use optparse applicative for parsing arguments

completions/nom.fish

@@ -1 +1,7 @@
-complete --command nom --wraps nix
+complete --command nom-build --wraps nix-build
+complete --command nom-shell --wraps nix-shell
+
+complete --command nom --condition "__fish_seen_subcommand_from build" --wraps "nix build"
+complete --command nom --condition "__fish_seen_subcommand_from develop" --wraps "nix develop"
+complete --command nom --condition "__fish_seen_subcommand_from shell" --wraps "nix shell"
+complete --command nom --condition "__fish_seen_subcommand_from copy" --wraps "nix copy"

default.nix

@@ -1,8 +1,9 @@
 { mkDerivation, ansi-terminal, async, attoparsec, base, bytestring
 , cassava, containers, directory, extra, filelock, filepath
-, hermes-json, HUnit, lib, nix-derivation, optics, random, relude
-, safe, safe-exceptions, stm, streamly-core, strict, terminal-size
-, text, time, transformers, typed-process, unix, word8
+, hermes-json, HUnit, lib, nix-derivation, optics
+, optparse-applicative, random, relude, safe, safe-exceptions, stm
+, streamly-core, strict, terminal-size, text, time, transformers
+, typed-process, unix, word8
 }:
 mkDerivation {
   pname = "nix-output-monitor";
@@ -19,8 +20,9 @@ mkDerivation {
   executableHaskellDepends = [
     ansi-terminal async attoparsec base bytestring cassava containers
     directory extra filelock filepath hermes-json nix-derivation optics
-    relude safe safe-exceptions stm streamly-core strict terminal-size
-    text time transformers typed-process unix word8
+    optparse-applicative relude safe safe-exceptions stm streamly-core
+    strict terminal-size text time transformers typed-process unix
+    word8
   ];
   testHaskellDepends = [
     ansi-terminal async attoparsec base bytestring cassava containers

exe/Main.hs

@@ -23,6 +23,8 @@ import NOM.Update (detectLocalFinishedBuilds, maintainState)
 import NOM.Update.Monad (UpdateMonad)
 import Optics ((%), (%~), (.~), (^.))
 import Optics.TH (makeFieldLabelsNoPrefix)
+import Options.Applicative
+import Options.Applicative.Help
 import Paths_nix_output_monitor (version)
 import Relude
 import System.Console.ANSI qualified as Terminal
@@ -40,6 +42,16 @@ data ProcessState a = MkProcessState
   , printFunction :: Maybe (Window Int) -> (ZonedTime, Double) -> Text
   }
 
+data SubCommand = CmdBuild | CmdShell | CmdDevelop | CmdCopy
+  deriving stock (Show)
+
+data Options = Options
+  { version :: Bool
+  , json :: Bool
+  , subCommand :: Maybe SubCommand -- This is always Nothing
+  }
+  deriving stock (Show)
+
 makeFieldLabelsNoPrefix ''ProcessState
 
 outputHandle :: Handle
@@ -55,31 +67,76 @@ defaultConfig =
 replaceCommandWithExit :: [String] -> [String]
 replaceCommandWithExit = (<> ["--command", "sh", "-c", "exit"]) . takeWhile (\x -> x /= "--command" && x /= "-c")
 
-knownSubCommands :: [String]
-knownSubCommands = ["build", "copy", "shell", "develop"]
-
-knownFlags :: [String]
-knownFlags = ["--version", "-h", "--help", "--json"]
-
 withJSON :: [String] -> [String]
 withJSON x = "-v" : "--log-format" : "internal-json" : x
 
