{ depot, pkgs, lib, ... }:

let
  bins = depot.nix.getBins pkgs.stow [ "stow" ]
      // depot.nix.getBins pkgs.coreutils [ "mkdir" "ln" "printenv" "rm" ]
      // depot.nix.getBins pkgs.xe [ "xe" ]
      // depot.nix.getBins pkgs.lr [ "lr" ]
      ;

  # run stow to populate the target directory with the given stow package, read from stowDir.
  # Bear in mind that `stowDirOriginPath` should always be semantically bound to the given `stowDir`, otherwise stow might become rather confused.
  runStow = {
    # “stow package” to stow (see manpage)
    stowPackage,
    # “target directory” to stow in (see manpage)
    targetDir,
    # The “stow directory” (see manpage), containing “stow packages” (see manpage)
    stowDir,
    # representative directory for the stowDir in the file system, against which stow will create relative links.
    # ATTN: this is always overwritten with the contents of `stowDir`! You shouldn’t re-use the same `stowDirOriginPath` for different `stowDir`s, otherwise there might be surprises.
    stowDirOriginPath,
  }: depot.nix.writeExecline "stow-${stowPackage}" {} [
    # first, create a temporary stow directory to use as source
    # (stow will use it to determine the origin of files)
    "if" [ bins.mkdir "-p" stowDirOriginPath ]
    # remove old symlinks
    "if" [
      "pipeline" [
        bins.lr "-0" "-t" "depth == 1 && type == l" stowDirOriginPath
      ]
      bins.xe "-0" bins.rm
    ]
    # populate with new stow targets
    "if" [
      "elglob" "-w0" "stowPackages" "${stowDir}/*"
      bins.ln "--force" "-st" stowDirOriginPath "$stowPackages"
    ]
    # stow always looks for $HOME/.stowrc to read more arguments
    "export" "HOME" "/homeless-shelter"
    bins.stow
      # always run restow for now; this does more stat but will remove stale links
      "--restow"
      "--dir" stowDirOriginPath
      "--target" targetDir
      stowPackage
  ];

  # create a stow dir from a list of drv paths and a stow package name.
  makeStowDir =
    (with depot.nix.yants;
     defun
       [ (list (struct {
          originalDir = drv;
          stowPackage = string;
        }))
        drv
       ] )
    (dirs:
      depot.nix.runExecline "make-stow-dir" {
        stdin = lib.pipe dirs [
          (map depot.users.Profpatsch.netencode.gen.dwim)
          depot.users.Profpatsch.netstring.toNetstringList
        ];
      } [
        "importas" "out" "out"
        "if" [ bins.mkdir "-p" "$out" ]
        "forstdin" "-d" "" "-o" "0" "line"
        "pipeline" [
          depot.users.Profpatsch.execline.print-one-env "line"
        ]
        depot.users.Profpatsch.netencode.record-splice-env
        "importas" "-ui" "originalDir" "originalDir"
        "importas" "-ui" "stowPackage" "stowPackage"
        bins.ln "-sT" "$originalDir" "\${out}/\${stowPackage}"
      ]);

in

# TODO: temp
lib.pipe {} [
  (_: makeStowDir [{
    stowPackage = "hello";
    originalDir = pkgs.hello;
  }])
  (d: runStow {
    stowDir = d;
    stowPackage = "hello";
    targetDir = "/home/philip/tmp";
    stowDirOriginPath = "/home/philip/tmp/stowOrigin";
  })
]