ogma-cli: Provide CLI argument to set auxiliary template source direc…

…tory in standalone command. Refs nasa#189.

The standalone backend uses a fixed template to generate the Copilot
monitor. That template does not fit all use cases, so we are finding
users heavily modifying the output (which is hard to keep up with when
there are changes), and or not using ogma altogether for that reason.

A recent commit introduced into ogma-core the ability to use a custom
template and expand variables using mustache.

This commit exposes that new parameter to the user in the CLI.

ogma-cli/src/CLI/CommandStandalone.hs

@@ -43,7 +43,7 @@ module CLI.CommandStandalone
   where
 
 -- External imports
-import Options.Applicative (Parser, help, long, metavar, many, short,
+import Options.Applicative (Parser, help, long, many, metavar, optional, short,
                             showDefault, strOption, switch, value)
 
 -- External imports: command results
@@ -58,12 +58,13 @@ import qualified Command.Standalone
 
 -- | Options to generate Copilot from specification.
 data CommandOpts = CommandOpts
-  { standaloneTargetDir  :: FilePath
-  , standaloneFileName   :: FilePath
-  , standaloneFormat     :: String
-  , standalonePropFormat :: String
-  , standaloneTypes      :: [String]
-  , standaloneTarget     :: String
+  { standaloneTargetDir   :: FilePath
+  , standaloneTemplateDir :: Maybe FilePath
+  , standaloneFileName    :: FilePath
+  , standaloneFormat      :: String
+  , standalonePropFormat  :: String
+  , standaloneTypes       :: [String]
+  , standaloneTarget      :: String
   }
 
 -- | Transform an input specification into a Copilot specification.
@@ -73,6 +74,7 @@ command c = standalone (standaloneFileName c) internalCommandOpts
     internalCommandOpts :: Command.Standalone.StandaloneOptions
     internalCommandOpts = Command.Standalone.StandaloneOptions
       { Command.Standalone.standaloneTargetDir   = standaloneTargetDir c
+      , Command.Standalone.standaloneTemplateDir = standaloneTemplateDir c
       , Command.Standalone.standaloneFormat      = standaloneFormat c
       , Command.Standalone.standalonePropFormat  = standalonePropFormat c
       , Command.Standalone.standaloneTypeMapping = types
@@ -106,6 +108,13 @@ commandOptsParser = CommandOpts
         <> value "copilot"
         <> help strStandaloneTargetDirDesc
         )
+  <*> optional
+        ( strOption
+            (  long "template-dir"
+            <> metavar "DIR"
+            <> help strStandaloneTemplateDirArgDesc
+            )
+        )
   <*> strOption
         (  long "file-name"
         <> metavar "FILENAME"
@@ -146,6 +155,10 @@ commandOptsParser = CommandOpts
 strStandaloneTargetDirDesc :: String
 strStandaloneTargetDirDesc = "Target directory"
 
+-- | Template dir flag description.
+strStandaloneTemplateDirArgDesc :: String
+strStandaloneTemplateDirArgDesc = "Directory holding standalone source template"
+
 -- | Filename flag description.
 strStandaloneFilenameDesc :: String
 strStandaloneFilenameDesc = "File with properties or requirements"