+parseOptions :: ParserInfo Options
+parseOptions =
+  info
+    (helper <*> parseOptionsNoInfo)
+    ( progDesc "Outputs nix build info in a pretty way"
+        <> footerDoc (Just usageDoc)
+    )
+ where
+  usageDoc :: Doc
+  usageDoc =
+    vsep
+      [ "Wrappers (when invoked as nom-build, nom-shell, etc.):"
+      , indent 2
+          $ vsep
+            [ "nom-build <nix-args>"
+            , "nom-shell <nix-args>"
+            ]
+      , mempty
+      , "Direct piping:"
+      , indent 2
+          $ vsep
+            [ "via json parsing:"
+            , indent 2
+                $ vsep
+                  [ "nix build --log-format internal-json -v <nix-args> |& nom --json"
+                  , "nix-build --log-format internal-json -v <nix-args> |& nom --json"
+                  ]
+            , mempty
+            , "via human-readable log parsing:"
+            , indent 2 "nix-build |& nom"
+            , mempty
+            , "Don't forget to redirect stderr, too. That's what the `&` does."
+            ]
+      , mempty
+      , "Please see the readme for more details:"
+      , "https://code.maralorn.de/maralorn/nix-output-monitor#readme"
+      ]
+
+  parseSubCommand :: Parser SubCommand
+  parseSubCommand =
+    subparser
+      ( command "build" (info (pure CmdBuild) $ progDesc "Wrapper over `nix build`")
+          <> command "shell" (info (pure CmdShell) $ progDesc "Wrapper over `nix shell`")
+          <> command "develop" (info (pure CmdDevelop) $ progDesc "Wrapper over `nix develop`")
+          <> command "copy" (info (pure CmdDevelop) $ progDesc "Wrapper over `nix copy`")
+      )
+  parseOptionsNoInfo :: Parser Options
+  parseOptionsNoInfo =
+    Options
+      <$> switch (long "version" <> help "Show version")
+      <*> switch (long "json" <> help "Parse input as nix internal-json")
+      <*> optional parseSubCommand
+
 main :: IO Void
 main = do
   installSignalHandlers
 
   prog_name <- Environment.getProgName
   args <- Environment.getArgs
 
-  lookupEnv "NIX_GET_COMPLETIONS" >>= \case
-    Just _ -> printNixCompletion prog_name args
-    Nothing -> runApp prog_name args
+  runApp prog_name args
 
 runApp :: String -> [String] -> IO Void
 runApp = \cases
-  _ ["--version"] -> do
-    hPutStrLn stderr ("nix-output-monitor " <> fromString (showVersion version))
-    exitWith =<< runProcess (proc "nix" ["--version"])
+  -- _ ["--version"] -> do
+  --   hPutStrLn stderr ("nix-output-monitor " <> fromString (showVersion version))
+  --   exitWith =<< runProcess (proc "nix" ["--version"])
   "nom-build" args -> exitWith =<< runMonitoredCommand defaultConfig (proc "nix-build" (withJSON args))
   "nom-shell" args -> do
     exitOnFailure =<< runMonitoredCommand defaultConfig{silent = True} (proc "nix-shell" (withJSON args <> ["--run", "exit"]))
@@ -92,37 +149,20 @@ runApp = \cases
   "nom" ("develop" : args) -> do
     exitOnFailure =<< runMonitoredCommand defaultConfig{silent = True} (proc "nix" ("develop" : withJSON (replaceCommandWithExit args)))
     exitWith =<< runProcess (proc "nix" ("develop" : args))
-  "nom" [] -> do
-    finalState <- monitorHandle OldStyleInput defaultConfig{piping = True} stdin
-    if CMap.size finalState.fullSummary.failedBuilds + length finalState.nixErrors == 0
-      then exitSuccess
-      else exitFailure
-  "nom" ["--json"] -> do
-    finalState <- monitorHandle NixJSONMessage defaultConfig{piping = True} stdin
-    if CMap.size finalState.fullSummary.failedBuilds + length finalState.nixErrors == 0
-      then exitSuccess
-      else exitFailure
-  _ xs -> do
-    hPutStrLn stderr helpText
-    -- It's not a mistake if the user requests the help text, otherwise tell
-    -- them off with a non-zero exit code.
-    if any (liftA2 (||) (== "-h") (== "--help")) xs then exitSuccess else exitFailure
-
-printNixCompletion :: String -> [String] -> IO Void
-printNixCompletion = \cases
-  "nom" [input] -> do
-    putStrLn "normal"
-    mapM_ putStrLn $ findMatches input (knownSubCommands <> knownFlags)
-    exitSuccess
-  "nom" args@(sub_cmd : _)
-    | sub_cmd `elem` knownSubCommands ->
-        exitWith =<< Process.runProcess (Process.proc "nix" args)
-  prog args -> do
-    putTextLn $ "No completion support for " <> unwords (toText <$> prog : args)
-    exitFailure
-
-findMatches :: String -> [String] -> [String]
-findMatches input = filter (input `isPrefixOf`)
+  _ _ -> do
+    parsedArgs <- execParser parseOptions
+    case parsedArgs of
+      Options{version = True} -> do
+        hPutStrLn stderr ("nix-output-monitor " <> fromString (showVersion version))
+        exitWith =<< runProcess (proc "nix" ["--version"])
+      _ -> do
+        finalState <-
+          (bool (monitorHandle OldStyleInput) (monitorHandle NixJSONMessage) parsedArgs.json)
+            defaultConfig{piping = True}
+            stdin
+        if CMap.size finalState.fullSummary.failedBuilds + length finalState.nixErrors == 0
+          then exitSuccess
+          else exitFailure
 
