header.nix

{ lib, ... }:

rec {
  parse = fpath:
    fpath
    |> lib.fpath.toPath
    |> lib.readFile
    |> lib.splitString "\n"
    |> lib.filter (a: lib.hasPrefix "#include " a)
    |> map (x: x
      |> lib.strings.split ''#include ( |(/\*.*\*/))*(".*")|(<.*>)''
      |> lib.filter (a: lib.isList a)
      |> lib.lists.flatten
      |> lib.filter (a: builtins.isString a)
      |> lib.lists.last
    )
    |> lib.filter (a: lib.hasPrefix "\"" a)
    |> map (x: x
      |> lib.strings.removePrefix "\""
      |> lib.strings.removeSuffix "\""
    )
    |> lib.lists.unique;
  parseRecursivelyFpath = fpath:
  let
    includes = parse fpath;
    fpathIncludes = (lib.forEach includes (include: fpath |> lib.fpath.leave |> lib.fpath.enter include));
  in
    fpathIncludes ++ (lib.forEach fpathIncludes (include: parseRecursivelyFpath include)) |> lib.flatten;
}