GUI installer for AppImageLauncherLite

[probonopd]

Currently the AppImageLauncherLite AppImage is not intuitive. Double-clicking it achieves nothing.

When the AppImageLauncherLite AppImage is double-clicked, a GUI installer should check whether AppImageLauncherLite is correctly installed in the system and if yes, launch it using systemd; if no, install it and then launch it using systemd. Since we are already bundling Qt this should be low overhead.

[TheAssassin]

I guess the whole point of AppImageLauncher Lite is that you need the CLI once, but only once. But don't get me wrong, I like this idea. Not a priority for me, but PRs highly welcome.

[probonopd]

After thinking about it some more, I think the best cause of action is to actually embed some dialogs into the existing AppRun bash script. Maybe using qarma?

[TheAssassin]

An alternative is to make a GUI in C++ with Qt. I don't care however it's done, as long as the UX is good.

Bloating the existing script is however a bad idea. Just make a separate one, and launch that if there's no arguments passed and e.g., $DISPLAY is not set. That way you can also test it easily.

[probonopd]

That was my original thought, but the more I think about it I believe the best way is to wrap each and every step in proper error handling with GUI, hence to combine the logic that does stuff with checking error codes and using the GUI to react to them.

[TheAssassin]

Err... what?

[probonopd]

Pseudo-code:

test_someting
if $RESULT != FOO ; then qarma "Question..." ; fi
do_something
if $? != 0 ; then qarma "Error..." ; fi

You see, the GUI stuff and the "business logic" need to be interwoven.

[TheAssassin]

I still think it makes sense to move any form of GUI into a second script. What you suggest also seems very verbose and hard to debug. Therefore separating it makes sense, too.

[probonopd]

Do you realize that it will be orders of magnitude more work that way unless I am missing something?

[TheAssassin]

You're thinking way too simple and complicated, and that creates complexity and a lot of redundant and ugly code. That's what makes you think it's "magnitudes more of work". But that's not the case, as I will demonstrate in the following lines.

But first of all, let's have another look to the problems I see with your approach. Most notably, it ignores the fact that not every user of AppImageLauncher Lite might be on a desktop. So there's a lot more error handling required anyway. Furthermore, in your approach you could just make use of Bash's trap call, e.g., trap error_handler EXIT, where the handler is something like:

error_handler() {
    if [[ $? -ne 0 ]]; then
        if [[ "$DISPLAY" != "" ]]; then
            show_generic_gui_error_dialog
        else
            echo "generic error message"
        fi
    fi
}

Your entire idea is adding a lot of complexity and, as I said, makes the script unmaintainable. The script as it is right now is rock solid.

The entire approach of wrapping lines one by one with verbose error handling is completely wrong thinking, though.
Thinking a bit more about it, however, I came up with a bash-only solution.

The easiest way I can think of to allow for providing both CLI and UI would be to extract the install_ methods into a sourceable script, source that from the respective UI/CLI installers and then call the install steps one by one with appropriate error messages. A user isn't interested in what exactly broke when using the UI, we can still just print that to the CLI and if there's a bug have the user provide the CLI output (which hopefully won't happen). All you have to do is call the install steps in the right order, and that's something that rarely changes, so I'd be willing to have a little redundancy there. If we want to avoid that redundancy, we can even just define the install order in some single install method that calls them in the right order (disadvantage: no fine-grained error messages possible).

TL;DR: All you have to write, if done right, is to write a script that shows an initial installer UI (maybe just an "Install" button in a small dialog -- just make sure the user has to confirm that they want to install), and then just call a few methods in a defined order (or even just one, if you want to make it even more simple!), checks whether they reported success and if not displays an error message.

In fact I'm tempted to get rid of the entire shell script and code the whole CLI installer in C++. I could do that in a way then to allow for hooking up error handlers for the UI as well as for CLI. But that's not a priority either. The Lite user base is... pretty much, you. And I have tons of other things to do right now. Hence I am willing to refactor the existing script a bit to allow you to write something based on zenity, qarma or whatever, and produce a good, maintainable result quickly.

[probonopd]

The easiest way I can think of to allow for providing both CLI and UI would be to extract the install_ methods into a sourceable script, source that from the respective UI/CLI installers and then call the install steps one by one with appropriate error messages

Yes, that'd be a good way of doing it.

In fact I'm tempted to get rid of the entire shell script and code the whole CLI installer in C++.

That as well ;-)

[TheAssassin]

Prepared everything for you to get started. You can start off by copying the existing CLI AppRun script and modifying it to display UI messages. The "interesting" bits have been extracted into a sourceable script.