{ pkgs, config, username, ... }:

  ###################################################################################
  #
  #  macOS's System configuration
  #
  #  All the configuration options are documented here:
  #    https://daiderd.com/nix-darwin/manual/index.html#sec-options
  #  Incomplete list of macOS `defaults` commands :
  #    https://github.com/yannbertrand/macos-defaults
  #
  ###################################################################################
{
  system = {
    primaryUser = username;
    stateVersion = 6;

    # activationScripts are executed every time you boot the system or run `nixos-rebuild` / `darwin-rebuild`.
    activationScripts.extraActivation.text = ''
      # activateSettings -u will reload the settings from the database and apply them to the current session,
      # so we do not need to logout and login again to make the changes take effect.
      sudo -u ${username} /System/Library/PrivateFrameworks/SystemAdministration.framework/Resources/activateSettings -u
    '';

    activationScripts.applications.text = let
      env = pkgs.buildEnv {
        name = "system-applications";
        paths = config.environment.systemPackages;
        pathsToLink = "/Applications";
      };
    in
      pkgs.lib.mkForce ''
      # Set up applications.
      echo "setting up /Applications..." >&2
      rm -rf /Applications/Nix\ Apps
      mkdir -p /Applications/Nix\ Apps
      find ${env}/Applications -maxdepth 1 -type l -exec readlink '{}' + |
      while read -r src; do
        app_name=$(basename "$src")
        echo "copying $src" >&2
        ${pkgs.mkalias}/bin/mkalias "$src" "/Applications/Nix Apps/$app_name"
      done
          '';

    defaults = {
      # login window
      loginwindow = {
        GuestEnabled = false;  # disable guest user
        SHOWFULLNAME = true;  # show full name in login window
      };

      # control center
      controlcenter = {
        Sound = false;
        Bluetooth = false;
        AirDrop = false;
        Display = false;
        NowPlaying = false;
      };

      # clock
      menuExtraClock = {
        Show24Hour = true;
        ShowAMPM = false;
        ShowDayOfWeek = false;
      };
      
      # dock
      dock = {
        autohide = true;
        autohide-delay = 0.01;
        autohide-time-modifier = 0.1;
        mineffect = "suck";
        show-recents = false;
        tilesize = 50;
        magnification = true;
        largesize = 70;
        wvous-bl-corner = 11;
      };

      # finder
      finder = {
        AppleShowAllFiles = true;
        ShowStatusBar = true;
        ShowPathbar = true;
        FXPreferredViewStyle = "Nlsv";
        AppleShowAllExtensions = true;
        QuitMenuItem = true;
        _FXShowPosixPathInTitle = true;
        _FXSortFoldersFirst = true;
        FXEnableExtensionChangeWarning = false;
        NewWindowTarget = "Home";
      };

      # trackpad
      trackpad = {
        Clicking = true;
        TrackpadRightClick = true;  # enable two finger right click
        TrackpadThreeFingerDrag = true;  # enable three finger drag
      };

      # customize settings that not supported by nix-darwin directly
      # Incomplete list of macOS `defaults` commands :
      #   https://github.com/yannbertrand/macos-defaults
      NSGlobalDomain = {
        # `defaults read NSGlobalDomain "xxx"`
        "com.apple.swipescrolldirection" = true;
        AppleInterfaceStyle = "Dark";
        AppleKeyboardUIMode = 3;
        ApplePressAndHoldEnabled = false;
        InitialKeyRepeat = 15;
        KeyRepeat = 2;

        AppleShowScrollBars = "WhenScrolling";
        AppleScrollerPagingBehavior = true;
        AppleEnableMouseSwipeNavigateWithScrolls = true;
        AppleEnableSwipeNavigateWithScrolls = true;

        NSAutomaticCapitalizationEnabled = false;
        NSAutomaticDashSubstitutionEnabled = false;
        NSAutomaticPeriodSubstitutionEnabled = false;
        NSAutomaticQuoteSubstitutionEnabled = false;
        NSAutomaticSpellingCorrectionEnabled = false;
        NSNavPanelExpandedStateForSaveMode = true;
        NSNavPanelExpandedStateForSaveMode2 = true;
        NSTableViewDefaultSizeMode = 2;

        "com.apple.keyboard.fnState" = true;
      };

