[original Medium post](https://medium.com/@thabogre/turning-a-c-structure-into-a-lua-table-563f5f99fc1d)

# Telegram-cli Notifications for i3wm

My first experience with a Linux desktop environment was gnome. It was fine, I guess, but I spent most of my time in the terminal so I never really learned where anythign was or how to do anything using gnome. I just had it.<br/>
Later on I got introduced to i3wm(i3 for short). Love at first sight.<br/>
I use vim, I use tmux, you'd think I already had enough tabs, panes, windows, sessions. You'd be most certainly wrong. After i3 I realised I still needed more.<br/>
I use telegram because friends, family, life.<br/>
It's annoying to have to pay attention to my cellphone(I know I'm a horrible person, no need to point that out). Having i3 notifications is just more convinient.<br/>
So the next obvious step was to get just that. Telegram-cli has both Python and Lua APIs. I used the Lua API. I have no reason whatsoever to back my decision up other than I just felt like doing it in Lua.<br/>
TL;DR.<br/>
A Telegram-cli Lua script has to implement a couple of hook functions(the API gives us hooks and callbacks).<br/>
* `on_binlog_replay_end(ok_cb, extra)` this one runs when replay of old events has finished.<br/>
* `on_get_difference_end(ok_cb, extra)` runs after the first call to `get_difference`.<br/>
* `on_our_id(our_id)` using this, you can check the id of the user you are logged in as.<br/>
* `on_msg_receive(msg)` it's called when we receive a new message.<br/>
* `on_user_update(user, what_changed)` is called when there is an update on the user's info.<br/>
* `on_chat_update(user, what_changed)` is called when there is an update on a chat info.<br>
* `on_secret_chat_update(user, what_changed)` is called when there is updated info for a secret chat.<br/>

You can read the Lua API documentation [here](https://github.com/vysheng/tg/blob/master/README-LUA). The documentation could use some help. If you can't find anything there, either look at the source code for the Lua API [here](https://github.com/vysheng/tg/blob/master/lua-tg.c) or just look at the Python API doc [here](https://github.com/vysheng/tg/blob/master/README-PY.md).<br/>
We are only going to implement `on_binlog_replay_end` and `on_msg_receive`.<br/>
Implementing those two hooks would give us a way to know when we receive a new maessage and if for whatever reason we missed that, how many unread messages we have.<br/>
The version of the script I use presonally, sends notifications to a server. Then, a client can query the server for updates. The client is what i3 calls for a block update(I use i3-blocks).<br/>
Also note that telegram-cli will output a lot of things to stdout, so we can't just have our Lua script dump info to stdout and then use `telegram-cli -s myscript.lua` for i3.<br/>
You could run `telegram-cli` in daemon mode and achieve the same thing without a server-client set-up, then register our hook functions as telegram-cli commands and then use `netcat` to have our custom command executed by the daemon(the command registered with i3 would be the netcat command). For more on that you can look [here](https://github.com/vysheng/tg/wiki/Running-Telegram-CLI-as-Daemon).<br/>
How you use this is up to you and I'll leave that part to you. We'll just cover the hook functions.<br/>
For `on_msg_receive` we have:<br/>
```lua
function on_msg_receive(msg)
  if (msg.from.print_name == "JohnDoe") then
    return
  end
  local socket = require("socket")
  local host, port = "localhost", 11111
  local tcp = assert(socket.tcp())
  tcp:connect(host, port)
  print(msg.from.print_name)
  tcp:send("JohnDoe".."\n")
  tcp:close()
end
```
The function above will only notify us if our contact `JohnDoe` has sent us a message. If you want to be notified of all new messages, you can just get rid of the if.<br/>

To get the unread messages we do:<br/>
```lua
function ok_cb(extra, success, result)
  for k, v in pairs(result) do
    if v["unread"] ~= 0. then
      if v["peer"]["username"] == "johndoe82" then
        local socket = require("socket")
        local host, port = "localhost", 11111
        local tcp = assert(socket.tcp())
        tcp:connect(host, port)
        tcp:send("JohnDoe".."\n")
        tcp:close()
      end
    end
  end
end

function on_binlog_replay_end()
  get_dialog_list(ok_cb, result)
end
```
For the daemon+netcat variation, you can put the call to `dialog_list` inside a new function and register that as a telegram-cli command and run that command with netcat.<br/>
The last thing is, if you don't want to have telegram-cli runnning all the time, daemon or not, you can call `safe_quit()` in your Lua script to quit telegram-cli.<br/>