.files/nix/configurations/vanadium/nixos/display.nix

{
  pkgs,
  lib,
  ...
}: {
  imports = [
    #
    # builtin screen
    #
    {
      me.extraGroups = ["video"];
      programs.light.enable = true;
    }

    #
    # external screen
    #
    {
      me.extraGroups = ["i2c"];
      hardware.i2c.enable = true;
      environment.systemPackages = [pkgs.ddcutil];
      boot.kernelModules = ["i2c-dev"];
    }
  ];

  #
  # Auto setup external screen
  #
  services.autorandr = {
    enable = true;
    hooks.postswitch = {
      "10_xmobar" = "pkill xmobar"; # make sure there are no duplicated xmobar
      "20_xmonad" = "xmonad --restart"; # make sure feh keeps up
    };

    profiles = let
      singleton = k: v: {${k} = v;};

      fingerprints = {
        built-in = singleton "eDP-1" "00ffffffffffff0009e5ca0b000000002f200104a51c137803de50a3544c99260f505400000001010101010101010101010101010101115cd01881e02d50302036001dbe1000001aa749d01881e02d50302036001dbe1000001a000000fe00424f452043510a202020202020000000fe004e4531333546424d2d4e34310a0073";
        amethyst = device: singleton device "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";
      };

      devices = rec {
        built-in = "eDP-1";
        # Run `xrandr` to see the max number
        extern = map (portNumber: "DP-${toString portNumber}") (lib.range 1 8);
        all = [built-in] ++ extern;
      };

      switches = {
        setDPI = {dpi}:
          singleton "10_xrdb-dpi" "xrdb -merge ${pkgs.writeText "xrdb-dpi-config" ''
            Xcursor.size: 64
            Xft.dpi:   ${toString dpi}
          ''}";

        # Is scoped to an output device, no need to be called on built-in display
        setSoftwareBrightness = {
          device, # obtain with `xrandr`
          brightness, # [0..1]
        }:
          singleton "10_xrandr_brightness" ''
            xrandr --output ${device} --brightness ${toString brightness}
          '';

        # Is scoped to an output device, no need to be called on built-in display
        setDDCBrightness = {
          modelName, # obtain with `ddcutil detect`
          brightness, # [0..1]
        }:
          singleton "10_ddc_brightness" ''
            ddcutil --model ${modelName} setvcp 10 ${toString (builtins.floor (brightness * 100))}
          '';

        setDDCContrast = {
          modelName, # obtain with `ddcutil detect`
          contrast, # [0..1]
        }:
          singleton "10_ddc_contrast" ''
            ddcutil --model ${modelName} setvcp 12 ${toString (builtins.floor (contrast * 100))}
          '';
      };

      # Note: the "position" field corresponds to the "pos" field outputted by autorandr
      # To get the current config, run `xrandr --auto` and then `autorandr --config`
      configs = {
        allOff = lib.genAttrs devices.all (_: {enable = lib.mkDefault false;});
        enableBuiltin = {
          eDP-1 = {
            enable = true;
            crtc = 0;
            mode = "2256x1504";
            rate = "60.00";
            primary = true;
          };
        };
        enableDevice = name: {
          ${name} = {
            enable = true;
            primary = true;
            crtc = 1;
            mode = "2560x1440";
            position = "2256x0"; # on the right of built-in
            rate = "59.95";
          };
        };
      };

      frameworkBuiltin = {
        fingerprint = fingerprints.built-in;
        config = lib.mkMerge [
          configs.allOff
          configs.enableBuiltin
        ];
        hooks.postswitch = switches.setDPI {dpi = 150;};
      };

      mkAmethyst = name: {
        fingerprint = lib.mkMerge [
          fingerprints.built-in
          (fingerprints.amethyst name)
        ];
        config = lib.mkMerge [
          configs.allOff
          (configs.enableDevice name)
        ];
        hooks.postswitch = lib.mkMerge [
          (switches.setDPI {dpi = 110;})
          (switches.setSoftwareBrightness {
            device = name;
            brightness = 1;
          })
          (switches.setDDCBrightness {
            modelName = "VG27AQL3A";
            brightness = 0;
          })
          (switches.setDDCContrast {
            modelName = "VG27AQL3A";
            contrast = 0.5;
          })
        ];
      };
    in
      lib.mkMerge [
        {default = frameworkBuiltin;}
        (lib.genAttrs' devices.extern (name: lib.nameValuePair "amethyst-${name}" (mkAmethyst name)))
      ];
  };
}