Add generic theme command

src/QBar/Cli.hs

@@ -2,18 +2,25 @@
 
 module QBar.Cli where
 
+import QBar.Theme
+
 import qualified Data.Text as T
+import qualified Data.Text.Lazy as TL
 import Options.Applicative
 
-data BarCommand = BarServer | DefaultTheme | RainbowTheme
+data BarCommand = BarServerCommand | SetThemeCommand Text
 
 barCommandParser :: Parser BarCommand
-barCommandParser = hsubparser
-  ( command "server" (info (pure BarServer) (progDesc "Start a new qbar server. Should be called by swaybar, i3bar or or another i3bar-protocol compatible host process.")) <>
-    command "default" (info (pure DefaultTheme) (progDesc "Send a message to a running qbar server.")) <>
-    command "rainbow" (info (pure RainbowTheme) (progDesc "Send a message to a running qbar server."))
+barCommandParser = hsubparser (
+    command "server" (info (pure BarServerCommand) (progDesc "Start a new qbar server. Should be called by swaybar, i3bar or or another i3bar-protocol compatible host process.")) <>
+    command "theme" (info themeCommandParser (progDesc "Change the theme of the running qbar server.")) <>
+    command "default" (info (pure $ SetThemeCommand "default") (progDesc "Shortcut for 'qbar theme default'.")) <>
+    command "rainbow" (info (pure $ SetThemeCommand "rainbow") (progDesc "Shortcut for 'qbar theme rainbow'."))
   )
 
+themeCommandParser :: Parser BarCommand
+themeCommandParser = SetThemeCommand <$> strArgument (metavar "THEME" <> completeWith (map TL.unpack themeNames))
+
 data MainOptions = MainOptions {
   verbose :: Bool,
   indicator :: Bool,

src/QBar/Server.hs

@@ -193,6 +193,5 @@ runBarServer defaultBarConfig options = runBarHost barServer (swayBarInput optio
 runQBar :: BarIO () -> MainOptions -> IO ()
 runQBar barConfiguration options@MainOptions{barCommand} = runCommand barCommand
   where
-    runCommand BarServer = runBarServer barConfiguration options
-    runCommand DefaultTheme = sendIpc options $ SetTheme "default"
-    runCommand RainbowTheme = sendIpc options $ SetTheme "rainbow"
+    runCommand BarServerCommand = runBarServer barConfiguration options
+    runCommand (SetThemeCommand themeName) = sendIpc options $ SetTheme themeName

src/QBar/Theme.hs

@@ -9,6 +9,7 @@ import Control.Lens ((^.))
 import Control.Monad.State.Lazy (State, evalState, get, put)
 import Data.Colour.RGBSpace
 import Data.Colour.RGBSpace.HSV (hsv)
+import qualified Data.HashMap.Lazy as HM
 import qualified Data.Text.Lazy as T
 import Data.Time.Clock.POSIX (getPOSIXTime)
 import Pipes
@@ -50,10 +51,23 @@ isAnimated (AnimatedTheme _) = True
 isAnimated _ = False
 
 
+themesList :: [(Text, Theme)]
+themesList = [
+    ("default", defaultTheme),
+    ("rainbow", rainbowTheme)
+  ]
+
+themeNames :: [Text]
+themeNames = map fst themesList
+
+themes :: HM.HashMap Text Theme
+themes = HM.fromList themesList
+
+
 findTheme :: Text -> Either Text Theme
-findTheme "default" = Right defaultTheme
-findTheme "rainbow" = Right rainbowTheme
-findTheme name = Left $ "Invalid theme: " <> name
+findTheme themeName = maybe invalidThemeName Right $ HM.lookup themeName themes
+  where
+    invalidThemeName = Left $ "Invalid theme: " <> themeName
 
 
 mkTheme :: SimplifiedTheme -> Theme