Add dry run option

escape-from-itunes.cabal

@@ -19,6 +19,7 @@ library
                      , Args
                      , Attributes
                      , Channel
+                     , Actions
   build-depends:       base >= 4.7 && < 5
                      , idiii == 0.1.3.3
                      , optparse-applicative == 0.14.3.0

src/Actions.hs

@@ -0,0 +1,15 @@
+module Actions where
+
+import Itunes (Copy (Copy))
+import System.Directory (copyFile)
+
+data ActionType = DryRun
+                | CopyFiles
+                deriving (Show, Eq)
+
+getAction :: ActionType -> (Copy -> IO ())
+getAction DryRun = putStrLn . show
+getAction CopyFiles = copy
+
+copy :: Copy -> IO ()
+copy (Copy from to) = copyFile from to

src/Args.hs

@@ -4,11 +4,13 @@ import Options.Applicative
 import Data.Semigroup ((<>))
 import Text.Regex (mkRegex, splitRegex)
 import Attributes
+import Actions (ActionType (DryRun, CopyFiles))
 
 data Args = Args {
           source :: String
           , target :: String
           , attributes :: [Attribute]
+          , action :: ActionType
           }
   deriving (Show, Eq)
 
@@ -23,6 +25,10 @@ getArgs = Args
       short 't' <>
       help "Root of new library")
   <*> attrList
+  <*> flag CopyFiles DryRun
+    ( long "dry-run" <>
+      short 'd' <>
+      help "Print intended work, but do not copy any files")
 
 attrList :: Parser [Attribute]
 attrList = option (maybeReader attrList) (

src/Itunes.hs

@@ -17,6 +17,9 @@ data Copy = Copy { from :: From
                  , to :: To
                  }
 
+instance Show Copy where
+    show (Copy from to) = "Copy " ++ show from ++ " to " ++ to
+
 type Action = Copy -> IO ()
 type Transform = From -> IO To
 

test/ArgsSpec.hs

@@ -3,6 +3,7 @@ module ArgsSpec where
 import Test.Hspec
 import Options.Applicative
 import Attributes
+import Actions
 import Args
 
 spec = do
@@ -18,7 +19,8 @@ spec = do
                                         ])
         `shouldBe` (Just $ Args "/Users/shterrett/iTunesMusic"
                                 "/Users/shterrett/music"
-                                [Composer, Album, Artist])
+                                [Composer, Album, Artist]
+                                CopyFiles)
     it "parses properly supplied long arguments" $ do
       getParseResult (
         execParserPure defaultPrefs app [ "--source"
@@ -30,4 +32,29 @@ spec = do
                                         ])
         `shouldBe` (Just $ Args "/Users/shterrett/iTunesMusic"
                                 "/Users/shterrett/music"
-                                [Composer, Album, Artist])
+                                [Composer, Album, Artist]
+                                CopyFiles)
+    it "fails if the attribute list does not match allowed attributes" $ do
+      getParseResult (
+        execParserPure defaultPrefs app [ "--source"
+                                        , "/Users/shterrett/iTunesMusic"
+                                        , "--target"
+                                        , "/Users/shterrett/music"
+                                        , "--attributes"
+                                        , "composer,period,artist"
+                                        ])
+        `shouldBe` Nothing
+    it "sets the action to dry run when the flag is passed" $ do
+      getParseResult (
+        execParserPure defaultPrefs app [ "--source"
+                                        , "/Users/shterrett/iTunesMusic"
+                                        , "--target"
+                                        , "/Users/shterrett/music"
+                                        , "--attributes"
+                                        , "composer,album,artist"
+                                        , "--dry-run"
+                                        ])
+        `shouldBe` (Just $ Args "/Users/shterrett/iTunesMusic"
+                                "/Users/shterrett/music"
+                                [Composer, Album, Artist]
+                                DryRun)