# DualSense rumble/trigger firmware-level attenuation.
#
# The PS5 controller's haptic actuators are linear resonant actuators (LRAs) —
# voice coils, not ERM rotors. When driven near max amplitude they emit an
# audible high-pitched whine in addition to the intended rumble. This is a
# hardware property of the actuator, not a kernel or Steam Input bug, and
# can't be fixed in any rumble path that talks to the LRAs at full strength.
#
# Sony exposes a firmware knob ("rumble emulation amplitude modifier", in
# DS_OUTPUT report 0x05/0x31, gated by valid_flag2 bit RUMBLE_EMULATION_SELECT)
# that clamps haptic / trigger amplitude before the actuator is driven. This
# module sends that report once on plug-in via dualsensectl. The setting
# lives in controller RAM until the next power-cycle (USB unplug or BT
# disconnect-with-power-off), so re-applying on every udev `add` covers
# every reconnect.
#
# Coexists with Steam Input's rumble path: Steam writes rumble in the same
# output report, but only sets COMPATIBLE_VIBRATION / HAPTICS_SELECT in
# valid_flag0 — not RUMBLE_EMULATION_SELECT — so its writes don't reset the
# attenuation. Verified live with Steam (gamepadui) and forza-trigger both
# holding hidraw concurrently.
{
  config,
  lib,
  pkgs,
  ...
}:
let
  cfg = config.services.dualsenseAttenuation;

  applyScript = pkgs.writeShellScript "dualsense-apply-attenuation" ''
    set -eu
    # Retry briefly: the hidraw node exists by udev `add`, but the device
    # may still be settling its initial HID descriptor exchange. dualsensectl
    # needs to read the firmware report before it can write attenuation.
    for _ in 1 2 3 4 5 6 7 8 9 10; do
      if ${pkgs.dualsensectl}/bin/dualsensectl -l 2>/dev/null | grep -q ":"; then
        exec ${pkgs.dualsensectl}/bin/dualsensectl attenuation \
          ${toString cfg.rumble} ${toString cfg.trigger}
      fi
      sleep 0.2
    done
    echo "no DualSense detected; nothing to attenuate" >&2
    exit 0
  '';
in
{
  options.services.dualsenseAttenuation = {
    enable = lib.mkEnableOption "Apply DualSense haptic attenuation on plug-in";

    rumble = lib.mkOption {
      type = lib.types.ints.between 0 7;
      default = 3;
      description = ''
        Rumble (LRA) attenuation, 0-7. Higher = weaker. 3 keeps the LRAs
        below their audible-whine threshold while leaving rumble clearly
        perceptible. 0 disables attenuation (full strength).
      '';
    };

    trigger = lib.mkOption {
      type = lib.types.ints.between 0 7;
      default = 0;
      description = ''
        Adaptive trigger attenuation, 0-7. Higher = weaker. 0 leaves
        trigger feedback untouched — forza-trigger drives the triggers
        with bounded amplitudes already, so the trigger LRAs don't
        normally hit the audible regime.
      '';
    };
  };

  config = lib.mkIf cfg.enable {
    services.udev.extraRules = ''
      # DualSense (USB)
      ACTION=="add", SUBSYSTEM=="hidraw", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="0ce6", TAG+="systemd", ENV{SYSTEMD_WANTS}+="dualsense-attenuation.service"
      # DualSense Edge (USB)
      ACTION=="add", SUBSYSTEM=="hidraw", ATTRS{idVendor}=="054c", ATTRS{idProduct}=="0df2", TAG+="systemd", ENV{SYSTEMD_WANTS}+="dualsense-attenuation.service"
      # DualSense (Bluetooth)
      ACTION=="add", SUBSYSTEM=="hidraw", KERNELS=="*054C:0CE6*", TAG+="systemd", ENV{SYSTEMD_WANTS}+="dualsense-attenuation.service"
      # DualSense Edge (Bluetooth)
      ACTION=="add", SUBSYSTEM=="hidraw", KERNELS=="*054C:0DF2*", TAG+="systemd", ENV{SYSTEMD_WANTS}+="dualsense-attenuation.service"
    '';

    systemd.services.dualsense-attenuation = {
      description = "Apply DualSense rumble/trigger attenuation in controller firmware";
      serviceConfig = {
        Type = "oneshot";
        ExecStart = applyScript;
      };
    };
  };
}