From 6888814f309f206d6b9860f3ae9b5e6c8525f17b Mon Sep 17 00:00:00 2001
From: Artyom Kazak <yom@artyom.me>
Date: Mon, 24 Apr 2017 13:51:40 +0300
Subject: Take package imports into account when prettifying imports

Fixes #106
---
 lib/Language/Haskell/Stylish/Step/Imports.hs       | 33 ++++++++++++++++------
 .../Language/Haskell/Stylish/Step/Imports/Tests.hs | 27 ++++++++++++++++++
 2 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/lib/Language/Haskell/Stylish/Step/Imports.hs b/lib/Language/Haskell/Stylish/Step/Imports.hs
index be60cba..78912d6 100644
--- a/lib/Language/Haskell/Stylish/Step/Imports.hs
+++ b/lib/Language/Haskell/Stylish/Step/Imports.hs
@@ -104,16 +104,33 @@ imports _                     = []
 importName :: H.ImportDecl l -> String
 importName i = let (H.ModuleName _ n) = H.importModule i in n
 
+importPackage :: H.ImportDecl l -> Maybe String
+importPackage i = H.importPkg i
+
+
+--------------------------------------------------------------------------------
+-- | A "compound import name" is import's name and package (if present). For
+-- instance, if you have an import @Foo.Bar@ from package @foobar@, the full
+-- name will be @"foobar" Foo.Bar@.
+compoundImportName :: H.ImportDecl l -> String
+compoundImportName i =
+  case importPackage i of
+    Nothing  -> importName i
+    Just pkg -> show pkg ++ " " ++ importName i
+
 
 --------------------------------------------------------------------------------
 longestImport :: [H.ImportDecl l] -> Int
-longestImport = maximum . map (length . importName)
+longestImport = maximum . map (length . compoundImportName)
 
 
 --------------------------------------------------------------------------------
 -- | Compare imports for ordering
 compareImports :: H.ImportDecl l -> H.ImportDecl l -> Ordering
-compareImports = comparing (map toLower . importName &&& H.importQualified)
+compareImports =
+  comparing (map toLower . importName &&&
+             fmap (map toLower) . importPackage &&&
+             H.importQualified)
 
 
 --------------------------------------------------------------------------------
@@ -292,9 +309,9 @@ prettyImport columns Options{..} padQualified padName longest imp
           . withTail (", " ++))
         ++ [")"])
 
-    paddedBase = base $ padImport $ importName imp
+    paddedBase = base $ padImport $ compoundImportName imp
 
-    paddedNoSpecBase = base $ padImportNoSpec $ importName imp
+    paddedNoSpecBase = base $ padImportNoSpec $ compoundImportName imp
 
     padImport = if hasExtras && padName
         then padRight longest
@@ -304,12 +321,11 @@ prettyImport columns Options{..} padQualified padName longest imp
         then padRight longest
         else id
 
-    base' baseName importAs hasHiding' = unwords $ concat $ filter (not . null)
+    base' baseName importAs hasHiding' = unwords $ concat $
         [ ["import"]
         , source
         , safe
         , qualified
-        , show <$> maybeToList (H.importPkg imp)
         , [baseName]
         , importAs
         , hasHiding'
@@ -319,9 +335,10 @@ prettyImport columns Options{..} padQualified padName longest imp
         ["as " ++ as | H.ModuleName _ as <- maybeToList $ H.importAs imp]
         ["hiding" | hasHiding]
 
-    inlineBaseLength = length $ base' (padImport $ importName imp) [] []
+    inlineBaseLength = length $
+                       base' (padImport $ compoundImportName imp) [] []
 
-    afterAliasBaseLength = length $ base' (padImport $ importName imp)
+    afterAliasBaseLength = length $ base' (padImport $ compoundImportName imp)
         ["as " ++ as | H.ModuleName _ as <- maybeToList $ H.importAs imp] []
 
     (hasHiding, importSpecs) = case H.importSpecs imp of
diff --git a/tests/Language/Haskell/Stylish/Step/Imports/Tests.hs b/tests/Language/Haskell/Stylish/Step/Imports/Tests.hs
index e1a7462..02f7076 100644
--- a/tests/Language/Haskell/Stylish/Step/Imports/Tests.hs
+++ b/tests/Language/Haskell/Stylish/Step/Imports/Tests.hs
@@ -48,6 +48,7 @@ tests = testGroup "Language.Haskell.Stylish.Step.Imports.Tests"
     , testCase "case 19d" case19d
     , testCase "case 20" case20
     , testCase "case 21" case21
+    , testCase "case 22" case22
     ]
 
 
@@ -562,3 +563,29 @@ case21 = expected
         , "import X8 (type (+), (+))"
         , "import X9 hiding (x, y, z, x)"
         ]
+
+--------------------------------------------------------------------------------
+case22 :: Assertion
+case22 = expected
+    @=? testStep (step 80 defaultOptions) input'
+  where
+    expected = unlines
+        [ "{-# LANGUAGE PackageImports #-}"
+        , "import           A"
+        , "import           \"blah\" A"
+        , "import           \"foo\" A"
+        , "import qualified \"foo\" A  as X"
+        , "import           \"foo\" B  (shortName, someLongName, someLongerName,"
+        , "                           theLongestNameYet)"
+        ]
+    input' = unlines
+        [ "{-# LANGUAGE PackageImports #-}"
+        , "import A"
+        , "import \"foo\" A"
+        , "import \"blah\" A"
+        , "import qualified \"foo\" A as X"
+        -- this import fits into 80 chats without "foo",
+        -- but doesn't fit when "foo" is included into the calculation
+        , "import \"foo\" B (someLongName, someLongerName, " ++
+          "theLongestNameYet, shortName)"
+        ]
-- 
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