Background

At LitRes there is a system of bonuses and coupons that appear with enviable regularity. To make his wife happy, and in general, he can find an interesting book for himself, he began to monitor the site in which fresh coupons appear and dropped them in telegrams. But just a few days later I was tired of this business and I decided to automate this process so that it could be available to everyone who wants it.

Implementation

Since I constantly posted new coupons in telegrams, and in general I like this tool, I decided to create another bot for telegrams, as long as a sufficient number of libraries have already been created for it. Take golang and the telegram-bot-api library as the language . We also need to choose a resource from which to pull information, I had several sites in mind and I thought to write a universal parser as a whole, but at some point I became lazy, and I decided to choose one resource. In order to store coupons even after restart, I decided to use a simple sqlite3 database. We will store information about coupons in it, as well as information about registered users in the telegram bot, as well as information about which coupons the user has already received and which are not yet.

It looks something like this

Site parsing

The parsing of the site will be done by the goquery library - it works in much the same way as jquery.
Using the goquery.Document structure html . , , . . unixtime, . , , . , , js .

Telegram bot

BotFather , telegram . telegram api , http websocket. , telegram-bot-api updater .

type SNBot struct {
    cfg *Config
    bot *tgbotapi.BotAPI
    upd tgbotapi.UpdatesChannel
}

func New(cfg *Config) (*SNBot, error) {
    bot, err := tgbotapi.NewBotAPI(cfg.Token)
    if err != nil {
        return nil, err
    }
    level.Info(cfg.Logger).Log("msg", "Authorized on account", "bot-name", bot.Self.UserName)
    u := tgbotapi.NewUpdate(0)
    u.Timeout = cfg.UpdateTime
    updates, err := bot.GetUpdatesChan(u)
    if err != nil {
        return nil, err
    }
    return &SNBot{
        cfg: cfg,
        bot: bot,
        upd: updates,
    }, nil
}

, , gocron. task gocron storage storage .

func task(bot *snbot.SNBot, s *storage.Storage, c *collector.Collector, logger kitlog.Logger) {
    c.Collect(collector.ConditionQuery{
        URI: "https://lovikod.ru/knigi/promokody-litres",
    })
    chats, err := s.GetChat()
    if err != nil {
        level.Error(logger).Log("msg", "failed get chats", "err", err)
    }
    for _, id := range chats {
        records, err := s.GetNotUseCoupon(id)
        if err != nil {
            level.Error(logger).Log("msg", "failed get coupons", "err", err)
            return
        }
        var msg string
        for i, rec := range records {
            msg = fmt.Sprintf("%v%v:\t%s \n--->: %s\n : %v\n: %s\n\n", msg, i+1, rec.Link, rec.Code, time.Unix(rec.Date, 0).Format("02.01.2006"), rec.Description)
        }
        if len(msg) != 0 {
            err = bot.Send(id, msg)
            if err != nil {
                level.Error(logger).Log("msg", "failed send message", "err", err)
                continue
            }
            err = s.MarkAsRead(id, records)
            if err != nil {
                level.Error(logger).Log("msg", "failed marked as read", "err", err)
                continue
            }
        }
    }
    level.Info(logger).Log("msg", "send all chats new coupons")
}

- , , , .

func (s *SNBot) Send(chatID int64, msg string) error {
    level.Error(s.cfg.Logger).Log("msg", "try send", "chatID", chatID)
    var numericKeyboard = tgbotapi.NewReplyKeyboard(
        tgbotapi.NewKeyboardButtonRow(
            tgbotapi.NewKeyboardButton("/print5"),
        ),
    )
    m := tgbotapi.NewMessage(chatID, msg)
    m.ReplyMarkup = numericKeyboard
    _, err := s.bot.Send(m)
    if err != nil {
        if err.Error() == errBlockedByUser {
            s.cfg.Storage.UpdChatActivity(chatID, false)
        }
        return err
    }
    return nil
}

  Dockerfile

,   .

# build binary
FROM golang:1.10.3-alpine3.8 AS build
RUN apk add --no-cache linux-headers gcc g++
ARG VERSION=dev
WORKDIR /go/src/github.com/wenkaler/xfreehack
COPY . /go/src/github.com/wenkaler/xfreehack
RUN CGO_ENABLED=1 go build \
    -o /out/xfree \
    -ldflags "-X main.serviceVersion=$VERSION" \
    github.com/wenkaler/xfreehack/cmd

# copy to alpine image
FROM alpine:3.8
WORKDIR /app
RUN mkdir /db
COPY --from=build /out/xfree /app
RUN apk add --no-cache tzdata
RUN apk --no-cache add ca-certificates
ENV TZ Europe/Moscow
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
CMD ["/app/xfree"]

Systemd

. 2.6, upgrad- systemd. ? — 3.

[Unit]
Description=Xfree service
After=network.target
After=network-online.target

[Service]
ExecStart=/urs/local/bin/xfree
Environment="TELEGRAM_TOKEN=$TELEGRAM_TOKEN" "PATH_DB=/db/xfree.db"
TimeoutSec=30
Restart=on-failure
RestartSec=30

[Install]
WantedBy=multi-user.target

 Now my wife is happy that she can receive free books on LitRes, but I was just interested to solve this problem. There is still something that can be improved, add an alert system if MarkAsRead fails (so far this has not happened, but you never know) , he also now unsubscribes and no longer sends messages to people who have unsubscribed from him and you need to return them to the active state after pressing the / start command again. Well, in general, add the ability to choose the time of distribution and the choice of coupons, because the site has not only coupons from LiteRes. But this is all necessary, so far no such applications have been received.

References

1. Project itself
2. Coupon Website
3. Bot Name @xFreeCouponBot