Product creation: Add search functionality into category selection

[hafizrahman]

Closes: https://github.com/woocommerce/woomobile-private/issues/340

Description

This is a quick HACK Week project (1 day size) to add search to product category selection in product creation.

What it does:

1. Adds a search icon with SearchView to the product category selection screen,
2. Does API call to search when search is entered
3. Adds a "flat list" functionality where if the current category list has orphans (e.g: if search result returns only child categories), then display the whole list as a flat list instead of hierarchical.

---

Technical discussion

1. Implementation
Currently, there are two implementations of category selection:

1. ProductCategoriesFragment used in product creation,
2. ProductCategorySelectorFragment used in coupon creation.

The latter one is more modern and has a component that already has a search functionality added. Initially I thought to implement its component to ProductCategoriesFragment, but I found the task to be non-trivial and definitely not a one-day HACK week work for me. One reason is that ProductCategoriesFragment is tightly coupled with the product creation process (e.g: each category selection automatically updates product draft without leaving the category screen).

So instead, I chose to replicate the search functionality from ProductCategorySelectorFragment, into ProductCategoriesFragment.

For future improvement, it'd be great to refactor ProductCategoriesFragment to use the component on ProductCategorySelectorFragment.

2. Searching limitation

The search is hardcoded to return maximum of 100 results, and doesn't support load more functionality. I think this is fine for a v1, and supporting more than 100 results can be considered an edge case.

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Testing instructions

1. Prepare a demo site with multiple categories and parent/sub-categories. It'd be good to have some parent and child categories that have similar names, for testing purposes.
2. Open app, then go to Products and select a Product,
3. Edit the product category,
4. Ensure search icon appears on top right,
5. Tap the icon, ensure that the search box appears,
6. Enter a search term, ensure that after a little bit, the search is being done and shows the result
7. Delete the search term, ensure that the list of categories are shown as before
8. Enter a search term where the result should be a mix of parent and child categories. Ensure the result is shown in a flat list.
9. Play around and check the selection state, it should remain consistent when searching and clearing search.

---

Images/gif

Screen_recording_20240318_220803.webm

• I have considered if this change warrants release notes and have added them to RELEASE-NOTES.txt if necessary. Use the "[Internal]" label for non-user-facing changes.

[hafizrahman]

starts from 1 because index 0 happens when the parent product details screen is shown (since this is a shared viewmodel).

[hafizrahman]

This is marked outdated because after merging trunk, it got shifted to a different line, but the logic is still there:

https://github.com/woocommerce/woocommerce-android/pull/11102/files#diff-7696cd0f556208deab716a3491d22562cdfb3c6ad5f04ff7d1e17737e03b34e2R2552-R2553

[hafizrahman]

Also checks for margin differences to allow for redrawing when changing from hierarchical to flat list, or otherwise.

[wpmobilebot]

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

	App Name	WooCommerce Android
	Flavor	Jalapeno
	Build Type	Debug
	Commit	b98ec68
	Direct Download	woocommerce-prototype-build-pr11102-b98ec68.apk

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 35.93750% with 41 lines in your changes missing coverage. Please review.

Project coverage is 40.21%. Comparing base (9a7ef14) to head (b98ec68).
Report is 113 commits behind head on trunk.

Files	Patch %	Lines
...roid/ui/products/details/ProductDetailViewModel.kt	51.11%	17 Missing and 5 partials ⚠️
...products/categories/ProductCategoriesRepository.kt	0.00%	19 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##              trunk   #11102      +/-   ##
============================================
- Coverage     40.22%   40.21%   -0.01%     
- Complexity     5311     5313       +2     
============================================
  Files          1128     1128              
  Lines         64985    65044      +59     
  Branches       8977     8988      +11     
============================================
+ Hits          26141    26160      +19     
- Misses        36456    36491      +35     
- Partials       2388     2393       +5     

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[JorgeMucientes]

Nice catch!