{ stdenv
, lib
, buildEnv
, substituteAll
, makeWrapper
, runCommand
, coreutils
, gawk
, dwarf-fortress
, dwarf-therapist
, enableDFHack ? false
, dfhack
, enableSoundSense ? false
, soundSense
, jdk
, expect
, xvfb-run
, writeText
, enableStoneSense ? false
, enableTWBT ? false
, twbt
, themes ? { }
, theme ? null
, extraPackages ? [ ]
  # General config options:
, enableIntro ? true
, enableTruetype ? null # defaults to 24, see init.txt
, enableFPS ? false
, enableTextMode ? false
, enableSound ? true
# An attribute set of settings to override in data/init/*.txt.
# For example, `init.FOO = true;` is translated to `[FOO:YES]` in init.txt
, settings ? { }
# TODO world-gen.txt, interface.txt require special logic
}:

let
  dfhack' = dfhack.override {
    inherit enableStoneSense;
  };

  isAtLeast50 = dwarf-fortress.baseVersion >= 50;

  # If TWBT is null or the dfVersion is wrong, it isn't supported (for example, on version 50).
  enableTWBT' = enableTWBT && twbt != null && (twbt.dfVersion or null) == dwarf-fortress.version;

  ptheme =
    if builtins.isString theme
    then builtins.getAttr theme themes
    else theme;

  baseEnv = buildEnv {
    name = "dwarf-fortress-base-env-${dwarf-fortress.dfVersion}";

    # These are in inverse order for first packages to override the next ones.
    paths = extraPackages
         ++ lib.optional (theme != null) ptheme
         ++ lib.optional enableDFHack dfhack'
         ++ lib.optional enableSoundSense soundSense
         ++ lib.optionals enableTWBT' [ twbt.lib twbt.art ]
         ++ [ dwarf-fortress ];

    ignoreCollisions = true;
  };

  settings' = lib.recursiveUpdate {
    init = {
      PRINT_MODE =
        if enableTextMode then "TEXT"
        else if enableTWBT' then "TWBT"
        else if stdenv.hostPlatform.isDarwin then "STANDARD" # https://www.bay12games.com/dwarves/mantisbt/view.php?id=11680
        else null;
      INTRO = enableIntro;
      TRUETYPE = enableTruetype;
      FPS = enableFPS;
      SOUND = enableSound;
    };
  } settings;

  forEach = attrs: f: lib.concatStrings (lib.mapAttrsToList f attrs);

  toTxt = v:
    if lib.isBool v then if v then "YES" else "NO"
    else if lib.isInt v then toString v
    else if lib.isString v then v
    else throw "dwarf-fortress: unsupported configuration value ${toString v}";

  config = runCommand "dwarf-fortress-config" {
    nativeBuildInputs = [ gawk makeWrapper ];
  } (''
    mkdir -p $out/data/init

    edit_setting() {
      v=''${v//'&'/'\&'}
      if [ -f "$out/$file" ]; then
        if ! gawk -i inplace -v RS='\r?\n' '
          { n += sub("\\[" ENVIRON["k"] ":[^]]*\\]", "[" ENVIRON["k"] ":" ENVIRON["v"] "]"); print }
          END { exit(!n) }
        ' "$out/$file"; then
          echo "error: no setting named '$k' in $out/$file" >&2
          exit 1
        fi
      else
        echo "warning: no file $out/$file; cannot edit" >&2
      fi
    }
  '' + forEach settings' (file: kv: ''
    file=data/init/${lib.escapeShellArg file}.txt
    if [ -f "${baseEnv}/$file" ]; then
      cp "${baseEnv}/$file" "$out/$file"
    else
      echo "warning: no file ${baseEnv}/$file; cannot copy" >&2
    fi
  '' + forEach kv (k: v: lib.optionalString (v != null) ''
    export k=${lib.escapeShellArg k} v=${lib.escapeShellArg (toTxt v)}
    edit_setting
  '')) + lib.optionalString enableDFHack ''
    mkdir -p $out/hack

    # Patch the MD5
    orig_md5=$(< "${dwarf-fortress}/hash.md5.orig")
    patched_md5=$(< "${dwarf-fortress}/hash.md5")
    input_file="${dfhack'}/hack/symbols.xml"
    output_file="$out/hack/symbols.xml"

    echo "[DFHack Wrapper] Fixing Dwarf Fortress MD5:"
    echo "  Input:   $input_file"
    echo "  Search:  $orig_md5"
    echo "  Output:  $output_file"
    echo "  Replace: $patched_md5"

    substitute "$input_file" "$output_file" --replace-fail "$orig_md5" "$patched_md5"
  '');

