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

{

  options = {
    firefox = {
      enable = lib.mkEnableOption {
        description = "Enable Firefox.";
        default = false;
      };
    };
  };

  config = lib.mkIf (config.gui.enable && config.firefox.enable) {

    unfreePackages = [
      (lib.mkIf config._1password.enable "onepassword-password-manager")
      "okta-browser-plugin"
    ];

    home-manager.users.${config.user} = {

      programs.firefox = {
        enable = true;
        package = if pkgs.stdenv.isDarwin then pkgs.firefox-bin else pkgs.firefox;
        profiles.default = {
          id = 0;
          name = "default";
          isDefault = true;
          # https://nur.nix-community.org/repos/rycee/
          extensions = with pkgs.nur.repos.rycee.firefox-addons; [
            (lib.mkIf config._1password.enable onepassword-password-manager)
            darkreader
            don-t-fuck-with-paste
            facebook-container
            markdownload
            multi-account-containers
            okta-browser-plugin
            reddit-enhancement-suite
            return-youtube-dislikes
            sponsorblock
            ublock-origin
            ublacklist
            vimium
          ];
          settings = {
            "app.update.auto" = false;
            "browser.aboutConfig.showWarning" = false;
            "browser.warnOnQuit" = false;
            "browser.quitShortcut.disabled" = if pkgs.stdenv.isLinux then true else false;
            "browser.theme.dark-private-windows" = true;
            "browser.toolbars.bookmarks.visibility" = false;
            "browser.startup.page" = 3; # Restore previous session
            "browser.newtabpage.enabled" = false; # Make new tabs blank
            "trailhead.firstrun.didSeeAboutWelcome" = true; # Disable welcome splash
            "dom.forms.autocomplete.formautofill" = false; # Disable autofill
            "extensions.formautofill.creditCards.enabled" = false; # Disable credit cards
            "dom.payments.defaults.saveAddress" = false; # Disable address save
            "general.autoScroll" = true; # Drag middle-mouse to scroll
            "services.sync.prefs.sync.general.autoScroll" = false; # Prevent disabling autoscroll
            "extensions.pocket.enabled" = false;
            "toolkit.legacyUserProfileCustomizations.stylesheets" = true; # Allow userChrome.css
            "layout.css.color-mix.enabled" = true;
            "ui.systemUsesDarkTheme" = if config.theme.dark == true then 1 else 0;
            "media.ffmpeg.vaapi.enabled" = true; # Enable hardware video acceleration
            "cookiebanners.ui.desktop.enabled" = true; # Reject cookie popups
            "devtools.command-button-screenshot.enabled" = true; # Scrolling screenshot of entire page
            "svg.context-properties.content.enabled" = true; # Sidebery styling
          };
          userChrome = ''
            :root {
              --focus-outline-color: ${config.theme.colors.base04} !important;
              --toolbar-color: ${config.theme.colors.base07} !important;
              --tab-min-height: 30px !important;
            }
            /* Background of tab bar */
            .toolbar-items {
              background-color: ${config.theme.colors.base00} !important;
            }
            /* Extra tab bar sides on macOS */
            .titlebar-spacer {
              background-color: ${config.theme.colors.base00} !important;
            }
            .titlebar-buttonbox-container {
              background-color: ${config.theme.colors.base00} !important;
            }
            #tabbrowser-tabs {
              border-inline-start: 0 !important;
            }
            /* Private Browsing indicator on macOS */
            #private-browsing-indicator-with-label {
              background-color: ${config.theme.colors.base00} !important;
              margin-inline: 0 !important;
              padding-inline: 7px;
            }
            /* Tabs themselves */
            .tabbrowser-tab .tab-stack {
              border-radius: 5px 5px 0 0;
              overflow: hidden;
              background-color: ${config.theme.colors.base00};
              color: ${config.theme.colors.base06} !important;
            }
            .tab-content {
              border-bottom: 2px solid color-mix(in srgb, var(--identity-tab-color) 40%, transparent);
              border-radius: 5px 5px 0 0;
              background-color: ${config.theme.colors.base00};
              color: ${config.theme.colors.base06} !important;
            }
            .tab-content[selected] {
              border-bottom: 2px solid color-mix(in srgb, var(--identity-tab-color) 25%, transparent);
              background-color: ${config.theme.colors.base01} !important;
              color: ${config.theme.colors.base07} !important;
            }
            /* Below tab bar */
            #nav-bar {
              background: ${config.theme.colors.base01} !important;
            }
            /* URL bar in nav bar */
            #urlbar[focused=true] {
              color: ${config.theme.colors.base07} !important;
              background: ${config.theme.colors.base02} !important;
              caret-color: ${config.theme.colors.base05} !important;
            }
            #urlbar:not([focused=true]) {
              color: ${config.theme.colors.base04} !important;
              background: ${config.theme.colors.base02} !important;
            }
            #urlbar ::-moz-selection {
              color: ${config.theme.colors.base07} !important;
              background: ${config.theme.colors.base02} !important;
            }
            #urlbar-input-container {
              border: 1px solid ${config.theme.colors.base01} !important;
            }
            #urlbar-background {
              background: ${config.theme.colors.base01} !important;
            }
            /* Text in URL bar */
            #urlbar-input, #urlbar-scheme, .searchbar-textbox {
              color: ${config.theme.colors.base07} !important;
            }
          '';
          userContent = ''
            @-moz-document url-prefix(about:blank) {
              * {
                background-color:${config.theme.colors.base01} !important;
              }
            }
          '';

          extraConfig = "";
        };
      };

      xdg.mimeApps = {
        associations.added = {
          "text/html" = [ "firefox.desktop" ];
        };
        defaultApplications = {
          "text/html" = [ "firefox.desktop" ];
        };
        associations.removed = {
          "text/html" = [ "wine-extension-htm.desktop" ];
        };

      };

      xsession.windowManager.i3.config.keybindings = lib.mkIf pkgs.stdenv.isLinux {
        "${
          config.home-manager.users.${config.user}.xsession.windowManager.i3.config.modifier
        }+Shift+b" = "exec ${
          # Don't name the script `firefox` or it will affect grep
          builtins.toString (
            pkgs.writeShellScript "focus-ff.sh" ''
              count=$(ps aux | grep -c firefox)
              if [ "$count" -eq 1 ]; then
                  i3-msg "exec --no-startup-id firefox"
                  sleep 0.5
              fi
              i3-msg "[class=firefox] focus"
            ''
          )
        }";
      };
    };
  };
}