Add tool-requirements subcommand

lib/GHCup/Download.hs

@@ -94,7 +94,7 @@ getDownloads :: ( FromJSONKey Tool
                 , MonadFail m
                 )
              => URLSource
-             -> Excepts '[JSONError , DownloadFailed] m GHCupDownloads
+             -> Excepts '[JSONError , DownloadFailed] m GHCupInfo
 getDownloads urlSource = do
   lift $ $(logDebug) [i|Receiving download info from: #{urlSource}|]
   case urlSource of

lib/GHCup/Errors.hs

@@ -92,6 +92,9 @@ data TooManyRedirs = TooManyRedirs
 data PatchFailed = PatchFailed
   deriving Show
 
+-- | The tool requirements could not be found.
+data NoToolRequirements = NoToolRequirements
+  deriving Show
 
 
     -------------------------

lib/GHCup/Requirements.hs

@@ -0,0 +1,46 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module GHCup.Requirements where
+
+import           GHCup.Types
+import           GHCup.Types.JSON               ( )
+import           GHCup.Types.Optics
+
+import           Control.Applicative
+import           Data.Maybe
+import           Optics
+import           Prelude                 hiding ( abs
+                                                , readFile
+                                                , writeFile
+                                                )
+
+import qualified Data.Text                     as T
+
+
+-- | Get the requirements. Right now this combines GHC and cabal
+-- and doesn't do fine-grained distinction. However, the 'ToolRequirements'
+-- type allows it.
+getCommonRequirements :: PlatformResult
+                      -> ToolRequirements
+                      -> Maybe Requirements
+getCommonRequirements pr tr =
+  preview (ix GHC % ix Nothing % ix (_platform pr) % ix (_distroVersion pr)) tr
+    <|> preview (ix GHC % ix Nothing % ix (_platform pr) % ix Nothing) tr
+    <|> preview
+          ( ix GHC
+          % ix Nothing
+          % ix (set _Linux UnknownLinux $ _platform pr)
+          % ix Nothing
+          )
+          tr
+
+
+prettyRequirements :: Requirements -> T.Text
+prettyRequirements Requirements {..} =
+  let d = if not . null $ _distroPKGs
+        then
+          "\n  Install the following distro packages: "
+            <> T.intercalate " " _distroPKGs
+        else ""
+      n = if not . T.null $ _notes then "\n  Note: " <> _notes else ""
+  in  "System requirements " <> d <> n

lib/GHCup/Types.hs

@@ -12,6 +12,39 @@ import qualified GHC.Generics                  as GHC
 
 
 
+    --------------------
+    --[ GHCInfo Tree ]--
+    --------------------
+
+
+data GHCupInfo = GHCupInfo
+  { _toolRequirements :: ToolRequirements
+  , _ghcupDownloads   :: GHCupDownloads
+  }
+  deriving (Show, GHC.Generic)
+
+
+
+    -------------------------
+    --[ Requirements Tree ]--
+    -------------------------
+
+
+type ToolRequirements = Map Tool ToolReqVersionSpec
+type ToolReqVersionSpec = Map (Maybe Version) PlatformReqSpec
+type PlatformReqSpec = Map Platform PlatformReqVersionSpec
+type PlatformReqVersionSpec = Map (Maybe Versioning) Requirements
+
+
+data Requirements = Requirements
+  { _distroPKGs :: [Text]
+  , _notes      :: Text
+  }
+  deriving (Show, GHC.Generic)
+
+
+
+
 
     ---------------------
     --[ Download Tree ]--
@@ -99,7 +132,7 @@ data DownloadInfo = DownloadInfo
 -- | Where to fetch GHCupDownloads from.
 data URLSource = GHCupURL
                | OwnSource URI
-               | OwnSpec GHCupDownloads
+               | OwnSpec GHCupInfo
                deriving Show
 
 

lib/GHCup/Types/JSON.hs

@@ -39,6 +39,8 @@ deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''VUnit
 deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''VersionInfo
 deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''Tag
 deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''DownloadInfo
+deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''GHCupInfo
+deriveJSON defaultOptions { fieldLabelModifier = removeLensFieldLabel } ''Requirements
 
 
 instance ToJSON URI where
@@ -69,11 +71,11 @@ instance FromJSONKey Versioning where
 instance ToJSONKey (Maybe Versioning) where
   toJSONKey = toJSONKeyText $ \case
     Just x  -> prettyV x
-    Nothing -> T.pack "unknown_version"
+    Nothing -> T.pack "unknown_versioning"
 
 instance FromJSONKey (Maybe Versioning) where
   fromJSONKey = FromJSONKeyTextParser $ \t ->
-    if t == T.pack "unknown_version" then pure Nothing else pure $ just t
+    if t == T.pack "unknown_versioning" then pure Nothing else pure $ just t
    where
     just t = case versioning t of
       Right x -> pure x
@@ -112,6 +114,19 @@ instance ToJSONKey Architecture where
 instance FromJSONKey Architecture where
   fromJSONKey = genericFromJSONKey defaultJSONKeyOptions
 
+instance ToJSONKey (Maybe Version) where
+  toJSONKey = toJSONKeyText $ \case
+    Just x  -> prettyVer x
+    Nothing -> T.pack "unknown_version"
+
+instance FromJSONKey (Maybe Version) where
+  fromJSONKey = FromJSONKeyTextParser $ \t ->
+    if t == T.pack "unknown_version" then pure Nothing else pure $ just t
+   where
+    just t = case version t of
+      Right x -> pure x
+      Left  e -> fail $ "Failure in (Maybe Version) (FromJSONKey)" <> show e
+
 instance ToJSON Version where
   toJSON = toJSON . prettyVer
 

lib/GHCup/Types/Optics.hs

@@ -19,6 +19,7 @@ makeLenses ''DownloadInfo
 makeLenses ''Tag
 makeLenses ''VersionInfo
 
+makeLenses ''GHCupInfo
 
 uriSchemeL' :: Lens' (URIRef Absolute) Scheme
 uriSchemeL' = lensVL uriSchemeL