      # Customize settings that not supported by nix-darwin directly
      # see the source code of this project to get more undocumented options:
      #    https://github.com/rgcr/m-cli
      # 
      # All custom entries can be found by running `defaults read` command.
      # or `defaults read xxx` to read a specific domain.
      CustomUserPreferences = {
        ".GlobalPreferences" = {
          # automatically switch to a new space when switching to the application
          AppleSpacesSwitchOnActivate = true;
        };
        NSGlobalDomain = {
          # Add a context menu item for showing the Web Inspector in web views
          WebKitDeveloperExtras = true;
        };
        "com.apple.finder" = {
          ShowExternalHardDrivesOnDesktop = true;
          ShowHardDrivesOnDesktop = true;
          ShowMountedServersOnDesktop = true;
          ShowRemovableMediaOnDesktop = true;
          _FXSortFoldersFirst = true;
          # When performing a search, search the current folder by default
          FXDefaultSearchScope = "SCcf";
        };
        "com.apple.desktopservices" = {
          # Avoid creating .DS_Store files on network or USB volumes
          DSDontWriteNetworkStores = true;
          DSDontWriteUSBStores = true;
        };
        "com.apple.WindowManager" = {
          EnableStandardClickToShowDesktop = 0; # Click wallpaper to reveal desktop
          StandardHideDesktopIcons = 0; # Show items on desktop
          HideDesktop = 0; # Do not hide items on desktop & stage manager
          StageManagerHideWidgets = 0;
          StandardHideWidgets = 0;
        };
        "com.apple.screensaver" = {
          # Require password immediately after sleep or screen saver begins
          askForPassword = 1;
          askForPasswordDelay = 0;
        };
        "com.apple.AdLib" = {
          allowApplePersonalizedAdvertising = false;
        };
        # Prevent Photos from opening automatically when devices are plugged in
        "com.apple.ImageCapture".disableHotPlug = true;
        "com.apple.dock" = {
          springboard-columns = 10;
          springboard-rows = 10;
          ResetLaunchPad = true;
        };
      };
    };

    # keyboard settings is not very useful on macOS
    # the most important thing is to remap option key to alt key globally,
    # but it's not supported by macOS yet.
    keyboard = {
      enableKeyMapping = true;  # enable key mapping so that we can use `option` as `control`

      # NOTE: do NOT support remap capslock to both control and escape at the same time
      remapCapsLockToControl = false;  # remap caps lock to control, useful for emac users
      remapCapsLockToEscape  = false;  # remap caps lock to escape, useful for vim users
    };
  };

  # Add ability to used TouchID for sudo authentication
  security.pam.services.sudo_local.touchIdAuth = true;

  # Create /etc/zshrc that loads the nix-darwin environment.
  # this is required if you want to use darwin's default shell - zsh
  programs.zsh = {
    enable = true;
    enableCompletion = true;
    enableAutosuggestions = true;
    enableFastSyntaxHighlighting = true;
    enableFzfCompletion = true;
    enableFzfGit = true;
    enableFzfHistory = true;
    promptInit = ''
    fastfetch
    source ${pkgs.zsh-powerlevel10k}/share/zsh-powerlevel10k/powerlevel10k.zsh-theme
    source ${pkgs.zsh-fzf-tab}/share/fzf-tab/fzf-tab.plugin.zsh
    '';
  };

  environment = {
    shells = [
      pkgs.zsh
    ];
    shellAliases = {
      ls = "lsd --color=auto";
      l = "lsd -lhG";
      lt = "l --tree";
      ll = "lsd -alhG";
      lh = "lsd -dl .*";
      lsd = "lsd --group-directories-first";
      filecount="find . -type f | wc -l";
      cat = "bat --color=always";
      man = "tldr";
      nixrebuild = "sudo darwin-rebuild switch --flake ~/.config/nix-darwin";
      nixupgrade = "cd ~/.config/nix-darwin && nix flake update";
      nixconfig = "nvim ~/.config/nix-darwin";
      sshconfig = "nvim ~/.ssh/config";

      # git
      g = "git";
      gaa = "git add --all";
      gcm = "git commit -m";
      gca = "git commit --amend";
      gst = "git status";
      gco = "git checkout";
      gl = "git pull";
      gp = "git push";
      glg = "git log --graph --pretty='%Cred%h%Creset -%C(auto)%d%Creset %s %Cgreen(%ad) %C(bold blue)<%an>%Creset' --date=short";
    };
  };

  # Set your time zone.
  time.timeZone = "Asia/Seoul";
}