We now use the found_oldest flag from the server to determine
whether we should load older messages.
This requires us to change a few places in the code where we
pass the whole payload around now instead of just the messages.
Actually, many of the "cont" callbacks don't even look at the
data, so this change wasn't as invasive as I might have
predicted.
We now attach a fetch_status to message lists, so that they
can track their fetch status individually. When you go
back in a narrow and get all the older messages, we turn
off future fetches.
The narrow.js code no longer needs to orchestrate anything
here. The "home" message list won't have as many redundant
fetches after this commit, because we don't need to reset
flags every time we do `narrow.deactivate`.
And then actual narrows get a new message list every time
you narrow, so their fetch status gets reset implicitly
as part of constructing the MessageList object.
We are going to remove message_fetch.reset_for_narrow() soon,
but its callers probably still want to hide any scrolling
indicators, and we just let them do that directly.
This helps us consolidate the fetching constants without
having to export them. It will also remove some
responsibility for narrow.js to track fetching state.
This mostly moves code from ui.js.
We change the arguments to `message_fetch.load_more_messages()`
to be `opts` with callbacks for `show_loading` and `hide_loading`.
We also defer starting the scroll handler until `message_fetch.js`
has been initialized.
We want to call `set_message_booleans` as soon as we
get data from the server, to avoid confusion about whether
`flags` is the authoritative field.
This commit has callers to `add_message_metadata` call
`set_message_booleans`.
This also sets us up to **not** call `set_message_booleans`
in the local echo codepath, where we can just have the
markdown processor set booleans natively.
There's no advantage to doing a small batch size towards current here,
since latency isn't an issue at this point, and performance on the
server side generally favors larger batch sizes.
This also will make it significantly harder to start getting 429 rate
limiting errors when loading when far behind current.
Despite the length of this commit, it is a very straightforward
moving of code from narrow.js -> narrow_state.js, and then
everything else is just s/narrow.foo()/narrow_state.foo()/
(with a few tiny cleanups to remove some code duplication
in certain callers).
The only new functions are simple setter/getters that
encapsulate the current_filter variable:
narrow_state.reset_current_filter()
narrow_state.set_current_filter()
narrow_state.get_current_filter()
We removed narrow.predicate() as part of this, since it was dead
code.
Also, we removed the shim for narrow_state.set_compose_defaults(),
and since that was the last shim, we removed shim.js from the app.