ref(calendar): refactored view outside of calendar module

[andreadev-it]

This PR is just a refactor to propose a way to separate the handling of different views and modes from the actual drawing. Views are extracted into their own modules (in this case, inside the folder core.ui.calendar.views) and can add themselves to the calendar module through the public.add_view method. This allows other plugins (like GTD, for example) to create their own views and add them to the calendar through an API.

Let me know if you guys like this, the API is pretty simple. The add_view function of the calendar module accepts two arguments: the view name and the view details. The details have to include a setup function that will be called with the following arguments: ui_info, mode and options.

This is how it looks to add the monthly view:

core/ui/calendar/views/monthly.lua:

module.public = {

    view_name = "monthly",

    setup = function (ui_info, mode, options)
        -- ...
    end
}

module.load = function ()
    module.required['core.ui.calendar'].add_view(module.public.view_name, module.public)
end

The new functions that were added are:
calendar.public.add_view
calendar.private.get_view
monthly.public.setup

It also slightly changes the api for the modes. The closing of the calendar window is now automatic whenever the callback that requested the date selection is called. This means that the calendar mode are not required to return true in order to close the calendar. They can now return true if they want the view to be redrawn (that's how the mode on_select return value should be considered after this change)

One thing to note: since the calendar views could be very different in how they work (based on the goal they're trying to achieve), I think that the drawing of the last line, that shows how to get the help menu and also shows the view name, should be handled by the view itself. That's of course my opinion, and I'll be happy to see what everyone else think about this whole PR 🙂

Have a nice day!

[vhyrro]

Yes!! I really like this refactor, makes things much more readable.

You're right, it would be better to make the current view/help components a per-view thing instead of a global thing, I'm happy with such a change later down the line :)

One very small nitpick: be sure to run make format every now and again, or set up a git hook to do it for you - just for the sake of consistency :p

[andreadev-it]

Thank you, I'm sorry I keep forgetting the formatting 😅
Will look into git hooks for that!