{
  config,
  pkgs,
  lib,
  ...
}: let
  inherit (builtins) attrNames;
  inherit (lib.modules) mkIf mkMerge;
  inherit (lib.trivial) boolToString;
  inherit (lib.lists) isList;
  inherit (lib.options) mkEnableOption mkOption;
  inherit (lib.types) enum either listOf package nullOr str bool;
  inherit (lib.strings) optionalString;
  inherit (lib.nvim.lua) expToLua;
  inherit (lib.nvim.types) mkGrammarOption;
  inherit (lib.nvim.dag) entryAfter;

  cfg = config.vim.languages.dart;
  ftcfg = cfg.flutter-tools;

  defaultServer = "dart";
  servers = {
    dart = {
      package = pkgs.dart;
      lspConfig = ''
        lspconfig.dartls.setup{
          capabilities = capabilities;
          on_attach=default_on_attach;
          cmd = ${
          if isList cfg.lsp.package
          then expToLua cfg.lsp.package
          else ''{"${cfg.lsp.package}/bin/dart", "language-server", "--protocol=lsp"}''
        };
          ${optionalString (cfg.lsp.opts != null) "init_options = ${cfg.lsp.dartOpts}"}
        }
      '';
    };
  };
in {
  options.vim.languages.dart = {
    enable = mkEnableOption "Dart language support";

    treesitter = {
      enable = mkEnableOption "Dart treesitter" // {default = config.vim.languages.enableTreesitter;};
      package = mkGrammarOption pkgs "dart";
    };

    lsp = {
      enable = mkEnableOption "Dart LSP support";
      server = mkOption {
        description = "The Dart LSP server to use";
        type = enum (attrNames servers);
        default = defaultServer;
      };
      package = mkOption {
        type = either package (listOf str);
        default = servers.${cfg.lsp.server}.package;
        example = ''[lib.getExe pkgs.jdt-language-server "-data" "~/.cache/jdtls/workspace"]'';
        description = "Dart LSP server package, or the command to run as a list of strings";
      };

      opts = mkOption {
        type = nullOr str;
        default = null;
        description = "Options to pass to Dart LSP server";
      };
    };

    dap = {
      enable = mkOption {
        description = "Enable Dart DAP support via flutter-tools";
        type = bool;
        default = config.vim.languages.enableDAP;
      };
    };

    flutter-tools = {
      enable = mkOption {
        type = bool;
        default = config.vim.languages.enableLSP;
        description = "Enable flutter-tools for flutter support";
      };

      flutterPackage = mkOption {
        type = nullOr package;
        default = pkgs.flutter;
        description = "Flutter package, or null to detect the flutter path at runtime instead.";
      };

      enableNoResolvePatch = mkOption {
        type = bool;
        default = false;
        description = ''
          Whether to patch flutter-tools so that it doesn't resolve
          symlinks when detecting flutter path.

          This is required if flutterPackage is set to null and the flutter
          package in your PATH was built with nix. If you are using a flutter
          SDK installed from a different source and encounter the error "`dart`
          missing from PATH", leave this option disabled.
        '';
      };

      color = {
        enable = mkEnableOption "highlighting color variables";

        highlightBackground = mkOption {
          type = bool;
          default = false;
          description = "Highlight the background";
        };

        highlightForeground = mkOption {
          type = bool;
          default = false;
          description = "Highlight the foreground";
        };

        virtualText = {
          enable = mkEnableOption "Show the highlight using virtual text";

          character = mkOption {
            type = str;
            default = "■";
            description = "Virtual text character to highlight";
          };
        };
      };
    };
  };

  config.vim = mkIf cfg.enable (mkMerge [
    (mkIf cfg.treesitter.enable {
      treesitter.enable = true;
      treesitter.grammars = [cfg.treesitter.package];
    })

    (mkIf cfg.lsp.enable {
      lsp.lspconfig.enable = true;
      lsp.lspconfig.sources.dart-lsp = servers.${cfg.lsp.server}.lspConfig;
    })

    (mkIf ftcfg.enable {
      lsp.enable = true;

      startPlugins = [
        (
          if ftcfg.enableNoResolvePatch
          then "flutter-tools-patched"
          else "flutter-tools-nvim"
        )
        "plenary-nvim"
      ];

      pluginRC.flutter-tools = entryAfter ["lsp-setup"] ''
        require('flutter-tools').setup {
          ${optionalString (ftcfg.flutterPackage != null) "flutter_path = \"${ftcfg.flutterPackage}/bin/flutter\","}
          lsp = {
            color = { -- show the derived colours for dart variables
              enabled = ${boolToString ftcfg.color.enable}, -- whether or not to highlight color variables at all, only supported on flutter >= 2.10
              background = ${boolToString ftcfg.color.highlightBackground}, -- highlight the background
              foreground = ${boolToString ftcfg.color.highlightForeground}, -- highlight the foreground
              virtual_text = ${boolToString ftcfg.color.virtualText.enable}, -- show the highlight using virtual text
              virtual_text_str = ${ftcfg.color.virtualText.character} -- the virtual text character to highlight
            },

            capabilities = capabilities,
            on_attach = default_on_attach;
          },
          ${optionalString cfg.dap.enable ''
          debugger = {
            enabled = true,
          },
        ''}
        }
      '';
    })
  ]);
}