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

with lib;
let
  cfg = config.desktop.theming;

  # Font module type
  fontModule = types.submodule {
    options = {
      name = mkOption {
        type = types.str;
        description = "Font family name.";
      };
      package = mkOption {
        type = types.anything;
        description = "Font package";
      };
      recommendedSize = mkOption {
        type = types.nullOr types.int;
        default = null;
        description = "Recommended size for displaying this font.";
      };
      fallbackFonts = mkOption {
        type = types.listOf types.str;
        default = [ ];
        description = "Fallback fonts for specified font.";
      };
    };
  };

  fontModules = [
    # Import all fonts
    ./fonts/cozette-vector.nix
    ./fonts/cozette.nix
    ./fonts/dejavu-sans.nix
    ./fonts/dejavu-serif.nix
    ./fonts/dina.nix
    ./fonts/fira-code.nix
    ./fonts/nerd-fonts-symbols.nix
    ./fonts/noto-color-emoji.nix
    ./fonts/wqy-bitmapsong.nix
    ./fonts/wqy-microhei-mono.nix
    ./fonts/wqy-microhei.nix
    ./fonts/wqy-zenhei-mono.nix
    ./fonts/wqy-zenhei-sharp.nix
    ./fonts/wqy-zenhei.nix
  ];

  # Gather enabled fonts.
  enabledFonts = [
    cfg.fonts.serif.name
    cfg.fonts.sansSerif.name
    cfg.fonts.monospace.name
    cfg.fonts.emoji.name
  ] ++ map (font: font.name) cfg.fonts.extraFonts;

  # Flatten dependencies of fonts
  fontPackages =
    converge
      (
        fonts:
        listToAttrs (
          map
            (font: {
              name = font;
              value = true;
            })
            (
              flatten (map (font: [ font.name ] ++ cfg.fonts.pkgs.${font.name}.fallbackFonts) (attrsToList fonts))
            )
        )
      )
      (
        listToAttrs (
          map (font: {
            name = font;
            value = true;
          }) enabledFonts
        )
      );

  # Convert set of fonts to list of packages
  fontNameList = map (font: font.name) (attrsToList fontPackages);
  fontPackageList = map (font: cfg.fonts.pkgs.${font}.package) fontNameList;
in
{
  imports = [
    ./background.nix
    ./colors.nix
  ];

  options.desktop.theming = {
    layout = {
      borderRadius = mkOption {
        type = types.int;
        default = 0;
        description = "Border radius of windows.";
      };

      borderSize = mkOption {
        type = types.int;
        default = 1;
        description = "Size of borders used throughout UI.";
      };

      windowPadding = mkOption {
        type = types.int;
        default = 2;
        description = "Margin of each window, actual space between windows will be twice this number.";
      };
    };

    fonts = {
      pkgs = mkOption {
        type = types.attrsOf fontModule;
        default = builtins.listToAttrs (
          map (module: {
            name = module.name;
            value = module;
          }) (map (module: (import module) { inherit lib config pkgs; }) fontModules)
        );
        description = "All available font modules.";
      };

      installed = mkOption {
        type = types.listOf types.str;
        default = fontNameList;
        description = "List of installed fonts.";
      };

      serif = mkOption {
        type = fontModule;
        description = "Default serif font";
      };

      sansSerif = mkOption {
        type = fontModule;
        description = "Default sansSerif font.";
      };

      monospace = mkOption {
        type = fontModule;
        description = "Default monospace font.";
      };

      emoji = mkOption {
        type = fontModule;
        description = "Default emoji font.";
      };

      interface = mkOption {
        type = fontModule;
        description = "Default emoji font.";
      };

      extraFonts = mkOption {
        type = types.listOf fontModule;
        default = [ ];
        description = "Additional fonts to install.";
      };
    };
  };

  config = mkIf config.desktop.enable {
    # Enable fontconfig
    modules.fontconfig.enable = true;

    # Install configured fonts
    home.packages = fontPackageList;

    # Configure gtk theme
    gtk =
      let
        disableCSD = ''
          headerbar.default-decoration {
            margin-bottom: 50px;
            margin-top: -100px;
          }
          window.csd,
          window.csd decoration {
            box-shadow: none;
          }
        '';
      in
      {
        enable = true;
        # TODO: Toggles
        gtk3.extraCss = disableCSD;
        gtk4.extraCss = disableCSD;
      };

    # TODO: Make cursors configurable using modules.
    home.pointerCursor = {
      gtk.enable = true;
      name = lib.mkForce "BreezeX-RosePine-Linux";
      package = lib.mkForce pkgs.rose-pine-cursor;
      size = lib.mkForce 24;
      x11 = {
        defaultCursor = lib.mkForce "BreezeX-RosePine-Linux";
        enable = true;
      };
    };

    # Enable stylix
    # TODO: Move to own module
    stylix = {
      fonts = {
        serif = getAttrs [
          "name"
          "package"
        ] cfg.fonts.serif;
        sansSerif = getAttrs [
          "name"
          "package"
        ] cfg.fonts.sansSerif;
        monospace = getAttrs [
          "name"
          "package"
        ] cfg.fonts.monospace;
        emoji = getAttrs [
          "name"
          "package"
        ] cfg.fonts.emoji;

        sizes = {
          applications = mkDefault cfg.fonts.serif.recommendedSize;
          desktop = mkDefault cfg.fonts.monospace.recommendedSize; # TODO: See below
          popups = mkDefault cfg.fonts.monospace.recommendedSize; # TODO: Add dedicated UI font
          terminal = mkDefault cfg.fonts.monospace.recommendedSize;
        };
      };
    };
  };
}