{ pkgs, stdenv, lib, python }:

self:

let
  inherit (self) callPackage;

  namePrefix = python.libPrefix + "-";

  # Derivations built with `buildPythonPackage` can already be overridden with `override`, `overrideAttrs`, and `overrideDerivation`.
  # This function introduces `overridePythonAttrs` and it overrides the call to `buildPythonPackage`.
  makeOverridablePythonPackage = f:
    lib.mirrorFunctionArgs f (origArgs:
      let
        args = lib.fix (lib.extends (_: previousAttrs: {
          passthru = (previousAttrs.passthru or { }) // {
            overridePythonAttrs = newArgs:
              makeOverridablePythonPackage f (overrideWith newArgs);
          };
        }) (_: origArgs));
        result = f args;
        overrideWith = newArgs:
          args
          // (if pkgs.lib.isFunction newArgs then newArgs args else newArgs);
      in if builtins.isAttrs result then
        result
      else if builtins.isFunction result then {
        overridePythonAttrs = newArgs:
          makeOverridablePythonPackage f (overrideWith newArgs);
        __functor = self: result;
      } else
        result);

  mkPythonDerivation = if python.isPy3k then
    ./mk-python-derivation.nix
  else
    ./python2/mk-python-derivation.nix;

  buildPythonPackage = makeOverridablePythonPackage (lib.makeOverridable
    (callPackage mkPythonDerivation {
      inherit
        namePrefix; # We want Python libraries to be named like e.g. "python3.6-${name}"
      inherit toPythonModule; # Libraries provide modules
    }));

  buildPythonApplication = makeOverridablePythonPackage (lib.makeOverridable
    (callPackage mkPythonDerivation {
      namePrefix = ""; # Python applications should not have any prefix
      toPythonModule = x: x; # Application does not provide modules.
    }));

  # Check whether a derivation provides a Python module.
  hasPythonModule = drv: drv ? pythonModule && drv.pythonModule == python;

  # Get list of required Python modules given a list of derivations.
  requiredPythonModules = drvs:
    let modules = lib.filter hasPythonModule drvs;
    in lib.unique ([ python ] ++ modules
      ++ lib.concatLists (lib.catAttrs "requiredPythonModules" modules));

  # Create a PYTHONPATH from a list of derivations. This function recurses into the items to find derivations
  # providing Python modules.
  makePythonPath = drvs:
    lib.makeSearchPath python.sitePackages (requiredPythonModules drvs);

  removePythonPrefix = lib.removePrefix namePrefix;

  # Convert derivation to a Python module.
  toPythonModule = drv:
    drv.overrideAttrs (oldAttrs: {
      # Use passthru in order to prevent rebuilds when possible.
      passthru = (oldAttrs.passthru or { }) // {
        pythonModule = python;
        pythonPath = [ ]; # Deprecated, for compatibility.
        requiredPythonModules = requiredPythonModules drv.propagatedBuildInputs;
      };
    });

  # Convert a Python library to an application.
  toPythonApplication = drv:
    drv.overrideAttrs (oldAttrs: {
      passthru = (oldAttrs.passthru or { }) // {
        # Remove Python prefix from name so we have a "normal" name.
        # While the prefix shows up in the store path, it won't be
        # used by `nix-env`.
        name = removePythonPrefix oldAttrs.name;
        pythonModule = false;
      };
    });

  disabled = drv:
    throw "${
      removePythonPrefix (drv.pname or drv.name)
    } not supported for interpreter ${python.executable}";

  disabledIf = x: drv: if x then disabled drv else drv;

in {
  inherit lib pkgs stdenv;
  inherit (python.passthru)
    isPy27 isPy37 isPy38 isPy39 isPy310 isPy311 isPy3k isPyPy pythonAtLeast
    pythonOlder;
  inherit buildPythonPackage buildPythonApplication;
  inherit hasPythonModule requiredPythonModules makePythonPath disabled
    disabledIf;
  inherit toPythonModule toPythonApplication;

  python = toPythonModule python;
  # Dont take pythonPackages from "global" pkgs scope to avoid mixing python versions
  pythonPackages = self;
}