birthdaybot/notification/service_telegram.go

package notification

import (
	"bytes"
	"fmt"
	"os"
	"strconv"
	"text/template"

	"git.ctrlz.es/mgdelacroix/birthdaybot/model"
	"git.ctrlz.es/mgdelacroix/birthdaybot/utils"
	"github.com/charmbracelet/log"
	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
)

type TelegramNotificationService struct {
	logger *log.Logger
	config *model.Config
	bot    *tgbotapi.BotAPI
}

func NewTelegramNotificationService(logger *log.Logger, config *model.Config) (*TelegramNotificationService, error) {
	bot, err := tgbotapi.NewBotAPI(config.TelegramNotifications.BotToken)
	if err != nil {
		return nil, fmt.Errorf("cannot create bot: %w", err)
	}

	botUser, err := bot.GetMe()
	if err != nil {
		return nil, fmt.Errorf("cannot get bot information: %w", err)
	}

	logger.Info("telegram bot initialized", "id", botUser.ID, "username", botUser.UserName)

	return &TelegramNotificationService{
		logger: logger,
		config: config,
		bot:    bot,
	}, nil
}

func (tns *TelegramNotificationService) Notify(birthday *model.Birthday, template *template.Template) error {
	var msgText string
	if template != nil {
		var stringBuffer bytes.Buffer
		if err := template.Execute(&stringBuffer, birthday); err != nil {
			return fmt.Errorf("cannot execute template for birthday: %w", err)
		}

		msgText = stringBuffer.String()
	} else {
		msgText = fmt.Sprintf("It's %s's birthday! You can reach them out at %s or %s", birthday.Name, birthday.Email, birthday.Phone)
	}

	chatID, err := strconv.Atoi(tns.config.TelegramNotifications.ChannelID)
	if err != nil {
		return fmt.Errorf("cannot parse ChannelID: %w", err)
	}

	picture, err := utils.GetPictureForBirthday(birthday, tns.config.Birthdays.Pictures)
	if err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("cannot get picture for birthday: %w", err)
	}

	var msg tgbotapi.Chattable
	if picture == "" {
		msg = tgbotapi.NewMessage(int64(chatID), msgText)

	} else {
		photo := tgbotapi.NewPhoto(int64(chatID), tgbotapi.FilePath(picture))
		photo.Caption = msgText
		msg = photo
	}

	if _, err := tns.bot.Send(msg); err != nil {
		return fmt.Errorf("error sending message: %w", err)
	}

	return nil
}