Where to find structures of e-book formats?

Question

Programming

Good day.
We are writing a reader, the following problem has arisen: the zoo format and internal versions for them are confusing, the incredible fragmentation even among common ones, for example, epub, is even more frightening. In one file there can be a clear structure, where meta-inf, OEBPS and chapter by chapter are all, and in another - everything is in one folder and go figure out how to parse this miracle. All this, it seems, is in content.opf, but there are a lot of such epubs, from fb2 to mobi, and the same trouble with structures.
Where can you find them? Those. where and what information, what to do with it and all that. Or, perhaps, there are ready-made algorithms for parsing mobile formats?
And for connoisseurs: what is more optimal, to write a parsing of one format (for example, epub), and for the rest - a converter to the main one, or is parsing better for everyone?

Answer 1

it is better to use ready-made implementations. There are plenty of them on all githubs.

Answer 2

I completely agree with the previous speaker, it will be difficult to support all these formats, but if someone is already doing this, you can take their development and do not suffer.