Cache downloads

[rgreinho]

Feature request

Current Behavior

The files are downloaded every time we delete the prepared files or when we run the tests.

Expected Behavior

We should cache the downloads instead of re-downloading the files for nothing.

Possible Solution

• We should create a .bna_cache folder which would contain the files successfully downloaded.
• When we would prepare the fhe files required for an analysis we would check in the cache folder first.
  • For example the water_census_blocks file or the speed_limits file are always the same for any US city. The OSM files should be cached as well in case we re-run an analysis for a city, or for several cities in the same state/region.

[rgreinho]

When caching the downloads, we must also add the ability to disable the cache. The use case for that is that the cache may not always be necessary, for instance when using this tool in a Docker container.

[rgreinho]

Another idea would be to detect the standard cache directory per platform and use it:

• macOS: ~/Library/Caches/
• Windows: C:\Users\\AppData\Local\\Cache
• Unix: ~/.cache/

[rgreinho]

It looks like PlatformDirs would come to the rescue 😃