dotfiles/homes/modules/editor/helix.nix

{
  pkgs,
  pkgs-unstable,
  ...
}: let
  lsps = let
    mkLsp = pkg: path: {inherit pkg path;};
  in {
    bash-language-server =
      mkLsp
      pkgs.bash-language-server
      "/bin/bash-language-server";

    clangd =
      mkLsp
      pkgs.clang-tools
      "/bin/clangd";

    haskell-language-server =
      mkLsp
      pkgs.haskell-language-server
      "/bin/haskell-language-server-wrapper";

    # TODO: once upgraded past Nix-24.07 this line won't be necessary (I think)
    #       helix will support nixd by default
    # SOURCE: https://github.com/nix-community/nixd/blob/main/nixd/docs/editor-setup.md#Helix
    nixd =
      mkLsp
      pkgs.nixd
      "/bin/nixd";

    OmniSharp =
      mkLsp
      pkgs.omnisharp-roslyn
      "/bin/OmniSharp";

    rust-analyzer =
      mkLsp
      pkgs.rust-analyzer
      "/bin/rust-analyzer";

    ty =
      mkLsp
      pkgs.ty
      "/bin/ty";
  };
in {
  environment.systemPackages =
    lsps
    |> map (lsp: lsp.pkg);

  # REF: https://docs.helix-editor.com/editor.html
  programs.helix = {
    enable = true;
    settings = {
      theme = "dracula";

      editor = {
        line-number = "absolute";
        popup-border = "all";
        scroll-lines = 3;
        color-modes = true; # colour the mode indicator depending on mode
        shell = ["zsh" "-c"];

        auto-format = true;
        auto-completion = true; # enable popup for autocomplete
        completion-timeout = 250; # time before completions display
        preview-completion-insert = true;
        completion-trigger-len = 2; # min word length to trigger completions
        completion-replace = true; # completions replace entire word

        indent-heuristic = "tree-sitter"; # how indentation is computed
        # TODO: make this configurable (enabled on myputer, disabled on lolcathost)
        middle-click-paste = true;
        insert-final-newline = true; # append newline to file on write

        gutters = [
          "diagnostics"
          "spacer"
          "line-numbers"
          "spacer"
          "diff"
        ];

        whitespace = {
          render = {
            space = "none"; # "all"
            tab = "none"; #"all"
            nbsp = "none";
            nnbsp = "none";
            newline = "none";
          };
          characters = {
            space = "·";
            nbsp = "⍽";
            nnbsp = "␣";
            tab = "→";
            newline = "⤶";
            tabpad = "·"; # Tabs will look like "→···" (depending on tab width)
          };
        };

        indent-guides = {
          render = true;
          character = "▏"; # "｜"
          skip-levels = 1;
        };

        lsp = {
          enable = true;
          auto-signature-help = true; # hints for function parameters
          display-inlay-hints = true; # inline hints
          snippets = true;
        };

        cursor-shape = {
          normal = "block";
          insert = "bar";
          select = "block";
        };

        file-picker = {
          hidden = true; # show hidden files
          follow-symlinks = true;
          deduplicate-links = true;
          git-ignore = false; # dont read .gitignore files
          ignore = true; # use .ignore for helix instead of .gitignore
        };

        statusline = {
          left = [
            "mode"
            "spacer"
            "version-control"
            "spinner"
          ];
          center = [
            "file-name"
            "read-only-indicator"
            "file-modification-indicator"
          ];
          right = [
            "position"
            "total-line-numbers"
            "file-encoding"
            "file-line-ending"
            "file-type"
          ];
          separator = "|";
          mode.normal = "NORMAL";
          mode.insert = "INSERT";
          mode.select = "SELECT";
        };
      };
    };

    languages = {
      language = [
        {
          name = "nix";
          indent = {
            tab-width = 2;
            unit = "  ";
          };
          block-comment-tokens = {
            start = "/*";
            end = "*/";
          };
          auto-format = true;
          formatter.command = "${pkgs.alejandra}/bin/alejandra";
          language-servers = ["nixd"];
        }
        {
          name = "python";
          indent = {
            tab-width = 4;
            unit = "    ";
          };
          auto-format = false; # my python is beautiful ^_^
          rulers = [80];
          language-servers = ["ty"];
        }
        {
          name = "c";
          file-types = ["c" "h"]; # use .hpp for C++
          auto-format = true;
          formatter.command = "${pkgs.clang-tools}/bin/clang-format";
          language-servers = ["clangd"];
        }
        {
          name = "haskell";
          auto-format = true;
          formatter.command = "${pkgs.ormolu}/bin/ormolu";
          language-servers = ["haskell-language-server"];
        }
        {
          name = "rust";
          indent = {
            tab-width = 2;
            unit = "  ";
          };
          auto-format = true;
          formatter.command = "${pkgs.rustfmt}/bin/rustfmt";
          language-servers = ["rust-analyzer"];
        }
        {
          name = "c-sharp";
          source = "source.cs";
          file-types = ["cs"];
          indent = {
            tab-width = 4;
            unit = "  ";
          };
          block-comment-tokens = {
            start = "/*";
            end = "*/";
          };
          # auto-format = false;
          # formatter.command = "${pkgs.omnisharp-roslyn}/bin/OmniSharp";
          # language-servers = ["OmniSharp"];
        }
      ];

      language-server =
        lsps
        |> builtins.mapAttrs (_: lsp: "${lsp.pkg}${lsp.path}");
    };
  };
}