Add basic copying functionality

[upsicleclown]

Copy an existing .mbtiles file to a new file.

mbtiles copy  <src_file.mbtiles> <dst_file.mbtiles>

Optionally filters by zooms. Supports de-duplicated and simple mbtiles

[nyurik]

thanks! I left a few inline comments.

Overall, good approach, and I like that you attach the source rather than dst - might solve a few weird cases. My overall understanding of the process (correct if i miss something)

• open source file in a read-only mode
• detect mbtiles type + any other validations
• close source file

---

• open dst file
• check that SELECT count(*) = 0 FROM sqlite_schema; returns 1, and error that we don't support copying to the non-empty mbtiles yet
• set/update any initial pragmas/vacuum
• attach source file
• copy sql schema
• copy data using one of the copy methods

I will think about this some more. Also, I suspect i might be wrong in overal structure, still thinking how to organize it best. One thing that kinda bothers me is that the API currently does not consume the options when it starts copying - a better path might be

• a "builder" option struct CopyOptions
• a function pub async fn copy_mbtiles(options: CopyOptions) (consumes options)
• a bunch of private functions that actually do the copying

[nyurik]

a few minor nits, but looks good! Need to implement some tests too... I wonder if we should implement some basic info dump first so that we can use them in the integration tests? Otherwise we won't have a good way to test if the copying actually happened... So perhaps mbtiles summary <file> that prints a nice output of sorts? It could show something like...

(definitly a separate PR, possibly later, this is not a blocker for this PR!)

 file: <file>
 type: deduplicated mbtiles
tiles: 123,456 tiles sized 10..45,455,574, 12,345.678 on average
available zooms:
  0: 2,000bytes
  1: 4 tiles sized 10..45,455,574, 12,345.678 on average
  2: 16 tiles sized 10..45,455,574, 12,345.678 on average
  ...
metadata:
  <all metadata fields here?>

[nyurik]

they are all standard compliant - need a better name that matches the ones in the Type enum. BTW, the Type enum seems kinda weird tbh, maybe MbtType instead for clarity, and consistency with the errors?

[nyurik]

P.S. You will need to run just bless

[nyurik]

nits

[nyurik]

looks great, thanks!