The "Change Period" feature in #13501 does not work fully as expected.

Use case reproduced:

• Select period = year, and select a date in 2018 (for example clicking on a day in february 2018)
• Matomo calendar shows 2018 indicating the reports will show data for the year of 2018 Jan 1st->Dec 31st (that's how Matomo works)
• Visitors > Overview > Evolution graphs shows Years by default and shows the last 5 years including 2018
• Now below this evolution graph, select "Change period" and select "Week"
• Got: the calendar shows the last 26 weeks from the selected date in February 2018
• Expected: the calendar shows the last 26 weeks from the last week of the selected period ie. the week Dec 30th 2018 -> Jan 5th 2019.

Similarly:

• when users look at the "Month of March 2019"
• and then select "Change period: week" in the calendar,
• they expect to see the last 26 weeks before the week of "31st March -> 6th April",
• and don't expect to see, for example, the graph ending on the week of March 2nd (which is possible if you happened to click on that day in the calendar).

The evolution graph shouldn't depend on which day you've clicked in the calendar (but should depend on the whole date range/period, consistent with how date/period and calendar works in Matomo).

Changing the behaviour to showing Evolution graph ending on the end of the selected period will help make this feature more useful and predictable (reduce confusion and possible frustration when trying to generate a simple evolution graph) 👍