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

with lib;

let
  inherit (pkgs) stdenv;
  cfg = config.programs.tabnine;
  lspConfigFile = config:
    pkgs.runCommand "TabNine.toml"
      {
         buildInputs = [ pkgs.remarshal ];
         preferLocalBuild = true;
         allowSubstitutes = false;
      }
      ''
        remarshal -if json -of toml \
          < ${pkgs.writeText "config.json" (builtins.toJSON cfg.lspConfig)} \
          | sed  -e 's/^\["\(.*\)"\]/[\1]/' \
          > $out
      '';
in
{

  options.programs.tabnine = {
    enable = mkEnableOption "TabNine, Smart Compose for code.";

    configDir = mkOption {
      type = types.str;
      default = if stdenv.isDarwin then "Library/Preferences/TabNine" else "${config.xdg.configHome}/TabNine";
      description = ''
        Location of TabNine configuration directory relative to \$HOME
      '';
    };

    config = mkOption {
      type = types.attrs;
      default = { };
      description = ''
        TabNine configuration written to
        <filename>\${configDir}/tabnine_config.json</filename>
      '';
    };

    registrationKey = mkOption {
      type = types.str;
      description = ''
        Registration key for TabNine.  For one-time-purchase users, this should be the e-mail address and base-64-encoded key joined together without spacing.
      '';
    };

    lspConfig = mkOption {
      type = types.attrs;
      default = {};
      description = ''
        LSP Server configuration written to
        <filename>\${configDir}/TabNine.toml</filename>
        </para><para>
      '';
    };
  };

  config = mkIf cfg.enable {
    home.file."${cfg.configDir}/TabNine.toml" = {
      source = lspConfigFile cfg.lspConfig;
    };
    home.file."${cfg.configDir}/tabnine_config.json" = {
      source = pkgs.writeText "tabnine_config.json" (builtins.toJSON cfg.config);
    };
    home.file."${cfg.configDir}/registration_key" = {
      text = cfg.registrationKey;
    };
  };
}