Welcome Bot

package main

import (
	"fmt"

	"github.com/amarnathcjd/gogram/telegram"
)

func main() {
	// Create and authenticate the client
	client, _ := telegram.NewClient(telegram.ClientConfig{
		AppID:   6,
		AppHash: "YOUR_APP_HASH",
	})
	client.LoginBot("YOUR_BOT_TOKEN")

	// Listen for participant updates (joins/leaves)
	client.On("participant", UserJoinHandle)

	// Handle /start command
	client.On("cmd:start", func(message *telegram.NewMessage) error {
		message.Reply("Hello, I am a bot!")
		return nil
	})
	
	// Keep the bot running
	client.Idle()
}

// Handle user join events
func UserJoinHandle(m *telegram.ParticipantUpdate) error {
	// Check if user joined or was added to the group
	if m.IsJoined() || m.IsAdded() {
		// Send welcome message with user's first name
		// m.ChannelID() returns the chat/group ID where user joined
		// m.User contains the user information
		fmt.Println(m.Client.SendMessage(
			m.ChannelID(), 
			"Welcome to the group <b>"+m.User.FirstName+"!</b>",
		))
	}

	return nil
}

// Welcome with username mention
func UserJoinHandle(m *telegram.ParticipantUpdate) error {
	if m.IsJoined() || m.IsAdded() {
		welcomeMsg := fmt.Sprintf(
			"👋 Welcome to the group, <a href='tg://user?id=%d'>%s</a>!\n\n"+
			"Please read the group rules and enjoy your stay!",
			m.User.ID,
			m.User.FirstName,
		)
		m.Client.SendMessage(m.ChannelID(), welcomeMsg)
	}
	return nil
}

// Handle user leaving
func UserJoinHandle(m *telegram.ParticipantUpdate) error {
	if m.IsJoined() || m.IsAdded() {
		m.Client.SendMessage(m.ChannelID(), "Welcome "+m.User.FirstName+"! 👋")
	} else if m.IsLeft() {
		m.Client.SendMessage(m.ChannelID(), m.User.FirstName+" left the group 😢")
	}
	return nil
}