Add in-app log viewer

[mnalis]

Use case
To help debug issues, in-app log viewer would be useful.

Proposed Solution
It has been mentioned several times by @westnordost, and that @matkoniecz might want to do it and that the ticket for it would be created, but is seems to have slipped, so I'm opening this one.

See for example #3290 (comment), #1892 (comment), #3406 (comment)

[westnordost]

I guess this is forthcoming of you, but I don't need a public issue in this tracker for everything I plan to do for this app.

[westnordost]

Is this something I can assign to you, @matkoniecz ? I think I rememeber you mentioning you wanted to work on this?

[westnordost]

Here is a rough outline how it should look.

Interface-wise

I think easiest would be to let our Log object have the same interface as the Android one, so no code changes other than changing the import are necessary. Roughly it shall look like this:

interface Logger {
  fun i(tag: String, message: String)
  // ... etc
}

object Log {
  var instance: Logger? = null

  override fun i(tag: String, message: String) = instance?.i(tag, message)
  // ...etc
}

class AndroidLogger : Logger {
  // implement...
}

And on application start, Log.instance = AndroidLogger(...) is set.
In tests, it is simply not set or some TestLogger (or mock) that does some testing is used.

Implementation-wise

The AndroidLogger should append the logs into a database table. Logs that exceed a certain size (or age) must be deleted. Maybe using the same mechanism as old quest data is deleted.
Additionally, it could append the log to the system log (as now) but not sure if this is necessary or useful.

UI

In the about screen next to the links to reporting a bug etc, there should be a link to a list-view of the log. For the best utility, it should have the following features:

• filter by string
• supply start and end date+time
• dropdown for selecting which severity to display (verbose, debug, info, error), like in Android Studio
• a way to export the filtered log output*

* since the app should not require file storage permission, exporting to a file in e.g. Downloads directory is out of question. Maybe "copy to clipboard" would work. Or "attach to mail (to [email protected])" would work. Maybe there is a better idea.

Furthermore, whenever a crash report is sent, the part of the log directly preceding the crash should also be attached to the error-report mail.

So, the log messages from the database are 1. displayed in a RecyclerView list and 2. can be converted into a newline-concatenated string

[westnordost]

@matkoniecz did not start working on it yet, so for the time being, this is free for the taking / can be done by other people interested in this. If you do, I can assign you to "reserve" this.