_port)
	satel_conn, err := net.Dial("tcp", satel_addr)
	if err != nil {
		panic(err)
	}
	s := satel.NewConfig(satel_conn, satel.Config{EventsQueueSize: 1000})
	bot, err := tgbotapi.NewBotAPI(os.Getenv("TELEGRAM_APITOKEN"))
	if err != nil {
		panic(err)
	}

	go tg_sender_worker(tg_events, bot, &wg)
	for e, ok := <-s.Events; ok; e, ok = <-s.Events {
		sec_events <- SatelEvent{e}
	}

	for ev := range sec_events {
		ev.Execute(chat_ids, tg_events)
	}

	close(tg_events)
	wg.Wait()
}