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

with lib;

let
  cfg = config.programs.sm64ex;

  # This is required for tests, we cannot overwrite the dummy package.
  package = if cfg.region == null && cfg.baserom == null
  && cfg.extraCompileFlags == null then
    cfg.package

  else
    cfg.package.override (attrs:
      { } // optionalAttrs (cfg.region != null) { region = cfg.region; }
      // optionalAttrs (cfg.baserom != null) { baseRom = cfg.baserom; }
      // optionalAttrs (cfg.extraCompileFlags != null) {
        compileFlags = cfg.extraCompileFlags;
      });

  mkConfig = key: value:
    let
      generatedValue = if isBool value then
        (if value then "true" else "false")
      else if isList value then
        concatStringsSep " " value
      else
        toString value;
    in "${key} ${generatedValue}";

in {
  meta.maintainers = [ maintainers.ivar ];

  options.programs.sm64ex = {
    enable = mkEnableOption "sm64ex";

    package = mkOption {
      type = types.package;
      default = pkgs.sm64ex;
      description = "The sm64ex package to use.";
    };

    region = mkOption {
      type = types.nullOr (types.enum [ "us" "eu" "jp" ]);
      default = null;
      defaultText =
        literalExpression "us"; # This is set both in nixpkgs and upstream
      description = ''
        Your baserom's region. Note that only "us", "eu", and "jp" are supported.
      '';
      example = literalExpression "jp";
    };

    baserom = mkOption {
      type = types.nullOr types.path;
      default = null;
      description =
        "The path to the Super Mario 64 baserom to extract assets from.";
      example = literalExpression "/home/foo/baserom.us.z64";
    };

    extraCompileFlags = mkOption {
      type = with types; nullOr (listOf str);
      default = null;
      description = ''
        Extra flags to pass to the compiler. See
        <link xlink:href="https://github.com/sm64pc/sm64ex/wiki/Build-options"/>
        for more information.
      '';
      example = literalExpression ''
        [
          "BETTERCAMERA=1"
          "NODRAWINGDISTANCE=1"
        ];
      '';
    };

    settings = mkOption {
      type = with types;
        nullOr (attrsOf (either str (either int (either bool (listOf str)))));
      default = null;
      description =
        "Settings for sm64ex's <filename>$XDG_DATA_HOME/sm64pc/sm64config.txt</filename> file.";
      example = literalExpression ''
        {
          fullscreen = false;
          window_x = 0;
          window_y = 0;
          window_w = 1920;
          window_h = 1080;
          vsync = 1;
          texture_filtering = 1;
          master_volume = 127;
          music_volume = 127;
          sfx_volume = 127;
          env_volume = 127;
          key_a = [ "0026" "1000" "1103" ];
          key_b = [ "0033" "1002" "1101" ];
          key_start = [ "0039" "1006" "ffff" ];
          key_l = [ "0034" "1007" "1104" ];
          key_r = [ "0036" "100a" "1105" ];
          key_z = [ "0025" "1009" "1102" ];
          key_cup = [ "100b" "ffff" "ffff" ];
          key_cdown = [ "100c" "ffff" "ffff" ];
          key_cleft = [ "100d" "ffff" "ffff" ];
          key_cright = [ "100e" "ffff" "ffff" ];
          key_stickup = [ "0011" "ffff" "ffff" ];
          key_stickdown = [ "001f" "ffff" "ffff" ];
          key_stickleft = [ "001e" "ffff" "ffff" ];
          key_stickright = [ "0020" "ffff" "ffff" ];
          stick_deadzone = 16;
          rumble_strength = 10;
          skip_intro = 1;
        };
      '';
    };
  };

  config = let
    configFile = optionals (cfg.settings != null)
      (concatStringsSep "\n" ((mapAttrsToList mkConfig cfg.settings)));
  in mkIf cfg.enable {
    home.packages = [ package ];

    xdg.dataFile."sm64pc/sm64config.txt" =
      mkIf (cfg.settings != null) { text = configFile; };
  };
}