Add morning greeter bot

cmd/morninggreeter/main.go

@@ -0,0 +1,85 @@
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"strconv"
+	"time"
+
+	TGBotAPI "github.com/zwirec/TGChatScanner/TGBotApi"
+)
+
+const (
+	greetingHour   = 10
+	greetingMinute = 0
+	timezone       = "Europe/Moscow"
+	greeting       = "Привет! Доброе утро ☀️"
+)
+
+func main() {
+	token := os.Getenv("BOT_TOKEN")
+	if token == "" {
+		log.Fatal("BOT_TOKEN is not set")
+	}
+
+	chatIDRaw := os.Getenv("CHAT_ID")
+	if chatIDRaw == "" {
+		log.Fatal("CHAT_ID is not set")
+	}
+	chatID, err := strconv.ParseInt(chatIDRaw, 10, 64)
+	if err != nil {
+		log.Fatalf("CHAT_ID must be an integer: %v", err)
+	}
+
+	loc, err := time.LoadLocation(timezone)
+	if err != nil {
+		log.Fatalf("failed to load timezone %s: %v", timezone, err)
+	}
+
+	api := TGBotAPI.NewBotAPI(token)
+	log.Printf("morning greeter started: chat=%d tz=%s at %02d:%02d", chatID, timezone, greetingHour, greetingMinute)
+
+	for {
+		next := nextGreetingTime(time.Now().In(loc), greetingHour, greetingMinute)
+		wait := time.Until(next)
+		log.Printf("next greeting at %s (in %s)", next.Format(time.RFC3339), wait.Truncate(time.Second))
+		time.Sleep(wait)
+
+		if err := sendGreeting(api, chatID, greeting); err != nil {
+			log.Printf("send failed: %v", err)
+		} else {
+			log.Printf("greeting sent")
+		}
+	}
+}
+
+func nextGreetingTime(now time.Time, hour, minute int) time.Time {
+	candidate := time.Date(now.Year(), now.Month(), now.Day(), hour, minute, 0, 0, now.Location())
+	if !candidate.After(now) {
+		candidate = candidate.AddDate(0, 0, 1)
+	}
+	return candidate
+}
+
+func sendGreeting(api *TGBotAPI.BotAPI, chatID int64, text string) error {
+	resp, err := api.SendMessage(chatID, text, true)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode >= 300 {
+		body, _ := ioutil.ReadAll(resp.Body)
+		return &telegramError{Status: resp.StatusCode, Body: string(body)}
+	}
+	return nil
+}
+
+type telegramError struct {
+	Status int
+	Body   string
+}
+
+func (e *telegramError) Error() string {
+	return "telegram api error: status=" + strconv.Itoa(e.Status) + " body=" + e.Body
+}