The TextCleaner step has been moved from chat message’s validation to create_message/update_message services. It allows us to easily tweak part of its behavior depending on the needs.
For example we will now disable strip_whitespaces by default when streaming messages as we want to keep newlines and spaces at the end of the message.
Forcing a thread will work even in channel which don't have `threading_enabled` or in direct message channels.
For now this feature is only available through the `ChatSDK`:
```ruby
ChatSDK::Message.create(in_reply_to_id: 1, guardian: guardian, raw: "foo bar baz", channel_id: 2, force_thread: true)
```
```ruby
ChatSDK::Message.start_stream(message_id: 1, guardian: guardian)
ChatSDK::Message.stream(raw: "foo", message_id: 1, guardian: guardian)
ChatSDK::Message.stream(raw: "bar", message_id: 1, guardian: guardian)
ChatSDK::Message.stop_stream(message_id: 1, guardian: guardian)
```
Generally speaking only admins or owners of the message can interact with a message. Also note, Streaming to an existing message with a different user won't change the initial user of the message.
This commit introduces the possibility to stream messages. To allow plugins to use streaming this commit also ships a `ChatSDK` library to allow to interact with few parts of discourse chat.
```ruby
ChatSDK::Message.create_with_stream(raw: "test") do |helper|
5.times do |i|
is_streaming = helper.stream(raw: "more #{i}")
next if !is_streaming
sleep 2
end
end
```
This commit also introduces all the frontend parts:
- messages can now be marked as streaming
- when streaming their content will be updated when a new content is appended
- a special UI will be showing (a blinking indicator)
- a cancel button allows the user to stop the streaming, when cancelled `helper.stream(...)` will return `false`, and the plugin can decide exit early
