Add support for external CLI commands

Author: ad-si

docs-source/usage/cli.md

@@ -248,3 +248,24 @@ and
 ```sh
 tl metadata set kanban-state sprint 01e0k6a1p00002zgzc0845vayw
 ```
+
+
+## External Commands
+
+Like Git, TaskLite also supports external commands.
+This allows you to easily extend TaskLite's functionality with your own scripts.
+
+For this to work, simply add an executable script (`chmod +x`)
+with the prefix `tasklite-` to your `$PATH`
+
+For example, to add a `grin` command which simply prints a smiley:
+
+```sh
+$ cat /usr/local/bin/tasklite-grin
+#! /usr/bin/env bash
+
+echo '😁' "$@"
+
+$ tasklite grin Hi
+😁 Hi
+```

tasklite-core/app/Main.hs

@@ -50,7 +50,9 @@ import Protolude (
   (<&>),
   (||),
  )
+import Protolude qualified as P
 
+import Control.Monad.Catch (catchAll)
 import Data.Aeson as Aeson (KeyValue ((.=)), encode, object)
 import Data.FileEmbed (embedStringFile, makeRelativeToProject)
 import Data.Hourglass (
@@ -66,9 +68,6 @@ import Data.Text.Lazy.Encoding qualified as TL
 import Data.Time.ISO8601.Duration qualified as Iso
 import Data.Version (showVersion)
 import Data.Yaml (decodeFileEither, prettyPrintParseException)
-
--- Special module provided by Cabal
-
 import Database.SQLite.Simple (Connection (..))
 import Database.SQLite.Simple qualified as SQLite
 import GHC.IO.Encoding (setLocaleEncoding, utf8)
@@ -154,6 +153,7 @@ import Options.Applicative (
   fullDesc,
   headerDoc,
   help,
+  helpHeader,
   helper,
   idm,
   info,
@@ -169,6 +169,7 @@ import Options.Applicative (
   subparser,
   switch,
  )
+import Options.Applicative.Help.Chunk (Chunk (Chunk), (<<+>>))
 import Options.Applicative.Help.Core (parserHelp)
 import Paths_tasklite_core (version)
 import Prettyprinter (
@@ -185,10 +186,11 @@ import Prettyprinter (
  )
 import Prettyprinter.Render.Terminal (
   AnsiStyle,
-  Color (Black, Blue, Cyan, Yellow),
+  Color (Black, Blue, Cyan, Red, Yellow),
   bold,
   color,
   colorDull,
+  hPutDoc,
   putDoc,
  )
 import System.Directory (
@@ -202,6 +204,7 @@ import System.Directory (
   listDirectory,
  )
 import System.FilePath ((</>))
+import System.Process (readProcess)
 import Time.System (timeCurrentP)
 
 import Config (
@@ -342,13 +345,15 @@ data Command
   | Help
   | PrintConfig
   | UlidToUtc Text
+  | ExternalCommand Text (Maybe [Text])
   deriving (Show, Eq)
 
 
 data CliArgs = CliArgs
   { cliCommand :: Command
   , runHelpCommand :: Bool
   }
+  deriving (Show, Eq)
 
 
 nameToAliasList :: [(Text, Text)]
@@ -944,26 +949,27 @@ commandParser conf =
     -- <> command "utc-quarter"  -- … last day of the quarter
     -- <> command "utc-year"  -- … last day of the year
     )
+
+  -- Catch-all parser for any external "tasklite-???" command
+  -- Do not show in help
+  <|> ExternalCommand
+        <$> strArgument P.mempty
+        <*> optional (some (strArgument P.mempty))
   )
 
 {- FOURMOLU_ENABLE -}
 
 
-runHelpSwitch :: Parser Bool
-runHelpSwitch =
-  switch
-    ( long "help"
-        <> short 'h'
-        <> help "Display current help page"
-        <> internal
-    )
-
-
 cliArgsParser :: Config -> Parser CliArgs
 cliArgsParser conf =
   CliArgs
     <$> commandParser conf
-    <*> runHelpSwitch
+    <*> switch
+      ( long "help"
+          <> short 'h'
+          <> help "Display current help page"
+          <> internal
+      )
 
 
 parserInfo :: Config -> ParserInfo CliArgs
@@ -1101,7 +1107,7 @@ executeCLiCommand conf now connection = do
 
   if runHelpCommand cliArgs
     then pure $ extendHelp $ parserHelp defaultPrefs $ cliArgsParser conf
-    else case cliCommand cliArgs of
+    else case cliArgs.cliCommand of
       ListAll -> listAll conf now connection
       ListHead -> headTasks conf now connection
       ListNew -> newTasks conf now connection
@@ -1191,6 +1197,40 @@ executeCLiCommand conf now connection = do
       PrintConfig -> pure $ pretty conf
       Alias alias _ -> pure $ aliasWarning alias
       UlidToUtc ulid -> pure $ prettyUlid ulid
+      ExternalCommand cmd argsMb -> do
+        let
+          args =
+            argsMb & P.fromMaybe []
+
+          runCmd = do
+            output <-
+              readProcess
+                ("tasklite-" <> T.unpack cmd)
+                (args <&> T.unpack)
+                ""
+            pure $ pretty output
+
+          handleException exception = do
+            hPutDoc P.stderr $
+              if not $ exception & show & T.isInfixOf "does not exist"
+                then pretty (show exception :: Text)
+                else do
+                  let
+                    theHelp = parserHelp defaultPrefs $ cliArgsParser conf
+                    newHeader =
+                      Chunk
+                        ( Just $
+                            annotate (color Red) $
+                              "ERROR: Command \""
+                                <> pretty cmd
+                                <> "\" does not exist"
+                        )
+                        <<+>> helpHeader theHelp
+                  extendHelp theHelp{helpHeader = newHeader}
+
+            P.exitFailure
+
+        catchAll runCmd handleException
 
 
 printOutput :: [Char] -> Config -> IO ()

tasklite-core/package.yaml

@@ -91,6 +91,7 @@ executables:
     dependencies:
       - aeson
       - directory
+      - exceptions
       - file-embed
       - filepath
       - githash
@@ -99,6 +100,7 @@ executables:
       - optparse-applicative
       - prettyprinter
       - prettyprinter-ansi-terminal
+      - process
       - sqlite-simple
       - tasklite-core
       - text

tasklite-core/tasklite-core.cabal

@@ -120,6 +120,7 @@ executable tasklite
       aeson
     , base >=4.7 && <5
     , directory
+    , exceptions
     , file-embed
     , filepath
     , githash
@@ -128,6 +129,7 @@ executable tasklite
     , optparse-applicative
     , prettyprinter
     , prettyprinter-ansi-terminal
+    , process
     , protolude
     , sqlite-simple
     , tasklite-core