[adrianratnapala]

A problem that genuinely takes a few thousand lines to solve doesn't sound "hard to deal with". It sounds just the right size for a module or tool that solves a problem big enough to be non-trivial, but small enough to be solved well.

However you end up solving it, it is way to big for a single function. On the other hand, a moderate bunch of functions can do it nicely -- and at that scale you don't need big complicated object-oriented abstractions other than the external interface itself.