 installSignalHandlers :: IO ()
 installSignalHandlers = do
@@ -217,35 +257,3 @@ finalizer config = do
       { updaterState = nomState @a .~ newState $ old_state.updaterState
       , printFunction = stateToText config newState
       }
-
-helpText :: Text
-helpText =
-  unlines
-    [ "nix-output-monitor usages:"
-    , "  Wrappers:"
-    , "    nom build <nix-args>"
-    , "    nom shell <nix-args>"
-    , "    nom develop <nix-args>"
-    , "    nom copy <nix-args>"
-    , ""
-    , "    nom-build <nix-args>"
-    , "    nom-shell <nix-args>"
-    , ""
-    , "  Direct piping:"
-    , "    via json parsing:"
-    , "      nix build --log-format internal-json -v <nix-args> |& nom --json"
-    , "      nix-build --log-format internal-json -v <nix-args> |& nom --json"
-    , ""
-    , "    via human-readable log parsing:"
-    , "      nix-build |& nom"
-    , ""
-    , "    Don't forget to redirect stderr, too. That's what the & does."
-    , ""
-    , "Flags:"
-    , "  --version  Show version."
-    , "  -h, --help Show this help."
-    , "  --json     Parse input as nix internal-json"
-    , ""
-    , "Please see the readme for more details:"
-    , "https://code.maralorn.de/maralorn/nix-output-monitor#readme"
-    ]

flake.nix

@@ -47,19 +47,35 @@
             (haskellPackages.callPackage self)
             haskellPackages.buildFromCabalSdist
             hlib.justStaticExecutables
-            (hlib.appendConfigureFlag "--ghc-option=-Werror --ghc-option=-Wno-error=unrecognised-warning-flags")
+            (hlib.appendConfigureFlag "--ghc-option=-Wno-error=unrecognised-warning-flags")
 
             (hlib.overrideCabal (
               {
                 src = cleanSelf;
                 doCheck = false;
-                buildTools = [ pkgs.installShellFiles ];
-                postInstall = ''
-                  ln -s nom "$out/bin/nom-build"
-                  ln -s nom "$out/bin/nom-shell"
-                  chmod a+x $out/bin/nom-shell
-                  installShellCompletion completions/*
-                '';
+                postInstall =
+                  # bash
+                  ''
+                    ln -s nom "$out/bin/nom-build"
+                    ln -s nom "$out/bin/nom-shell"
+
+                    bashCompDir="''${!outputBin}/share/bash-completion/completions"
+                    zshCompDir="''${!outputBin}/share/zsh/vendor-completions"
+                    fishCompDir="''${!outputBin}/share/fish/vendor_completions.d"
+
+                    mkdir -p "$bashCompDir" "$zshCompDir" "$fishCompDir"
+
+                    # Optparse applicative builtin completions
+                    "''${!outputBin}/bin/nom" --bash-completion-script "''${!outputBin}/bin/nom" >"$bashCompDir/nom"
+                    "''${!outputBin}/bin/nom" --zsh-completion-script "''${!outputBin}/bin/nom" >"$zshCompDir/_nom"
+                    "''${!outputBin}/bin/nom" --fish-completion-script "''${!outputBin}/bin/nom" >"$fishCompDir/nom.fish"
+
+                    # Nix 2 wrappers (nix-*) without fish
+                    cp completions/zsh/_nom-*.zsh "$zshCompDir"
+
+                    # Both Nix 2 and Nix 3 wrappers for fish
+                    cat completions/nom.fish >> "$fishCompDir/nom.fish"
+                  '';
               }
               // lib.optionalAttrs (system == "x86_64-linux") {
                 doCheck = true;

hls.json

@@ -0,0 +1,8 @@
+{
+    "plugin": {
+        "hlint": {
+            "codeActionsOn": false,
+            "diagnosticsOn": false
+        }
+    }
+}

nix-output-monitor.cabal

@@ -15,8 +15,6 @@ author: maralorn <[email protected]>
 maintainer: maralorn <[email protected]>
 build-type: Simple
 extra-source-files:
-  completions/completion.bash
-  completions/completion.zsh
   test/golden/fail/stderr
   test/golden/fail/stderr.json
   test/golden/fail/stdout
@@ -151,6 +149,7 @@ executable nom
   other-modules: Paths_nix_output_monitor
   build-depends:
     nix-output-monitor,
+    optparse-applicative,
     typed-process,
     unix,