{ lib, pkgs, ... }:
let
  pythonPackages = pkgs.python3Packages;

  # Vosk is not present in the current nixpkgs revision, although it is one
  # of the backends shipped with Kdenlive. Package its upstream manylinux
  # wheel until it is available from nixpkgs.
  vosk = pythonPackages.buildPythonPackage rec {
    pname = "vosk";
    version = "0.3.45";
    format = "wheel";

    src = pkgs.fetchPypi {
      inherit pname version format;
      python = "py3";
      dist = "py3";
      platform = "manylinux_2_12_x86_64.manylinux2010_x86_64";
      hash = "sha256-JeAlCTxDmdcnj1Q1aO2MxUYKw6S/SMI2c6zh4l0mYZ8=";
    };

    # The upstream wheel bundles libvosk.so without an RPATH. Patch it to
    # the Nix C++ runtime so importing vosk works outside a FHS environment.
    nativeBuildInputs = [ pkgs.autoPatchelfHook ];
    buildInputs = [ pkgs.stdenv.cc.cc.lib ];

    propagatedBuildInputs = with pythonPackages; [
      cffi
      srt
      requests
      tqdm
      websockets
    ];

    meta = with pkgs.lib; {
      description = "Offline open source speech recognition toolkit";
      homepage = "https://alphacephei.com/vosk/";
      license = licenses.asl20;
    };
  };

  # Kdenlive's speech-to-text scripts are launched through
  # /usr/bin/env python3. Keep this environment private to Kdenlive so the
  # other Python environments installed on the system remain independent.
  kdenlivePython = pkgs.python3.withPackages (
    pythonPackages: with pythonPackages; [
      pip
      numba
      openai-whisper
      srt
      torch
      vosk
    ]
  );

  kdenlive = pkgs.kdePackages.kdenlive.overrideAttrs (old: {
    nativeBuildInputs = (old.nativeBuildInputs or [ ]) ++ [ pkgs.makeWrapper ];
    postFixup = (old.postFixup or "") + ''
      wrapProgram $out/bin/kdenlive \
        --prefix PATH : ${kdenlivePython}/bin \
        --set PYTHONNOUSERSITE 1
    '';
  });
in
{
  home.packages = [ kdenlive ];

  # Kdenlive otherwise prefers its mutable ~/.local/share/kdenlive/venv.
  # That venv was created by pip and its native Torch libraries do not have
  # the Nix runtime paths. Point Kdenlive at the immutable environment above.
  home.activation.kdenliveSpeechPython = lib.hm.dag.entryAfter [ "writeBoundary" ] ''
    run ${pkgs.kdePackages.kconfig}/bin/kwriteconfig6 \
      --file "$HOME/.config/kdenliverc" \
      --group speech \
      --key speech_system_python true
    run ${pkgs.kdePackages.kconfig}/bin/kwriteconfig6 \
      --file "$HOME/.config/kdenliverc" \
      --group speech \
      --key speech_system_python_path ${kdenlivePython}/bin/python3
  '';
}