implement stats

[juliangruber]

@mafintosh @joehand

Let's implement here what dat-js has been doing manually. I created issues for all the stat fields to support, with implementation ideas where I had some.

It would be great if we could all collaborate on getting those nailed, as reliable stats behavior is required for all our tools.

Feel free to ignore the initial implementation of some of the stats in this repo.

[juliangruber]

The interface I thought of is

const stats = Stats(archive)
stats.on('update', stats => console.log(stats))
stats.on('update:filesProgress', progress => console.log(progress))

[okdistribute]

yes!

[joehand]

Sweet! Interface looks good.

[pfrazee]

Yeah that's all looking good to me.

I have code, right now, where I'm converting the file-listing into a tree structure, and then calculating the blocks progress for each entry. It percolates up the tree, so that directories reflect their combined children progress. I don't think that needs to be in here, but I thought I'd mention it.