18. As a user, I'd like to have the option to uncheck an item

[wheninseattle]

Summary

We've all accidentally deleted something before. Let's give this app a CTRL+Z! We initially discussed accomplishing this by storing all purchase dates as an array, however, Andrew made the excellent point that if you use the app for years, those array entries start to add up. If memory serves, he suggested adding two fields to the item document in firestore:

• previousDateLastPurchased
• previousDateNextPurchased

Acceptance criteria

• Implement the logic to add and utilize these two fields in order to successfully uncheck an item
• When a user unchecks an item, the values fordateNextpurchased and dateLastPurchased should return to their previous values, isChecked should be false, and the totalPurchases should be decremented by 1.

Notes

-You're brilliant!
-Think about what happens to the values of our two, new fields. What should these be set to?