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

with lib;

mkIf (elem "emacs::lsp" config.machine.pkgs) {
  programs.emacs.init.usePackage = {
    lsp-mode = {
      enable = true;
      command = [ "lsp-mode" ];
      config = ''
        (setq lsp-keymap-prefix "C-c")
        (setq lsp-eldoc-render-all nil)

        (defvar lsp-language-id-configuration '(
          ${optionalString (elem "emacs::rust" config.machine.pkgs)
            ''(rust-mode . "rust")''}
        ))
      '';
    };

    lsp-ui = {
      enable = true;
      after = [ "lsp" ];
      command = [ "lsp-ui-mode" "lsp-ui-sideline-mode" ];
      config = ''
        (setq lsp-ui-sideline-enable t
              lsp-ui-sideline-show-symbol nil
              lsp-ui-sideline-show-hover nil
              lsp-ui-sideline-show-code-actions t
              lsp-ui-sideline-update-mode 'point)
      '';
    };

    lsp-ui-flycheck = {
      enable = true;
      package = epkgs: [ epkgs.lsp-ui ];
      after = [ "lsp-ui" ]
              ++ optional (elem "emacs::flycheck" config.machine.pkgs) "flycheck";
    };

    lsp-java = {
      enable = (elem "emacs::java" config.machine.pkgs);
      command = [ "lsp-java-enable" ];
      hook = [ ''
        (java-mode . (lambda ()
          (lsp-java-enable)
          (lsp-ui-sideline-mode)
          (lsp-ui-flycheck-enable t)
          (setq-local company-backends (list 'company-lsp))))
        '' ];
    };
  };
}