dispatcher.go

/*
 * Echotron
 * Copyright (C) 2019  Nicolò Santamaria
 *
 * Echotron is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Echotron is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package echotron

// Bot is the interface that must be implemented by your definition of
// the struct thus it represent each open session with a user on Telegram.
type Bot interface {
	// Update will be called upon receiving any update from Telegram.
	Update(*Update)
}

type Dispatcher struct {
	api        Api
	sessionMap map[int64]Bot
	newBot     func(api Api, chatId int64) Bot
}

// NewDispatcher returns a new instance of the Dispatcher object;
// useful for polling telegram and dispatch every update to the
// corresponding Bot instance.
func NewDispatcher(token string, newBot func(api Api, chatId int64) Bot) Dispatcher {
	return Dispatcher{
		NewApi(token),
		make(map[int64]Bot),
		newBot,
	}
}

// DelSession deletes the Bot instance, seen as a session, from the
// map with all of them.
func (d *Dispatcher) DelSession(chatId int64) {
	delete(d.sessionMap, chatId)
}

// AddSession allows to arbitrarily create a new Bot instance.
func (d *Dispatcher) AddSession(chatId int64) {
	if _, isIn := d.sessionMap[chatId]; !isIn {
		d.sessionMap[chatId] = d.newBot(d.api, chatId)
	}
}

// Run starts the polling loop and calls the function Update
// upon receiving any update from Telegram.
func (d *Dispatcher) Run() {
	var timeout int
	var chatId int64
	var response APIResponseUpdate

	var firstRun = true
	var lastUpdateId = -1

	for {
		response = d.api.GetUpdates(lastUpdateId+1, timeout)
		if response.Ok {
			for _, update := range response.Result {
				lastUpdateId = update.ID

				if update.Message != nil {
					chatId = update.Message.Chat.ID
				} else if update.EditedMessage != nil {
					chatId = update.EditedMessage.Chat.ID
				} else if update.ChannelPost != nil {
					chatId = update.ChannelPost.Chat.ID
				} else if update.EditedChannelPost != nil {
					chatId = update.EditedChannelPost.Chat.ID
				} else {
					continue
				}

				if _, isIn := d.sessionMap[chatId]; !isIn {
					d.sessionMap[chatId] = d.newBot(d.api, chatId)
				}

				if !firstRun {
					if bot, ok := d.sessionMap[chatId]; ok {
						go bot.Update(update)
					}
				}
			}
		}

		if firstRun {
			firstRun = false
			timeout = 120
		}
	}
}