From 4ea02d3a8a6aec056e58eb1c15e12e0835041549 Mon Sep 17 00:00:00 2001
From: Zubin Duggal <zubin@cmi.ac.in>
Date: Thu, 18 Jul 2019 16:30:45 +0530
Subject: Start implementing Distribution.Helper.Discover

---
 cabal-helper.cabal                              |  1 +
 lib/Distribution/Helper/Discover.hs             | 38 +++++++++++++++++++++++--
 src/CabalHelper/Compiletime/Compat/Directory.hs | 26 +++++++++++++++++
 3 files changed, 63 insertions(+), 2 deletions(-)
 create mode 100644 src/CabalHelper/Compiletime/Compat/Directory.hs

diff --git a/cabal-helper.cabal b/cabal-helper.cabal
index 9cc7215..cb43f72 100644
--- a/cabal-helper.cabal
+++ b/cabal-helper.cabal
@@ -131,6 +131,7 @@ library c-h-internal
   import:             build-deps, extensions
   exposed-modules:
                        CabalHelper.Compiletime.Cabal
+                       CabalHelper.Compiletime.Compat.Directory
                        CabalHelper.Compiletime.Compat.Environment
                        CabalHelper.Compiletime.Compat.ProgramDb
                        CabalHelper.Compiletime.Compat.Version
diff --git a/lib/Distribution/Helper/Discover.hs b/lib/Distribution/Helper/Discover.hs
index d4abe69..a748b25 100644
--- a/lib/Distribution/Helper/Discover.hs
+++ b/lib/Distribution/Helper/Discover.hs
@@ -14,6 +14,8 @@
 -- You should have received a copy of the GNU General Public License
 -- along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+{-# LANGUAGE GADTs #-}
+
 {-|
 Module      : Distribution.Helper.Discover
 Description : Finding project contexts
@@ -30,12 +32,44 @@ module Distribution.Helper.Discover
   , findDistDirsWithHints
   ) where
 
+import Control.Monad.Writer
+import Data.List
+import System.Directory
+import System.FilePath
+
 import CabalHelper.Compiletime.Types
+import CabalHelper.Compiletime.Cabal
+import CabalHelper.Compiletime.Compat.Directory
 
 findProjects :: FilePath -> IO [Ex ProjLoc]
 findDistDirs :: ProjLoc pt -> [DistDir pt]
 findDistDirsWithHints :: ProjLoc pt -> [FilePath] -> [DistDir pt]
 
-findProjects = undefined
-findDistDirs = undefined
+findProjects dir = execWriterT $ do
+  let cabalProject = dir </> "cabal.project"
+  whenM (liftIO $ doesFileExist cabalProject) $
+    tell [Ex $ ProjLocV2File cabalProject]
+  let stackYaml = dir </> "stack.yaml"
+  whenM (liftIO $ doesFileExist stackYaml) $
+    tell [Ex $ ProjLocStackYaml stackYaml]
+  join $ traverse (tell . pure . Ex . ProjLocV1CabalFile) <$>
+    liftIO (findCabalFiles dir)
+
+findDistDirs (ProjLocV1CabalFile cabal) =
+  [DistDirV1 $ replaceFileName cabal "dist/"]
+findDistDirs (ProjLocV1Dir dir) = [DistDirV1 $ dir </> "dist/"]
+findDistDirs (ProjLocV2File cabal) =
+  [DistDirV2 $ replaceFileName cabal "dist-newstyle/"]
+findDistDirs (ProjLocV2Dir dir) = [DistDirV2 $ dir </> "dist-newstyle/"]
+findDistDirs (ProjLocStackYaml _) = [DistDirStack Nothing]
+
 findDistDirsWithHints = undefined
+
+findCabalFiles :: FilePath -> IO [FilePath]
+findCabalFiles dir = do
+  fs <- listDirectory dir
+  let cs = filter (".cabal" `isSuffixOf`) fs
+  filterM doesFileExist cs
+
+whenM :: Monad m => m Bool -> m () -> m ()
+whenM p x = p >>= (`when` x)
diff --git a/src/CabalHelper/Compiletime/Compat/Directory.hs b/src/CabalHelper/Compiletime/Compat/Directory.hs
new file mode 100644
index 0000000..0a65164
--- /dev/null
+++ b/src/CabalHelper/Compiletime/Compat/Directory.hs
@@ -0,0 +1,26 @@
+-- cabal-helper: Simple interface to Cabal's configuration state
+-- Copyright (C) 2019  Daniel Gröber <cabal-helper@dxld.at>
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+{-# LANGUAGE CPP #-}
+module CabalHelper.Compiletime.Compat.Directory where
+
+import System.Directory (getDirectoryContents)
+
+#if !MIN_VERSION_directory(1,2,5)
+listDirectory :: FilePath -> IO [FilePath]
+listDirectory path =
+  filter (\f -> f /= "." && f /= "..") <$> getDirectoryContents path
+#endif
-- 
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