  # This is a separate environment because the config files to modify may come
  # from any of the paths in baseEnv.
  env = buildEnv {
    name = "dwarf-fortress-env-${dwarf-fortress.dfVersion}";
    paths = [ config baseEnv ];
    ignoreCollisions = true;
  };
in

lib.throwIf (enableTWBT' && !enableDFHack) "dwarf-fortress: TWBT requires DFHack to be enabled"
lib.throwIf (enableStoneSense && !enableDFHack) "dwarf-fortress: StoneSense requires DFHack to be enabled"
lib.throwIf (enableTextMode && enableTWBT') "dwarf-fortress: text mode and TWBT are mutually exclusive"

stdenv.mkDerivation rec {
  pname = "dwarf-fortress";
  version = dwarf-fortress.dfVersion;

  dfInit = substituteAll {
    name = "dwarf-fortress-init";
    src = ./dwarf-fortress-init.in;
    inherit env;
    inherit (dwarf-fortress) exe;
    stdenv_shell = "${stdenv.shell}";
    cp = "${coreutils}/bin/cp";
    rm = "${coreutils}/bin/rm";
    ln = "${coreutils}/bin/ln";
    cat = "${coreutils}/bin/cat";
    mkdir = "${coreutils}/bin/mkdir";
    printf = "${coreutils}/bin/printf";
    uname = "${coreutils}/bin/uname";
  };

  runDF = ./dwarf-fortress.in;
  runSoundSense = ./soundSense.in;

  passthru = {
    inherit dwarf-fortress dwarf-therapist twbt env;
    dfhack = dfhack';
  };

  dontUnpack = true;
  dontBuild = true;
  preferLocalBuild = true;
  installPhase = ''
    mkdir -p $out/bin

    substitute $runDF $out/bin/dwarf-fortress \
      --subst-var-by stdenv_shell ${stdenv.shell} \
      --subst-var-by dfExe ${dwarf-fortress.exe} \
      --subst-var dfInit
    chmod 755 $out/bin/dwarf-fortress
  '' + lib.optionalString enableDFHack ''
    substitute $runDF $out/bin/dfhack \
      --subst-var-by stdenv_shell ${stdenv.shell} \
      --subst-var-by dfExe dfhack \
      --subst-var dfInit
    chmod 755 $out/bin/dfhack
  '' + lib.optionalString enableSoundSense ''
    substitute $runSoundSense $out/bin/soundsense \
      --subst-var-by stdenv_shell ${stdenv.shell} \
      --subst-var-by jre ${jdk.jre} \
      --subst-var dfInit
    chmod 755 $out/bin/soundsense
  '';

  doInstallCheck = stdenv.hostPlatform.isLinux;
  nativeInstallCheckInputs = lib.optionals stdenv.hostPlatform.isLinux [ expect xvfb-run ];

  installCheckPhase = let
    commonExpectStatements = fmod: lib.optionalString isAtLeast50 ''
      expect "Loading audio..."
    '' + lib.optionalString (!fmod && isAtLeast50) ''
      expect "Failed to load fmod, trying SDL_mixer"
    '' + lib.optionalString isAtLeast50 ''
      expect "Audio loaded successfully!"
    '' + ''
      expect "Loading bindings from data/init/interface.txt"
    '';
    dfHackExpectScript = writeText "dfhack-test.exp" (''
      spawn env NIXPKGS_DF_OPTS=debug xvfb-run $env(out)/bin/dfhack
    '' + commonExpectStatements false + ''
      expect "DFHack is ready. Have a nice day!"
      expect "DFHack version ${version}"
      expect "\[DFHack\]#"
      send -- "lua print(os.getenv('out'))\r"
      expect "$env(out)"
      # Don't send 'die' here; just exit. Some versions of dfhack crash on exit.
      exit 0
    '');
    vanillaExpectScript = fmod: writeText "vanilla-test.exp" (''
      spawn env NIXPKGS_DF_OPTS=debug,${lib.optionalString fmod "fmod"} xvfb-run $env(out)/bin/dwarf-fortress
    '' + commonExpectStatements fmod + ''
      exit 0
    '');
  in
  ''
    export HOME="$(mktemp -dt dwarf-fortress.XXXXXX)"
  '' + lib.optionalString enableDFHack ''
    expect ${dfHackExpectScript}
    df_home="$(find ~ -name "df_*" | head -n1)"
    test -f "$df_home/dfhack"
  '' + lib.optionalString isAtLeast50 ''
    expect ${vanillaExpectScript true}
    df_home="$(find ~ -name "df_*" | head -n1)"
    test ! -f "$df_home/dfhack"
    test -f "$df_home/libfmod_plugin.so"
  '' + ''
    expect ${vanillaExpectScript false}
    df_home="$(find ~ -name "df_*" | head -n1)"
    test ! -f "$df_home/dfhack"
    test ! -f "$df_home/libfmod_plugin.so"
  '' + ''
    test -d "$df_home/data"
  '';

  inherit (dwarf-fortress) meta;
}