Users sending text messages are sometimes unaware that long messages
will cost more.
Users sending broadcast messages need to be aware that there’s a
character limit, so they can take this into account when planning their
messages.
This commit adds an endpoint which counts the number of characters in
some template content, and returns a snippet of useful info about how
long the message is.
In subsequent commits we’ll be able to use AJAX to fetch this snippet as
the user types.
There’s a surprising amount of complexity in counting the length of
messages. So we’ll need to do this in Python because it would be too
convoluted to re-implement the length counting in client side code, let
alone ensuring it had parity with its Python equivalent.