# BirdyChat Tech Challenge

This repository implements BirdyChat tech challenge.

# Start here

Firstly, check out this repository locally.
Then install required versions of Elixir and Erlang from .tool-versions. asdf-vm will pick them up automatically.
Then you run the test suite with `mix test`.
Then, a scripted demo release is prepared in the prod environment:

```
MIX_ENV=prod mix build_release
```

Then you can run 3 servers connected to one another:

`_build/prod/rel/birdy_chat/bin/server_1` - runs at localhost:4001
`_build/prod/rel/birdy_chat/bin/server_2` - runs at localhost:4002
`_build/prod/rel/birdy_chat/bin/server_3` - runs at localhost:4003

Out of the box they communicate with one another. Send a json request to one of them and observe the results. Feel free to modify the examples below.

### A local request:

```
curl --request POST \
  --url http://localhost:4001/api/messages \
  --header 'content-type: application/json' \
  --data '{"message":"123","to":"1-user","from":"1-user"}'
```

### A remote request:

```
curl --request POST \
  --url http://localhost:4001/api/messages \
  --header 'content-type: application/json' \
  --data '{"message":"123","to":"2-user","from":"1-user"}'
```

### A request to unknown server:

```
curl --request POST \
  --url http://localhost:4001/api/messages \
  --header 'content-type: application/json' \
  --data '{"message":"123","to":"4-user","from":"1-user"}'
```

Files are saved to `priv/messages`.


## Key rundown of technical details

First and foremost, I tried to keep it as simple as possible - stick to know conventions, leverage existing libraries or frameworks, hence the usage of both Phoenix and Ecto - conventions they provide are understandable to pretty much any Elixir developer.

All important modules are documented and there is a test suite that exacutes all known code paths.

Servers authenticate with one another using Phoenix tokens. Servers communicate via HTTP using JSON. There were other options but I decided to use this one for reasons enumerated in documentation for BirdyChatWeb.Api.Server.Internal.Controller.