Fix: Stats showing stale unique visitors count when views are updated

[pmusolino]

Fixes #24114

While I was not able to reproduce the issue mentioned here #24114 and while it seems it's not a specific issue related to the app because of this Automattic/jetpack#42176 I noticed that the login for updating stats with mostRecentChartData was too restrictive. Even when new API data was available, the existing code would sometimes keep using old cached data due to specific date matching requirements.

So, I revised the conditional logic that now prioritizes using the newest data by simplifying the conditions and always choosing the most recent data available. In this way, we ensure that both views and unique visitors metrics update simultaneously when new data arrives from the API.

Testing

Verified that both views and unique visitors data update synchronously when new stats data is fetched. Please, also check that this change does not introduce any regression, like reintroducing this issue #19688

Regression Notes

1. Potential unintended areas of impact

2. What I did to test those areas of impact (or what existing automated tests I relied on)

3. What automated tests I added (or what prevented me from doing so)

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Testing checklist:

• WordPress.com sites and self-hosted Jetpack sites.
• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• VoiceOver.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• iPhone and iPad.
• Multi-tasking: Split view and Slide over. (iPad)

[dangermattic]

	1 Warning
⚠️	PR is not assigned to a milestone.

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📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	26844
	Version	PR #24356
	Bundle ID	org.wordpress.alpha
	Commit	b00c570
	Installation URL	13hldqp5smfcg

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[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	26844
	Version	PR #24356
	Bundle ID	com.jetpack.alpha
	Commit	b00c570
	Installation URL	66qs22mhnnbs8

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[kean]

It seems to work OK, but after reviewing this file for a good 30+ minutes, I can't tell that I understand what's going on in it.

The most problematic aspect is that mostRecentChartData and other state gets mutated inside of a method you would expect to be stateless: func overviewTableRows(). When and how often does it get called? It's really hard to tell:

[pmusolino]

It seems to work OK, but after reviewing this file for a good 30+ minutes, I can't tell that I understand what's going on in it.

The most problematic aspect is that mostRecentChartData and other state gets mutated inside of a method you would expect to be stateless: func overviewTableRows(). When and how often does it get called? It's really hard to tell:

I understand your feelings, and I feel the same way. It's all so outdated that working on it and debugging something have become unnecessarily complex, without considering the use of WordPressFlux. I think it's worth considering how radical it could be to throw out the entire stats screen to completely rewrite it in SwiftUI in the future.