{ config, lib, pkgs, ... }:

with lib;

let
  cfg = config;
  speak = cfg.speak;
in rec {
  options.speak = {
    enable = mkOption {
      type = types.bool;
      default = false;
      description = ''
        Enable NixOS speak module.
      '';
    };
    installPackages = mkOption {
      type = types.bool;
      default = true;
      description = ''
        Add spech related packages to environment.
      '';
    };
    user = mkOption {
      type = types.str;
      default = "root";
      description = ''
        User which runs services like espeakup and speech-dispatcher.
        User needs to be in audio group.
      '';
    };
    config = {
      speakup = mkOption {
        type = types.attrs;
        default = {};
        example = ''
          {
            synth = "soft";
            punc_level = "0";
            reading_punc = "0";
            soft = {
              rate = "6";
            };
          }
        '';
      };
    };
  };

  config = mkIf speak.enable rec {
    boot.kernelModules = [ "speakup_soft" ];
    nixpkgs.config.packageOverrides = {
      espeakup = pkgs.callPackage ../pkgs/espeakup.nix {};
    };

    # needed for orca
    services.gnome3.at-spi2-core.enable = mkDefault (cfg.services.xserver.enable);

    # allow users in the audio group to use and configure speakup_soft
    services.udev.extraRules = ''
      KERNEL=="synth", SUBSYSTEM=="misc", GROUP="audio", MODE="0660"
      KERNEL=="softsynth", SUBSYSTEM=="misc", GROUP="audio", MODE="0660"
      KERNEL=="softsynthu", SUBSYSTEM=="misc", GROUP="audio", MODE="0660"
    '';

    # See https://aur.archlinux.org/cgit/aur.git/tree/espeakup.service?h=espeakup-git
    systemd.services = {
      speakup-configure = let
        # This whole thing still feels a little bit awkward
        pathList = collect (v: isList v) (mapAttrsRecursive (p: v: p) speak.config.speakup);
        mkCommand = p: v: "echo ${v} > /sys/accessibility/speakup/${p}";
        commandList = (map (l: (mkCommand (concatStringsSep "/" l) (attrByPath l "0" speak.config.speakup))) pathList);
      in {
        enable = true;
        description = "configure speakup.";
        wantedBy = [ "default.target" ];
        wants = [ "systemd-udev-settle.service" ];
        after = [ "systemd-udev-settle.service" "sound.target" ];
        script = (concatStringsSep "\n" commandList);
        serviceConfig.Type = "oneshot";
      };
      espeakup = {
        enable = (speak.user == "root");
        description = "Software speech output system wide settings.";
        wantedBy = [ "default.target" ];
        wants = [ "systemd-udev-settle.service" ];
        after = [ "systemd-udev-settle.service" "sound.target" ];

        serviceConfig = {
          Type = "forking";
          ExecStart = "${pkgs.espeakup}/bin/espeakup";
          ExecStop = "${pkgs.utillinux.bin}/bin/kill -HUP $MAINPID";
          Restart= "always";
        };
      };
    };
    systemd.user.services.espeakup = {
      enable = (speak.user != "root");
      description = "Software speech output system wide settings.";
      wantedBy = [ "default.target" ];
      wants = [ "systemd-udev-settle.service" ];
      after = [ "systemd-udev-settle.service" "sound.target" ];

      serviceConfig = {
        Type = "forking";
        ExecStart = "${pkgs.espeakup}/bin/espeakup";
        ExecStop = "${pkgs.utillinux.bin}/bin/kill -HUP $MAINPID";
        Restart= "always";
      };
    };
    environment.systemPackages = optionals speak.installPackages (with pkgs; [
      (lowPrio espeak-classic) espeak-ng
      espeakup
    ]);
  };
}