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

{
  # Fish Shell
  # https://rycee.gitlab.io/home-manager/options.html#opt-programs.fish.enable
  programs.fish.enable = true;

  # Add Fish plugins
  home.packages = with pkgs.fishPlugins; [
    done
  ];

  programs.fish.plugins = [
    {
      name = "fisher";
      src = pkgs.fetchFromGitHub {
        owner = "jorgebucaran";
        repo = "fisher";
        rev = "93dafd242b52a0dc6bea54130d0ea041830c7fd6";
        sha256 = "0qbqlydh7b928473f7c4gy68sr1wnwyhcvvqzcik1vx5hdbka7ad";
      };
    }
  ];

  home.file.".config/fish/fish_plugins".text = ''
    jorgebucaran/autopair.fish
    jorgebucaran/replay.fish
    jorgebucaran/getopts.fish
    americanhanko/fish-spin
    joseluisq/gitnow
    fishpkg/fish-humanize-duration
    oh-my-fish/plugin-bang-bang
    matthewess/fish-autovenv
    jethrokuan/z
    Gazorby/fish-abbreviation-tips
  '';

  # Fish functions ----------------------------------------------------------------------------- {{{

  programs.fish.functions = {
    # User functions
    mkdcd = {
      argumentNames = [ "target" ];
      body = ''
        mkdir -p $target
        cd $target
      '';
    };
    unz = {
      argumentNames = [ "target" ];
      body = ''
        # strip extensions
        string match \*.zip $target; and set target (string split -r -m1 . $target)[1]
        unzip -d $target $target
      '';
    };

    # Helpers
    # Toggles `$term_background` between "light" and "dark". Other Fish functions trigger when this
    # variable changes. We use a universal variable so that all instances of Fish have the same
    # value for the variable.
    toggle-background.body = ''
      if test "$term_background" = light
        set -U term_background dark
      else
        set -U term_background light
      end
    '';

    # Set `$term_background` based on whether macOS is light or dark mode. Other Fish functions
    # trigger when this variable changes. We use a universal variable so that all instances of Fish
    # have the same value for the variable.
    set-background-to-macOS.body = ''
      if is-dark-mode
        set -U term_background dark
      else
        set -U term_background light
      end
    '';

    # Set `$term_background` based on an env var.
    set-background-to-env = {
      argumentNames = [ "env_var" ];
      body = ''
        switch $$env_var
        case 1
          set -U term_background dark
        case 0
          set -U term_background light
        end
      '';
    };

    # Sets Fish Shell to light or dark colorscheme based on `$term_background`.
    set-shell-colors = {
      body = ''
        # Use correct theme for `btm`
        if test "$term_background" = light
          alias btm "btm --color default-light"
        else
          alias btm "btm --color default"
        end
        # Set LS_COLORS
        set -xg LS_COLORS (${pkgs.vivid}/bin/vivid generate one-$term_background)
        # Set color variables
        if test "$term_background" = light
          set emphasized_text  brgreen  # base01
          set normal_text      bryellow # base00
          set secondary_text   brcyan   # base1
          set background_light white    # base2
          set background       brwhite  # base3
        else
          set emphasized_text  brcyan   # base1
          set normal_text      brblue   # base0
          set secondary_text   brgreen  # base01
          set background_light black    # base02
          set background       brblack  # base03
        end
        # Set Fish colors that change when background changes
        set -g fish_color_command                    $emphasized_text --bold  # color of commands
        set -g fish_color_param                      $normal_text             # color of regular command parameters
        set -g fish_color_comment                    $secondary_text          # color of comments
        set -g fish_color_autosuggestion             $secondary_text          # color of autosuggestions
        set -g fish_pager_color_prefix               $emphasized_text --bold  # color of the pager prefix string
        set -g fish_pager_color_description          $selection_text          # color of the completion description
        set -g fish_pager_color_selected_prefix      $background
        set -g fish_pager_color_selected_completion  $background
        set -g fish_pager_color_selected_description $background
      '';
      onVariable = "term_background";
    };

    init-shell-colors.body = ''
      set -g fish_color_quote        cyan      # color of commands
      set -g fish_color_redirection  brmagenta # color of IO redirections
      set -g fish_color_end          blue      # color of process separators like ';' and '&'
      set -g fish_color_error        red       # color of potential errors
      set -g fish_color_match        --reverse # color of highlighted matching parenthesis
      set -g fish_color_search_match --background=yellow
      set -g fish_color_selection    --reverse # color of selected text (vi mode)
      set -g fish_color_operator     green     # color of parameter expansion operators like '*' and '~'
      set -g fish_color_escape       red       # color of character escapes like '\n' and and '\x70'
      set -g fish_color_cancel       red       # color of the '^C' indicator on a canceled command
    '';

    from-dir = {
      argumentNames = [ "dir" ];
      body = ''
        pushd $dir
        set -e argv[1]
        $argv
        popd
      '';
    };
  };
  # }}}

  # Fish configuration ------------------------------------------------------------------------- {{{

  # Aliases
  programs.fish.shellAliases =
    let
      nixConfigDir = "${config.home.homeDirectory}/dotfiles.nix";
    in
    with pkgs; {
      # Nix related
      from-nix = "from-dir ${nixConfigDir}";
      # darwin-rebuild build 
      drb = "from-nix darwin-rebuild build --flake .";
      # darwin-rebuild switch full
      drsf = "from-nix darwin-rebuild switch --flake .";
      # darwin-rebuild switch (no homebrew)
      drs = "from-nix darwin-rebuild switch --flake . --override-input homebrew-enabled github:boolean-option/false";
      # edit darwin-rebuild config in codium
      drc = "codium ${nixConfigDir}";
      # edit darwin-rebuild config in vim
      drv = "vim ${nixConfigDir}";
      # edit darwin-rebuild config in kakoune
      drk = "from-nix kak flake.nix";
      flakeup = "nix flake update ${nixConfigDir}/";
      nb = "nix build";
      nd = "nix develop";
      nf = "nix flake";
      nr = "nix run";
      ns = "nix search nixpkgs";
      nsh = "nix shell";
      nrp = "nix repl --expr '{pkgs=(import <nixpkgs> {});}'";

      # Other
      ".." = "cd ..";
      ":q" = "exit";
      cat = "${bat}/bin/bat";
      du = "${du-dust}/bin/dust";
      g = "${gitAndTools.git}/bin/git";
      ls = "${exa}/bin/exa";
      ll = "ls -l --time-style long-iso --icons";
      la = "ll -a";
      ps = "${procs}/bin/procs";
      code = "${vscodium}/bin/codium";
      http = "${xh}/bin/xh";
      https = "${xh}/bin/xhs";
      top = "${bottom}/bin/btm";
      htop = "${bottom}/bin/btm";
      tb = "toggle-background";
      sb = "set-background-to-macOS";
    };

  # Configuration that should be above `loginShellInit` and `interactiveShellInit`.
  programs.fish.shellInit = ''
    set -U fish_term24bit 1
    ${lib.optionalString pkgs.stdenv.isDarwin "set-background-to-macOS"}
  '';

  programs.fish.interactiveShellInit = ''
    set -g fish_greeting "ヽ(´ᗜ｀)ノ welcome ヽ(´ᗜ｀)ノ"
    fish_vi_key_bindings
    set VIRTUAL_ENV_DISABLE_PROMPT true
    bind -M insert ! __history_previous_command
    bind -M insert '$' __history_previous_command_arguments
    ${pkgs.thefuck}/bin/thefuck --alias | source
    # Run function to set colors that are dependent on `$term_background` and to register them so
    # they are triggered when the relevent event happens or variable changes.
    set-shell-colors
    # Set Fish colors that aren't dependent the `$term_background`.
    init-shell-colors
  '';
  # }}}

  # Starship Prompt
  # https://rycee.gitlab.io/home-manager/options.html#opt-programs.starship.enable
  programs.starship.enable = true;

  # Starship settings -------------------------------------------------------------------------- {{{

  programs.starship.settings = {
    # See docs here: https://starship.rs/config/
    # Symbols config configured in Flake.

    battery.display = [
      { threshold = 25; } # display battery information if charge is <= 25%
    ];
    directory.fish_style_pwd_dir_length = 1; # turn on fish directory truncation
    directory.truncation_length = 2; # number of directories not to truncate
    # hostname.style = "bold green"; # don't like the default
    memory_usage.disabled = true; # because it includes cached memory it's reported as full a lot
    # username.style_user = "bold blue"; # don't like the default
  };
  # }}}

  # dark-mode-notify configuration
  # {{{
  launchd.enable = true;
  launchd.agents.dark-mode-notify = {
    enable = true;
    config = {
      Label = "ke.bou.dark-mode-notify";
      KeepAlive = true;
      StandardErrorPath = null;
      StandardOutPath = null;
      ProgramArguments = [
        "${pkgs.dark-mode-notify}/bin/dark-mode-notify"
        "${pkgs.fish}/bin/fish"
        "-c"
        "set-background-to-env DARKMODE"
      ];
    };
  };
  # }}}
}